Energy conversion in natural and artificial photosynthesis.

PubMed

McConnell, Iain; Li, Gonghu; Brudvig, Gary W

2010-05-28

Modern civilization is dependent upon fossil fuels, a nonrenewable energy source originally provided by the storage of solar energy. Fossil-fuel dependence has severe consequences, including energy security issues and greenhouse gas emissions. The consequences of fossil-fuel dependence could be avoided by fuel-producing artificial systems that mimic natural photosynthesis, directly converting solar energy to fuel. This review describes the three key components of solar energy conversion in photosynthesis: light harvesting, charge separation, and catalysis. These processes are compared in natural and in artificial systems. Such a comparison can assist in understanding the general principles of photosynthesis and in developing working devices, including photoelectrochemical cells, for solar energy conversion. 2010 Elsevier Ltd. All rights reserved.

A method for evaluating photovoltaic potential in China based on GIS platform

NASA Astrophysics Data System (ADS)

Wang, L. Z.; Tan, H. W.; Ji, L.; Wang, D.

2017-11-01

Solar photovoltaic systems are commonly utilized in China. However, the associated research is still lack of its resource potential analysis in all regions in China. Based on the existed data about solar radiation and system conversion efficiency data, a new method for distributed photovoltaic potential assessment has been presented. The experiment of three kinds of solar photovoltaic system has been set up for the purpose of analyzing the relationship between conversion efficiency and environmental parameters. This paper fits the relationship between conversion efficiency and solar radiation intensity. This method takes into account the amount of solar radiation that is effectively generated and drives away the weak values. With the spatial analysis function of geographic information system (GIS) platform, frequency distribution of solar radiation intensity and PV potential in China can be derived. Furthermore, analytical results show that monocrystalline-silicon PV generation in the north-western and northern areas have reached a level of more than 200 kWh/(m2.a), making those areas be suitable for the development of PV system. However, the potential for southwest areas reaches a level of only 130 kWh/(m2.a). This paper can provide the baseline reference for solar energy development planning.

Photovoltaics and solar thermal conversion to electricity - Status and prospects

NASA Technical Reports Server (NTRS)

Alper, M. E.

1979-01-01

Photovoltaic power system technology development includes flat-plate silicon solar arrays and concentrating solar cell systems, which use silicon and other cell materials such as gallium arsenide. System designs and applications include small remote power systems ranging in size from tens of watts to tens of kilowatts, intermediate load-center applications ranging in size from tens to hundreds of kilowatts, and large central plant installations, as well as grid-connected rooftop applications. The thermal conversion program is concerned with large central power systems and small power applications.

Phase 1 of the First Solar Small Power System Experiment (experimental System No. 1). Volume 1: Technical Studies for Solar Point-focusing, Distributed Collector System, with Energy Conversion at the Collector, Category C

NASA Technical Reports Server (NTRS)

Clark, T. B. (Editor)

1979-01-01

The technical and economic feasibility of a solar electric power plant for a small community is evaluated and specific system designs for development and demonstration are selected. All systems investigated are defined as point focusing, distributed receiver concepts, with energy conversion at the collector. The preferred system is comprised of multiple parabolic dish concentrators employing Stirling cycle engines for power conversion. The engine, AC generator, cavity receiver, and integral sodium pool boiler/heat transport system are combined in a single package and mounted at the focus of each concentrator. The output of each concentrator is collected by a conventional electrical distribution system which permits grid-connected or stand-alone operation, depending on the storage system selected.

10.2% power conversion efficiency polymer tandem solar cells consisting of two identical sub-cells.

PubMed

You, Jingbi; Chen, Chun-Chao; Hong, Ziruo; Yoshimura, Ken; Ohya, Kenichiro; Xu, Run; Ye, Shenglin; Gao, Jing; Li, Gang; Yang, Yang

2013-08-07

Polymer tandem solar cells with 10.2% power conversion efficiency are demonstrated via stacking two PDTP-DFBT:PC₇₁ BM bulk heterojunctions, connected by MoO₃/PEDOT:PSS/ZnO as an interconnecting layer. The tandem solar cells increase the power conversion efficiency of the PDTP-DFBT:PC₇₁ BM system from 8.1% to 10.2%, successfully demonstrating polymer tandem solar cells with identical sub-cells of double-digit efficiency. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solar power satellite system definition study. Volume 1, phase 2: Executive summary

NASA Technical Reports Server (NTRS)

1979-01-01

A review of solar energy conversion and utilization is presented. The solar power satellite system is then described. Overall system definition and integration is discussed. Principal reference system study accomplishments and conclusions are presented.

Laser power conversion system analysis, volume 2

NASA Technical Reports Server (NTRS)

Jones, W. S.; Morgan, L. L.; Forsyth, J. B.; Skratt, J. P.

1979-01-01

The orbit-to-ground laser power conversion system analysis investigated the feasibility and cost effectiveness of converting solar energy into laser energy in space, and transmitting the laser energy to earth for conversion to electrical energy. The analysis included space laser systems with electrical outputs on the ground ranging from 100 to 10,000 MW. The space laser power system was shown to be feasible and a viable alternate to the microwave solar power satellite. The narrow laser beam provides many options and alternatives not attainable with a microwave beam.

Shifting the Sun: Solar Spectral Conversion and Extrinsic Sensitization in Natural and Artificial Photosynthesis

PubMed Central

Tyystjärvi, Esa; Méndez‐Ramos, Jorge; Müller, Frank A.; Zhang, Qinyuan

2015-01-01

Solar energy harvesting is largely limited by the spectral sensitivity of the employed energy conversion system, where usually large parts of the solar spectrum do not contribute to the harvesting scheme, and where, of the contributing fraction, the full potential of each photon is not efficiently used in the generation of electrical or chemical energy. Extrinsic sensitization through photoluminescent spectral conversion has been proposed as a route to at least partially overcome this problem. Here, we discuss this approach in the emerging context of photochemical energy harvesting and storage through natural or artificial photosynthesis. Clearly contrary to application in photovoltaic energy conversion, implementation of solar spectral conversion for extrinsic sensitization of a photosynthetic machinery is very straightforward, and—when compared to intrinsic sensitization—less‐strict limitations with regard to quantum coherence are seen. We now argue the ways in which extrinsic sensitization through photoluminescent spectral converters will—and will not—play its role in the area of ultra‐efficient photosynthesis, and also illustrate how such extrinsic sensitization requires dedicated selection of specific conversion schemes and design strategies on system scale. PMID:27774377

Shifting the Sun: Solar Spectral Conversion and Extrinsic Sensitization in Natural and Artificial Photosynthesis.

PubMed

Wondraczek, Lothar; Tyystjärvi, Esa; Méndez-Ramos, Jorge; Müller, Frank A; Zhang, Qinyuan

2015-12-01

Solar energy harvesting is largely limited by the spectral sensitivity of the employed energy conversion system, where usually large parts of the solar spectrum do not contribute to the harvesting scheme, and where, of the contributing fraction, the full potential of each photon is not efficiently used in the generation of electrical or chemical energy. Extrinsic sensitization through photoluminescent spectral conversion has been proposed as a route to at least partially overcome this problem. Here, we discuss this approach in the emerging context of photochemical energy harvesting and storage through natural or artificial photosynthesis. Clearly contrary to application in photovoltaic energy conversion, implementation of solar spectral conversion for extrinsic sensitization of a photosynthetic machinery is very straightforward, and-when compared to intrinsic sensitization-less-strict limitations with regard to quantum coherence are seen. We now argue the ways in which extrinsic sensitization through photoluminescent spectral converters will-and will not-play its role in the area of ultra-efficient photosynthesis, and also illustrate how such extrinsic sensitization requires dedicated selection of specific conversion schemes and design strategies on system scale.

Power processing and control requirements of dispersed solar thermal electric generation systems

NASA Technical Reports Server (NTRS)

Das, R. L.

1980-01-01

Power Processing and Control requirements of Dispersed Receiver Solar Thermal Electric Generation Systems are presented. Kinematic Stirling Engines, Brayton Engines and Rankine Engines are considered as prime movers. Various types of generators are considered for ac and dc link generations. It is found that ac-ac Power Conversion is not suitable for implementation at this time. It is also found that ac-dc-ac Power Conversion with a large central inverter is more efficient than ac-dc-ac Power Conversion using small dispersed inverters. Ac-link solar thermal electric plants face potential stability and synchronization problems. Research and development efforts are needed in improving component performance characteristics and generation efficiency to make Solar Thermal Electric Generation economically attractive.

Hybrid bioinorganic approach to solar-to-chemical conversion.

PubMed

Nichols, Eva M; Gallagher, Joseph J; Liu, Chong; Su, Yude; Resasco, Joaquin; Yu, Yi; Sun, Yujie; Yang, Peidong; Chang, Michelle C Y; Chang, Christopher J

2015-09-15

Natural photosynthesis harnesses solar energy to convert CO2 and water to value-added chemical products for sustaining life. We present a hybrid bioinorganic approach to solar-to-chemical conversion in which sustainable electrical and/or solar input drives production of hydrogen from water splitting using biocompatible inorganic catalysts. The hydrogen is then used by living cells as a source of reducing equivalents for conversion of CO2 to the value-added chemical product methane. Using platinum or an earth-abundant substitute, α-NiS, as biocompatible hydrogen evolution reaction (HER) electrocatalysts and Methanosarcina barkeri as a biocatalyst for CO2 fixation, we demonstrate robust and efficient electrochemical CO2 to CH4 conversion at up to 86% overall Faradaic efficiency for ≥ 7 d. Introduction of indium phosphide photocathodes and titanium dioxide photoanodes affords a fully solar-driven system for methane generation from water and CO2, establishing that compatible inorganic and biological components can synergistically couple light-harvesting and catalytic functions for solar-to-chemical conversion.

Hybrid bioinorganic approach to solar-to-chemical conversion

PubMed Central

Nichols, Eva M.; Gallagher, Joseph J.; Liu, Chong; Su, Yude; Resasco, Joaquin; Yu, Yi; Sun, Yujie; Yang, Peidong; Chang, Michelle C. Y.; Chang, Christopher J.

2015-01-01

Natural photosynthesis harnesses solar energy to convert CO2 and water to value-added chemical products for sustaining life. We present a hybrid bioinorganic approach to solar-to-chemical conversion in which sustainable electrical and/or solar input drives production of hydrogen from water splitting using biocompatible inorganic catalysts. The hydrogen is then used by living cells as a source of reducing equivalents for conversion of CO2 to the value-added chemical product methane. Using platinum or an earth-abundant substitute, α-NiS, as biocompatible hydrogen evolution reaction (HER) electrocatalysts and Methanosarcina barkeri as a biocatalyst for CO2 fixation, we demonstrate robust and efficient electrochemical CO2 to CH4 conversion at up to 86% overall Faradaic efficiency for ≥7 d. Introduction of indium phosphide photocathodes and titanium dioxide photoanodes affords a fully solar-driven system for methane generation from water and CO2, establishing that compatible inorganic and biological components can synergistically couple light-harvesting and catalytic functions for solar-to-chemical conversion. PMID:26305947

Solar converter system with thermal overload protection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popovich, J.M.; Thornbury, T.R.

1979-10-02

A solar energy conversion system comprises: (a) a solar converter in which liquid absorbs solar radiation, the liquid being solar energy absorptive; (b) first means to circulate said liquid for flow through the converter; and (c) means to effect removal of liquid from the converter in response to an undesirable operation condition in said system. 12 claims.

Solar photovoltaic research and development program of the Air Force Aero Propulsion Laboratory. [silicon solar cell applicable to satellite power systems

NASA Technical Reports Server (NTRS)

Wise, J.

1979-01-01

Progress is reported in the following areas: laser weapon effects, solar silicon solar cell concepts, and high voltage hardened, high power system technology. Emphasis is placed on solar cells with increased energy conversion efficiency and radiation resistance characteristics for application to satellite power systems.

Design of wide-angle solar-selective absorbers using aperiodic metal-dielectric stacks.

PubMed

Sergeant, Nicholas P; Pincon, Olivier; Agrawal, Mukul; Peumans, Peter

2009-12-07

Spectral control of the emissivity of surfaces is essential in applications such as solar thermal and thermophotovoltaic energy conversion in order to achieve the highest conversion efficiencies possible. We investigated the spectral performance of planar aperiodic metal-dielectric multilayer coatings for these applications. The response of the coatings was optimized for a target operational temperature using needle-optimization based on a transfer matrix approach. Excellent spectral selectivity was achieved over a wide angular range. These aperiodic metal-dielectric stacks have the potential to significantly increase the efficiency of thermophotovoltaic and solar thermal conversion systems. Optimal coatings for concentrated solar thermal conversion were modeled to have a thermal emissivity <7% at 720K while absorbing >94% of the incident light. In addition, optimized coatings for solar thermophotovoltaic applications were modeled to have thermal emissivity <16% at 1750K while absorbing >85% of the concentrated solar radiation.

Design and simulation of maximum power point tracking (MPPT) system on solar module system using constant voltage (CV) method

NASA Astrophysics Data System (ADS)

Bhatara, Sevty Satria; Iskandar, Reza Fauzi; Kirom, M. Ramdlan

2016-02-01

Solar energy is one of renewable energy resource where needs a photovoltaic module to convert it into electrical energy. One of the problems on solar energy conversion is the process of battery charging. To improve efficiency of energy conversion, PV system needs another control method on battery charging called maximum power point tracking (MPPT). This paper report the study on charging optimation using constant voltage (CV) method. This method has a function of determining output voltage of the PV system on maximal condition, so PV system will always produce a maximal energy. A model represented a PV system with and without MPPT was developed using Simulink. PV system simulation showed a different outcome energy when different solar radiation and numbers of solar module were applied in the model. On the simulation of solar radiation 1000 W/m2, PV system with MPPT produces 252.66 Watt energy and PV system without MPPT produces 252.66 Watt energy. The larger the solar radiation, the greater the energy of PV modules was produced.

Radiation energy conversion in space; Conference, 3rd, NASA Ames Research Center, Moffett Field, Calif., January 26-28, 1978, Technical Papers

NASA Technical Reports Server (NTRS)

Billman, K. W.

1978-01-01

Concepts for space-based conversion of space radiation energy into useful energy for man's needs are developed and supported by studies of costs, material and size requirements, efficiency, and available technology. Besides the more studied solar power satellite system using microwave transmission, a number of alternative space energy concepts are considered. Topics covered include orbiting mirrors for terrestrial energy supply, energy conversion at a lunar polar site, ultralightweight structures for space power, radiatively sustained cesium plasmas for solar electric conversion, solar pumped CW CO2 laser, superelastic laser energy conversion, laser-enhanced dynamics in molecular rate processes, and electron beams in space for energy storage.

Solar Energy: Its Technologies and Applications

DOE R&D Accomplishments Database

Auh, P. C.

1978-06-01

Solar heat, as a potential source of clean energy, is available to all of us. Extensive R and D efforts are being made to effectively utilize this renewable energy source. A variety of different technologies for utilizing solar energy have been proven to be technically feasible. Here, some of the most promising technologies and their applications are briefly described. These are: Solar Heating and Cooling of Buildings (SHACOB), Solar Thermal Energy Conversion (STC), Wind Energy Conversion (WECS), Bioconversion to Fuels (BCF), Ocean Thermal Energy Conversion (OTEC), and Photovoltaic Electric Power Systems (PEPS). Special emphasis is placed on the discussion of the SHACOB technologies, since the technologies are being expeditiously developed for the near commercialization.

Radiation energy conversion in space

NASA Technical Reports Server (NTRS)

Billman, K. W.

1979-01-01

Topics discussed at the third NASA conference on radiant energy conversion are reviewed. The unconcentrated-photovoltaic-generation version of a solar power satellite is described, noting that it will consist of a 21.3 x 5.3-sq-km silicon-solar-cell array expected to provide 17 Gw of electrical power, with 1 km in diam transmitters oriented to beam 2.45 GHz microwave power to two receiving/rectifying 'rectennas' on earth. The Solares space-energy-system concept, designed for providing a large fraction of the world's energy needs at costs comparable to those of future coal/nuclear alternative, is considered, as are subsystems for improving the economics of the solar power satellite. A concept proposing the use of relativistic-electron-storage rings for electron-beam energy transmission and storage, and a report on the production of a high temperature plasma with concentrated solar radiation are taken into account. Laser-conversion systems, including the direct-solar-pumped space laser, and the telec-powered spacecraft, are discussed.

Radiation energy conversion in space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Billman, K.W.

1979-03-01

Topics discussed at the third NASA conference on radiant energy conversion are reviewed. The unconcentrated-photovoltaic-generation version of a solar power satellite is described, noting that it will consist of a 21.3 x 5.3-sq-km silicon-solar-cell array expected to provide 17 Gw of electrical power, with 1 km in diam transmitters oriented to beam 2.45 GHz microwave power to two receiving/rectifying 'rectennas' on earth. The Solares space-energy-system concept, designed for providing a large fraction of the world's energy needs at costs comparable to those of future coal/nuclear alternative, is considered, as are subsystems for improving the economics of the solar power satellite.more » A concept proposing the use of relativistic-electron-storage rings for electron-beam energy transmission and storage, and a report on the production of a high temperature plasma with concentrated solar radiation are taken into account. Laser-conversion systems, including the direct-solar-pumped space laser, and the telec-powered spacecraft, are discussed.« less

A review on solar cells from Si-single crystals to porous materials and quantum dots

PubMed Central

Badawy, Waheed A.

2013-01-01

Solar energy conversion to electricity through photovoltaics or to useful fuel through photoelectrochemical cells was still a main task for research groups and developments sectors. In this article we are reviewing the development of the different generations of solar cells. The fabrication of solar cells has passed through a large number of improvement steps considering the technological and economic aspects. The first generation solar cells were based on Si wafers, mainly single crystals. Permanent researches on cost reduction and improved solar cell efficiency have led to the marketing of solar modules having 12–16% solar conversion efficiency. Application of polycrystalline Si and other forms of Si have reduced the cost but on the expense of the solar conversion efficiency. The second generation solar cells were based on thin film technology. Thin films of amorphous Si, CIS (copper–indium–selenide) and t-Si were employed. Solar conversion efficiencies of about 12% have been achieved with a remarkable cost reduction. The third generation solar cells are based on nano-crystals and nano-porous materials. An advanced photovoltaic cell, originally developed for satellites with solar conversion efficiency of 37.3%, based on concentration of the solar spectrum up to 400 suns was developed. It is based on extremely thin concentration cells. New sensitizer or semiconductor systems are necessary to broaden the photo-response in solar spectrum. Hybrids of solar and conventional devices may provide an interim benefit in seeking economically valuable devices. New quantum dot solar cells based on CdSe–TiO2 architecture have been developed. PMID:25750746

A review on solar cells from Si-single crystals to porous materials and quantum dots.

PubMed

Badawy, Waheed A

2015-03-01

Solar energy conversion to electricity through photovoltaics or to useful fuel through photoelectrochemical cells was still a main task for research groups and developments sectors. In this article we are reviewing the development of the different generations of solar cells. The fabrication of solar cells has passed through a large number of improvement steps considering the technological and economic aspects. The first generation solar cells were based on Si wafers, mainly single crystals. Permanent researches on cost reduction and improved solar cell efficiency have led to the marketing of solar modules having 12-16% solar conversion efficiency. Application of polycrystalline Si and other forms of Si have reduced the cost but on the expense of the solar conversion efficiency. The second generation solar cells were based on thin film technology. Thin films of amorphous Si, CIS (copper-indium-selenide) and t-Si were employed. Solar conversion efficiencies of about 12% have been achieved with a remarkable cost reduction. The third generation solar cells are based on nano-crystals and nano-porous materials. An advanced photovoltaic cell, originally developed for satellites with solar conversion efficiency of 37.3%, based on concentration of the solar spectrum up to 400 suns was developed. It is based on extremely thin concentration cells. New sensitizer or semiconductor systems are necessary to broaden the photo-response in solar spectrum. Hybrids of solar and conventional devices may provide an interim benefit in seeking economically valuable devices. New quantum dot solar cells based on CdSe-TiO2 architecture have been developed.

Evaluating Performances of Solar-Energy Systems

NASA Technical Reports Server (NTRS)

Jaffe, L. D.

1987-01-01

CONC11 computer program calculates performances of dish-type solar thermal collectors and power systems. Solar thermal power system consists of one or more collectors, power-conversion subsystems, and powerprocessing subsystems. CONC11 intended to aid system designer in comparing performance of various design alternatives. Written in Athena FORTRAN and Assembler.

High efficiency solar cells combining a perovskite and a silicon heterojunction solar cells via an optical splitting system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uzu, Hisashi, E-mail: Hisashi.Uzu@kaneka.co.jp, E-mail: npark@skku.edu; Ichikawa, Mitsuru; Hino, Masashi

2015-01-05

We have applied an optical splitting system in order to achieve very high conversion efficiency for a full spectrum multi-junction solar cell. This system consists of multiple solar cells with different band gap optically coupled via an “optical splitter.” An optical splitter is a multi-layered beam splitter with very high reflection in the shorter-wave-length range and very high transmission in the longer-wave-length range. By splitting the incident solar spectrum and distributing it to each solar cell, the solar energy can be managed more efficiently. We have fabricated optical splitters and used them with a wide-gap amorphous silicon (a-Si) solar cellmore » or a CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cell as top cells, combined with mono-crystalline silicon heterojunction (HJ) solar cells as bottom cells. We have achieved with a 550 nm cutoff splitter an active area conversion efficiency of over 25% using a-Si and HJ solar cells and 28% using perovskite and HJ solar cells.« less

Solar power satellite, system definition study. Part 2, volume 3: SPS satellite systems

NASA Technical Reports Server (NTRS)

1977-01-01

The differences in approach to solar energy conversion by solar cells and thermal engine systems are examined. Systems requirements for the solar power satellite (SPS) are given along with a description of the primary subsystems. Trades leading to exact configuration selection, for example, selection of the Rankine cycle operating temperatures are explained, and two satellite configurations are discussed.

A space-based combined thermophotovoltaic electric generator and gas laser solar energy conversion system

NASA Technical Reports Server (NTRS)

Yesil, Oktay

1989-01-01

This paper describes a spaceborne energy conversion system consisting of a thermophotovoltaic electric generator and a gas laser. As a power source for the converson, the system utilizes an intermediate blackbody cavity heated to a temperature of 2000-2400 K by concentrated solar radiation. A double-layer solar cell of GaAs and Si forms a cylindrical surface concentric to this blackbody cavity, receiving the blackbody radiation and converting it into electricity with cell conversion efficiency of 50 percent or more. If the blackbody cavity encloses a laser medium, the blackbody radiation can also be used to simultaneously pump a lasing gas. The feasibility of blackbody optical pumping at 4.3 microns in a CO2-He gas mixture was experimentally demonstrated.

A solar simulator-pumped gas laser for the direct conversion of solar energy

NASA Technical Reports Server (NTRS)

Weaver, W. R.; Lee, J. H.

1981-01-01

Most proposed space power systems are comprised of three general stages, including the collection of the solar radiation, the conversion to a useful form, and the transmission to a receiver. The solar-pumped laser, however, effectively eliminates the middle stage and offers direct photon-to-photon conversion. The laser is especially suited for space-to-space power transmission and communication because of minimal beam spread, low power loss over large distances, and extreme energy densities. A description is presented of the first gas laser pumped by a solar simulator that is scalable to high power levels. The lasant is an iodide C3F7I that as a laser-fusion driver has produced terawatt peak power levels.

Workshop proceedings: Photovoltaic conversion of solar energy for terrestrial applications. Volume 2: Invited papers

NASA Technical Reports Server (NTRS)

1973-01-01

A photovoltaic device development plan is reported that considers technological as well as economical aspects of single crystal silicon, polycrystal silicon, cadmium sulfide/copper sulfide thin films, as well as other materials and devices for solar cell energy conversion systems.

Polymer-Polymer Förster Resonance Energy Transfer Significantly Boosts the Power Conversion Efficiency of Bulk-Heterojunction Solar Cells.

PubMed

Gupta, Vinay; Bharti, Vishal; Kumar, Mahesh; Chand, Suresh; Heeger, Alan J

2015-08-01

Optically resonant donor polymers can exploit a wider range of the solar spectrum effectively without a complicated tandem design in an organic solar cell. Ultrafast Förster resonance energy transfer (FRET) in a polymer-polymer system that significantly improves the power conversion efficiency in bulk heterojunction polymer solar cells from 6.8% to 8.9% is demonstrated, thus paving the way to achieving 15% efficient solar cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solar power satellite system definition study. Volume 2, phase 1: Systems analyses tradeoffs.

NASA Technical Reports Server (NTRS)

1979-01-01

A systems definition study of the solar power satellite system is presented. The satellite solar energy conversion and microwave power transmission systems are discussed. Space construction and support systems are examined including a series construction and equipment characteristics analysis. Space transportation for the satellite and the ground receiving station are assessed.

Performance Analysis of a Thermoelectric Solar Collector Integrated with a Heat Pump

NASA Astrophysics Data System (ADS)

Lertsatitthanakorn, C.; Jamradloedluk, J.; Rungsiyopas, M.; Therdyothin, A.; Soponronnarit, S.

2013-07-01

A novel heat pump system is proposed. A thermoelectric solar collector was coupled to a solar-assisted heat pump (TESC-HP) to work as an evaporator. The cooling effect of the system's refrigerant allowed the cold side of the system's thermoelectric modules to work at lower temperature, improving the conversion efficiency. The TESC-HP system mainly consisted of transparent glass, an air gap, an absorber plate that acted as a direct expansion-type collector/evaporator, an R-134a piston-type hermetic compressor, a water-cooled plate-type condenser, thermoelectric modules, and a water storage tank. Test results indicated that the TESC-HP has better coefficient of performance (COP) and conversion efficiency than the separate units. For the meteorological conditions in Mahasarakham, the COP of the TESC-HP system can reach 5.48 when the average temperature of 100 L of water is increased from 28°C to 40°C in 60 min with average ambient temperature of 32.5°C and average solar intensity of 815 W/m2, whereas the conversion efficiency of the TE power generator was around 2.03%.

Unbiased Sunlight-Driven Artificial Photosynthesis of Carbon Monoxide from CO2 Using a ZnTe-Based Photocathode and a Perovskite Solar Cell in Tandem.

PubMed

Jang, Youn Jeong; Jeong, Inyoung; Lee, Jaehyuk; Lee, Jinwoo; Ko, Min Jae; Lee, Jae Sung

2016-07-26

Solar fuel production, mimicking natural photosynthesis of converting CO2 into useful fuels and storing solar energy as chemical energy, has received great attention in recent years. Practical large-scale fuel production needs a unique device capable of CO2 reduction using only solar energy and water as an electron source. Here we report such a system composed of a gold-decorated triple-layered ZnO@ZnTe@CdTe core-shell nanorod array photocathode and a CH3NH3PbI3 perovskite solar cell in tandem. The assembly allows effective light harvesting of higher energy photons (>2.14 eV) from the front-side photocathode and lower energy photons (>1.5 eV) from the back-side-positioned perovskite solar cell in a single-photon excitation. This system represents an example of a photocathode-photovoltaic tandem device operating under sunlight without external bias for selective CO2 conversion. It exhibited a steady solar-to-CO conversion efficiency over 0.35% and a solar-to-fuel conversion efficiency exceeding 0.43% including H2 as a minor product.

The Geography of Solar Energy.

ERIC Educational Resources Information Center

LaHart, David E.; Allen, Rodney F.

1984-01-01

After learning about two promising techniques for generating electricity--photovoltaic cells and wind energy conversion systems--secondary students analyze two maps of the United States showing solar radiation and available wind power to determine which U.S. regions have potential for these solar electric systems. (RM)

Fully solar-powered photoelectrochemical conversion for simultaneous energy storage and chemical sensing.

PubMed

Wang, Yongcheng; Tang, Jing; Peng, Zheng; Wang, Yuhang; Jia, Dingsi; Kong, Biao; Elzatahry, Ahmed A; Zhao, Dongyuan; Zheng, Gengfeng

2014-06-11

We report the development of a multifunctional, solar-powered photoelectrochemical (PEC)-pseudocapacitive-sensing material system for simultaneous solar energy conversion, electrochemical energy storage, and chemical detection. The TiO2 nanowire/NiO nanoflakes and the Si nanowire/Pt nanoparticle composites are used as photoanodes and photocathodes, respectively. A stable open-circuit voltage of ∼0.45 V and a high pseudocapacitance of up to ∼455 F g(-1) are obtained, which also exhibit a repeating charging-discharging capability. The PEC-pseudocapacitive device is fully solar powered, without the need of any external power supply. Moreover, this TiO2 nanowire/NiO nanoflake composite photoanode exhibits excellent glucose sensitivity and selectivity. Under the sun light illumination, the PEC photocurrent shows a sensitive increase upon different glucose additions. Meanwhile in the dark, the open-circuit voltage of the charged pseudocapacitor also exhibits a corresponding signal over glucose analyte, thus serving as a full solar-powered energy conversion-storage-utilization system.

Statistical thermodynamics foundation for photovoltaic and photothermal conversion. II. Application to photovoltaic conversion

NASA Astrophysics Data System (ADS)

Badescu, Viorel; Landsberg, Peter T.

1995-08-01

The general theory developed in part I was applied to build up two models of photovoltaic conversion. To this end two different systems were analyzed. The first system consists of the whole absorber (converter), for which the balance equations for energy and entropy are written and then used to derive an upper bound for solar energy conversion. The second system covers a part of the absorber (converter), namely the valence and conduction electronic bands. The balance of energy is used in this case to derive, under additional assumptions, another upper limit for the conversion efficiency. This second system deals with the real location where the power is generated. Both models take into consideration the radiation polarization and reflection, and the effects of concentration. The second model yields a more accurate upper bound for the conversion efficiency. A generalized solar cell equation is derived. It is proved that other previous theories are particular cases of the present more general formalism.

Strategies for Efficient Charge Separation and Transfer in Artificial Photosynthesis of Solar Fuels.

PubMed

Xu, Yuxing; Li, Ailong; Yao, Tingting; Ma, Changtong; Zhang, Xianwen; Shah, Jafar Hussain; Han, Hongxian

2017-11-23

Converting sunlight to solar fuels by artificial photosynthesis is an innovative science and technology for renewable energy. Light harvesting, photogenerated charge separation and transfer (CST), and catalytic reactions are the three primary steps in the processes involved in the conversion of solar energy to chemical energy (SE-CE). Among the processes, CST is the key "energy pump and delivery" step in determining the overall solar-energy conversion efficiency. Efficient CST is always high priority in designing and assembling artificial photosynthesis systems for solar-fuel production. This Review not only introduces the fundamental strategies for CST but also the combinatory application of these strategies to five types of the most-investigated semiconductor-based artificial photosynthesis systems: particulate, Z-scheme, hybrid, photoelectrochemical, and photovoltaics-assisted systems. We show that artificial photosynthesis systems with high SE-CE efficiency can be rationally designed and constructed through combinatory application of these strategies, setting a promising blueprint for the future of solar fuels. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Potential active materials for photo-supercapacitor: A review

NASA Astrophysics Data System (ADS)

Ng, C. H.; Lim, H. N.; Hayase, S.; Harrison, I.; Pandikumar, A.; Huang, N. M.

2015-11-01

The need for an endless renewable energy supply, typically through the utilization of solar energy in most applications and systems, has driven the expansion, versatility, and diversification of marketed energy storage devices. Energy storage devices such as hybridized dye-sensitized solar cell (DSSC)-capacitors and DSSC-supercapacitors have been invented for energy reservation. The evolution and vast improvement of these devices in terms of their efficiencies and flexibilities have further sparked the invention of the photo-supercapacitor. The idea of coupling a DSSC and supercapacitor as a complete energy conversion and storage device arose because the solar energy absorbed by dye molecules can be efficiently transferred and converted to electrical energy by adopting a supercapacitor as the energy delivery system. The conversion efficiency of a photo-supercapacitor is mainly dependent on the use of active materials during its fabrication. The performances of the dye, photoactive metal oxide, counter electrode, redox electrolyte, and conducting polymer are the primary factors contributing to high-energy-efficient conversion, which enhances the performance and shelf-life of a photo-supercapacitor. Moreover, the introduction of compact layer as a primary adherent film has been earmarked as an effort in enhancing power conversion efficiency of solar cell. Additionally, the development of electrolyte-free solar cell such as the invention of hole-conductor or perovskite solar cell is currently being explored extensively. This paper reviews and analyzes the potential active materials for a photo-supercapacitor to enhance the conversion and storage efficiencies.

Satellite Power Study (SPS) concept definition study (Exhibit D). Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Hanley, G. M.

1981-01-01

Efforts concentrated on updating of the Rockwell reference concept, definition of new system options, studies of special emphasis topics, further definition of the transportation system, and further program definition. The Rockwell reference satellite concept has a gallium arsenide (GaAs) solar cell array having flat concentrators with an effective concentration ratio of 1.83at end of life. Alternatives to this concept includes solid state power amplifiers or magnetrons for dc/RF conversion and multibandgap solar cells for solar to dc energy conversion. Two solid state concepts were studied. It was determined that the magnetron approach was the lowest mass and cost system.

Experimental aspects of the thermochemical conversion of solar energy - Decarbonation of CaCO3

NASA Astrophysics Data System (ADS)

Flamant, G.; Hernandez, D.; Bonet, C.; Traverse, J.-P.

1980-01-01

The feasibility of thermochemical conversion of concentrated solar energy is investigated. Consideration is given to heterogeneous systems in the range 500-1500 C. A reaction volume is on a laboratory scale about 30 cu cm. An experimental set-up selected is a fluid bed and a rotary kiln. An endothermal reaction, namely, decarbonation of CaCO3, is selected as a possible application for solar power plants.

High performance a-Si solar cells and new fabrication methods for a-Si solar cells

NASA Astrophysics Data System (ADS)

Nakano, S.; Kuwano, Y.; Ohnishi, M.

1986-12-01

The super chamber, a separated UHV reaction-chamber system has been developed. A conversion efficiency of 11.7% was obtained for an a-Si solar cell using a high-quality i-layer deposited by the super chamber, and a p-layer fabricated by a photo-CVD method. As a new material, amorphous superlattice-structure films were fabricated by the photo-CVD method for the first time. Superlattice structure p-layer a-Si solar cells were fabricated, and a conversion efficiency of 10.5% was obtained. For the fabrication of integrated type a-Si solar cell modules, a laser pattering method was investigated. A thermal analysis of the multilayer structure was done. It was confirmed that selective scribing for a-Si, TCO and metal film is possible by controlling the laser power density. Recently developed a-Si solar power generation systems and a-Si solar cell roofing tiles are also described.

NASA and energy

NASA Technical Reports Server (NTRS)

1974-01-01

NASA technology contributions to create energy sources include direct solar heating and cooling systems, wind generation of electricity, solar thermal energy turbine drives, solar cells, and techniques for locating, producing, and collecting organic materials for conversion into fuel.

High-Efficiency Solar Thermal Vacuum Demonstration Completed for Refractive Secondary Concentrator

NASA Technical Reports Server (NTRS)

Wong, Wayne A.

2001-01-01

Common to many of the space applications that utilize solar thermal energy--such as electric power conversion, thermal propulsion, and furnaces--is a need for highly efficient, solar concentration systems. An effort is underway at the NASA Glenn Research Center to develop the refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. When used in combination with advanced lightweight primary concentrators, the refractive secondary concentrator enables very high system concentration ratios (10,000 to 1) and very high temperatures (>2000 K). The innovative refractive secondary concentrator offers significant advantages over all other types of secondary concentrators. The refractive secondary offers the highest throughput efficiency, provides for flux tailoring, requires no active cooling, relaxes the pointing and tracking requirements of the primary concentrator, and enables very high system concentration ratios. This technology has broad applicability to any system that requires the conversion of solar energy to heat. Glenn initiated the development of the refractive secondary concentrator in support of Shooting Star, a solar thermal propulsion flight experiment, and continued the development in support of Space Solar Power.

Assessment of the potential of solar thermal small power systems in small utilities

NASA Technical Reports Server (NTRS)

Steitz, P.; Mayo, L. G.; Perkins, S. P., Jr.

1978-01-01

The potential economic benefit of small solar thermal electric power systems to small municipal and rural electric utilities is assessed. Five different solar thermal small power system configurations were considered in three different solar thermal technologies. The configurations included: (1) 1 MW, 2 MW, and 10 MW parabolic dish concentrators with a 15 kW heat engine mounted at the focal point of each dish, these systems utilized advanced battery energy storage; (2) a 10 MW system with variable slat concentrators and central steam Rankine energy conversion, this system utilized sensible thermal energy storage; and (3) a 50 MW central receiver system consisting of a field of heliostats concentrating energy on a tower-mounted receiver and a central steam Rankine conversion system, this system also utilized sensible thermal storage. The results are summarized in terms of break-even capital costs. The break-even capital cost was defined as the solar thermal plant capital cost which would have to be achieved in order for the solar thermal plants to penetrate 10 percent of the reference small utility generation mix by the year 2000. The calculated break-even capital costs are presented.

Candidate solar cell materials for photovoltaic conversion in a solar power satellite /SPS/

NASA Technical Reports Server (NTRS)

Glaser, P. E.; Almgren, D. W.

1978-01-01

In recognition of the obstacles to solar-generated baseload power on earth, proposals have been made to locate solar power satellites in geosynchronous earth orbit (GEO), where solar energy would be available 24 hours a day during most of the time of the year. In an SPS, the electricity produced by solar energy conversion will be fed to microwave generators forming part of a planar phase-array transmitting antenna. The antenna is designed to precisely direct a microwave beam of very low intensity to one or more receiving antennas at desired locations on earth. At the receiving antenna, the microwave energy will be safely and efficiently reconverted to electricity and then be transmitted to consumers. An SPS system will include a number of satellites in GEO. Attention is given to the photovoltaic option for solar energy conversion in GEO, solar cell requirements, the availability of materials, the implication of large production volumes, requirements for high-volume manufacture of solar cell arrays, and the effects of concentration ratio on solar cell array area.

SPS silicon reference system

NASA Technical Reports Server (NTRS)

Woodcock, G. R.

1980-01-01

The design analysis of a silicon power conversion system for the solar power satellite (SPS) is summarized. The solar array, consisting of glass encapsulated 50 micrometer silicon solar cells, is described. The general scheme for power distribution to the array/antenna interface is described. Degradation by proton irradiation is considered. The interface between the solar array and the klystron equipped power transmitter is described.

Ultrafast Electron Dynamics in Solar Energy Conversion.

PubMed

Ponseca, Carlito S; Chábera, Pavel; Uhlig, Jens; Persson, Petter; Sundström, Villy

2017-08-23

Electrons are the workhorses of solar energy conversion. Conversion of the energy of light to electricity in photovoltaics, or to energy-rich molecules (solar fuel) through photocatalytic processes, invariably starts with photoinduced generation of energy-rich electrons. The harvesting of these electrons in practical devices rests on a series of electron transfer processes whose dynamics and efficiencies determine the function of materials and devices. To capture the energy of a photogenerated electron-hole pair in a solar cell material, charges of opposite sign have to be separated against electrostatic attractions, prevented from recombining and being transported through the active material to electrodes where they can be extracted. In photocatalytic solar fuel production, these electron processes are coupled to chemical reactions leading to storage of the energy of light in chemical bonds. With the focus on the ultrafast time scale, we here discuss the light-induced electron processes underlying the function of several molecular and hybrid materials currently under development for solar energy applications in dye or quantum dot-sensitized solar cells, polymer-fullerene polymer solar cells, organometal halide perovskite solar cells, and finally some photocatalytic systems.

Solar power satellite system definition study. Volume 3: Reference system description, phase 1

NASA Technical Reports Server (NTRS)

1979-01-01

An analysis of the solar power satellite system is presented. The satellite solar energy conversion and microwave power transmission systems are discussed including the structure, power distribution, thermal control, and energy storage. Space construction and support systems are described including the work support facilities and construction equipment. An assessment of the space transportation system for the satellite and the ground receiving station is presented.

Space-based solar power conversion and delivery systems study. Volume 4: Energy conversion systems studies

NASA Technical Reports Server (NTRS)

1977-01-01

Solar cells and optical configurations for the SSPS were examined. In this task, three specific solar cell materials were examined: single crystal silicon, single crystal gallium arsenide, and polycrystalline cadmium sulfide. The comparison of the three different cells on the basis of a subsystem parametric cost per kW of SSPS-generated power at the terrestrial utility interface showed that gallium arsenide was the most promising solar cell material at high concentration ratios. The most promising solar cell material with no concentration, was dependent upon the particular combination of parameters representing cost, mass and performance that were chosen to represent each cell in this deterministic comparative analysis. The potential for mass production, based on the projections of the present state-of-the-art would tend to favor cadmium sulfide in lieu of single crystal silicon or gallium arsenide solar cells.

800 Hours of Operational Experience from a 2 kW(sub e) Solar Dynamic System

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Mason, Lee S.

1999-01-01

From December 1994 to September 1998, testing with a 2 kW(sub e) Solar Dynamic power system resulted in 33 individual tests, 886 hours of solar heating, and 783 hours of power generation. Power generation ranged from 400 watts to over 2 kW(sub e), and SD system efficiencies have been measured up to 17 per cent, during simulated low-Earth orbit operation. Further, the turbo-alternator-compressors successfully completed 100 start/stops on foil bearings. Operation was conducted in a large thermal/vacuum facility with a simulated Sun at the NASA Lewis Research Center. The Solar Dynamic system featured a closed Brayton conversion unit integrated with a solar heat receiver, which included thermal energy storage for continuous power output through a typical low-Earth orbit. Two power conversion units and three alternator configurations were used during testing. This paper will review the test program, provide operational and performance data, and review a number of technology issues.

Solar thermal program summary. Volume 1: Overview, fiscal year 1988

NASA Astrophysics Data System (ADS)

1989-02-01

The goal of the solar thermal program is to improve overall solar thermal systems performance and provide cost-effective energy options that are strategically secure and environmentally benign. Major research activities include energy collection technology, energy conversion technology, and systems and applications technology for both CR and DR systems. This research is being conducted through research laboratories in close coordination with the solar thermal industry, utilities companies, and universities. The Solar Thermal Technology Program is pursuing the development of critical components and subsystems for improved energy collection and conversion devices. This development follows two basic paths: for CR systems, critical components include stretched membrane heliostats, direct absorption receivers (DARs), and transport subsystems for molten salt heat transfer fluids. These components offer the potential for a significant reduction in system costs; and for DR systems, critical components include stretched membrane dishes, reflux receivers, and Stirling engines. These components will significantly increase system reliability and efficiency, which will reduce costs. The major thrust of the program is to provide electric power. However, there is an increasing interest in the use of concentrated solar energy for applications such as detoxifying hazardous wastes and developing high-value transportable fuels. These potential uses of highly concentrated solar energy still require additional experiments to prove concept feasibility. The program goal of economically competitive energy reduction from solar thermal systems is being cooperatively addressed by industry and government.

Photovoltaic and thermal energy conversion for solar powered satellites

NASA Technical Reports Server (NTRS)

Von Tiesenhausen, G. F.

1976-01-01

A summary is provided concerning the most important aspects of present investigations related to a use of solar power satellites (SPS) as a future source of terrestrial energy. General SPS characteristics are briefly considered, early work is reviewed, and a description of current investigations is presented. System options presently under study include a photovoltaic array, a thermionic system, and a closed Brayton cycle. Attention is given to system reference options, basic building blocks, questions of system analysis and engineering, photovoltaic conversion, and the utility interface. It is concluded that an SPS may be cost effective compared to terrestrial systems by 1995.

Recent Progress on Integrated Energy Conversion and Storage Systems.

PubMed

Luo, Bin; Ye, Delai; Wang, Lianzhou

2017-09-01

Over the last few decades, there has been increasing interest in the design and construction of integrated energy conversion and storage systems (IECSSs) that can simultaneously capture and store various forms of energies from nature. A large number of IECSSs have been developed with different combination of energy conversion technologies such as solar cells, mechanical generators and thermoelectric generators and energy storage devices such as rechargeable batteries and supercapacitors. This review summarizes the recent advancements to date of IECSSs based on different energy sources including solar, mechanical, thermal as well as multiple types of energies, with a special focus on the system configuration and working mechanism. With the rapid development of new energy conversion and storage technologies, innovative high performance IECSSs are of high expectation to be realised for diverse practical applications in the near future.

Recent Progress on Integrated Energy Conversion and Storage Systems

PubMed Central

Luo, Bin; Ye, Delai

2017-01-01

Over the last few decades, there has been increasing interest in the design and construction of integrated energy conversion and storage systems (IECSSs) that can simultaneously capture and store various forms of energies from nature. A large number of IECSSs have been developed with different combination of energy conversion technologies such as solar cells, mechanical generators and thermoelectric generators and energy storage devices such as rechargeable batteries and supercapacitors. This review summarizes the recent advancements to date of IECSSs based on different energy sources including solar, mechanical, thermal as well as multiple types of energies, with a special focus on the system configuration and working mechanism. With the rapid development of new energy conversion and storage technologies, innovative high performance IECSSs are of high expectation to be realised for diverse practical applications in the near future. PMID:28932673

Space-based solar power conversion and delivery systems study. Volume 2: Engineering analysis of orbital systems

NASA Technical Reports Server (NTRS)

1976-01-01

Program plans, schedules, and costs are determined for a synchronous orbit-based power generation and relay system. Requirements for the satellite solar power station (SSPS) and the power relay satellite (PRS) are explored. Engineering analysis of large solar arrays, flight mechanics and control, transportation, assembly and maintenance, and microwave transmission are included.

Collection, processing and dissemination of data for the national solar demonstration program

NASA Technical Reports Server (NTRS)

Day, R. E.; Murphy, L. J.; Smok, J. T.

1978-01-01

A national solar data system developed for the DOE by IBM provides for automatic gathering, conversion, transfer, and analysis of demonstration site data. NASA requirements for this system include providing solar site hardware, engineering, data collection, and analysis. The specific tasks include: (1) solar energy system design/integration; (2) developing a site data acquisition subsystem; (3) developing a central data processing system; (4) operating the test facility at Marshall Space Flight Center; (5) collecting and analyzing data. The systematic analysis and evaluation of the data from the National Solar Data System is reflected in a monthly performance report and a solar energy system performance evaluation report.

Reliability and cost/worth evaluation of generating systems utilizing wind and solar energy

NASA Astrophysics Data System (ADS)

Bagen

The utilization of renewable energy resources such as wind and solar energy for electric power supply has received considerable attention in recent years due to adverse environmental impacts and fuel cost escalation associated with conventional generation. At the present time, wind and/or solar energy sources are utilized to generate electric power in many applications. Wind and solar energy will become important sources for power generation in the future because of their environmental, social and economic benefits, together with public support and government incentives. The wind and sunlight are, however, unstable and variable energy sources, and behave far differently than conventional sources. Energy storage systems are, therefore, often required to smooth the fluctuating nature of the energy conversion system especially in small isolated applications. The research work presented in this thesis is focused on the development and application of reliability and economic benefits assessment associated with incorporating wind energy, solar energy and energy storage in power generating systems. A probabilistic approach using sequential Monte Carlo simulation was employed in this research and a number of analyses were conducted with regards to the adequacy and economic assessment of generation systems containing wind energy, solar energy and energy storage. The evaluation models and techniques incorporate risk index distributions and different operating strategies associated with diesel generation in small isolated systems. Deterministic and probabilistic techniques are combined in this thesis using a system well-being approach to provide useful adequacy indices for small isolated systems that include renewable energy and energy storage. The concepts presented and examples illustrated in this thesis will help power system planners and utility managers to assess the reliability and economic benefits of utilizing wind energy conversion systems, solar energy conversion systems and energy storage in electric power systems and provide useful input to the managerial decision process.

Nature-driven photochemistry for catalytic solar hydrogen production: a Photosystem I-transition metal catalyst hybrid.

PubMed

Utschig, Lisa M; Silver, Sunshine C; Mulfort, Karen L; Tiede, David M

2011-10-19

Solar energy conversion of water into the environmentally clean fuel hydrogen offers one of the best long-term solutions for meeting future energy demands. Nature provides highly evolved, finely tuned molecular machinery for solar energy conversion that exquisitely manages photon capture and conversion processes to drive oxygenic water-splitting and carbon fixation. Herein, we use one of Nature's specialized energy-converters, the Photosystem I (PSI) protein, to drive hydrogen production from a synthetic molecular catalyst comprised of inexpensive, earth-abundant materials. PSI and a cobaloxime catalyst self-assemble, and the resultant complex rapidly produces hydrogen in aqueous solution upon exposure to visible light. This work establishes a strategy for enhancing photosynthetic efficiency for solar fuel production by augmenting natural photosynthetic systems with synthetically tunable abiotic catalysts.

Toward cost-effective solar energy use.

PubMed

Lewis, Nathan S

2007-02-09

At present, solar energy conversion technologies face cost and scalability hurdles in the technologies required for a complete energy system. To provide a truly widespread primary energy source, solar energy must be captured, converted, and stored in a cost-effective fashion. New developments in nanotechnology, biotechnology, and the materials and physical sciences may enable step-change approaches to cost-effective, globally scalable systems for solar energy use.

Business developments of nonthermal solar technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, S.A.; Watts, R.L.; Williams, T.A.

1985-10-01

Information on the developments of nonthermal solar technologies is presented. The focus is on the success of wind energy conversion systems (WECS) and photovoltaics. Detailed information on the installed generating capacity, market sectors, financing sources, systems costs and warranties of WECS and photovoltaic systems is summarized. (BCS)

Status of the advanced Stirling conversion system project for 25 kW dish Stirling applications

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Schreiber, Jeffrey G.

1991-01-01

Technology development for Stirling convertors directed toward a dynamic power source for space applications is discussed. Space power requirements include high reliability with very long life, low vibration, and high system efficiency. The free-piston Stirling engine has the potential for future high power space conversion systems, either nuclear or solar powered. Although these applications appear to be quite different, their requirements complement each other. The advanced Stirling conversion system (ASCS) project at NASA Lewis Research Center is described. Each system design features a solar receiver/liquid metal heat transport system and a free-piston Stirling convertor with a means to provide nominally 25 kW of electric power to utility grid while meeting the US Department of Energy (DOE) performance and long term cost goals. The design is compared with other ASCS designs.

Performance of the Southern California Edison Company Stirling dish

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez, C.W.; Stone, K.W.

1993-10-01

McDonnell Douglas Astronautics Company (MDAC) and United Stirling AB of Sweden (USAB) formed a joint venture in 1982 to develop and produce a Stirling dish solar generating system. In this report, the six year development and testing program continued by the Southern California Edison Company (SCE) is described. Each Stirling dish module consists of a sun tracking dish concentrator developed by the MDAC and a Stirling engine driven power conversion unit (PCU) developed by USAB. The Stirling dish system demonstrated twice the peak and daily solar-to-electric conversion efficiency of any other system then under development. This system continues to setmore » the performance standard for solar to electric systems being developed in the early 1990`s. Test data are presented and used to estimate the performance of a commercial system.« less

Phase 1 of the First Small Power System Experiment (engineering Experiment No. 1). Volume 1: Executive Summary. [development and testing of a solar thermal power plant

NASA Technical Reports Server (NTRS)

Holl, R. J.

1979-01-01

The development of a modular solar thermal power system for application in the 1 to 10 MWe range is presented. The system is used in remote utility applications, small communities, rural areas, and for industrial uses. Investigations are performed on the energy storage requirements and type of energy storage, concentrator design and field optimization, energy transport, and power conversion subsystems. The system utilizes a Rankine cycle, an axial flow steam turbine for power conversion, and heat transfer sodium for collector fluid.

Solar concentrator technology development for space based applications, volume 1

NASA Technical Reports Server (NTRS)

Pintz, A.; Castle, C. H.; Reimer, R. R.

1992-01-01

Thermoelectric conversion using a radio-isotope heat source has been used where outer planetary space craft are too far away for absorbing significant solar energy. Solar dynamic power (SDP) conversion is one technology that offers advantages for applications within the inner planet region. Since SDP conversion efficiency can be 2 to 3 times higher than photovoltaic, the collecting surfaces are much reduced in area and therefore lighter. This becomes an advantage in allocating more weight to launched payloads. A second advantage results for low earth orbit applications. The reduced area results in lower drag forces on the spacecraft and requires less reboost propellant to maintain orbit. A third advantage occurs because of the sun-to-shade cycling while in earth orbit. Photovoltaic systems require batteries to store energy for use when in the shade, and battery life for periods of 10 to 15 years is not presently achievable. For these reasons the Solar Dynamics and Thermal Systems Branch at NASA LeRC has funded work in developing SDP systems. The generic SDP system uses a large parabolic solar concentrator to focus solar energy onto a power conversion device. The concentrators are large areas and must therefore be efficient and have low specific weights. Yet these surfaces must be precise and capable of being stowed in a launch vehicle and then deployed and sometimes unfurled in space. There are significant technical challenges in engineering such structures, and considerable investigation has been made to date. This is the first of two volumes reporting on the research done by the Advanced Manufacturing Center at Cleveland State University to assist NASA LeRC in evaluating this technology. The objective of the grant was to restore the solar concentrator development technology of the 1960s while improving it with advances that have occurred since then. This report summarizes the work done from January 1989 through December 1991.

Solar concentrator technology development for space based applications, volume 2

NASA Technical Reports Server (NTRS)

Pintz, A.; Castle, C. H.; Reimer, R. R.

1992-01-01

Thermoelectric conversion using a radio-isotope heat source has been used where outer planetary space craft are too far away for absorbing significant solar energy. Solar dynamic power (SDP) conversion is one technology that offers advantages for applications within the inner planet region. Since SDP conversion efficiency can be 2 to 3 times higher than photovoltaic, the collecting surfaces are much reduced in area and therefore lighter. This becomes an advantage in allocating more weight to launched payloads. A second advantage results for low earth orbit applications. The reduced area results in lower drag forces on the spacecraft and requires less reboost propellant to maintain orbit. A third advantage occurs because of the sun-to-shade cycling while in earth orbit. Photovoltaic systems require batteries to store energy for use when in the shade, and battery life for periods of 10 to 15 years is not presently achievable. For these reasons the Solar Dynamics and Thermal Systems Branch at NASA LeRC has funded work in developing SDP systems. The generic SDP system uses a large parabolic solar concentrator to focus solar energy onto a power conversion device. The concentrators are large areas and must therefore be efficient and have low specific weights. Yet these surfaces must be precise and capable of being stowed in a launch vehicle and then deployed and sometimes unfurled in space. There are significant technical challenges in engineering such structures, and considerable investigation has been made to date. This is the second of two volumes reporting on the research done by the Advanced Manufacturing Center at Cleveland State University to assist NASA LeRC in evaluating this technology. This volume includes the appendices of selected data sets, drawings, and procedures. The objective of the grant was to restore the solar concentrator development technology of the 1960s while improving it with advances that have occurred since then. This report summarizes the work done from January 1989 through December 1991.

Aqueous Lithium-Iodine Solar Flow Battery for the Simultaneous Conversion and Storage of Solar Energy.

PubMed

Yu, Mingzhe; McCulloch, William D; Beauchamp, Damian R; Huang, Zhongjie; Ren, Xiaodi; Wu, Yiying

2015-07-08

Integrating both photoelectric-conversion and energy-storage functions into one device allows for the more efficient solar energy usage. Here we demonstrate the concept of an aqueous lithium-iodine (Li-I) solar flow battery (SFB) by incorporation of a built-in dye-sensitized TiO2 photoelectrode in a Li-I redox flow battery via linkage of an I3(-)/I(-) based catholyte, for the simultaneous conversion and storage of solar energy. During the photoassisted charging process, I(-) ions are photoelectrochemically oxidized to I3(-), harvesting solar energy and storing it as chemical energy. The Li-I SFB can be charged at a voltage of 2.90 V under 1 sun AM 1.5 illumination, which is lower than its discharging voltage of 3.30 V. The charging voltage reduction translates to energy savings of close to 20% compared to conventional Li-I batteries. This concept also serves as a guiding design that can be extended to other metal-redox flow battery systems.

Efficient Solar Energy Conversion Systems for Hydrogen Production from Water using Semiconductor Photoelectrodes and Photocatalysts

NASA Astrophysics Data System (ADS)

Sayama, K.; Arai, T.

2008-02-01

Efficient solar energy conversion system for hydrogen production from water, solar-hydrogen system, is one of most important technologies for genuinely sustainable development of the society in the world wide scale. However, there are many problems to breakthrough such as low solar-to-H2 efficiency (STH), high cost, low stability, etc in order to realize the system practically and economically. The solar-hydrogen systems using semiconductors are mainly classified as follows; solar cell-electrolysis system, semiconductor photoelectrode system, and photocatalyst system. There are various merits and demerits in each system. The solar cell-electrolysis system is very efficient but is very high cost. The photocatalyst system is very simple and relatively low cost, but the efficiency is still very low. On the other hand, various semiconductor systems with high efficiency have been investigated. A high STH more than 10% was reported using non-oxide semiconductor photoelectrodes such as InGaP, while the preparation methods were costly. In a European project, some simple oxide semiconductor photoelectrodes such as Fe2O3 and WO3 are mainly studied. Here, we investigated various photoelectrodes using mixed metal oxide especially on BiVO4 semiconductor, and a high throughput screening system of new visible light responsible semiconductors for photoelectrode and photocatalyst. Moreover, photocatalysis-electrolysis hybrid system for economical H2 production is studied to overcome the demerit of photocatalyst system on the gas separation and low efficiency.

Review of NASA programs in applying aerospace technology to energy

NASA Technical Reports Server (NTRS)

Schwenk, F. C.

1981-01-01

NASA's role in energy research and development, with the aid of aerospace technology, is reviewed. A brief history, which began in 1974 with studies of solar energy systems on earth, is presented, and the major energy programs, consisting of over 60 different projects, are described, and include solar terrestrial systems, conservation and fossil energy systems, and space utilization systems. Special attention is given to the Satellite Power System and the isolation of nuclear wastes in space. Emerging prospects for NASA programs in energy technology include bioenergy, and ocean thermal energy conversion, coal extraction and conversion technologies, and support to the nuclear industry in power plant systems safety.

Application of solar energy; Proceedings of the Third Southeastern Conference, Huntsville, Ala., April 17-19, 1978

NASA Technical Reports Server (NTRS)

Wu, S. T. (Editor); Christensen, D. L.; Head, R. R.

1978-01-01

Demonstration projects, systems-subsystems simulation programs, applications (heating, cooling, agricultural, industrial), and climatic data testing (standards, economics, institutional) are the topics of the book. Economics of preheating water for commercial use and collecting, processing, and dissemination of data for the national demonstration program are discussed. Computer simulation of a solar energy system and graphical representation of solar collector performance are considered. Attention is given to solar driven heat pumps, solar cooling equipment, hybrid passive/active solar systems, and solar farm buildings. Evaluation of a thermographic scanning device for solar energy and conservation applications, use of meteorological data in system evaluation, and biomass conversion potential are presented.

Symposium on the Physical Chemistry of Solar Energy Conversion, Indianapolis American Chemical Society Meetings, Fall 2013

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian, Tianquan

2013-09-20

The Symposium on the Physical Chemistry of Solar Energy Conversion at the Fall ACS Meeting in Indianapolis, IN (Sept. 8-12) featured the following sessions (approx. 6 speakers per session): (1) Quantum Dots and Nanorods for Solar Energy Conversion (2 half-day sessions); (2) Artificial Photosynthesis: Water Oxidation; (3) Artificial Photosynthesis: Solar Fuels (2 half-day sessions); (4) Organic Solar Cells; (5) Novel Concepts for Solar Energy Conversion (2 half-day sessions); (6) Emerging Techniques for Solar Energy Conversion; (7) Interfacial Electron Transfer

Photo Degradation of Methyl Orange by Persulfate Activated with Zero Valent Iron

NASA Astrophysics Data System (ADS)

Munkoeva, V. A.; Sizykh, M. R.; Batoeva, A. A.

2017-11-01

The oxidative degradation of Methyl Orange (MO) subjected to direct photolysis (Solar) and various oxidative systems was studied. The comparative experiments have shown that MO conversion and mineralization increases in the following order: Solar ∼ Solar/Fe0 ∼ Solar/S2O82- < S2O82-/Fe0 < Solar/S2O82-/Fe0. The influence of the main factors (duration of exposure, the ratio of initial concentrations of MO:S2O82-:Fe0, pH and temperature of the reaction medium) on the degree of MO conversion and mineralization was studied. The optimal pH and temperature of the reaction medium were 5.8 and 25°C, respectively. The rate of MO decomposition and mineralization increased proportionally to the initial concentration of the oxidant at the molar ratios [S2O82-] :[MO] ≤ 12. Judging by the nature of the kinetic curves, a further increase of this ratio is impractical. However, an increase in the oxidant concentration had a positive effect on the degrees of conversion and mineralization of total organic carbon (TOC). Thus, at the ratios of 12:1 and 48:1, the conversion efficiency of TOC was 23 and 60 %, respectively. The optimal concentration of Fe0 was 100 mg/l.

Modeling, simulation, and fabrication of a fully integrated, acid-stable, scalable solar-driven water-splitting system.

PubMed

Walczak, Karl; Chen, Yikai; Karp, Christoph; Beeman, Jeffrey W; Shaner, Matthew; Spurgeon, Joshua; Sharp, Ian D; Amashukeli, Xenia; West, William; Jin, Jian; Lewis, Nathan S; Xiang, Chengxiang

2015-02-01

A fully integrated solar-driven water-splitting system comprised of WO3 /FTO/p(+) n Si as the photoanode, Pt/TiO2 /Ti/n(+) p Si as the photocathode, and Nafion as the membrane separator, was simulated, assembled, operated in 1.0 M HClO4 , and evaluated for performance and safety characteristics under dual side illumination. A multi-physics model that accounted for the performance of the photoabsorbers and electrocatalysts, ion transport in the solution electrolyte, and gaseous product crossover was first used to define the optimal geometric design space for the system. The photoelectrodes and the membrane separators were then interconnected in a louvered design system configuration, for which the light-absorbing area and the solution-transport pathways were simultaneously optimized. The performance of the photocathode and the photoanode were separately evaluated in a traditional three-electrode photoelectrochemical cell configuration. The photocathode and photoanode were then assembled back-to-back in a tandem configuration to provide sufficient photovoltage to sustain solar-driven unassisted water-splitting. The current-voltage characteristics of the photoelectrodes showed that the low photocurrent density of the photoanode limited the overall solar-to-hydrogen (STH) conversion efficiency due to the large band gap of WO3 . A hydrogen-production rate of 0.17 mL hr(-1) and a STH conversion efficiency of 0.24 % was observed in a full cell configuration for >20 h with minimal product crossover in the fully operational, intrinsically safe, solar-driven water-splitting system. The solar-to-hydrogen conversion efficiency, ηSTH , calculated using the multiphysics numerical simulation was in excellent agreement with the experimental behavior of the system. The value of ηSTH was entirely limited by the performance of the photoelectrochemical assemblies employed in this study. The louvered design provides a robust platform for implementation of various types of photoelectrochemical assemblies, and can provide an approach to significantly higher solar conversion efficiencies as new and improved materials become available. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Handbook of data on selected engine components for solar thermal applications

NASA Technical Reports Server (NTRS)

1979-01-01

A data base on developed and commercially available power conversion system components for Rankine and Brayton cycle engines, which have potential application to solar thermal power-generating systems is presented. The status of the Stirling engine is discussed.

United Stirling's Solar Engine Development: the Background for the Vanguard Engine

NASA Technical Reports Server (NTRS)

Holgersson, S.

1984-01-01

The development and testing resulting in the Vanguard engine and some of the characteristics of the Stirling engine based power conversion unit are described. The major part of the solar engine development is concentrated to the three different areas, the receiver, the lubrication system and the control system. Five engines are on test within the solar project. The function of the components are validated in actual solar tests.

Tandem photovoltaic solar cells and increased solar energy conversion efficiency

NASA Technical Reports Server (NTRS)

Loferski, J. J.

1976-01-01

Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

Utility-Scale Solar Power Converter: Agile Direct Grid Connect Medium Voltage 4.7-13.8 kV Power Converter for PV Applications Utilizing Wide Band Gap Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Solar ADEPT Project: Satcon is developing a compact, lightweight power conversion device that is capable of taking utility-scale solar power and outputting it directly into the electric utility grid at distribution voltage levels—eliminating the need for large transformers. Transformers “step up” the voltage of the power that is generated by a solar power system so it can be efficiently transported through transmission lines and eventually “stepped down” to usable voltages before it enters homes and businesses. Power companies step up the voltage because less electricity is lost along transmission lines when the voltage is high and current is low. Satcon’smore » new power conversion devices will eliminate these heavy transformers and connect a utility-scale solar power system directly to the grid. Satcon’s modular devices are designed to ensure reliability—if one device fails it can be bypassed and the system can continue to run.« less

Development of a concentrating solar power system using fluidized-bed technology for thermal energy conversion and solid particles for thermal energy storage

DOE PAGES

Ma, Z.; Mehos, M.; Glatzmaier, G.; ...

2015-05-01

Concentrating solar power (CSP) is an effective way to convert solar energy into electricity with an economic energy-storage capability for grid-scale, dispatchable renewable power generation. However, CSP plants need to reduce costs to be competitive with other power generation methods. Two ways to reduce CSP cost are to increase solar-to-electric efficiency by supporting a high-efficiency power conversion system, and to use low-cost materials in the system. The current nitrate-based molten-salt systems have limited potential for cost reduction and improved power-conversion efficiency with high operating temperatures. Even with significant improvements in operating performance, these systems face challenges in satisfying the costmore » and performance targets. This paper introduces a novel CSP system with high-temperature capability that can be integrated into a high-efficiency CSP plant and that meets the low-cost, high-performance CSP targets. Unlike a conventional salt-based CSP plant, this design uses gas/solid, two-phase flow as the heat-transfer fluid (HTF); separated solid particles as storage media; and stable, inexpensive materials for the high-temperature receiver and energy storage containment. We highlight the economic and performance benefits of this innovative CSP system design, which has thermal energy storage capability for base-load power generation.« less

Thin concentrator photovoltaic module with micro-solar cells which are mounted by self-align method using surface tension of melted solder

NASA Astrophysics Data System (ADS)

Hayashi, Nobuhiko; Terauchi, Masaharu; Aya, Youichirou; Kanayama, Shutetsu; Nishitani, Hikaru; Nakagawa, Tohru; Takase, Michihiko

2017-09-01

We are developing a thin and lightweight CPV module using small size lens system made from poly methyl methacrylate (PMMA) with a short focal length and micro-solar cells to decrease the transporting and the installing costs of CPV systems. In order to achieve high conversion efficiency in CPV modules using micro-solar cells, the micro-solar cells need to be mounted accurately to the irradiated region of the concentrated sunlight. In this study, we have successfully developed self-align method thanks to the surface tension of the melted solder even utilizing commercially available surface-mounting technology (SMT). Solar cells were self-aligned to the specified positions of the circuit board by this self-align method with accuracy within ±10 µm. We actually fabricated CPV modules using this self-align method and demonstrated high conversion efficiency of our CPV module.

Solar energy, its conversion and utilization

NASA Technical Reports Server (NTRS)

Farber, E. A.

1972-01-01

The work being carried out at the University of Florida Solar Energy and Energy Conversion Laboratory in converting solar energy, our only income, into other needed and useful forms of energy is described. A treatment such as this demonstrates, in proper perspective, how solar energy can benefit mankind with its many problems of shortages and pollution. Descriptions were given of the conversion processes, equipment, and performance. The testing of materials, solar water heating, space heating, cooking and baking, solar distillation, refrigeration and air-conditioning, work with the solar furnace, conversion to mechanical power, hot air engines, solar-heated sewage digestion, conversion to electricity, and other devices will be discussed.

Megawatt solar power systems for lunar surface operations

NASA Technical Reports Server (NTRS)

Adams, Brian; Alhadeff, Sam; Beard, Shawn; Carlile, David; Cook, David; Douglas, Craig; Garcia, Don; Gillespie, David; Golingo, Raymond; Gonzalez, Drew

1990-01-01

Lunar surface operations require habitation, transportation, life support, scientific, and manufacturing systems, all of which require some form of power. As an alternative to nuclear power, the development of a modular one megawatt solar power system is studied, examining both photovoltaic and dynamic cycle conversion methods, along with energy storage, heat rejection, and power backup subsystems. For photovoltaic power conversion, two systems are examined. First, a substantial increase in photovoltaic conversion efficiency is realized with the use of new GaAs/GaSb tandem photovoltaic cells, offering an impressive overall array efficiency of 23.5 percent. Since these new cells are still in the experimental phase of development, a currently available GaAs cell providing 18 percent efficiency is examined as an alternate to the experimental cells. Both Brayton and Stirling cycles, powered by linear parabolic solar concentrators, are examined for dynamic cycle power conversion. The Brayton cycle is studied in depth since it is already well developed and can provide high power levels fairly efficiently in a compact, low mass system. The dynamic conversion system requires large scale waste heat rejection capability. To provide this heat rejection, a comparison is made between a heat pipe/radiative fin system using advanced composites, and a potentially less massive liquid droplet radiator system. To supply power through the lunar night, both a low temperature alkaline fuel cell system and an experimental high temperature monolithic solid-oxide fuel cell system are considered. The reactants for the fuel cells are stored cryogenically in order to avoid the high tankage mass required by conventional gaseous storage. In addition, it is proposed that the propellant tanks from a spent, prototype lunar excursion vehicle be used for this purpose, therefore resulting in a significant overall reduction in effective storage system mass.

Solar energy collection system

NASA Technical Reports Server (NTRS)

Selcuk, M. K. (Inventor)

1977-01-01

An improved solar energy collection system, having enhanced energy collection and conversion capabilities, is delineated. The system is characterized by a plurality of receivers suspended above a heliostat field comprising a multiplicity of reflector surfaces, each being adapted to direct a concentrated beam of solar energy to illuminate a target surface for a given receiver. A magnitude of efficiency, suitable for effectively competing with systems employed in collecting and converting energy extracted from fossil fuels, is indicated.

Semiconductor nanostructures for artificial photosynthesis

NASA Astrophysics Data System (ADS)

Yang, Peidong

2012-02-01

Nanowires, with their unique capability to bridge the nanoscopic and macroscopic worlds, have already been demonstrated as important materials for different energy conversion. One emerging and exciting direction is their application for solar to fuel conversion. The generation of fuels by the direct conversion of solar energy in a fully integrated system is an attractive goal, but no such system has been demonstrated that shows the required efficiency, is sufficiently durable, or can be manufactured at reasonable cost. One of the most critical issues in solar water splitting is the development of a suitable photoanode with high efficiency and long-term durability in an aqueous environment. Semiconductor nanowires represent an important class of nanostructure building block for direct solar-to-fuel application because of their high surface area, tunable bandgap and efficient charge transport and collection. Nanowires can be readily designed and synthesized to deterministically incorporate heterojunctions with improved light absorption, charge separation and vectorial transport. Meanwhile, it is also possible to selectively decorate different oxidation or reduction catalysts onto specific segments of the nanowires to mimic the compartmentalized reactions in natural photosynthesis. In this talk, I will highlight several recent examples in this lab using semiconductor nanowires and their heterostructures for the purpose of direct solar water splitting.

Solar Technology Validation Project - USS Data, LLC: Cooperative Research and Development Final Report, CRADA Number CRD-09-367-04

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilcox, S.

2013-08-01

Under this Agreement, NREL will work with Participant to improve concentrating solar power system performance characterizations. This work includes, but is not limited to, research and development of methods for acquiring renewable resource characterization information using site-specific measurements of solar radiation and meteorological conditions; collecting system performance data; and developing tools for improving the design, installation, operation, and maintenance of solar energy conversion systems. This work will be conducted at NREL and Participant facilities.

Solar Technology Validation Project - RES Americas: Cooperative Research and Development Final Report, CRADA Number CRD-09-367-11

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilcox, S.

Under this Agreement, NREL will work with Participant to improve concentrating solar power system performance characterizations. This work includes, but is not limited to, research and development of methods for acquiring renewable resource characterization information using site-specific measurements of solar radiation and meteorological conditions; collecting system performance data; and developing tools for improving the design, installation, operation, and maintenance of solar energy conversion systems. This work will be conducted at NREL and Participant facilities.

2-kW Solar Dynamic Space Power System Tested in Lewis' Thermal Vacuum Facility

NASA Technical Reports Server (NTRS)

1995-01-01

Working together, a NASA/industry team successfully operated and tested a complete solar dynamic space power system in a large thermal vacuum facility with a simulated sun. This NASA Lewis Research Center facility, known as Tank 6 in building 301, accurately simulates the temperatures, high vacuum, and solar flux encountered in low-Earth orbit. The solar dynamic space power system shown in the photo in the Lewis facility, includes the solar concentrator and the solar receiver with thermal energy storage integrated with the power conversion unit. Initial testing in December 1994 resulted in the world's first operation of an integrated solar dynamic system in a relevant environment.

Status of the advanced Stirling conversion system project for 25 kW dish Stirling applications

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Schreiber, Jeffrey G.

1991-01-01

Heat engines were evaluated for terrestrial Solar Distributed Heat Receivers. The Stirling engine was identified as one of the most promising heat engines for terrestrial applications. Technology development is also conducted for Stirling convertors directed toward a dynamic power source for space applications. Space power requirements include high reliability with very long life, low vibration, and high system efficiency. The free-piston Stirling engine has the potential for future high power space conversion systems, either nuclear or solar powered. Although both applications appear to be quite different, their requirements complement each other.

Modern Topics in Energy and Power Technical Meeting

DTIC Science & Technology

2016-09-01

systems are abysmally low, primarily due to their poor electronic structure. The III-V-based solar cells show the highest solar PV efficiency and thus are...initiatives include creating jet fuel based on seawater, research on photovoltaics ( PVs ) of different types, lightweight fuel cell systems for unmanned air...technoeconomic analysis studies indicate that a 20% solar -to-hydrogen PEC conversion efficiency is necessary for a commercially viable system. Additional

Basic and applied research related to the technology of space energy conversion systems, 1982 - 1983

NASA Technical Reports Server (NTRS)

Hertzberg, A.

1983-01-01

Topics on solar energy conversion concepts and applications are discussed. An overview of the current status and future utilization of radiation receivers for electrical energy generation, liquid droplet radiation systems, and liquid droplet heat exchangers is presented.

Solar thermal electric power plants - Their performance characteristics and total social costs

NASA Technical Reports Server (NTRS)

Caputo, R. S.; Truscello, V. C.

1976-01-01

The central receiver (power tower) concept as a thermal conversion approach to the conversion of solar energy into electricity is compared to other solar power plant designs which feature distributed solar collection and use other types of solar collector configurations. A variety of solar thermal storage concepts are discussed and their impacts on system performance are assessed. Although a good deal of quantification is possible in a comparative study, the subjective judgments carry enormous weight in a socio-economic decision, the ultimate choice of central power plant being more a social than an economic or technical decision. Major elements of the total social cost of each type of central plant are identified as utility economic costs, R&D funds, health costs, and other relevant social impacts.

Projected techno-economic improvements for advanced solar thermal power plants

NASA Technical Reports Server (NTRS)

Fujita, T.; Manvi, R.; Roschke, E. J.

1979-01-01

The projected characteristics of solar thermal power plants (with outputs up to 10 MWe) employing promising advanced technology subsystems/components are compared to current (or pre-1985) steam-Rankine systems. Improvements accruing to advanced technology development options are delineated. The improvements derived from advanced systems result primarily from achieving high efficiencies via solar collector systems which (1) capture a large portion of the available insolation and (2) concentrate this captured solar flux to attain high temperatures required for high heat engine/energy conversion performance. The most efficient solar collector systems employ two-axis tracking. Attractive systems include the central receiver/heliostat and the parabolic dish.

Thermodynamic limits for solar energy conversion by a quantum-thermal hybrid system

NASA Technical Reports Server (NTRS)

Byvik, C. E.; Buoncristiani, A. M.; Smith, B. T.

1981-01-01

The limits are presented fo air mass 1.5 conditions. A maximum conversion efficiency of 74 percent is thermodynamically achievable for the quantum device operating at 3500 K and the heat engine in contact with a reservoir at 0 K. The efficiency drops to 56 percent for a cold reservoir at approximately room temperature conditions. Hybrid system efficiencies exceed 50 percent over receiver temperatures ranging from 1400 K to 4000 K, suggesting little benefit is gained in operating the system above 1400 K. The results are applied to a system consisting of a photovoltaic solar cell in series with a heat engine.

Space-based solar power conversion and delivery systems study

NASA Technical Reports Server (NTRS)

1976-01-01

Even at reduced rates of growth, the demand for electric power is expected to more than triple between now and 1995, and to triple again over the period 1995-2020. Without the development of new power sources and advanced transmission technologies, it may not be possible to supply electric energy at prices that are conductive to generalized economic welfare. Solar power is renewable and its conversion and transmission from space may be advantageous. The goal of this study is to assess the economic merit of space-based photovoltaic systems for power generation and a power relay satellite for power transmission. In this study, satellite solar power generation and transmission systems, as represented by current configurations of the Satellite Solar Station (SSPS) and the Power Relay Satellite (PRS), are compared with current and future terrestrial power generation and transmission systems to determine their technical and economic suitability for meeting power demands in the period of 1990 and beyond while meeting ever-increasing environmental and social constraints.

Energy: A continuing bibliography with indexes, February 1975. [solar energy, energy conversion

NASA Technical Reports Server (NTRS)

1975-01-01

Reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1974 through September 30, 1974 are cited. Regional, national, and international energy systems; research and development on fuels and other sources of energy; energy conversion, transport, transmission, distribution, and storage, with emphasis on the use of hydrogen and solar energy are included along with methods of locating or using new energy resources. Emphasis is placed on energy for heating, lighting, and powering aircraft, surface vehicles, or other machinery.

Final design of a free-piston hydraulic advanced Stirling conversion system

NASA Technical Reports Server (NTRS)

Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

1991-01-01

Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

Final design of a free-piston hydraulic advanced Stirling conversion system

NASA Astrophysics Data System (ADS)

Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

Satellite Power Systems (SPS) Concept Definition Study. Volume 3: SPS Concept Evolution

NASA Technical Reports Server (NTRS)

Hanley, G.

1978-01-01

A solar photovoltaic satellite based upon the utilization of a GaAlAs solar cell is defined. Topics covered include silicon-based photovoltaics, solar thermal power conversion, microwave energy transmission, power distribution, structures, attitude control and stationkeeping, thermal, and information management and control.

Sodium heat pipe use in solar Stirling power conversion systems

NASA Astrophysics Data System (ADS)

Zimmerman, W. F.; Divakaruni, S. M.; Won, Y. S.

1980-08-01

Sodium heat pipes were selected for use as a thermal transport method in a focus-mounted, distributed concentrator solar Stirling power conversion system intended to produce 15-20 kWe per unit. Heat pipes were used both to receive thermal power in the solar receiver and to transmit it to a secondary heat pipe containing both latent heat salt (for up to 1.25 hours of thermal storage) and the heat exchanger of the Stirling engine. Experimental tests were performed on five solar receiver heat pipes with various internal wicking configurations. The performance of the heat pipes at various power levels and operating attitudes was investigated at temperatures near 1550 F; the unidirectional heat transfer in these heat pipes was demonstrated in normal operating attitudes and particularly in the inverted position required during overnight stowage of the concentrator.

Sodium heat pipe use in solar Stirling power conversion systems

NASA Technical Reports Server (NTRS)

Zimmerman, W. F.; Divakaruni, S. M.; Won, Y. S.

1980-01-01

Sodium heat pipes were selected for use as a thermal transport method in a focus-mounted, distributed concentrator solar Stirling power conversion system intended to produce 15-20 kWe per unit. Heat pipes were used both to receive thermal power in the solar receiver and to transmit it to a secondary heat pipe containing both latent heat salt (for up to 1.25 hours of thermal storage) and the heat exchanger of the Stirling engine. Experimental tests were performed on five solar receiver heat pipes with various internal wicking configurations. The performance of the heat pipes at various power levels and operating attitudes was investigated at temperatures near 1550 F; the unidirectional heat transfer in these heat pipes was demonstrated in normal operating attitudes and particularly in the inverted position required during overnight stowage of the concentrator.

Design and testing of a uniformly solar energy TIR-R concentration lenses for HCPV systems.

PubMed

Shen, S C; Chang, S J; Yeh, C Y; Teng, P C

2013-11-04

In this paper, total internal reflection-refraction (TIR-R) concentration (U-TIR-R-C) lens module were designed for uniformity using the energy configuration method to eliminate hot spots on the surface of solar cell and increase conversion efficiency. The design of most current solar concentrators emphasizes the high-power concentration of solar energy, however neglects the conversion inefficiency resulting from hot spots generated by uneven distributions of solar energy concentrated on solar cells. The energy configuration method proposed in this study employs the concept of ray tracing to uniformly distribute solar energy to solar cells through a U-TIR-R-C lens module. The U-TIR-R-C lens module adopted in this study possessed a 76-mm diameter, a 41-mm thickness, concentration ratio of 1134 Suns, 82.6% optical efficiency, and 94.7% uniformity. The experiments demonstrated that the U-TIR-R-C lens module reduced the core temperature of the solar cell from 108 °C to 69 °C and the overall temperature difference from 45 °C to 10 °C, and effectively relative increased the conversion efficiency by approximately 3.8%. Therefore, the U-TIR-R-C lens module designed can effectively concentrate a large area of sunlight onto a small solar cell, and the concentrated solar energy can be evenly distributed in the solar cell to achieve uniform irradiance and effectively eliminate hot spots.

A solar photovoltaic system with ideal efficiency close to the theoretical limit.

PubMed

Zhao, Yuan; Sheng, Ming-Yu; Zhou, Wei-Xi; Shen, Yan; Hu, Er-Tao; Chen, Jian-Bo; Xu, Min; Zheng, Yu-Xiang; Lee, Young-Pak; Lynch, David W; Chen, Liang-Yao

2012-01-02

In order to overcome some physical limits, a solar system consisting of five single-junction photocells with four optical filters is studied. The four filters divide the solar spectrum into five spectral regions. Each single-junction photocell with the highest photovoltaic efficiency in a narrower spectral region is chosen to optimally fit into the bandwidth of that spectral region. Under the condition of solar radiation ranging from 2.4 SUN to 3.8 SUN (AM1.5G), the measured peak efficiency under 2.8 SUN radiation reaches about 35.6%, corresponding to an ideal efficiency of about 42.7%, achieved for the photocell system with a perfect diode structure. Based on the detailed-balance model, the calculated theoretical efficiency limit for the system consisting of 5 single-junction photocells can be about 52.9% under 2.8 SUN (AM1.5G) radiation, implying that the ratio of the highest photovoltaic conversion efficiency for the ideal photodiode structure to the theoretical efficiency limit can reach about 80.7%. The results of this work will provide a way to further enhance the photovoltaic conversion efficiency for solar cell systems in future applications.

A Comparison Of A Solar Power Satellite Concept To A Concentrating Solar Power System

NASA Technical Reports Server (NTRS)

Smitherman, David V.

2013-01-01

A comparison is made of a Solar Power Satellite concept in geostationary Earth orbit to a Concentrating Solar Power system on the ground to analyze overall efficiencies of each infrastructure from solar radiance at 1 AU to conversion and transmission of electrical energy into the power grid on the Earth's surface. Each system is sized for a 1-gigawatt output to the power grid and then further analyzed to determine primary collector infrastructure areas. Findings indicate that even though the Solar Power Satellite concept has a higher end-to-end efficiency, that the combined space and ground collector infrastructure is still about the same size as a comparable Concentrating Solar Power system on the ground.

Solar Reforming of Carbon Dioxide to Produce Diesel Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennis Schuetzle; Robert Schuetzle

2010-12-31

This project focused on the demonstration of an innovative technology, referred to as the Sunexus CO2 Solar Reformer, which utilizes waste CO2 as a feedstock for the efficient and economical production of synthetic diesel fuel using solar thermal energy as the primary energy input. The Sunexus technology employs a two stage process for the conversion of CO2 to diesel fuel. A solar reforming system, including a specially designed reactor and proprietary CO2 reforming catalyst, was developed and used to convert captured CO2 rich gas streams into syngas (primarily hydrogen and carbon monoxide) using concentrated solar energy at high conversion efficiencies.more » The second stage of the system (which has been demonstrated under other funding) involves the direct conversion of the syngas into synthetic diesel fuel using a proprietary catalyst (Terra) previously developed and validated by Pacific Renewable Fuels and Chemicals (PRFC). The overall system energy efficiency for conversion of CO2 to diesel fuel is 74%, due to the use of solar energy. The results herein describe modeling, design, construction, and testing of the Sunexus CO2 Solar Reformer. Extensive parametric testing of the solar reformer and candidate catalysts was conducted and chemical kinetic models were developed. Laboratory testing of the Solar Reformer was successfully completed using various gas mixtures, temperatures, and gas flow rates/space velocities to establish performance metrics which can be employed for the design of commercial plants. A variety of laboratory tests were conducted including dry reforming (CO2 and CH{sub 4}), combination dry/steam reforming (CO2, CH{sub 4} & H{sub 2}O), and tri-reforming (CO2, CH{sub 4}, H{sub 2}O & O{sub 2}). CH{sub 4} and CO2 conversions averaged 95-100% and 50-90% per reformer cycle, respectively, depending upon the temperatures and gas space velocities. No formation of carbon deposits (coking) on the catalyst was observed in any of these tests. A 16 ft. diameter, concentrating solar dish was modified to accommodate the Sunexus CO2 Solar Reformer and the integrated system was installed at the Pacific Renewable Fuels and Chemicals test site at McClellan, CA. Several test runs were conducted without catalyst during which the ceramic heat exchanger in the Sunexus Solar Reformer reached temperatures between 1,050 F (566 C) and 2,200 F (1,204 C) during the test period. A dry reforming mixture of CO2/CH{sub 4} (2.0/1.0 molar ratio) was chosen for all of the tests on the integrated solar dish/catalytic reformer during December 2010. Initial tests were carried out to determine heat transfer from the collimated solar beam to the catalytic reactor. The catalyst was operated successfully at a steady-state temperature of 1,125 F (607 C), which was sufficient to convert 35% of the 2/1 CO2/CH{sub 4} mixture to syngas. This conversion efficiency confirmed the results from laboratory testing of this catalyst which provided comparable syngas production efficiencies (40% at 1,200 F [650 C]) with a resulting syngas composition of 20% CO, 16% H{sub 2}, 39% CO2 and 25% CH{sub 4}. As based upon the laboratory results, it is predicted that 90% of the CO2 will be converted to syngas in the solar reformer at 1,440 F (782 C) resulting in a syngas composition of 50% CO: 43% H{sub 2}: 7% CO2: 0% CH{sub 4}. Laboratory tests show that the higher catalyst operating temperature of 1,440 F (782 C) for efficient conversion of CO2 can certainly be achieved by optimizing solar reactor heat transfer, which would result in the projected 90% CO2-to-syngas conversion efficiencies. Further testing will be carried out during 2011, through other funding support, to further optimize the solar dish CO2 reformer. Additional studies carried out in support of this project and described in this report include: (1) An Assessment of Potential Contaminants in Captured CO2 from Various Industrial Processes and Their Possible Effect on Sunexus CO2 Reforming Catalysts; (2) Recommended Measurement Methods for Assessing Contaminant Levels in Captured CO2 Streams; (3) An Assessment of Current Commercial Scale Fisher-Tropsch (F-T) Technologies for the Conversion of Syngas to Fuels; (4) An Overview of CO2 Capture Technologies from Various Industrial Sources; and (5) Lifecycle Analysis for the Capture and Conversion of CO2 to Synthetic Diesel Fuel. Commercial scale Sunexus CO2 Solar Reformer plant designs, proposed in this report, should be able to utilize waste CO2 from a wide variety of industrial sources to produce a directly usable synthetic diesel fuel that replaces petroleum derived fuel, thus improving the United States energy security while also sequestering CO2. Our material balance model shows that every 5.0 lbs of CO2 is transformed using solar energy into 6.26 lbs (1.0 U.S. gallon) of diesel fuel and into by-products, which includes water. Details are provided in the mass and energy model in this report.« less

Thermodynamic analysis of a combined-cycle solar thermal power plant with manganese oxide-based thermochemical energy storage

NASA Astrophysics Data System (ADS)

Lei, Qi; Bader, Roman; Kreider, Peter; Lovegrove, Keith; Lipiński, Wojciech

2017-11-01

We explore the thermodynamic efficiency of a solar-driven combined cycle power system with manganese oxide-based thermochemical energy storage system. Manganese oxide particles are reduced during the day in an oxygen-lean atmosphere obtained with a fluidized-bed reactor at temperatures in the range of 750-1600°C using concentrated solar energy. Reduced hot particles are stored and re-oxidized during night-time to achieve continuous power plant operation. The steady-state mass and energy conservation equations are solved for all system components to calculate the thermodynamic properties and mass flow rates at all state points in the system, taking into account component irreversibilities. The net power block and overall solar-to-electric energy conversion efficiencies, and the required storage volumes for solids and gases in the storage system are predicted. Preliminary results for a system with 100 MW nominal solar power input at a solar concentration ratio of 3000, designed for constant round-the-clock operation with 8 hours of on-sun and 16 hours of off-sun operation and with manganese oxide particles cycled between 750 and 1600°C yield a net power block efficiency of 60.0% and an overall energy conversion efficiency of 41.3%. Required storage tank sizes for the solids are estimated to be approx. 5-6 times smaller than those of state-of-the-art molten salt systems.

Phase 1 of the First Small Power System Experiment (engineering Experiment No. 1). Volume 2: System Concept Selection. [development and testing of a solar thermal power plant

NASA Technical Reports Server (NTRS)

Holl, R. J.

1979-01-01

The development of a modular solar thermal power system for application in the 1 to 10 MWe range is presented. The system is used in remote utility applications, small communities, rural areas, and for industrial uses. Systems design and systems optimization studies are conducted which consider plant size, annual capacity factors, and startup time as variables. Investigations are performed on the energy storage requirements and type of energy storage, concentrator design and field optimization, energy transport, and power conversion subsystems. The system utilizes a Rankine cycle, an axial flow steam turbine for power conversion, and heat transfer sodium for collector fluid.

Investigation of direct solar-to-microwave energy conversion techniques

NASA Technical Reports Server (NTRS)

Chatterton, N. E.; Mookherji, T. K.; Wunsch, P. K.

1978-01-01

Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive with current baseline concepts. The most direct methods of conversion appear to require an initial step of production of coherent laser radiation. Other methods generally require production of electron streams for use in solid-state or cavity-oscillator systems. Further development is suggested to be worthwhile for suggested devices and on concepts utilizing a free-electron stream for the intraspace station power transport mechanism.

Design of a new concentrated photovoltaic system under UAE conditions

NASA Astrophysics Data System (ADS)

Hachicha, Ahmed Amine; Tawalbeh, Muahammad

2017-06-01

Concentrated Photovoltaic Systems (CPVs) are considered one of the innovative designs for concentrated solar power applications. By concentrating the incident radiation, the solar cells will be able to produce much more electricity compared to conventional PV systems. However, the temperature of the solar cells increases significantly with concentration. Therefore, cooling of the solar cells will be needed to maintain high conversion efficiency. In this work, a novel design of CPV system is proposed and implemented under UAE conditions for electricity generation and hot water production. The proposed design integrates a water cooling system and PV system to optimize both the electrical and thermal performances of the CPV system.

Hybrid photosynthesis-powering biocatalysts with solar energy captured by inorganic devices.

PubMed

Zhang, Tian; Tremblay, Pier-Luc

2017-01-01

The biological reduction of CO 2 driven by sunlight via photosynthesis is a crucial process for life on earth. However, the conversion efficiency of solar energy to biomass by natural photosynthesis is low. This translates in bioproduction processes relying on natural photosynthesis that are inefficient energetically. Recently, hybrid photosynthetic technologies with the potential of significantly increasing the efficiency of solar energy conversion to products have been developed. In these systems, the reduction of CO 2 into biofuels or other chemicals of interest by biocatalysts is driven by solar energy captured with inorganic devices such as photovoltaic cells or photoelectrodes. Here, we explore hybrid photosynthesis and examine the strategies being deployed to improve this biotechnology.

Spectral splitting for thermal management in photovoltaic cells

NASA Astrophysics Data System (ADS)

Apostoleris, Harry; Chiou, Yu-Cheng; Chiesa, Matteo; Almansouri, Ibraheem

2017-09-01

Spectral splitting is widely employed as a way to divide light between different solar cells or processes to optimize energy conversion. Well-understood but less explored is the use of spectrum splitting or filtering to combat solar cell heating. This has impacts both on cell performance and on the surrounding environment. In this manuscript we explore the design of spectral filtering systems that can improve the thermal and power-conversion performance of commercial PV modules.

Efficient Solar Energy Harvesting and Storage through a Robust Photocatalyst Driving Reversible Redox Reactions.

PubMed

Zhou, Yangen; Zhang, Shun; Ding, Yu; Zhang, Leyuan; Zhang, Changkun; Zhang, Xiaohong; Zhao, Yu; Yu, Guihua

2018-06-14

Simultaneous solar energy conversion and storage is receiving increasing interest for better utilization of the abundant yet intermittently available sunlight. Photoelectrodes driving nonspontaneous reversible redox reactions in solar-powered redox cells (SPRCs), which can deliver energy via the corresponding reverse reactions, present a cost-effective and promising approach for direct solar energy harvesting and storage. However, the lack of photoelectrodes having both high conversion efficiency and high durability becomes a bottleneck that hampers practical applications of SPRCs. Here, it is shown that a WO 3 -decorated BiVO 4 photoanode, without the need of extra electrocatalysts, can enable a single-photocatalyst-driven SPRC with a solar-to-output energy conversion efficiency as high as 1.25%. This SPRC presents stable performance over 20 solar energy storage/delivery cycles. The high efficiency and stability are attributed to the rapid redox reactions, the well-matched energy level, and the efficient light harvesting and charge separation of the prepared BiVO 4 . This demonstrated device system represents a potential alternative toward the development of low-cost, durable, and easy-to-implement solar energy technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solar parabolic dish technology evaluation report

NASA Technical Reports Server (NTRS)

Lucas, J. W.

1984-01-01

The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1983 are summarized. Included are discussions on designs of module development including concentrator, receiver, and power conversion subsystems together with a separate discussion of field tests, Small Community Experiment system development, and tests at the Parabolic Dish Test Site.

Thermionic energy conversion technology - Present and future

NASA Technical Reports Server (NTRS)

Shimada, K.; Morris, J. F.

1977-01-01

Aerospace and terrestrial applications of thermionic direct energy conversion and advances in direct energy conversion (DEC) technology are surveyed. Electrode materials, the cesium plasma drop (the difference between the barrier index and the collector work function), DEC voltage/current characteristics, conversion efficiency, and operating temperatures are discussed. Attention is centered on nuclear reactor system thermionic DEC devices, for in-core or out-of-core operation. Thermionic fuel elements, the radiation shield, power conditions, and a waste heat rejection system are considered among the thermionic DEC system components. Terrestrial applications include topping power systems in fossil fuel and solar power generation.

Activity and accomplishments of dish/Stirling electric power system development

NASA Technical Reports Server (NTRS)

Livingston, F. R.

1985-01-01

The development of the solar parabolic-dish/Stirling-engine electricity generating plant known as the dish/Stirling electric power system is described. The dish/Stirling electric power system converts sunlight to electricity more efficiently than any known existing solar electric power system. The fabrication and characterization of the test bed concentrators that were used for Stirling module testing and of the development of parabolic dish concentrator No. 2, an advanced solar concentrator unit considered for use with the Stirling power conversion unit is discussed.

Theoretical limits of the multistacked 1D and 2D microstructured inorganic solar cells

NASA Astrophysics Data System (ADS)

Yengel, Emre; Karaagac, Hakan; VJ, Logeeswaran; Islam, M. Saif

2015-09-01

Recent studies in monocrystalline semiconductor solar cells are focused on mechanically stacking multiple cells from different materials to increase the power conversion efficiency. Although, the results show promising increase in the device performance, the cost remains as the main drawback. In this study, we calculated the theoretical limits of multistacked 1D and 2D microstructered inorganic monocrstalline solar cells. This system is studied for Si and Ge material pair. The results show promising improvements in the surface reflection due to enhanced light trapping caused by photon-microstructures interactions. The theoretical results are also supported with surface reflection and angular dependent power conversion efficiency measurements of 2D axial microwall solar cells. We address the challenge of cost reduction by proposing to use our recently reported mass-manufacturable fracture-transfer- printing method which enables the use of a monocrystalline substrate wafer for repeated fabrication of devices by consuming only few microns of materials in each layer of devices. We calculated thickness dependent power conversion efficiencies of multistacked Si/Ge microstructured solar cells and found the power conversion efficiency to saturate at 26% with a combined device thickness of 30 μm. Besides having benefits of fabricating low-cost, light weight, flexible, semi-transparent, and highly efficient devices, the proposed fabrication method is applicable for other III-V materials and compounds to further increase the power conversion efficiency above 35% range.

Benchmarking of Typical Meteorological Year datasets dedicated to Concentrated-PV systems

NASA Astrophysics Data System (ADS)

Realpe, Ana Maria; Vernay, Christophe; Pitaval, Sébastien; Blanc, Philippe; Wald, Lucien; Lenoir, Camille

2016-04-01

Accurate analysis of meteorological and pyranometric data for long-term analysis is the basis of decision-making for banks and investors, regarding solar energy conversion systems. This has led to the development of methodologies for the generation of Typical Meteorological Years (TMY) datasets. The most used method for solar energy conversion systems was proposed in 1978 by the Sandia Laboratory (Hall et al., 1978) considering a specific weighted combination of different meteorological variables with notably global, diffuse horizontal and direct normal irradiances, air temperature, wind speed, relative humidity. In 2012, a new approach was proposed in the framework of the European project FP7 ENDORSE. It introduced the concept of "driver" that is defined by the user as an explicit function of the pyranometric and meteorological relevant variables to improve the representativeness of the TMY datasets with respect the specific solar energy conversion system of interest. The present study aims at comparing and benchmarking different TMY datasets considering a specific Concentrated-PV (CPV) system as the solar energy conversion system of interest. Using long-term (15+ years) time-series of high quality meteorological and pyranometric ground measurements, three types of TMY datasets generated by the following methods: the Sandia method, a simplified driver with DNI as the only representative variable and a more sophisticated driver. The latter takes into account the sensitivities of the CPV system with respect to the spectral distribution of the solar irradiance and wind speed. Different TMY datasets from the three methods have been generated considering different numbers of years in the historical dataset, ranging from 5 to 15 years. The comparisons and benchmarking of these TMY datasets are conducted considering the long-term time series of simulated CPV electric production as a reference. The results of this benchmarking clearly show that the Sandia method is not suitable for CPV systems. For these systems, the TMY datasets obtained using dedicated drivers (DNI only or more precise one) are more representative to derive TMY datasets from limited long-term meteorological dataset.

Design of a pool boiler heat transport system for a 25 kWe advanced Stirling conversion system

NASA Technical Reports Server (NTRS)

Anderson, W. G.; Rosenfeld, J. H.; Noble, J.; Kesseli, J.

1991-01-01

The overall operating temperature and efficiency of solar-powered Stirling engines can be improved by adding a heat transport system to more uniformly supply heat to the heater head tubes. One heat transport system with favorable characteristics is an alkali metal pool boiler. An alkali metal pool boiler heat transport system was designed for a 25-kW advanced Stirling conversion system (ASCS). Solar energy concentrated on the absorber dome boils a eutectic mixture of sodium and potassium. The alkali metal vapors condense on the heater head tubes, supplying the Stirling engine with a uniform heat flux at a constant temperature. Boiling stability is achieved with the use of an enhanced boiling surface and noncondensible gas.

Placement and efficiency effects on radiative forcing of solar installations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burg, Brian R.; Ruch, Patrick; Paredes, Stephan

2015-09-28

The promise for harnessing solar energy being hampered by cost, triggered efforts to reduce them. As a consequence low-efficiency, low-cost photovoltaics (PV) panels prevail. Conversely, in the traditional energy sector efficiency is extremely important due to the direct costs associated to fuels. This also affects solar energy due to the radiative forcing caused by the dark solar panels. In this paper we extend the concept of energy payback time by including the effect of albedo change, which gives a better assessment of the system sustainability. We present an analysis on the short and medium term climate forcing effects of differentmore » solar collectors in Riyadh, Saudi Arabia and demonstrate that efficiency is important to reduce the collector area and cost. This also influences the embodied energy and the global warming potential. We show that a placement of a high concentration photovoltaic thermal solar power station outside of the city using a district cooling system has a double beneficial effect since it improves the solar conversion efficiency and reduces the energy demand for cooling in the city. We also explain the mechanisms of the current economic development of solar technologies and anticipate changes.« less

IECEC '84: Advanced energy systems - Their role in our future; Proceedings of the Nineteenth Intersociety Energy Conversion Engineering Conference, San Francisco, CA, August 19-24, 1984. Volumes 1, 2, 3, & 4

NASA Astrophysics Data System (ADS)

Among the topics discussed are: advanced energy conversion concepts, power sources for aircraft and spacecraft, alternate fuels for industrial and vehicular applications, biomass-derived fuels, electric vehicle design and development status, electrochemical energy conversion systems, electric power generation cycles, energy-efficient industrial processes, and energy policy and system analysis. Also discussed are advanced methods for energy storage and transport, fossil fuel conversion systems, geothermal energy system development and performance, novel and advanced heat engines, hydrogen fuel-based energy systems, MHD technology development status, nuclear energy systems, solar energy conversion methods, advanced heating and cooling systems, Stirling cycle device development, terrestrial photovoltaic systems, and thermoelectric and thermionic systems.

Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, Nathan H.; Chen, Zhen; Fan, Shanhui

Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we then report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In fieldmore » tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. Furthemore, with straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat« less

Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion

DOE PAGES

Thomas, Nathan H.; Chen, Zhen; Fan, Shanhui; ...

2017-07-13

Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we then report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In fieldmore » tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. Furthemore, with straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat« less

Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion.

PubMed

Thomas, Nathan H; Chen, Zhen; Fan, Shanhui; Minnich, Austin J

2017-07-13

Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In field tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. With straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat.

Artificial photosynthesis: biomimetic approaches to solar energy conversion and storage.

PubMed

Kalyanasundaram, K; Graetzel, M

2010-06-01

Using sun as the energy source, natural photosynthesis carries out a number of useful reactions such as oxidation of water to molecular oxygen and fixation of CO(2) in the form of sugars. These are achieved through a series of light-induced multi-electron-transfer reactions involving chlorophylls in a special arrangement and several other species including specific enzymes. Artificial photosynthesis attempts to reconstruct these key processes in simpler model systems such that solar energy and abundant natural resources can be used to generate high energy fuels and restrict the amount of CO(2) in the atmosphere. Details of few model catalytic systems that lead to clean oxidation of water to H(2) and O(2), photoelectrochemical solar cells for the direct conversion of sunlight to electricity, solar cells for total decomposition of water and catalytic systems for fixation of CO(2) to fuels such as methanol and methane are reviewed here. Copyright 2010 Elsevier Ltd. All rights reserved.

Thermodynamic limits to the conversion of blackbody radiation by quantum systems. [with application to solar energy conversion devices

NASA Technical Reports Server (NTRS)

Buoncristiani, A. M.; Smith, B. T.; Byvik, C. E.

1982-01-01

Using general thermodynamic arguments, we analyze the conversion of the energy contained in the radiation from a blackbody to useful work by a quantum system. We show that the energy available for conversion is bounded above by the change in free energy in the incident and reradiated fields and that this free energy change depends upon the temperature of the receiving device. Universal efficiency curves giving the ultimate thermodynamic conversion efficiency of the quantum system are presented in terms of the blackbody temperature and the temperature and threshold energy of the quantum system. Application of these results is made to a variety of systems including biological photosynthetic, photovoltaic, and photoelectrochemical systems.

Full-spectrum volumetric solar thermal conversion via photonic nanofluids.

PubMed

Liu, Xianglei; Xuan, Yimin

2017-10-12

Volumetric solar thermal conversion is an emerging technique for a plethora of applications such as solar thermal power generation, desalination, and solar water splitting. However, achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge. In this work, full-spectrum volumetric solar thermal conversion is demonstrated over a thin layer of the proposed 'photonic nanofluids'. The underlying mechanism is found to be the photonic superposition of core resonances, shell plasmons, and core-shell resonances at different wavelengths, whose coexistence is enabled by the broken symmetry of specially designed composite nanoparticles, i.e., Janus nanoparticles. The solar thermal conversion efficiency can be improved by 10.8% compared with core-shell nanofluids. The extinction coefficient of Janus dimers with various configurations is also investigated to unveil the effects of particle couplings. This work provides the possibility to achieve full-spectrum volumetric solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

Thermally driven electrokinetic energy conversion with liquid water microjets

DOE PAGES

Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; ...

2015-11-01

One goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.

Thermally driven electrokinetic energy conversion with liquid water microjets

NASA Astrophysics Data System (ADS)

Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; Saykally, Richard J.

2015-11-01

A goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.

Thermodynamic Inefficiency of Conversion of Solar Energy to Work.

ERIC Educational Resources Information Center

Adamson, Arthur W.; And Others

1984-01-01

Considers the thermodynamic limitation to the efficiency with which light energy can be converted into work, indicating that no single chemical system converting solar energy into useful work can be very efficient. Also indicates that if solar energy is absorbed as heat for heating purposes, it is almost completely used. (JN)

Solar micro-power system for self-powered wireless sensor nodes

NASA Astrophysics Data System (ADS)

He, Yongtai; Li, Yangqiu; Liu, Lihui; Wang, Lei

2008-10-01

In self-powered wireless sensor nodes, the efficiency for environmental energy harvesting, storage and management determines the lifetime and environmental adaptability of the sensor nodes. However, the method of improving output efficiency for traditional photovoltaic power generation is not suitable for a solar micro-power system due to the special requirements for its application. This paper presents a solar micro-power system designed for a solar self-powered wireless sensor node. The Maximum Power Point Tracking (MPPT) of solar cells and energy storage are realized by the hybrid energy storage structure and "window" control. Meanwhile, the mathematical model of energy harvesting, storing and management is formulated. In the novel system, the output conversion efficiency of solar cells is 12%.

Refraction-Assisted Solar Thermoelectric Generator based on Phase-Change Lens

PubMed Central

Kim, Myoung-Soo; Kim, Min-Ki; Jo, Sung-Eun; Joo, Chulmin; Kim, Yong-Jun

2016-01-01

Solar thermoelectric generators (STEGs), which are used for various applications, (particularly small size electronic devices), have optical concentration systems for high energy conversion efficiency. In this study, a refraction-assisted STEG (R-STEG) is designed based on phase-change materials. As the phase-change material (PCM) changes phase from solid to liquid, its refractive index and transmittance also change, resulting in changes in the refraction of the sunlight transmitted through it, and concentration of solar energy in the phase-change lens. This innovative design facilitates double focusing the solar energy through the optical lens and a phase-change lens. This mechanism resulted in the peak energy conversion efficiencies of the R-STEG being 60% and 86% higher than those of the typical STEG at solar intensities of 1 kW m−2 and 1.5 kW m−2, respectively. In addition, the energy stored in PCM can help to generate steady electrical energy when the solar energy was removed. This work presents significant progress regarding the optical characteristic of PCM and optical concentration systems of STEGs. PMID:27283350

Refraction-Assisted Solar Thermoelectric Generator based on Phase-Change Lens.

PubMed

Kim, Myoung-Soo; Kim, Min-Ki; Jo, Sung-Eun; Joo, Chulmin; Kim, Yong-Jun

2016-06-10

Solar thermoelectric generators (STEGs), which are used for various applications, (particularly small size electronic devices), have optical concentration systems for high energy conversion efficiency. In this study, a refraction-assisted STEG (R-STEG) is designed based on phase-change materials. As the phase-change material (PCM) changes phase from solid to liquid, its refractive index and transmittance also change, resulting in changes in the refraction of the sunlight transmitted through it, and concentration of solar energy in the phase-change lens. This innovative design facilitates double focusing the solar energy through the optical lens and a phase-change lens. This mechanism resulted in the peak energy conversion efficiencies of the R-STEG being 60% and 86% higher than those of the typical STEG at solar intensities of 1 kW m(-2) and 1.5 kW m(-2), respectively. In addition, the energy stored in PCM can help to generate steady electrical energy when the solar energy was removed. This work presents significant progress regarding the optical characteristic of PCM and optical concentration systems of STEGs.

Design and realization of an autonomous solar system

NASA Astrophysics Data System (ADS)

Gaga, A.; Diouri, O.; Es-sbai, N.; Errahimi, F.

2017-03-01

The aim of this work is the design and realization of an autonomous solar system, with MPPT control, a regulator charge/discharge of batteries, an H-bridge multi-level inverter with acquisition system and supervising based on a microcontroller. The proposed approach is based on developing a software platform in the LabVIEW environment which gives the system a flexible structure for controlling, monitoring and supervising the whole system in real time while providing power maximization and best quality of energy conversion from DC to AC power. The reliability of the proposed solar system is validated by the simulation results on PowerSim and experimental results achieved with a solar panel, a Lead acid battery, solar regulator and an H-bridge cascaded topology of single-phase inverter.

Best Practices of Uncertainty Estimation for the National Solar Radiation Database (NSRDB 1998-2015): Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habte, Aron M; Sengupta, Manajit

It is essential to apply a traceable and standard approach to determine the uncertainty of solar resource data. Solar resource data are used for all phases of solar energy conversion projects, from the conceptual phase to routine solar power plant operation, and to determine performance guarantees of solar energy conversion systems. These guarantees are based on the available solar resource derived from a measurement station or modeled data set such as the National Solar Radiation Database (NSRDB). Therefore, quantifying the uncertainty of these data sets provides confidence to financiers, developers, and site operators of solar energy conversion systems and ultimatelymore » reduces deployment costs. In this study, we implemented the Guide to the Expression of Uncertainty in Measurement (GUM) 1 to quantify the overall uncertainty of the NSRDB data. First, we start with quantifying measurement uncertainty, then we determine each uncertainty statistic of the NSRDB data, and we combine them using the root-sum-of-the-squares method. The statistics were derived by comparing the NSRDB data to the seven measurement stations from the National Oceanic and Atmospheric Administration's Surface Radiation Budget Network, National Renewable Energy Laboratory's Solar Radiation Research Laboratory, and the Atmospheric Radiation Measurement program's Southern Great Plains Central Facility, in Billings, Oklahoma. The evaluation was conducted for hourly values, daily totals, monthly mean daily totals, and annual mean monthly mean daily totals. Varying time averages assist to capture the temporal uncertainty of the specific modeled solar resource data required for each phase of a solar energy project; some phases require higher temporal resolution than others. Overall, by including the uncertainty of measurements of solar radiation made at ground stations, bias, and root mean square error, the NSRDB data demonstrated expanded uncertainty of 17 percent - 29 percent on hourly and an approximate 5 percent - 8 percent annual bases.« less

The energy crisis and energy from the sun; Proceedings of the Symposium on Solar Energy Utilization, Washington, D.C., April 30, 1974

NASA Technical Reports Server (NTRS)

Thekaekara, M. P.

1974-01-01

Papers on the state of the art and future prospects of solar energy utilization in the United States are included. Research and technologies for heating and cooling of buildings, solar thermal energy conversion, photovoltaic conversion, biomass production and conversion, wind energy conversion and ocean thermal energy conversion are covered. The increasing funding of the National Solar Energy Program is noted. Individual items are announced in this issue.

A Comparison of a Solar Power Satellite Concept to a Concentrating Solar Power System

NASA Technical Reports Server (NTRS)

Smitherman, David V.

2013-01-01

A comparison is made of a solar power satellite (SPS) concept in geostationary Earth orbit to a concentrating solar power (CSP) system on the ground to analyze overall efficiencies of each infrastructure from solar radiance at 1 AU to conversion and transmission of electrical energy into the power grid on the Earth's surface. Each system is sized for a 1-gigawatt output to the power grid and then further analyzed to determine primary collector infrastructure areas. Findings indicate that even though the SPS concept has a higher end-to-end efficiency, the combined space and ground collector infrastructure is still about the same size as a comparable CSP system on the ground.

Conversations: with Carl Pilcher [interview by Johan Benson].

PubMed

Pilcher, C

1998-11-01

An interview with Carl Pilcher, science program director for solar system exploration at NASA, examines NASA's past, present, and planned missions to explore the solar system. Specific questions relate to the status of current and planned missions, science results of the Pathfinder mission to Mars, cooperation with the Japanese space agency, the status of the search for extraterrestrial life in solar system meteoroids and asteroids, mission size for more in-depth exploration, reports of water on the moon, and the exploration of near-Earth objects.

Progress in passive solar energy systems. Volume 8. Part 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, J.; Andrejko, D.A.

1983-01-01

This book presents the papers given at a conference sponsored by the US DOE, the Solar Energy Research Institute, SolarVision, Inc., and the Southern California Solar Energy Society. The topics considered at the conference included sizing solar energy systems for agricultural applications, a farm scale ethanol production plant, the EEC wind energy RandD program, the passive solar performance assessment of an earth-sheltered house, the ARCO 1 MW photovoltaic power plant, the performance of a dendritic web photovoltaic module, second generation point focused concentrators, linear fresnel lens concentrating photovoltaic collectors, photovoltaic conversion efficiency, amorphous silicon thin film solar cells, a photovoltaicmore » system for a shopping center, photovoltaic power generation for the utility industry, spectral solar radiation, and the analysis of insolation data.« less

Hierarchical Graphene Foam for Efficient Omnidirectional Solar-Thermal Energy Conversion.

PubMed

Ren, Huaying; Tang, Miao; Guan, Baolu; Wang, Kexin; Yang, Jiawei; Wang, Feifan; Wang, Mingzhan; Shan, Jingyuan; Chen, Zhaolong; Wei, Di; Peng, Hailin; Liu, Zhongfan

2017-10-01

Efficient solar-thermal energy conversion is essential for the harvesting and transformation of abundant solar energy, leading to the exploration and design of efficient solar-thermal materials. Carbon-based materials, especially graphene, have the advantages of broadband absorption and excellent photothermal properties, and hold promise for solar-thermal energy conversion. However, to date, graphene-based solar-thermal materials with superior omnidirectional light harvesting performances remain elusive. Herein, hierarchical graphene foam (h-G foam) with continuous porosity grown via plasma-enhanced chemical vapor deposition is reported, showing dramatic enhancement of broadband and omnidirectional absorption of sunlight, which thereby can enable a considerable elevation of temperature. Used as a heating material, the external solar-thermal energy conversion efficiency of the h-G foam impressively reaches up to ≈93.4%, and the solar-vapor conversion efficiency exceeds 90% for seawater desalination with high endurance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design and optimization of cascaded DCG based holographic elements for spectrum-splitting PV systems

NASA Astrophysics Data System (ADS)

Wu, Yuechen; Chrysler, Benjamin; Pelaez, Silvana Ayala; Kostuk, Raymond K.

2017-09-01

In this work, the technique of designing and optimizing broadband volume transmission holograms using dichromate gelatin (DCG) is summarized for solar spectrum-splitting application. Spectrum splitting photovoltaic system uses a series of single bandgap PV cells that have different spectral conversion efficiency properties to more fully utilize the solar spectrum. In such a system, one or more high performance optical filters are usually required to split the solar spectrum and efficiently send them to the corresponding PV cells. An ideal spectral filter should have a rectangular shape with sharp transition wavelengths. DCG is a near ideal holographic material for solar applications as it can achieve high refractive index modulation, low absorption and scattering properties and long-term stability to solar exposure after sealing. In this research, a methodology of designing and modeling a transmission DCG hologram using coupled wave analysis for different PV bandgap combinations is described. To achieve a broad diffraction bandwidth and sharp cut-off wavelength, a cascaded structure of multiple thick holograms is described. A search algorithm is also developed to optimize both single and two-layer cascaded holographic spectrum splitters for the best bandgap combinations of two- and three-junction SSPV systems illuminated under the AM1.5 solar spectrum. The power conversion efficiencies of the optimized systems under the AM1.5 solar spectrum are then calculated using the detailed balance method, and shows an improvement compared with tandem structure.

Tilt to horizontal global solar irradiance conversion: application to PV systems data

NASA Astrophysics Data System (ADS)

Housmans, Caroline; Leloux, Jonathan; Bertrand, Cédric

2017-04-01

Many transposition models have been proposed in the literature to convert solar irradiance on the horizontal plane to that on a tilted plane requiring that at least two of the three solar components (i.e. global, direct and diffuse) are known. When only global irradiance measurements are available, the conversion from horizontal to tilted planes is still possible but in this case transposition models have to be coupled with decomposition models (i.e. models that predict the direct and diffuse components from the global one). Here, two different approaches have been considered to solve the reverse process, i.e. the conversion from tilted to horizontal: (i) one-sensor approach and (ii) multi-sensors approach. Because only one tilted plane is involved in the one-sensor approach, a decomposition model need to be coupled with a transposition model to solve the problem. By contrast, at least two tilted planes being considered in the multi-sensors approach, only a transposition model is required to perform the conversion. First, global solar irradiance measurements recorded on the roof of the Royal Meteorological Institute of Belgium's radiation tower in Uccle were used to evaluate the performance of both approaches. Four pyranometers (one mounted in the horizontal plane and three on inclined surfaces with different tilts and orientations) were involved in the validation exercise. Second, the inverse transposition was applied to tilted global solar irradiance values retrieved from the energy production registered at residential PV systems located in the vicinity of Belgian radiometric stations operated by RMI (for validation purposes).

A Robust Design Approach to Cost Estimation: Solar Energy for Marine Corps Expeditionary Operations

DTIC Science & Technology

2014-04-30

areas as photovoltaic arrays for power harvesting, light emitting diodes (LED) for decreased energy consumption, and improved battery and smart power ...conversion system that allows Marines to power systems with solar energy. Each GREENS is comprised of eight photovoltaic array panels, four high-energy...Brandon Newell conducted an experiment where he assessed the capabilities of the HOMER model in forecasting the power output of a solar panel at the

Progress on alternative energy resources

NASA Astrophysics Data System (ADS)

Couch, H. T.

1982-03-01

Progress in the year 1981 toward the development of energy systems suitable for replacing petroleum products combustion and growing in use to fulfill a near term expansion in energy use is reviewed. Coal is noted to be a potentially heavy pollution source, and the presence of environmentally acceptable methods of use such as fluidized-bed combustion and gasification and liquefaction reached the prototype stage in 1981, MHD power generation was achieved in two U.S. plants, with severe corrosion problems remaining unsolved for the electrodes. Solar flat plate collectors sales amounted to 20 million sq ft in 1981, and solar thermal electric conversion systems with central receivers neared completion. Solar cells are progressing toward DOE goals of $.70/peak W by 1986, while wind energy conversion sales were 2000 machines in 1981, and the industry is regarded as maturing. Finally, geothermal, OTEC, and fusion systems are reviewed.

Direct solar-to-hydrogen conversion via inverted metamorphic multi-junction semiconductor architectures

DOE PAGES

Young, James L.; Steiner, Myles A.; Döscher, Henning; ...

2017-03-13

Solar water splitting via multi-junction semiconductor photoelectrochemical cells provides direct conversion of solar energy to stored chemical energy as hydrogen bonds. Economical hydrogen production demands high conversion efficiency to reduce balance-of-systems costs. For sufficient photovoltage, water-splitting efficiency is proportional to the device photocurrent, which can be tuned by judicious selection and integration of optimal semiconductor bandgaps. Here, we demonstrate highly efficient, immersed water-splitting electrodes enabled by inverted metamorphic epitaxy and a transparent graded buffer that allows the bandgap of each junction to be independently varied. Voltage losses at the electrolyte interface are reduced by 0.55 V over traditional, uniformly p-dopedmore » photocathodes by using a buried p-n junction. Lastly, advanced on-sun benchmarking, spectrally corrected and validated with incident photon-to-current efficiency, yields over 16% solar-to-hydrogen efficiency with GaInP/GaInAs tandem absorbers, representing a 60% improvement over the classical, high-efficiency tandem III-V device.« less

Direct solar-to-hydrogen conversion via inverted metamorphic multi-junction semiconductor architectures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, James L.; Steiner, Myles A.; Döscher, Henning

Solar water splitting via multi-junction semiconductor photoelectrochemical cells provides direct conversion of solar energy to stored chemical energy as hydrogen bonds. Economical hydrogen production demands high conversion efficiency to reduce balance-of-systems costs. For sufficient photovoltage, water-splitting efficiency is proportional to the device photocurrent, which can be tuned by judicious selection and integration of optimal semiconductor bandgaps. Here, we demonstrate highly efficient, immersed water-splitting electrodes enabled by inverted metamorphic epitaxy and a transparent graded buffer that allows the bandgap of each junction to be independently varied. Voltage losses at the electrolyte interface are reduced by 0.55 V over traditional, uniformly p-dopedmore » photocathodes by using a buried p-n junction. Lastly, advanced on-sun benchmarking, spectrally corrected and validated with incident photon-to-current efficiency, yields over 16% solar-to-hydrogen efficiency with GaInP/GaInAs tandem absorbers, representing a 60% improvement over the classical, high-efficiency tandem III-V device.« less

NASA-OAST program in photovoltaic energy conversion

NASA Technical Reports Server (NTRS)

Mullin, J. P.; Flood, D. J.

1982-01-01

The NASA program in photovoltaic energy conversion includes research and technology development efforts on solar cells, blankets, and arrays. The overall objectives are to increase conversion efficiency, reduce mass, reduce cost, and increase operating life. The potential growth of space power requirements in the future presents a major challenge to the current state of technology in space photovoltaic systems.

Solar Sea Power

ERIC Educational Resources Information Center

Zener, Clarence

1976-01-01

In their preoccupation with highly complex new energy systems, scientists and statesmen may be overlooking the possibilities of Ocean Thermal Energy Conversion (OTEC). That is the view of a Carnegie-Mellon University physicist who is in the forefront of solar sea power investigation. (Author/BT)

Free-Piston Stirling Engines

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.

1989-01-01

Engines promise cost-effective solar-power generation. Report describes two concepts for Stirling-engine systems for conversion of solar heat to electrical energy. Recognized most promising technologies for meeting U.S. Department of Energy goals for performance and cost for terrestrial electrical-energy sources.

Radioisotope Power Systems Program: A Program Overview

NASA Technical Reports Server (NTRS)

Hamley, John A.

2016-01-01

NASA's Radioisotope Power Systems (RPS) Program continues to plan, mature research in energy conversion, and partners with the Department of Energy (DOE) to make RPS ready and available to support the exploration of the solar system in environments where the use of conventional solar or chemical power generation is impractical or impossible to meet potential future mission needs. Recent programs responsibilities include providing investment recommendations to NASA stakeholders on emerging thermoelectric and Stirling energy conversion technologies and insight on NASA investments at DOE in readying a generator for the Mars 2020 mission. This presentation provides an overview of the RPS Program content and status and the approach used to maintain the readiness of RPS to support potential future NASA missions.

OAST Space Theme Workshop. Volume 3: Working group summary. 6: Power (P-2). A. Statement. B. Technology needs (form 1). C. Priority assessment (form 2)

NASA Technical Reports Server (NTRS)

1976-01-01

Power requirements for the multipurpose space power platform, for space industrialization, SETI, the solar system exploration facility, and for global services are assessed for various launch dates. Priorities and initiatives for the development of elements of space power systems are described for systems using light power input (solar energy source) or thermal power input, (solar, chemical, nuclear, radioisotopes, reactors). Systems for power conversion, power processing, distribution and control are likewise examined.

Space Photovoltaic Research and Technology, 1989

NASA Technical Reports Server (NTRS)

1991-01-01

Remarkable progress on a wide variety of approaches in space photovoltaics, for both near and far term applications is reported. Papers were presented in a variety of technical areas, including multi-junction cell technology, GaAs and InP cells, system studies, cell and array development, and non-solar direct conversion. Five workshops were held to discuss the following topics: mechanical versus monolithic multi-junction cells; strategy in space flight experiments; non-solar direct conversion; indium phosphide cells; and space cell theory and modeling.

A new dawn for industrial photosynthesis.

PubMed

Robertson, Dan E; Jacobson, Stuart A; Morgan, Frederick; Berry, David; Church, George M; Afeyan, Noubar B

2011-03-01

Several emerging technologies are aiming to meet renewable fuel standards, mitigate greenhouse gas emissions, and provide viable alternatives to fossil fuels. Direct conversion of solar energy into fungible liquid fuel is a particularly attractive option, though conversion of that energy on an industrial scale depends on the efficiency of its capture and conversion. Large-scale programs have been undertaken in the recent past that used solar energy to grow innately oil-producing algae for biomass processing to biodiesel fuel. These efforts were ultimately deemed to be uneconomical because the costs of culturing, harvesting, and processing of algal biomass were not balanced by the process efficiencies for solar photon capture and conversion. This analysis addresses solar capture and conversion efficiencies and introduces a unique systems approach, enabled by advances in strain engineering, photobioreactor design, and a process that contradicts prejudicial opinions about the viability of industrial photosynthesis. We calculate efficiencies for this direct, continuous solar process based on common boundary conditions, empirical measurements and validated assumptions wherein genetically engineered cyanobacteria convert industrially sourced, high-concentration CO(2) into secreted, fungible hydrocarbon products in a continuous process. These innovations are projected to operate at areal productivities far exceeding those based on accumulation and refining of plant or algal biomass or on prior assumptions of photosynthetic productivity. This concept, currently enabled for production of ethanol and alkane diesel fuel molecules, and operating at pilot scale, establishes a new paradigm for high productivity manufacturing of nonfossil-derived fuels and chemicals.

Advanced Energy Conversion Technologies and Architectures for Earth and Beyond

NASA Technical Reports Server (NTRS)

Howell, Joe T.; Fikes, John C.; Phillips, Dane J.; Laycock, Rustin L.; ONeill, Mark; Henley, Mark W.; Fork, Richard L.

2006-01-01

Research, development and studies of novel space-based solar power systems, technologies and architectures for Earth and beyond are needed to reduce the cost of clean electrical power for terrestrial use and to provide a stepping stone for providing an abundance of power in space, i.e., manufacturing facilities, tourist facilities, delivery of power between objects in space, and between space and surface sites. The architectures, technologies and systems needed for space to Earth applications may also be used for in-space applications. Advances in key technologies, i.e., power generation, power management and distribution, power beaming and conversion of beamed power are needed to achieve the objectives of both terrestrial and extraterrestrial applications. There is a need to produce "proof-ofconcept" validation of critical WPT technologies for both the near-term, as well as far-term applications. Investments may be harvested in near-term beam safe demonstrations of commercial WPT applications. Receiving sites (users) include ground-based stations for terrestrial electrical power, orbital sites to provide power for satellites and other platforms, future space elevator systems, space vehicle propulsion, and space surface sites. Space surface receiving sites of particular interest include the areas of permanent shadow near the moon s North and South poles, where WPT technologies could enable access to ice and other useful resources for human exploration. This paper discusses work addressing a promising approach to solar power generation and beamed power conversion. The approach is based on a unique high-power solar concentrator array called Stretched Lens Array (SLA) applied to both solar power generation and beamed power conversion. Since both versions (solar and laser) of SLA use many identical components (only the photovoltaic cells need to be different), economies of manufacturing and scale may be realized by using SLA on both ends of the laser power beaming system in a space solar power application. Near-term uses of this SLA-laser-SLA system may include terrestrial and space exploration in near Earth space. Later uses may include beamed power for bases or vehicles on Mars. Strategies for developing energy infrastructures in space which utilize this technology are presented. This dual use system produces electrical energy efficiently from either coherent light, such as from a highly coherent laser, or from conventional solar illumination. This allows, for example, supplementing solar energy with energy provided by highly coherent laser illumination during periods of low solar illumination or no illumination. This reduces the need for batteries and alternate sources of power. The capability of using laser illumination in a lowest order Gaussian laser mode provides means for transmitting power optically with maximum efficiency and precision over the long distances characteristic of space. A preliminary receiving system similar to that described here, has been produced and tested under solar and laser illumination. A summary of results is given.

Solar power satellite: System definition study. Part 1, volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1977-01-01

A study of the solar power satellite system, which represents a means of tapping baseload electric utility power from the sun on a large scale, was summarized. Study objectives, approach, and planning are presented along with an energy conversion evaluation. Basic requirements were considered in regard to space transportation, construction, and maintainability.

Solar Parabolic Dish Annual Technology Evaluation Report

NASA Technical Reports Server (NTRS)

1983-01-01

The activities of the JPL Solar Thermal Power Systems Parabolic Dish Project for FY 1982 are summarized. Included are discussions on designs of module development including their concentrator, receiver, and power conversion subsystems. Analyses and test results, along with progress on field tests, Small Community Experiment System development, and tests at the Parabolic Dish Test Site are also included.

Flexible, highly efficient all-polymer solar cells

PubMed Central

Kim, Taesu; Kim, Jae-Han; Kang, Tae Eui; Lee, Changyeon; Kang, Hyunbum; Shin, Minkwan; Wang, Cheng; Ma, Biwu; Jeong, Unyong; Kim, Taek-Soo; Kim, Bumjoon J.

2015-01-01

All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymer acceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices. PMID:26449658

Kinetic conversion of CO to CH4 in the Solar System

NASA Technical Reports Server (NTRS)

Yung, Y. L.; Allen, M.; Pinto, J. P.

1991-01-01

Some of the most interesting chemistry in the Solar System involves changes in the oxidation state of the simple carbon species. The chemical pathways for the conversion of CH4 to CO and CO2 are for the most part known. The reverse process, the reduction of CO to CH4, is, however, poorly understood. This is surprising in view of the importance of the reduction process in the chemistry of the Solar System. Recently we investigated the chemical kinetics of a hitherto unsuspected reaction. It is argued that the formation of the methoxy radical (CH3O) from H+H2CO may play an essential role in the reduction of CO to CH4. The rate coefficient for this reaction has been estimated using the approximate theory of J. Troe and transition state theory. We will discuss the implications of this reaction for the chemistry of CO on Jupiter, in the solar nebula, for interpreting the laboratory experiments of A. Bar-Nun and A. Shaviv and A. Bar-Nun and S. Chang, and for organic synthesis in the prebiotic terrestrial atmosphere. The possible relation of CO reduction in the solar nebula and polyoxymethylene observed in comet Halley will be discussed.

Dynamic conversion of solar generated heat to electricity

NASA Technical Reports Server (NTRS)

Powell, J. C.; Fourakis, E.; Hammer, J. M.; Smith, G. A.; Grosskreutz, J. C.; Mcbride, E.

1974-01-01

The effort undertaken during this program led to the selection of the water-superheated steam (850 psig/900 F) crescent central receiver as the preferred concept from among 11 candidate systems across the technological spectrum of the dynamic conversion of solar generated heat to electricity. The solar power plant designs were investigated in the range of plant capacities from 100 to 1000 Mw(e). The investigations considered the impacts of plant size, collector design, feed-water temperature ratio, heat rejection equipment, ground cover, and location on solar power technical and economic feasibility. For the distributed receiver systems, the optimization studies showed that plant capacities less than 100 Mw(e) may be best. Although the size of central receiver concepts was not parametrically investigated, all indications are that the optimal plant capacity for central receiver systems will be in the range from 50 to 200 Mw(e). Solar thermal power plant site selection criteria and methodology were also established and used to evaluate potentially suitable sites. The result of this effort was to identify a site south of Inyokern, California, as typically suitable for a solar thermal power plant. The criteria used in the selection process included insolation and climatological characteristics, topography, and seismic history as well as water availability.

Technical and economic feasibility study of solar/fossil hybrid power systems

NASA Technical Reports Server (NTRS)

Bloomfield, H. S.; Calogeras, J. E.

1977-01-01

Results show that new hybrid systems utilizing fossil fuel augmentation of solar energy can provide significant capital and energy cost benefits when compared with solar thermal systems requiring thermal storage. These benefits accrue from a reduction of solar collection area that results from both the use of highly efficient gas and combined cycle energy conversion subsystems and elimination of the requirement for long-term energy storage subsystems. Technical feasibility and fuel savings benefits of solar hybrid retrofit to existing fossil-fired, gas and vapor cycle powerplants was confirmed; however, economic viability of steam cycle retrofit was found to be dependent on the thermodynamic and operational characteristics of the existing powerplant.

Increasing conversion efficiency of two-step photon up-conversion solar cell with a voltage booster hetero-interface.

PubMed

Asahi, Shigeo; Kusaki, Kazuki; Harada, Yukihiro; Kita, Takashi

2018-01-17

Development of high-efficiency solar cells is one of the attractive challenges in renewable energy technologies. Photon up-conversion can reduce the transmission loss and is one of the promising concepts which improve conversion efficiency. Here we present an analysis of the conversion efficiency, which can be increased by up-conversion in a single-junction solar cell with a hetero-interface that boosts the output voltage. We confirm that an increase in the quasi-Fermi gap and substantial photocurrent generation result in a high conversion efficiency.

Conceptual design of free-piston Stirling conversion system for solar power units

NASA Astrophysics Data System (ADS)

Loktionov, Iu. V.

A conversion system has been conceptually designed for solar power units of the dish-Stirling type. The main design objectives were to demonstrate the possibility of attaining such performance characteristics as low manufacturing and life cycle costs, high reliability, long life, high efficiency, power output stability, self-balance, automatic (or self-) start-up, and easy maintenance. The system design includes a heat transfer and utilization subsystem with a solar receiver, a free-piston engine, an electric power generation subsystem, and a control subsystem. The working fluid is helium. The structural material is stainless steel for hot elements, aluminum alloys and plastics for others. The electric generation subunit can be fabricated in three options: with an induction linear alternator, with a permanent magnet linear alternator, and with a serial rotated induction generator and a hydraulic drive subsystem. The heat transfer system is based on heat pipes or the reflux boiler principle. Several models of heat transfer units using a liquid metal (Na or Na-K) have been created and demonstrated.

Design of hybrid nanoheterostructure systems for enhanced quantum and solar conversion efficiencies in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Kılıç, Bayram; Telli, Hakan; Tüzemen, Sebahattin; Başaran, Ali; Pirge, Gursev

2015-04-01

Dye sensitized solar cells (DSSCs) with an innovative design involving controlled-morphology vertically aligned (VA) ZnO nanowires within mesoporous TiO2 structures with ultrahigh surface area for implementation as photoanodes are herein reported. Although TiO2 nanostructures exhibit excellent power conversion efficiency, the electron transport rate is low owing to low electron mobility. To overcome this, ZnO nanowires with high electron mobility have been investigated as potential candidates for photoanodes. However, the power conversion efficiency of ZnO nanowires is still lower than that of TiO2 owing to their low internal surface area. Consequently, in this work, vertical growth of ZnO nanowires within mesoporous TiO2 structures is carried out to increase their solar power conversion efficiency. The photovoltaic performance of solar cells using ZnO nanowires, mesoporous TiO2, and TiO2/ZnO hybrid structures are compared. The VA TiO2/ZnO hybrid structures are found to provide direct electron transfer compared with the tortuous pathway of zero-dimensional nanostructures, resulting in an increased conversion efficiency. It is demonstrated that the light scattering of the photoanode film is increased and electron recombination is decreased when an appropriate amount of mesoporous TiO2 is used as a substrate for ZnO nanowires. The DSSC fabricated with the TiO2/ZnO hybrid photoanode prepared with 15.8 wt. % TiO2 showed the highest conversion efficiency of 7.30%, approximately 5%, 18%, and 40% higher than that of DSSCs fabricated with 3.99 wt. % TiO2, pure TiO2, and pure ZnO photoanodes, respectively.

Space Environmental Effects on the Optical Properties of Selected Transparent Polymers

NASA Technical Reports Server (NTRS)

Edwards, David L.; Willowby, Douglas J.; Hubbs, Whitney C.; Piszczor, Michael F., Jr.; Bowden, Mary L.

1997-01-01

Transparent polymer films are currently considered for use as solar concentrating lenses for spacecraft power and propulsion systems. These polymer films concentrate solar energy onto energy conversion devices such as solar cells and thermal energy systems. Conversion efficiency is directly related to the polymer transmission. Space environmental effects will decrease the transmission and thus reduce the conversion efficiency. This investigation focuses on the effects of ultraviolet and charged particle radiation on the transmission of selected transparent polymers. Multiple candidate polymer samples were exposed to near ultraviolet (NUV) radiation to screen the materials and select optimum materials for further study. All materials experienced transmission degradation of varying degree. A method was developed to normalize the transmission loss and thus rank the materials according to their tolerance of NUV. Teflon(Tm) FEP and Teflon(Tm) PFA were selected for further study. These materials were subjected to a combined charged particle dose equivalent to 5 years in a typical geosynchronous Earth orbit (GEO). Results from these NUV screening tests and the 5 year GEO equivalent dose are presented.

Achieving high performance polymer tandem solar cells via novel materials design

NASA Astrophysics Data System (ADS)

Dou, Letian

Organic photovoltaic (OPV) devices show great promise in low-cost, flexible, lightweight, and large-area energy-generation applications. Nonetheless, most of the materials designed today always suffer from the inherent disadvantage of not having a broad absorption range, and relatively low mobility, which limit the utilization of the full solar spectrum. Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of suitable low-bandgap polymers (near-IR absorbing polymers). In this dissertation, in order to achieve high performance, we focus on design and synthesis of novel low bandgap polymers specifically for tandem solar cells. In Chapter 3, I demonstrate highly efficient single junction and tandem polymer solar cells featuring a spectrally matched low-bandgap conjugated polymer (PBDTT-DPP: bandgap, ˜1.44 eV). The polymer has a backbone based on alternating benzodithiophene and diketopyrrolopyrrole units. A single-layer device based on the polymer provides a power conversion efficiency of ˜6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which was the highest certified efficiency for a polymer solar cell. To further improve this material system, in Chapter 4, I show that the reduction of the bandgap and the enhancement of the charge transport properties of the low bandgap polymer PBDTT-DPP can be accomplished simultaneously by substituting the sulfur atoms on the DPP unit with selenium atoms. The newly designed polymer PBDTT-SeDPP (Eg = 1.38 eV) shows excellent photovoltaic performance in single junction devices with PCEs over 7% and photo-response up to 900 nm. Tandem polymer solar cells based on PBDTT-SeDPP are also demonstrated with a 9.5% PCE, which are more than 10% enhancement over those based on PBDTT-DPP. Finally, in Chapter 5, I demonstrate a new polymer system based on alternating dithienopyran and benzothiadiazole units with a bandgap of 1.38 eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900 nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions, which is the first certified polymer solar cell efficiency over 10%.

A Conceptual Design Study on the Application of Liquid Metal Heat Transfer Technology to the Solar Thermal Power Plant

NASA Technical Reports Server (NTRS)

Zimmerman, W. F.; Robertson, C. S.; Ehde, C. L.; Divakaruni, S. M.; Stacy, L. E.

1979-01-01

Alkali metal heat transfer technology was used in the development of conceptual designs for the transport and storage of sensible and latent heat thermal energy in distributed concentrator, solar Stirling power conversion systems at a power level of 15 kWe per unit. Both liquid metal pumped loop and heat pipe thermal transport were considered; system configurations included: (1) an integrated, focal mounted sodium heat pipe solar receiver (HPSR) with latent heat thermal energy storage; (2) a liquid sodium pumped loop with the latent heat storage, Stirling engine-generator, pump and valves located on the back side of the concentrator; and (3) similar pumped loops serving several concentrators with more centralized power conversion and storage. The focus mounted HPSR was most efficient, lightest and lowest in estimated cost. Design confirmation testing indicated satisfactory performance at all angles of inclination of the primary heat pipes to be used in the solar receiver.

Supramolecular photochemistry and solar cells

PubMed

Iha

2000-01-01

Supramolecular photochemistry as well as solar cells are fascinating topics of current interest in Inorganic Photochemistry and very active research fields which have attracted wide attention in last two decades. A brief outline of the investigations in these fields carried out in our Laboratory of Inorganic Photochemistry and Energy Conversion is given here with no attempt of an exhaustive coverage of the literature. The emphasis is placed on recent work and information on the above mentioned subjects. Three types of supramolecular systems have been the focus of this work: (i) cage-type coordination compounds; (ii) second-sphere coordination compounds, exemplified by ion-pair photochemistry of cobalt complexes and (iii) covalently-linked systems. In the latter, modulation of the photoluminescence and photochemistry of some rhenium complexes are discussed. Solar energy conversion and development of thin-layer photoelectrochemical solar cells based on sensitization of nanocrystalline semiconductor films by some ruthenium polypyridyl complexes are presented as an important application that resulted from specifically engineered artificial assemblies.

Nanofluid Types, Their Synthesis, Properties and Incorporation in Direct Solar Thermal Collectors: A Review

PubMed Central

Chamsa-ard, Wisut; Brundavanam, Sridevi; Fung, Chun Che; Fawcett, Derek; Poinern, Gerrard

2017-01-01

The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented. PMID:28561802

The Physics of Energy

NASA Astrophysics Data System (ADS)

Jaffe, Robert L.; Taylor, Washington

2018-01-01

Part I. Basic Energy Physics and Uses: 1. Introduction; 2. Mechanical energy; 3. Electromagnetic energy; 4. Waves and light; 5. Thermodynamics I: heat and thermal energy; 6. Heat transfer; 7. Introduction to quantum physics; 8. Thermodynamics II: entropy and temperature; 9. Energy in matter; 10. Thermal energy conversion; 11. Internal combustion engines; 12. Phase-change energy conversion; 13. Thermal power and heat extraction cycles; Part II. Energy Sources: 14. The forces of nature; 15. Quantum phenomena in energy systems; 16. An overview of nuclear power; 17. Structure, properties and decays of nuclei; 18. Nuclear energy processes: fission and fusion; 19. Nuclear fission reactors and nuclear fusion experiments; 20. Ionizing radiation; 21. Energy in the universe; 22. Solar energy: solar production and radiation; 23. Solar energy: solar radiation on Earth; 24. Solar thermal energy; 25. Photovoltaic solar cells; 26. Biological energy; 27. Ocean energy flow; 28. Wind: a highly variable resource; 29. Fluids – the basics; 30. Wind turbines; 31. Energy from moving water: hydro, wave, tidal, and marine current power; 32. Geothermal energy; 33. Fossil fuels; Part III. Energy System Issues and Externalities: 34. Energy and climate; 35. Earth's climate: past, present, and future; 36. Energy efficiency, conservation, and changing energy sources; 37. Energy storage; 38. Electricity generation and transmission.

Nanofluid Types, Their Synthesis, Properties and Incorporation in Direct Solar Thermal Collectors: A Review.

PubMed

Chamsa-Ard, Wisut; Brundavanam, Sridevi; Fung, Chun Che; Fawcett, Derek; Poinern, Gerrard

2017-05-31

The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented.

Photon-enhanced thermionic emission for solar concentrator systems.

PubMed

Schwede, Jared W; Bargatin, Igor; Riley, Daniel C; Hardin, Brian E; Rosenthal, Samuel J; Sun, Yun; Schmitt, Felix; Pianetta, Piero; Howe, Roger T; Shen, Zhi-Xun; Melosh, Nicholas A

2010-09-01

Solar-energy conversion usually takes one of two forms: the 'quantum' approach, which uses the large per-photon energy of solar radiation to excite electrons, as in photovoltaic cells, or the 'thermal' approach, which uses concentrated sunlight as a thermal-energy source to indirectly produce electricity using a heat engine. Here we present a new concept for solar electricity generation, photon-enhanced thermionic emission, which combines quantum and thermal mechanisms into a single physical process. The device is based on thermionic emission of photoexcited electrons from a semiconductor cathode at high temperature. Temperature-dependent photoemission-yield measurements from GaN show strong evidence for photon-enhanced thermionic emission, and calculated efficiencies for idealized devices can exceed the theoretical limits of single-junction photovoltaic cells. The proposed solar converter would operate at temperatures exceeding 200 degrees C, enabling its waste heat to be used to power a secondary thermal engine, boosting theoretical combined conversion efficiencies above 50%.

Engineered nanomaterials for solar energy conversion.

PubMed

Mlinar, Vladan

2013-02-01

Understanding how to engineer nanomaterials for targeted solar-cell applications is the key to improving their efficiency and could lead to breakthroughs in their design. Proposed mechanisms for the conversion of solar energy to electricity are those exploiting the particle nature of light in conventional photovoltaic cells, and those using the collective electromagnetic nature, where light is captured by antennas and rectified. In both cases, engineered nanomaterials form the crucial components. Examples include arrays of semiconductor nanostructures as an intermediate band (so called intermediate band solar cells), semiconductor nanocrystals for multiple exciton generation, or, in antenna-rectifier cells, nanomaterials for effective optical frequency rectification. Here, we discuss the state of the art in p-n junction, intermediate band, multiple exciton generation, and antenna-rectifier solar cells. We provide a summary of how engineered nanomaterials have been used in these systems and a discussion of the open questions.

High-flux solar-driven thermochemical dissociation of CO2 and H2O using nonstoichiometric ceria.

PubMed

Chueh, William C; Falter, Christoph; Abbott, Mandy; Scipio, Danien; Furler, Philipp; Haile, Sossina M; Steinfeld, Aldo

2010-12-24

Because solar energy is available in large excess relative to current rates of energy consumption, effective conversion of this renewable yet intermittent resource into a transportable and dispatchable chemical fuel may ensure the goal of a sustainable energy future. However, low conversion efficiencies, particularly with CO(2) reduction, as well as utilization of precious materials have limited the practical generation of solar fuels. By using a solar cavity-receiver reactor, we combined the oxygen uptake and release capacity of cerium oxide and facile catalysis at elevated temperatures to thermochemically dissociate CO(2) and H(2)O, yielding CO and H(2), respectively. Stable and rapid generation of fuel was demonstrated over 500 cycles. Solar-to-fuel efficiencies of 0.7 to 0.8% were achieved and shown to be largely limited by the system scale and design rather than by chemistry.

The 15 kW sub e (nominal) solar thermal electric power conversion concept definition study: Steam Rankine turbine system

NASA Technical Reports Server (NTRS)

Bland, T. J.

1979-01-01

A study to define the performance and cost characteristics of a solar powered, steam Rankine turbine system located at the focal point of a solar concentrator is presented. A two stage re-entry turbine with reheat between stages, which has an efficiency of 27% at a turbine inlet temperature of 732 C was used. System efficiency was defined as 60 Hertz electrical output divided by absorbed thermal input in the working fluid. Mass production costs were found to be approximately 364 dollars/KW.

Potential impact of ZT = 4 thermoelectric materials on solar thermal energy conversion technologies.

PubMed

Xie, Ming; Gruen, Dieter M

2010-11-18

State-of-the-art methodologies for the conversion of solar thermal power to electricity are based on conventional electromagnetic induction techniques. If appropriate ZT = 4 thermoelectric materials were available, it is likely that conversion efficiencies of 30-40% could be achieved. The availability of all solid state electricity generation would be a long awaited development in part because of the elimination of moving parts. This paper presents a preliminary examination of the potential performance of ZT = 4 power generators in comparison with Stirling engines taking into account specific mass, volume and cost as well as system reliability. High-performance thermoelectrics appear to have distinct advantages over magnetic induction technologies.

Preliminary design of an advanced Stirling system for terrestrial solar energy conversion

NASA Astrophysics Data System (ADS)

White, M. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

A preliminary design was generated for an advanced Stirling conversion system (ASCS) that will be capable of delivering about 25 kW of electric power to an electric utility grid. Stirling engines are being evaluated for terrestrial solar applications. A two-year task to complete detailed design, fabrication, assembly and testing of an ASCS prototype began in April, 1990. The ASCS is designed to deliver maximum power per year over a range of solar inputs with a design life of 30 years (60,000 h). The ACSC has a long-term cost goal of about $450 per kilowatt, exclusive of the 11-m parabolic dish concentrator. The proposed system includes a Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator. The major thrusts of the preliminary design are described, including material selection for the hot-end components, heat transport system (reflux pool boiler) design, system thermal response, improved manufacturability, FMECA/FTA analysis, updated manufacturing cost estimate, and predicted system performance.

Preliminary design of an advanced Stirling system for terrestrial solar energy conversion

NASA Technical Reports Server (NTRS)

White, M. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

1990-01-01

A preliminary design was generated for an advanced Stirling conversion system (ASCS) that will be capable of delivering about 25 kW of electric power to an electric utility grid. Stirling engines are being evaluated for terrestrial solar applications. A two-year task to complete detailed design, fabrication, assembly and testing of an ASCS prototype began in April, 1990. The ASCS is designed to deliver maximum power per year over a range of solar inputs with a design life of 30 years (60,000 h). The ACSC has a long-term cost goal of about $450 per kilowatt, exclusive of the 11-m parabolic dish concentrator. The proposed system includes a Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator. The major thrusts of the preliminary design are described, including material selection for the hot-end components, heat transport system (reflux pool boiler) design, system thermal response, improved manufacturability, FMECA/FTA analysis, updated manufacturing cost estimate, and predicted system performance.

Monitoring of concentrated radiation beam for photovoltaic and thermal solar energy conversion applications.

PubMed

Parretta, Antonio; Privato, Carlo; Nenna, Giuseppe; Antonini, Andrea; Stefancich, Marco

2006-10-20

Methods for evaluating the light intensity distribution on receivers of concentrated solar radiation systems are described. They are based on the use of Lambertian diffusers in place of the illuminated receiver and on the acquisition of the scattered light, in reflection or transmission mode, by a CCD camera. The spatial distribution of intensity radiation is then numerically derived from the recorded images via a proprietary code. The details of the method are presented and a short survey of the main applications of the method in the photovoltaic and thermal solar energy conversion field is proposed. Methods for investigating the Lambertian character of commercial diffusers are also discussed.

Scattering-layer-induced energy storage function in polymer-based quasi-solid-state dye-sensitized solar cells.

PubMed

Zhang, Xi; Jiang, Hongrui

2015-03-09

Photo-self-charging cells (PSCs) are compact devices with dual functions of photoelectric conversion and energy storage. By introducing a scattering layer in polymer-based quasi-solid-state dye-sensitized solar cells, two-electrode PSCs with highly compact structure were obtained. The charge storage function stems from the formed ion channel network in the scattering layer/polymer electrolyte system. Both the photoelectric conversion and the energy storage functions are integrated in only the photoelectrode of such PSCs. This design of PSC could continuously output power as a solar cell with considerable efficiency after being photo-charged. Such PSCs could be applied in highly-compact mini power devices.

Solar thermophotovoltaic system using nanostructures.

PubMed

Ungaro, Craig; Gray, Stephen K; Gupta, Mool C

2015-09-21

This paper presents results on a highly efficient experimental solar thermophotovoltaic (STPV) system using simulated solar energy. An overall power conversion efficiency of 6.2% was recorded under solar simulation. This was matched with a thermodynamic model, and the losses within the system, as well as a path forward to mitigate these losses, have been investigated. The system consists of a planar, tungsten absorbing/emitting structure with an anti-reflection layer coated laser-microtextured absorbing surface and single-layer dielectric coated emitting surface. A GaSb PV cell was used to capture the emitted radiation and convert it into electrical energy. This simple structure is both easy to fabricate and temperature stable, and contains no moving parts or heat exchange fluids.

Conceptual design of an advanced Stirling conversion system for terrestrial power generation

NASA Technical Reports Server (NTRS)

1988-01-01

A free piston Stirling engine coupled to an electric generator or alternator with a nominal kWe power output absorbing thermal energy from a nominal 100 square meter parabolic solar collector and supplying electric power to a utility grid was identified. The results of the conceptual design study of an Advanced Stirling Conversion System (ASCS) were documented. The objectives are as follows: define the ASCS configuration; provide a manufacturability and cost evaluation; predict ASCS performance over the range of solar input required to produce power; estimate system and major component weights; define engine and electrical power condidtioning control requirements; and define key technology needs not ready by the late 1980s in meeting efficiency, life, cost, and with goalds for the ASCS.

Improving solar-pumped laser efficiency by a ring-array concentrator

NASA Astrophysics Data System (ADS)

Tibúrcio, Bruno D.; Liang, Dawei; Almeida, Joana; Matos, Rodrigo; Vistas, Cláudia R.

2018-01-01

We report here a compact pumping scheme for achieving large improvement in collection and conversion efficiency of a Nd:YAG solar-pumped laser by an innovative ring-array solar concentrator. An aspheric fused silica lens was used to further concentrate the solar radiation from the focal region of the 1.5-m-diameter ring-array concentrator to a 5.0-mm-diameter, 20-mm-length Nd:YAG single-crystal rod within a conical-shaped pump cavity, enabling multipass pumping to the laser rod. 67.3-W continuous-wave solar laser power was numerically calculated, corresponding to 38.2-W / m2 solar laser collection efficiency, being 1.22 and 1.27 times more than the state-of-the-art records by both heliostat-parabolic mirror and Fresnel lens solar laser systems, respectively. 4.0% conversion efficiency and 0.021-W brightness figure of merit were also numerically obtained, corresponding to 1.25 and 1.62 times enhancement over the previous records, respectively. The influence of tracking error on solar laser output power was also analyzed.

Parabolic Dish Solar Thermal Power Annual Program Review Proceedings

NASA Technical Reports Server (NTRS)

Lucas, J. W.

1982-01-01

The results of activities of the parabolic dish technology and applications development element of DOE's Solar Thermal Energy System Program are presented. Topics include the development and testing of concentrators, receivers, and power conversion units; system design and development for engineering experiments; economic analysis and marketing assessment; and advanced development activities. A panel discussion concerning industrial support sector requirements is also documented.

Holographic spectrum-splitting optical systems for solar photovoltaics

NASA Astrophysics Data System (ADS)

Zhang, Deming

Solar energy is the most abundant source of renewable energy available. The relatively high cost prevents solar photovoltaic (PV) from replacing fossil fuel on a larger scale. In solar PV power generation the cost is reduced with more efficient PV technologies. In this dissertation, methods to improve PV conversion efficiency with holographic optical components are discussed. The tandem multiple-junction approach has achieved very high conversion efficiency. However it is impossible to manufacture tandem PV cells at a low cost due to stringent fabrication standards and limited material types that satisfy lattice compatibility. Current produced by the tandem multi-junction PV cell is limited by the lowest junction due to series connection. Spectrum-splitting is a lateral multi-junction concept that is free of lattice and current matching constraints. Each PV cell can be optimized towards full absorption of a spectral band with tailored light-trapping schemes. Holographic optical components are designed to achieve spectrum-splitting PV energy conversion. The incident solar spectrum is separated onto multiple PV cells that are matched to the corresponding spectral band. Holographic spectrum-splitting can take advantage of existing and future low-cost technologies that produces high efficiency thin-film solar cells. Spectrum-splitting optical systems are designed and analyzed with both transmission and reflection holographic optical components. Prototype holograms are fabricated and high optical efficiency is achieved. Light-trapping in PV cells increases the effective optical path-length in the semiconductor material leading to improved absorption and conversion efficiency. It has been shown that the effective optical path length can be increased by a factor of 4n2 using diffusive surfaces. Ultra-light-trapping can be achieved with optical filters that limit the escape angle of the diffused light. Holographic reflection gratings have been shown to act as angle-wavelength selective filters that can function as ultra-light-trapping filters. Results from an experimental reflection hologram are used to model the absorption enhancement factor for a silicon solar cell and light-trapping filter. The result shows a significant improvement in current generation for thin-film silicon solar cells under typical operating conditions.

Rectenna System Design. [energy conversion solar power satellites

NASA Technical Reports Server (NTRS)

Woodcock, G. R.; Andryczyk, R. W.

1980-01-01

The fundamental processes involved in the operation of the rectenna system designed for the solar power satellite system are described. The basic design choices are presented based on the desired microwave rf field concentration prior to rectification and based on the ground clearance requirements for the rectenna structure. A nonconcentrating inclined planar panel with a 2 meter minimum clearance configuration is selected as a representative of the typical rectenna.

Proceedings of the First ERDA Semiannual Solar Photovoltaic Conversion Program Conference

NASA Technical Reports Server (NTRS)

1975-01-01

Organization, basic research and applied technology for the Solar Photovoltaic Conversion Program are outlined. The program aims to provide a technology base for low cost thin film solar cells and solar arrays.

Novel Space-based Solar Power Technologies and Architectures for Earth and Beyond

NASA Technical Reports Server (NTRS)

Howell, Joe T.; Fikes, John C.; O'Neill, Mark J.

2005-01-01

Research, development and studies of novel space-based solar power systems, technologies and architectures for Earth and beyond are needed to reduce the cost of clean electrical power for terrestrial use and to provide a stepping stone for providing an abundance of power in space, i.e., manufacturing facilities, tourist facilities, delivery of power between objects in space, and between space and surface sites. The architectures, technologies and systems needed for space to Earth applications may also be used for in-space applications. Advances in key technologies, i.e., power generation, power management and distribution, power beaming and conversion of beamed power are needed to achieve the objectives of both terrestrial and extraterrestrial applications. Power beaming or wireless power transmission (WPT) can involve lasers or microwaves along with the associated power interfaces. Microwave and laser transmission techniques have been studied with several promising approaches to safe and efficient WPT identified. These investigations have included microwave phased array transmitters, as well as laser transmission and associated optics. There is a need to produce "proof-of-concept" validation of critical WPT technologies for both the near-term, as well as far-term applications. Investments may be harvested in near-term beam safe demonstrations of commercial WPT applications. Receiving sites (users) include ground-based stations for terrestrial electrical power, orbital sites to provide power for satellites and other platforms, future space elevator systems, space vehicle propulsion, and space to surface sites. This paper briefly discusses achieving a promising approach to the solar power generation and beamed power conversion. The approach is based on a unique high-power solar concentrator array called Stretched Lens Array (SLA) for both solar power generation and beamed power conversion. Since both versions (solar and laser) of SLA use many identical components (only the photovoltaic cells need to be different), economies of manufacturing and scale may be realized by using SLA on both ends of the laser power beaming system in a space solar power application. Near-term uses of this SLA-laser-SLA system may include terrestrial and space exploration in near Earth space. Later uses may include beamed power for bases or vehicles on Mars.

Advantages of thin silicon solar cells for use in space

NASA Technical Reports Server (NTRS)

Denman, O. S.

1978-01-01

A system definition study on the Solar Power Satellite System showed that a thin, 50 micrometers, silicon solar cell has significant advantages. The advantages include a significantly lower performance degradation in a radiation environment and high power-to-mass ratios. The advantages of such cells for an employment in space is further investigated. Basic questions concerning the operation of solar cells are considered along with aspects of radiation induced performance degradation. The question arose in this connection how thin a silicon solar cell had to be to achieve resistance to radiation degradation and still have good initial performance. It was found that single-crystal silicon solar cells could be as thin as 50 micrometers and still develop high conversion efficiencies. It is concluded that the use of 50 micrometer silicon solar cells in space-based photovoltaic power systems would be advantageous.

The Solar Collector on Clementine Street.

ERIC Educational Resources Information Center

Stranix, Edward; Fleishman, Michael

1980-01-01

Listed are 12 energy activities, experiments, and projects which some eighth-grade students performed in their classroom and local community before they helped install a solar heating system on the roof of an old house during school time and on Saturdays. The building conversion project is described. (KC)

Conservation and solar energy program: congressional budget request, FY 1982

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1981-01-01

Funding summaries are presented for the Conservation and Solar Energy Program funding information and program overview on energy conservation (Volume 7 of 7, DOE/CR-0011/2) are included for the Buildings and Community Systems, Industrial, Transportation; State and Local, Multi-Sector, Energy Impact Assistance, and Residential/Commercial retrofit programs. Funding information and program overviews on solar technology (Volume 2 of 7, DOE/CR-011/2) are included for Active and Passive Solar Heating and Cooling, Photovoltaics Energy Systems, Solar Thermal Power Systems, Biomass Energy Systems, Wind Energy Conversion Systems, Ocean Systems, Solar International Activities, Solar Information Systems, SERI Facility, MX-RES, Program Direction, and Alcohol Fuels programs. Informationmore » and overviews on energy production, demonstration, and distribution (Volume 6 of 7, DOE/CR-0011/2) are given for the solar program. A funding summary and a program overview are included for electrochemical and physical and chemical storage systems as appearing in DOE/CR-0011/2, Volume 3 of 7. Relevant tabulated data from the FY 1981. Request to the Congress are presented for Supplementals, Rescissions, and Deferrals. (MCW)« less

An investigation of the Performance of a Conical Solar Water Heater in the Kingdom of Bahrain

NASA Astrophysics Data System (ADS)

Gaaliche, Nessreen; Ayhan, Teoman; Fathallah, Raouf

2017-11-01

Domestic water heater corresponds to 25% of the house energy consumption and can play an important role to reduce energy house expenses. Solar energy offers a preferred renewable energy resource because of its economic and environmental advantages. It is considered the best alternative to reduce domestic water heater energy consumption cost. Converting solar energy into heat can be considered among the simplest used systems. Solar thermal conversion is more efficient than solar electrical direct conversion method. Solar water heater systems are particularly easy to use and to repair. The integrated conical solar collector water heater (ICSCWH) is so far the easiest among water heating systems. The ICSCWH converts directly and efficiently the solar flux into heat. In order to expand the utilization of ICSCWH systems, many design modifications have been examined and analyzed. This study provides an experimental investigation and mathematical simulation of an ICSCWH system equipped with a glass cover resulting in the increase of the maximum absorption. Integrating the cone-shaped heat collector with an aluminum spiral pipe flow system may enhance the efficiency of the proposed system. In order to maximize the solar radiation of the system, the solar water heater has been designed in a conical shape, which removes the need to change its orientation toward the sun to receive the maximum sun radiation during the day. In this system, the heating of water has been obtained using the spiral pipe flow without the use of the solar cells and mirrors in order to reduce the total cost. The storage water tank of this system is coupled with a conical solar collector. Based on the above design, the solar water heater has been fabricated and tested. In addition, an analytical modeling approach aiming to predict the flow rate within the conical integrated collector storage solar water heater (ICSSWH) and its efficiency, was developed. Modeling through a numerical simulation approach based on energy equations was performed. Considering the entire water amount and the total area of the cone, the amount of water (facing the sun per unit absorbing area in the two symmetrical parts of the system) is found to increase, which is expected to reach a maximum water temperature at a high performance. Our experimental findings show that the daily performance is around 32% and the highest water temperature of about 45°C is obtained in the system at 4 pm, according to seasons and weather conditions. An efficient and simple mathematical simulation approach for the new conical solar water heater is described then validates using experimental data.

Electrospun TiO2 nanofibers incorporated with graphene nanoflakes for energy conversion

NASA Astrophysics Data System (ADS)

Shinde, Manish A.; Alarifi, Ibrahim; Alharbi, Abdulaziz; Asmatulu, Ramazan

2015-03-01

Solar energy has been used in many different ways, including solar water heater, solar cooking, space heating, and electricity generation. The major drawbacks of the solar energy conversion systems are the lower conversion efficiency and higher manufacturing and replacement costs. In order to eliminate these obstacles, many studies were focused on the energy and cost efficiencies of the solar cells (particularly dye sensitized solar cells - DSSC and thin film solar cells). In the present study, TiO2 nanofibers incorporated with graphene nanoflakes (0, 2, 4, and 8wt.%) were produced using electrospinning process. The chemical utilized for the electrospinning process included poly (vinyle acetate), dimetylfomamide (DMF), titanium (IV) isopropoxide and acetic acid in the presence and absence of graphene nanoflakes. The resultant nanofibers were heat treated at 300 °C for 2 hrs in a standard oven to remove all the organic parts of the nanofibers, and then further heated up to 500 °C in an argon atmosphere for additional 12 hrs to crystalline the nanofibers. SEM, TEM and XRD studies showed that graphene and TiO2 nanofibers are well integrated in the nanofiber structures. This study may guide some of the scientists and engineers to tailor the energy bang gap structures of some of the semiconductor materials for different industrial applications, including DSSC, water splitting, catalyst, batteries, and fuel cell.

Hybrid Organic/Inorganic Nanocomposites for Photovoltaic Cells

PubMed Central

Liu, Ruchuan

2014-01-01

Inorganic/organic hybrid solar cells have attracted a lot of interest due to their potential in combining the advantages of both components. To understand the key issues in association with photoinduced charge separation/transportation processes and to improve overall power conversion efficiency, various combinations with nanostructures of hybrid systems have been investigated. Here, we briefly review the structures of hybrid nanocomposites studied so far, and attempt to associate the power conversion efficiency with these nanostructures. Subsequently, we are then able to summarize the factors for optimizing the performance of inorganic/organic hybrid solar cells. PMID:28788591

Solar Energy.

ERIC Educational Resources Information Center

Eaton, William W.

Presented is the utilization of solar radiation as an energy resource principally for the production of electricity. Included are discussions of solar thermal conversion, photovoltic conversion, wind energy, and energy from ocean temperature differences. Future solar energy plans, the role of solar energy in plant and fossil fuel production, and…

Triplet-triplet annihilation photon-upconversion: towards solar energy applications.

PubMed

Gray, Victor; Dzebo, Damir; Abrahamsson, Maria; Albinsson, Bo; Moth-Poulsen, Kasper

2014-06-14

Solar power production and solar energy storage are important research areas for development of technologies that can facilitate a transition to a future society independent of fossil fuel based energy sources. Devices for direct conversion of solar photons suffer from poor efficiencies due to spectrum losses, which are caused by energy mismatch between the optical absorption of the devices and the broadband irradiation provided by the sun. In this context, photon-upconversion technologies are becoming increasingly interesting since they might offer an efficient way of converting low energy solar energy photons into higher energy photons, ideal for solar power production and solar energy storage. This perspective discusses recent progress in triplet-triplet annihilation (TTA) photon-upconversion systems and devices for solar energy applications. Furthermore, challenges with evaluation of the efficiency of TTA-photon-upconversion systems are discussed and a general approach for evaluation and comparison of existing systems is suggested.

Solar energy conversion through the interaction of plasmons with tunnel junctions. Part A: Solar cell analysis. Part B: Photoconductor analysis

NASA Technical Reports Server (NTRS)

Welsh, P. E.; Schwartz, R. J.

1988-01-01

A solar cell utilizing guided optical waves and tunnel junctions was analyzed to determine its feasibility. From this analysis, it appears that the limits imposed upon conventional multiple cell systems also limit this solar cell. Due to this limitation, it appears that the relative simplicity of the conventional multiple cell systems over the solar cell make the conventional multiple cell systems the more promising candidate for improvement. It was discovered that some superlattice structures studied could be incorporated into an infrared photodetector. This photoconductor appears to be promising as a high speed, sensitive (high D sup star sub BLIP) detector in the wavelength range from 15 to over 100 micrometers.

Indium oxide/n-silicon heterojunction solar cells

DOEpatents

Feng, Tom; Ghosh, Amal K.

1982-12-28

A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

Design and integration of a solar AMTEC power system with an advanced global positioning satellite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, G.; Hunt, M.E.; Determan, W.R.

1996-12-31

A 1,200-W solar AMTEC (alkali metal thermal-to-electric conversion) power system concept was developed and integrated with an advanced global positioning system (GPS) satellite. The critical integration issues for the SAMTEC with the GPS subsystems included (1) packaging within the Delta 2 launch vehicle envelope, (2) deployment and start-up operations for the SAMTEC, (3) SAMTEC operation during all mission phases, (4) satellite field of view restrictions with satellite operations, and (5) effect of the SAMTEC requirements on other satellite subsystems. The SAMTEC power system was compared with a conventional planar solar array/battery power system to assess the differences in system weight,more » size, and operations. Features of the design include the use of an advanced multitube, vapor anode AMTEC cell design with 24% conversion efficiency, and a direct solar insolation receiver design with integral LiF salt canisters for energy storage to generate power during the maximum solar eclipse cycle. The modular generator design consists of an array of multitube AMTEC cells arranged into a parallel/series electrical network with built-in cell redundancy. The preliminary assessment indicates that the solar generator design is scalable over a 500 to 2,500-W range. No battery power is required during the operational phase of the GPS mission. SAMTEC specific power levels greater than 5 We/kg and 160 We/m{sup 2} are anticipated for a mission duration of 10 to 12 yr in orbits with high natural radiation backgrounds.« less

Solar electricity and solar fuels

NASA Astrophysics Data System (ADS)

Spiers, David J.

1989-04-01

The nature of solar radiation and its variation with location is described. The distribution of energy in the solar spectrum places immediate limits on the theoretical efficiency of conversion processes, since practical absorbers cannot convert all wavelengths received to useful energy. The principles of solar energy conversion methods are described. Absorption of solar energy can give rise to direct electrical generation, heating, or chemical change. Electrical generation from sunlight can be achieved by photovoltaic systems directly or by thermal systems which use solar heat to drive a heat engine and generator. The technology used and under research for promising ways of producing electricity or fuel from solar energy is described. Photovoltaic technology is established today for remote area, small power applications, and photovoltaic module sales alone are over 100 million dollars per year at present. The photovoltaic market has grown steadily since the mid-1970's, as prices have fallen continuously. Future energy options are briefly described. The merits of a sustainable energy economy, based on renewable energy resources, including solar energy, are emphasized, as this seems to provide the only hope of eliminating the problems caused by the build-up of atmospheric carbon dioxide, acid rain pollution and nuclear waste disposal. There is no doubt that clean fuels which were derived from solar energy and either did not involve carbon dioxide and used atmospheric carbon dioxide as the source dioxide as the source of carbon would be a worthy ideal. Methods described could one day achieve this.

Evaluating Energy Conversion Efficiency

NASA Technical Reports Server (NTRS)

Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.

1983-01-01

Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.

Simple and Efficient System for Combined Solar Energy Harvesting and Reversible Hydrogen Storage.

PubMed

Li, Lu; Mu, Xiaoyue; Liu, Wenbo; Mi, Zetian; Li, Chao-Jun

2015-06-24

Solar energy harvesting and hydrogen economy are the two most important green energy endeavors for the future. However, a critical hurdle to the latter is how to safely and densely store and transfer hydrogen. Herein, we developed a reversible hydrogen storage system based on low-cost liquid organic cyclic hydrocarbons at room temperature and atmospheric pressure. A facile switch of hydrogen addition (>97% conversion) and release (>99% conversion) with superior capacity of 7.1 H2 wt % can be quickly achieved over a rationally optimized platinum catalyst with high electron density, simply regulated by dark/light conditions. Furthermore, the photodriven dehydrogenation of cyclic alkanes gave an excellent apparent quantum efficiency of 6.0% under visible light illumination (420-600 nm) without any other energy input, which provides an alternative route to artificial photosynthesis for directly harvesting and storing solar energy in the form of chemical fuel.

Energy conversion system

DOEpatents

Murphy, Lawrence M.

1987-01-01

The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weatherproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction, and operational with a minimal power draw.

Energy conversion system

DOEpatents

Murphy, L.M.

1985-09-16

The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weathproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction and operational with a minimal power draw.

Method for forming indium oxide/n-silicon heterojunction solar cells

DOEpatents

Feng, Tom; Ghosh, Amal K.

1984-03-13

A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

Current Status of Study on Hydrogen Production with Space Solar Power Systems (SSPS)

NASA Astrophysics Data System (ADS)

Mori, M.; Kagawa, H.; Nagayama, H.; Saito, Y.

2004-12-01

Japan Aerospace Exploration Agency (JAXA) has been conducting studies on Space Solar Power Systems (SSPS) using microwave and laser beams for years since FY1998 organizing a special committee and working groups. The microwave based SSPS are huge solar power systems that generate GW power by solar cells. The electric power is transmitted via microwave from the SSPS to the ground. In the laser based SSPS, a solar condenser equipped with lenses or mirrors and laser-generator would be put into orbit. A laser beam would be sent to Earth-based hydrogen generating device. We are proposing a roadmap that consists of a stepwise approach to achieve commercial SSPS in 20-30 years. The first step is 50kW class Technology Demonstration Satellite to demonstrate microwave power transmission. The second step is to demonstrate robotic assembly of 10MW class large scale flexible structure in space on ISS co-orbit. The third step is to build a prototype SSPS in GEO. The final step is to build commercial SSPS in GEO. We continue the study of SSPS concepts and architectures, technology flight demonstration and major technology development. System design of tens of kW class Technology Demonstration Satellite and conceptual study of 10MW class demonstration system on ISS co-orbit are also conducted. Several key technologies which are needed to be developed in appropriate R&D roadmap, such as high-voltage solar cell array, fiber type of direct solar pumping solid-state laser, high efficiency magnetron, thermal control technology and control technology of large scale flexible structure etc. are also investigated. In the study of concept design of commercial SSPS mentioned above, we have studied some configurations of both microwave based SSPS and laser based SSPS. In case of microwave based SSPS, the solar energy must be converted to electricity and then converted to a microwave beam. The on-ground rectifying antenna will collect the microwave beam and convert it to electricity to connect to commercial power grids. From the past experiences of the conceptual design of the1GW class SSPS, it is clear that system with the mirrors and modularized unit which integrated solar cells and microwave power transmitters is promising. In this type of SSPS, the solar lights are directed to the energy conversion unit integrated solar cells and microwave power transmitters using mirrors. The key factor in designing systems is feasibility of thermal system. Considering above these factors, some reference models are being considered now. FY2003 reference model is the model for formation flight without the center truss which connect to primary mirrors to energy conversion unit. Using this model as basis, we are carrying out examination from various viewpoints aiming at the cost minimum to build and maintain the systems. In case of laser based SSPS, the laser beam would be directly produced from the solar light using the direct solar pumping solid-state laser device. This laser beams would be collected on ground and used to produce hydrogen from seawater. The receiving / energy conversion station is settled on an ocean, and producing hydrogen can be stored and transported by ships to consumers. In designing laser based SSPS, conversion efficiency of the direct solar pumping solid-state laser and feasibility of thermal system are critical factors. Since magnification of solar concentrator is very high, improvement of thermal control system is important. Feasibility of its ground facilities and production technology of hydrogen using laser beams has been also studied. Both hydrogen generating systems with photo-catalyst device and electrolytic ones have been examined. From the past experiences of this study, high efficient electric power generating technology using the solar cell which suited the wavelength of laser is promising. The life cycle cost model of laser based SSPS was created and evaluated its validity. Sensitivity analysis of laser based SSPS are also continued aiming at hydrogen generating cost of around 20 cent per Nm3 . This paper presents a summary of studies on SSPS that JAXA has examined.

Nanocrystal Size-Dependent Efficiency of Quantum Dot Sensitized Solar Cells in the Strongly Coupled CdSe Nanocrystals/TiO2 System.

PubMed

Yun, Hyeong Jin; Paik, Taejong; Diroll, Benjamin; Edley, Michael E; Baxter, Jason B; Murray, Christopher B

2016-06-15

Light absorption and electron injection are important criteria determining solar energy conversion efficiency. In this research, monodisperse CdSe quantum dots (QDs) are synthesized with five different diameters, and the size-dependent solar energy conversion efficiency of CdSe quantum dot sensitized solar cell (QDSSCs) is investigated by employing the atomic inorganic ligand, S(2-). Absorbance measurements and transmission electron microscopy show that the diameters of the uniform CdSe QDs are 2.5, 3.2, 4.2, 6.4, and 7.8 nm. Larger CdSe QDs generate a larger amount of charge under the irradiation of long wavelength photons, as verified by the absorbance results and the measurements of the external quantum efficiencies. However, the smaller QDs exhibit faster electron injection kinetics from CdSe QDs to TiO2 because of the high energy level of CBCdSe, as verified by time-resolved photoluminescence and internal quantum efficiency results. Importantly, the S(2-) ligand significantly enhances the electronic coupling between the CdSe QDs and TiO2, yielding an enhancement of the charge transfer rate at the interfacial region. As a result, the S(2-) ligand helps improve the new size-dependent solar energy conversion efficiency, showing best performance with 4.2-nm CdSe QDs, whereas conventional ligand, mercaptopropionic acid, does not show any differences in efficiency according to the size of the CdSe QDs. The findings reported herein suggest that the atomic inorganic ligand reinforces the influence of quantum confinement on the solar energy conversion efficiency of QDSSCs.

Effect of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal solar cells

NASA Astrophysics Data System (ADS)

Sahin, Mehmet

2018-05-01

In this study, the effects of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal (QDNC) solar cells have been investigated in detail. For this purpose, the conventional, i.e. original, detailed balance model, developed by Shockley and Queisser to calculate an upper limit for the conversion efficiency of silicon p–n junction solar cells, is modified in a simple and effective way to calculate the conversion efficiency of core/shell QDNC solar cells. Since the existing model relies on the gap energy () of the solar cell, it does not make an estimation about the effect of QDNC materials on the efficiency of the solar cells, and gives the same efficiency values for several QDNC solar cells with the same . The proposed modification, however, estimates a conversion efficiency in relation to the material properties and also the confinement type of the QDNCs. The results of the modified model show that, in contrast to the original one, the conversion efficiencies of different QDNC solar cells, even if they have the same , become different depending upon the confinement type and shell material of the core/shell QDNCs, and this is crucial in the design and fabrication of the new generation solar cells to predict the confinement type and also appropriate QDNC materials for better efficiency.

Present Status and Future Prospects of Silicon Thin-Film Solar Cells

NASA Astrophysics Data System (ADS)

Konagai, Makoto

2011-03-01

In this report, an overview of the recent status of photovoltaic (PV) power generation is first presented from the viewpoint of reducing CO2 emission. Next, the Japanese roadmap for the research and development (R&D) of PV power generation and the progress in the development of various solar cells are explained. In addition, the present status and future prospects of amorphous silicon (a-Si) thin-film solar cells, which are expected to enter the stage of full-scale practical application in the near future, are described. For a-Si single-junction solar cells, the conversion efficiency of their large-area modules has now reached 6-8%, and their practical application to megawatt solar systems has started. Meanwhile, the focus of R&D has been shifting to a-Si and microcrystalline silicon (µc-Si) tandem solar cells. Thus far, a-Si/µc-Si tandem solar cell modules with conversion efficiency exceeding 13% have been reported. In addition, triple-junction solar cells, whose target year for practical application is 2025 or later, are introduced, as well as innovative thin-film full-spectrum solar cells, whose target year of realization is 2050.

Discovering Inexpensive, Effective Catalysts for Solar Energy Conversion: An Authentic Research Laboratory Experience

ERIC Educational Resources Information Center

Shaner, Sarah E.; Hooker, Paul D.; Nickel, Anne-Marie; Leichtfuss, Amanda R.; Adams, Carissa S.; de la Cerda, Dionisia; She, Yuqi; Gerken, James B.; Pokhrel, Ravi; Ambrose, Nicholas J.; Khaliqi, David; Stahl, Shannon S.; Schuttlefield Christus, Jennifer D.

2016-01-01

Electrochemical water oxidation is a major focus of solar energy conversion efforts. A new laboratory experiment has been developed that utilizes real-time, hands-on research to discover catalysts for solar energy conversion. The HARPOON, or Heterogeneous Anodes Rapidly Perused for Oxygen Overpotential Neutralization, experiment allows an array of…

Solar cell array design handbook - The principles and technology of photovoltaic energy conversion

NASA Technical Reports Server (NTRS)

Rauschenbach, H. S.

1980-01-01

Photovoltaic solar cell array design and technology for ground-based and space applications are discussed from the user's point of view. Solar array systems are described, with attention given to array concepts, historical development, applications and performance, and the analysis of array characteristics, circuits, components, performance and reliability is examined. Aspects of solar cell array design considered include the design process, photovoltaic system and detailed array design, and the design of array thermal, radiation shielding and electromagnetic components. Attention is then given to the characteristics and design of the separate components of solar arrays, including the solar cells, optical elements and mechanical elements, and the fabrication, testing, environmental conditions and effects and material properties of arrays and their components are discussed.

Solar thermophotovoltaic system using nanostructures

DOE PAGES

Ungaro, Craig; Gray, Stephen K.; Gupta, Mool C.

2015-08-20

This paper presents results on a highly efficient experimental solar thermophotovoltaic (STPV) system using simulated solar energy. An overall power conversion efficiency of 6.2% was recorded under solar simulation. This was matched with a thermodynamic model, and the losses within the system, as well as a path forward to mitigate these losses, have been investigated. The system consists of a planar, tungsten absorbing/emitting structure with an anti-reflection layer coated laser-microtextured absorbing surface and single-layer dielectric coated emitting surface. A GaSb PV cell was used to capture the emitted radiation and convert it into electrical energy. This simple structure is bothmore » easy to fabricate and temperature stable, and contains no moving parts or heat exchange fluids.« less

A photocatalyst-enzyme coupled artificial photosynthesis system for solar energy in production of formic acid from CO2.

PubMed

Yadav, Rajesh K; Baeg, Jin-Ook; Oh, Gyu Hwan; Park, No-Joong; Kong, Ki-jeong; Kim, Jinheung; Hwang, Dong Won; Biswas, Soumya K

2012-07-18

The photocatalyst-enzyme coupled system for artificial photosynthesis process is one of the most promising methods of solar energy conversion for the synthesis of organic chemicals or fuel. Here we report the synthesis of a novel graphene-based visible light active photocatalyst which covalently bonded the chromophore, such as multianthraquinone substituted porphyrin with the chemically converted graphene as a photocatalyst of the artificial photosynthesis system for an efficient photosynthetic production of formic acid from CO(2). The results not only show a benchmark example of the graphene-based material used as a photocatalyst in general artificial photosynthesis but also the benchmark example of the selective production system of solar chemicals/solar fuel directly from CO(2).

Development of an economic solar heating system with cost efficient flat plate collectors

NASA Astrophysics Data System (ADS)

Eder-Milchgeisser, W.; Burkart, R.

1980-10-01

Mass produced flat plate solar collectors were worked into the design of a system for heating a swimming pool and/or providing domestic hot water. The collector characteristics, including physical and mechanical data as well as theoretical energy conversion efficiency, are presented. The collector was tested and service life efficiency was determined. The mounting of the collector, depending on roof type, is explained. Both in service and laboratory test results demonstrate the cost effectiveness of the system. Further improvement of efficiency is envisaged with automatic flow control in the solar collector and hot water circuits.

Space power system utilizing Fresnel lenses for solar power and also thermal energy storage

NASA Technical Reports Server (NTRS)

Turner, R. H.

1983-01-01

A solar power plant suitable for earth orbits passing through Van Allen radiation belts is described. The solar-to-electricity conversion efficiency is estimated to be around 9 percent, and the expected power-to-weight ratio is competitive with photovoltaic arrays. The system is designed to be self-contained, to be indifferent to radiation belt exposures, store energy for periods when the orbiting system is in earth shadow (so that power generation is contant), have no moving parts and no working fluids, and be robust against micrometeorite attack. No electrical batteries are required.

Dual-Function Au@Y2O3:Eu3+ Smart Film for Enhanced Power Conversion Efficiency and Long-Term Stability of Perovskite Solar Cells.

PubMed

Kim, Chang Woo; Eom, Tae Young; Yang, In Seok; Kim, Byung Su; Lee, Wan In; Kang, Yong Soo; Kang, Young Soo

2017-07-28

In the present study, a dual-functional smart film combining the effects of wavelength conversion and amplification of the converted wave by the localized surface plasmon resonance has been investigated for a perovskite solar cell. This dual-functional film, composed of Au nanoparticles coated on the surface of Y 2 O 3 :Eu 3+ phosphor (Au@Y 2 O 3 :Eu 3+ ) nanoparticle monolayer, enhances the solar energy conversion efficiency to electrical energy and long-term stability of photovoltaic cells. Coupling between the Y 2 O 3 :Eu 3+ phosphor monolayer and ultraviolet solar light induces the latter to be converted into visible light with a quantum yield above 80%. Concurrently, the Au nanoparticle monolayer on the phosphor nanoparticle monolayer amplifies the converted visible light by up to 170%. This synergy leads to an increased solar light energy conversion efficiency of perovskite solar cells. Simultaneously, the dual-function film suppresses the photodegradation of perovskite by UV light, resulting in long-term stability. Introducing the hybrid smart Au@Y 2 O 3 :Eu 3+ film in perovskite solar cells increases their overall solar-to-electrical energy conversion efficiency to 16.1% and enhances long-term stability, as compared to the value of 15.2% for standard perovskite solar cells. The synergism between the wavelength conversion effect of the phosphor nanoparticle monolayer and the wave amplification by the localized surface plasmon resonance of the Au nanoparticle monolayer in a perovskite solar cell is comparatively investigated, providing a viable strategy of broadening the solar spectrum utilization.

Design and fabrication of cascaded dichromate gelatin holographic filters for spectrum-splitting PV systems

NASA Astrophysics Data System (ADS)

Wu, Yuechen; Chrysler, Benjamin; Kostuk, Raymond K.

2018-01-01

The technique of designing, optimizing, and fabricating broadband volume transmission holograms using dichromate gelatin (DCG) is summarized for solar spectrum-splitting applications. The spectrum-splitting photovoltaic (PV) system uses a series of single-bandgap PV cells that have different spectral conversion efficiency properties to more fully utilize the solar spectrum. In such a system, one or more high-performance optical filters are usually required to split the solar spectrum and efficiently send them to the corresponding PV cells. An ideal spectral filter should have a rectangular shape with sharp transition wavelengths. A methodology of designing and modeling a transmission DCG hologram using coupled wave analysis for different PV bandgap combinations is described. To achieve a broad diffraction bandwidth and sharp cutoff wavelength, a cascaded structure of multiple thick holograms is described. A search algorithm is then developed to optimize both single- and two-layer cascaded holographic spectrum-splitting elements for the best bandgap combinations of two- and three-junction spectrum-splitting photovoltaic (SSPV) systems illuminated under the AM1.5 solar spectrum. The power conversion efficiencies of the optimized systems are found to be 42.56% and 48.41%, respectively, using the detailed balance method, and show an improvement compared with a tandem multijunction system. A fabrication method for cascaded DCG holographic filters is also described and used to prototype the optimized filter for the three-junction SSPV system.

Space satellite power system. [conversion of solar energy by photovoltaic solar cell arrays

NASA Technical Reports Server (NTRS)

Glaser, P. E.

1974-01-01

The concept of a satellite solar power station was studied. It is shown that it offers the potential to meet a significant portion of future energy needs, is pollution free, and is sparing of irreplaceable earth resources. Solar energy is converted by photovoltaic solar cell arrays to dc energy which in turn is converted into microwave energy in a large active phased array. The microwave energy is beamed to earth with little attenuation and is converted back to dc energy on the earth. Economic factors are considered.

Carbon nanostructures for solar energy conversion schemes.

PubMed

Guldi, Dirk M; Sgobba, Vito

2011-01-14

Developing environmentally friendly, renewable energy is one of the challenges to society in the 21st century. One of the renewable energy technologies is solar energy conversion--a technology that directly converts daylight into electricity. This highlight surveys recent breakthroughs in the field of implementing carbon nanostructures--fullerenes (0D), carbon nanotubes (1D), carbon nanohorns, and graphene (2D)--into solar energy conversion schemes, that is, bulk heterojunction and dye-sensitized solar cells.

Review of solar fuel-producing quantum conversion processes

NASA Technical Reports Server (NTRS)

Peterson, D. B.; Biddle, J. R.; Fujita, T.

1984-01-01

The status and potential of fuel-producing solar photochemical processes are discussed. Research focused on splitting water to produce dihydrogen and is at a relatively early stage of development. Current emphasis is primarily directed toward understanding the basic chemistry underlying such quantum conversion processes. Theoretical analyses by various investigators predict a limiting thermodynamic efficiency of 31% for devices with a single photosystem operating with unfocused sunlight at 300 K. When non-idealities are included, it appears unlikely that actual devices will have efficiencies greater than 12 to 15%. Observed efficiencies are well below theoretical limits. Cyclic homogeneous photochemical processes for splitting water have efficiencies considerably less than 1%. Efficiency can be significantly increased by addition of a sacrificial reagent; however, such systems are no longer cyclic and it is doubtful that they would be economical on a commercial scale. The observed efficiencies for photoelectrochemical processes are also low but such systems appear more promising than homogeneous photochemical systems. Operating and systems options, including operation at elevated temperature and hybrid and coupled quantum-thermal conversion processes, are also considered.

Cobalt and Yttrium Modified TiO2 Nanotubes Based Dye-Sensitized Solar Cells for Solar-Energy Conversion

NASA Astrophysics Data System (ADS)

Shabanov, N. S.; Isaev, A. B.; Orudzhev, F. F.; Murliev, E. K.

2018-01-01

The solar-energy conversion in eosin-sensitized solar cells based on cobalt and yttrium modified TiO2 nanotubes has been studied.It is established that the doping with metal ions shifts the absorption edge for Co and Y doped titanium dioxide samples to longer and shorter wavelengths, respectively. The efficiency of solar energy conversion depends on the wide bandgap of the semiconductor anode and reaches a maximum (4.4%) for yttrium-doped TiO2 in comparison to that (4.1%) for pure titanium dioxide.

Enhanced Power Conversion Efficiency of Perovskite Solar Cells with an Up-Conversion Material of Er3+-Yb3+-Li+ Tri-doped TiO2

NASA Astrophysics Data System (ADS)

Zhang, Zhenlong; Qin, Jianqiang; Shi, Wenjia; Liu, Yanyan; Zhang, Yan; Liu, Yuefeng; Gao, Huiping; Mao, Yanli

2018-05-01

In this paper, Er3+-Yb3+-Li+ tri-doped TiO2 (UC-TiO2) was prepared by an addition of Li+ to Er3+-Yb3+ co-doped TiO2. The UC-TiO2 presented an enhanced up-conversion emission compared with Er3+-Yb3+ co-doped TiO2. The UC-TiO2 was applied to the perovskite solar cells. The power conversion efficiency (PCE) of the solar cells without UC-TiO2 was 14.0%, while the PCE of the solar cells with UC-TiO2 was increased to 16.5%, which presented an increase of 19%. The results suggested that UC-TiO2 is an effective up-conversion material. And this study provided a route to expand the spectral absorption of perovskite solar cells from visible light to near-infrared using up-conversion materials.

Enhanced Power Conversion Efficiency of Perovskite Solar Cells with an Up-Conversion Material of Er3+-Yb3+-Li+ Tri-doped TiO2.

PubMed

Zhang, Zhenlong; Qin, Jianqiang; Shi, Wenjia; Liu, Yanyan; Zhang, Yan; Liu, Yuefeng; Gao, Huiping; Mao, Yanli

2018-05-11

In this paper, Er 3+ -Yb 3+ -Li + tri-doped TiO 2 (UC-TiO 2 ) was prepared by an addition of Li + to Er 3+ -Yb 3+ co-doped TiO 2 . The UC-TiO 2 presented an enhanced up-conversion emission compared with Er 3+ -Yb 3+ co-doped TiO 2 . The UC-TiO 2 was applied to the perovskite solar cells. The power conversion efficiency (PCE) of the solar cells without UC-TiO 2 was 14.0%, while the PCE of the solar cells with UC-TiO 2 was increased to 16.5%, which presented an increase of 19%. The results suggested that UC-TiO 2 is an effective up-conversion material. And this study provided a route to expand the spectral absorption of perovskite solar cells from visible light to near-infrared using up-conversion materials.

Transparent Solar Concentrator for Flat Panel Display

NASA Astrophysics Data System (ADS)

Yeh, Chia-Hung; Chang, Fuh-Yu; Young, Hong-Tsu; Hsieh, Tsung-Yen; Chang, Chia-Hsiung

2012-06-01

A new concept of the transparent solar concentrator for flat panel display is experimentally demonstrated without adversely affecting the visual effects. The solar concentrator is based on a solar light-guide plate with micro prisms, not only increasing the absorption area of solar energy but also enhancing the conversion efficiency. The incident light is guided by the designed solar light-guide plate according to the total internal reflection (TIR), and converted into electrical power by photovoltaic solar cells. The designed transparent solar concentrator was made and measured with high transparency, namely 94.8%. The developed solar energy system for display can store energy and supply the bias voltage to light on two light-emitting diodes (LEDs) successfully.

Coherence-limited solar power conversion: the fundamental thermodynamic bounds and the consequences for solar rectennas

NASA Astrophysics Data System (ADS)

Mashaal, Heylal; Gordon, Jeffrey M.

2014-10-01

Solar rectifying antennas constitute a distinct solar power conversion paradigm where sunlight's spatial coherence is a basic constraining factor. In this presentation, we derive the fundamental thermodynamic limit for coherence-limited blackbody (principally solar) power conversion. Our results represent a natural extension of the eponymous Landsberg limit, originally derived for converters that are not constrained by the radiation's coherence, and are irradiated at maximum concentration (i.e., with a view factor of unity to the solar disk). We proceed by first expanding Landsberg's results to arbitrary solar view factor (i.e., arbitrary concentration and/or angular confinement), and then demonstrate how the results are modified when the converter can only process coherent radiation. The results are independent of the specific power conversion mechanism, and hence are valid for diffraction-limited as well as quantum converters (and not just classical heat engines or in the geometric optics regime). The derived upper bounds bode favorably for the potential of rectifying antennas as potentially high-efficiency solar converters.

Design of a Solar Tracking System Using the Brightest Region in the Sky Image Sensor

PubMed Central

Wei, Ching-Chuan; Song, Yu-Chang; Chang, Chia-Chi; Lin, Chuan-Bi

2016-01-01

Solar energy is certainly an energy source worth exploring and utilizing because of the environmental protection it offers. However, the conversion efficiency of solar energy is still low. If the photovoltaic panel perpendicularly tracks the sun, the solar energy conversion efficiency will be improved. In this article, we propose an innovative method to track the sun using an image sensor. In our method, it is logical to assume the points of the brightest region in the sky image representing the location of the sun. Then, the center of the brightest region is assumed to be the solar-center, and is mathematically calculated using an embedded processor (Raspberry Pi). Finally, the location information on the sun center is sent to the embedded processor to control two servo motors that are capable of moving both horizontally and vertically to track the sun. In comparison with the existing sun tracking methods using image sensors, such as the Hough transform method, our method based on the brightest region in the sky image remains accurate under conditions such as a sunny day and building shelter. The practical sun tracking system using our method was implemented and tested. The results reveal that the system successfully captured the real sun center in most weather conditions, and the servo motor system was able to direct the photovoltaic panel perpendicularly to the sun center. In addition, our system can be easily and practically integrated, and can operate in real-time. PMID:27898002

Design of a Solar Tracking System Using the Brightest Region in the Sky Image Sensor.

PubMed

Wei, Ching-Chuan; Song, Yu-Chang; Chang, Chia-Chi; Lin, Chuan-Bi

2016-11-25

Solar energy is certainly an energy source worth exploring and utilizing because of the environmental protection it offers. However, the conversion efficiency of solar energy is still low. If the photovoltaic panel perpendicularly tracks the sun, the solar energy conversion efficiency will be improved. In this article, we propose an innovative method to track the sun using an image sensor. In our method, it is logical to assume the points of the brightest region in the sky image representing the location of the sun. Then, the center of the brightest region is assumed to be the solar-center, and is mathematically calculated using an embedded processor (Raspberry Pi). Finally, the location information on the sun center is sent to the embedded processor to control two servo motors that are capable of moving both horizontally and vertically to track the sun. In comparison with the existing sun tracking methods using image sensors, such as the Hough transform method, our method based on the brightest region in the sky image remains accurate under conditions such as a sunny day and building shelter. The practical sun tracking system using our method was implemented and tested. The results reveal that the system successfully captured the real sun center in most weather conditions, and the servo motor system was able to direct the photovoltaic panel perpendicularly to the sun center. In addition, our system can be easily and practically integrated, and can operate in real-time.

Dish Stirling solar receiver program

NASA Technical Reports Server (NTRS)

Haglund, R. A.

1980-01-01

A technology demonstration of a Dish Stirling solar thermal electric system can be accomplished earlier and at a much lower cost than previous planning had indicated by employing technical solutions that allow already existing hardware, with minimum modifications, to be integrated into a total system with a minimum of development. The DSSR operates with a modified United Stirling p-40 engine/alternator and the JPL Test Bed Concentrator as a completely integrated solar thermal electric system having a design output of 25 kWe. The system is augmented by fossil fuel combustion which ensures a continuous electrical output under all environmental conditions. Technical and economic studies by government and industry in the United States and abroad identify the Dish Stirling solar electric system as the most appropriate, efficient and economical method for conversion of solar energy to electricity in applications when the electrical demand is 10 MWe and less.

Singlet fission/silicon solar cell exceeding 100% EQE (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pazos, Luis M.; Lee, Jumin; Kirch, Anton; Tabachnyk, Maxim; Friend, Richard H.; Ehrler, Bruno

2016-09-01

Current matching limits the commercialization of tandem solar cells due to their instability over spectral changes, leading to the need of using solar concentrators and trackers to keep the spectrum stable. We demonstrate that voltage-matched systems show far higher performance over spectral changes; caused by clouds, dust and other variations in atmospheric conditions. Singlet fission is a process in organic semiconductors which has shown very efficient, 200%, down-conversion yield and the generated excitations are long-lived, ideal for solar cells. As a result, the number of publications has grown exponentially in the past 5 years. Yet, so far no one has achieved to combine singlet fission with most low bandgap semiconductors, including crystalline silicon, the dominating solar cell material with a 90% share of the PV Market. Here we show that singlet fission can facilitate the fabrication of voltage-matched systems, opening a simple design route for the effective implementation of down-conversion in commercially available photovoltaic technologies, with no modification of the electronic circuitry of such. The implemention of singlet fission is achieved simply by decoupling the fabrication of the individual subcells. For this demonstration we used an ITO/PEDOT/P3HT/Pentacene/C60/Ag wide-bandgap subcell, and a commercial silicon solar cell as the low-bandgap component. We show that the combination of the two leads to the first tandem silicon solar cell which exceeds 100% external quantum efficiency.

An inverter/controller subsystem optimized for photovoltaic applications

NASA Technical Reports Server (NTRS)

Pickrell, R. L.; Osullivan, G.; Merrill, W. C.

1978-01-01

Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy.

Effect of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal solar cells.

PubMed

Sahin, Mehmet

2018-05-23

In this study, the effects of the shell material and confinement type on the conversion efficiency of core/shell quantum dot nanocrystal (QDNC) solar cells have been investigated in detail. For this purpose, the conventional, i.e. original, detailed balance model, developed by Shockley and Queisser to calculate an upper limit for the conversion efficiency of silicon p-n junction solar cells, is modified in a simple and effective way to calculate the conversion efficiency of core/shell QDNC solar cells. Since the existing model relies on the gap energy ([Formula: see text]) of the solar cell, it does not make an estimation about the effect of QDNC materials on the efficiency of the solar cells, and gives the same efficiency values for several QDNC solar cells with the same [Formula: see text]. The proposed modification, however, estimates a conversion efficiency in relation to the material properties and also the confinement type of the QDNCs. The results of the modified model show that, in contrast to the original one, the conversion efficiencies of different QDNC solar cells, even if they have the same [Formula: see text], become different depending upon the confinement type and shell material of the core/shell QDNCs, and this is crucial in the design and fabrication of the new generation solar cells to predict the confinement type and also appropriate QDNC materials for better efficiency.

Density Functional Theory Investigations of D-A-D' Structural Molecules as Donor Materials in Organic Solar Cell.

PubMed

Chen, Junxian; Liu, Qingyu; Li, Hao; Zhao, Zhigang; Lu, Zhiyun; Huang, Yan; Xu, Dingguo

2018-01-01

Squaraine core based small molecules in bulk heterojunction organic solar cells have received extensive attentions due to their distinguished photochemical properties in far red and infrared domain. In this paper, combining theoretical simulations and experimental syntheses and characterizations, three major factors (fill factor, short circuit and open-cirvuit voltage) have been carried out together to achieve improvement of power conversion efficiencies of solar cells. As model material systems with D-A-D' framework, two asymmetric squaraines (CNSQ and CCSQ-Tol) as donor materials in bulk heterojunction organic solar cell were synthesized and characterized. Intensive density functional theory computations were applied to identify some direct connections between three factors and corresponding molecular structural properties. It then helps us to predict one new molecule of CCSQ'-Ox that matches all the requirements to improve the power conversion efficiency.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Dongseok; Young, James L.; Lim, Haneol

Despite their excellent photophysical properties and record-high solar-to-hydrogen conversion efficiency, the high cost and limited stability of III-V compound semiconductors prohibit their practical application in solar-driven photoelectrochemical water splitting. Here in this paper we present a strategy for III-V photocatalysis that can circumvent these difficulties via printed assemblies of epitaxially grown compound semiconductors. A thin film stack of GaAs-based epitaxial materials is released from the growth wafer and printed onto a non-native transparent substrate to form an integrated photocatalytic electrode for solar hydrogen generation. The heterogeneously integrated electrode configuration together with specialized epitaxial design serve to decouple the material interfacesmore » for illumination and electrocatalysis. Subsequently, this allows independent control and optimization of light absorption, carrier transport, charge transfer, and material stability. Using this approach, we construct a series-connected wireless tandem system of GaAs photoelectrodes and demonstrate 13.1% solar-to-hydrogen conversion efficiency of unassisted-mode water splitting.« less

A Study of Solar Thermal Propulsion System Enhancement via Thermal Storage and Thermal-electric Conversion

DTIC Science & Technology

2010-03-24

currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 24-03-2010 2. REPORT TYPE...Technical Paper 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER A Study of Solar Thermal Propulsion System...explored here are the optimization of thermal storage using a phase change material, design considerations assuming a microsatellite system in low Earth

Quantum design of photosynthesis for bio-inspired solar-energy conversion.

PubMed

Romero, Elisabet; Novoderezhkin, Vladimir I; van Grondelle, Rienk

2017-03-15

Photosynthesis is the natural process that converts solar photons into energy-rich products that are needed to drive the biochemistry of life. Two ultrafast processes form the basis of photosynthesis: excitation energy transfer and charge separation. Under optimal conditions, every photon that is absorbed is used by the photosynthetic organism. Fundamental quantum mechanics phenomena, including delocalization, underlie the speed, efficiency and directionality of the charge-separation process. At least four design principles are active in natural photosynthesis, and these can be applied practically to stimulate the development of bio-inspired, human-made energy conversion systems.

Printed assemblies of GaAs photoelectrodes with decoupled optical and reactive interfaces for unassisted solar water splitting

DOE PAGES

Kang, Dongseok; Young, James L.; Lim, Haneol; ...

2017-03-27

Despite their excellent photophysical properties and record-high solar-to-hydrogen conversion efficiency, the high cost and limited stability of III-V compound semiconductors prohibit their practical application in solar-driven photoelectrochemical water splitting. Here in this paper we present a strategy for III-V photocatalysis that can circumvent these difficulties via printed assemblies of epitaxially grown compound semiconductors. A thin film stack of GaAs-based epitaxial materials is released from the growth wafer and printed onto a non-native transparent substrate to form an integrated photocatalytic electrode for solar hydrogen generation. The heterogeneously integrated electrode configuration together with specialized epitaxial design serve to decouple the material interfacesmore » for illumination and electrocatalysis. Subsequently, this allows independent control and optimization of light absorption, carrier transport, charge transfer, and material stability. Using this approach, we construct a series-connected wireless tandem system of GaAs photoelectrodes and demonstrate 13.1% solar-to-hydrogen conversion efficiency of unassisted-mode water splitting.« less

Printed assemblies of GaAs photoelectrodes with decoupled optical and reactive interfaces for unassisted solar water splitting

NASA Astrophysics Data System (ADS)

Kang, Dongseok; Young, James L.; Lim, Haneol; Klein, Walter E.; Chen, Huandong; Xi, Yuzhou; Gai, Boju; Deutsch, Todd G.; Yoon, Jongseung

2017-03-01

Despite their excellent photophysical properties and record-high solar-to-hydrogen conversion efficiency, the high cost and limited stability of III-V compound semiconductors prohibit their practical application in solar-driven photoelectrochemical water splitting. Here we present a strategy for III-V photocatalysis that can circumvent these difficulties via printed assemblies of epitaxially grown compound semiconductors. A thin film stack of GaAs-based epitaxial materials is released from the growth wafer and printed onto a non-native transparent substrate to form an integrated photocatalytic electrode for solar hydrogen generation. The heterogeneously integrated electrode configuration together with specialized epitaxial design serve to decouple the material interfaces for illumination and electrocatalysis. Subsequently, this allows independent control and optimization of light absorption, carrier transport, charge transfer, and material stability. Using this approach, we construct a series-connected wireless tandem system of GaAs photoelectrodes and demonstrate 13.1% solar-to-hydrogen conversion efficiency of unassisted-mode water splitting.

A Robust Design Approach to Cost Estimation: Solar Energy for Marine Corps Expeditionary Operations

DTIC Science & Technology

2014-07-14

solutions in such areas as photovoltaic arrays for power harvesting, light emitting diodes (LED) for decreased energy consumption, and improved battery...generation and conversion system that allows Marines to power systems with solar energy. Each GREENS is comprised of eight photovoltaic array panels...renewable power sources such as photovoltaic arrays and wind turbines. The HOMER model has been utilized for years by organizations and companies

Floating rGO-based black membranes for solar driven sterilization.

PubMed

Zhang, Yao; Zhao, Dengwu; Yu, Fan; Yang, Chao; Lou, Jinwei; Liu, Yanming; Chen, Yingying; Wang, Zhongyong; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2017-12-14

This paper presents a new steam sterilization approach that uses a solar-driven evaporation system at the water/air interface. Compared to the conventional solar autoclave, this new steam sterilization approach via interfacial evaporation requires no complex system design to bear high steam pressure. In such a system, a reduced graphene oxide/polytetrafluoroethylene composite membrane floating at the water/air interface serves as a light-to-heat conversion medium to harvest and convert incident solar light into localized heat. Such localized heat raises the temperature of the membrane substantially and helps generate steam with a temperature higher than 120 °C. A sterilization device that takes advantage of the interfacial solar-driven evaporation system was built and its successful sterilization capability was demonstrated through both chemical and biological sterilization tests. The interfacial evaporation-based solar driven sterilization approach offers a potential low cost solution to meet the need for sterilization in undeveloped areas that lack electrical power but have ample solar radiation.

Solar photovoltaic charging of lithium-ion batteries

NASA Astrophysics Data System (ADS)

Gibson, Thomas L.; Kelly, Nelson A.

Solar photovoltaic (PV) charging of batteries was tested by using high efficiency crystalline and amorphous silicon PV modules to recharge lithium-ion battery modules. This testing was performed as a proof of concept for solar PV charging of batteries for electrically powered vehicles. The iron phosphate type lithium-ion batteries were safely charged to their maximum capacity and the thermal hazards associated with overcharging were avoided by the self-regulating design of the solar charging system. The solar energy to battery charge conversion efficiency reached 14.5%, including a PV system efficiency of nearly 15%, and a battery charging efficiency of approximately 100%. This high system efficiency was achieved by directly charging the battery from the PV system with no intervening electronics, and matching the PV maximum power point voltage to the battery charging voltage at the desired maximum state of charge for the battery. It is envisioned that individual homeowners could charge electric and extended-range electric vehicles from residential, roof-mounted solar arrays, and thus power their daily commuting with clean, renewable solar energy.

Brayton Power Conversion System Study to Advance Technology Readiness for Nuclear Electric Propulsion

NASA Technical Reports Server (NTRS)

Allen, Bog; Delventhal, Rex; Frye, Patrick

2004-01-01

Recently, there has been significant interest within the aerospace community to develop space based nuclear power conversion technologies especially for exploring the outer planets of our solar system where the solar energy density is very low. To investigate these technologies NASA awarded several contracts under Project Prometheus, the Nuclear Systems Program. The studies described in this paper were performed under one of those contracts, which was to investigate the use of a nuclear power conversion system based on the closed Brayton cycle (CBC).The investigation performed included BPCS (Brayton Power Conversion System) trade studies to minimize system weight and radiator area and advance the state of the art of BPCS technology. The primary requirements for studies were a power level of 100 kWe (to the PPU), a low overall power system mass and a lifetime of 15 years (10 years full power). For the radiation environment, the system was to be capable of operation in the generic space environment and withstand the extreme environments surrounding Jupiter. The studies defined a BPCS design traceable to NEP (Nuclear Electric Propulsion) requirements and suitable for future missions with a sound technology plan for technology readiness level (TRL) advancement identified. The studies assumed a turbine inlet temperature approx. 100 C above the current the state of the art capabilities with materials issues and related development tasks identified. Analyses and evaluations of six different HRS (heat rejection system) designs and three primary power management and distribution (PMAD) configurations will be discussed in the paper.

NSF presentation. [summary on energy conversion research program

NASA Technical Reports Server (NTRS)

Morse, F. H.

1973-01-01

Wind energy conversion research is considered in the framework of the national energy problem. Research and development efforts for the practical application of solar energy -- including wind energy -- as alternative energy supplies are assessed in: (1) Heating and cooling of buildings; (2) photovoltaic energy conversion; (3) solar thermal energy conversion; (4) wind energy conversion; (5) ocean thermal energy conversion; (6) photosynthetic production of organic matter; and (7) conversion of organic matter into fuels.

Electrochemical energy storage systems for solar thermal applications

NASA Technical Reports Server (NTRS)

Krauthamer, S.; Frank, H.

1980-01-01

Existing and advanced electrochemical storage and inversion/conversion systems that may be used with terrestrial solar-thermal power systems are evaluated. The status, cost and performance of existing storage systems are assessed, and the cost, performance, and availability of advanced systems are projected. A prime consideration is the cost of delivered energy from plants utilizing electrochemical storage. Results indicate that the five most attractive electrochemical storage systems are the: iron-chromium redox (NASA LeRC), zinc-bromine (Exxon), sodium-sulfur (Ford), sodium-sulfur (Dow), and zinc-chlorine (EDA).

The economic viability of pursuing a space power system concept

NASA Technical Reports Server (NTRS)

Hazelrigg, G. A., Jr.

1977-01-01

The development of a space power system requires no fundamental technological breakthroughs. There are, however, uncertainties regarding the degree to which necessary developments can be achieved or exceeded. An analysis is conducted concerning the implementation of a 5000 MW space-based solar power system based on photovoltaic conversion of solar energy to electrical energy. The solar array is about 13 km long and 5 km wide. Placed in geosynchronous orbit, it provides power to the earth for 30 years. Attention is given to the economic feasibility of a space power system, a risk analysis for space power systems, and the use of the presented methodology for comparing alternative technology development programs.

Smart Microgrid Energy Management Controls for Improved Energy Efficiency and Renewables Integration at DoD Installations

DTIC Science & Technology

2013-04-01

products for energy generation, including solar, wind , and gas turbines , energy storage, power conversion, grid integration, and software for...potential security advantages over centralized systems • DER promote fuel diversity (e.g., biomass, landfill gas, flare gas, wind , solar) and...therefore reduce overall energy price volatility • Renewable DER such as wind and solar photovoltaics provide emissions-free energy • DER offer a quicker

A Digital Solar Aspect Sensor

NASA Technical Reports Server (NTRS)

Albus, James S.

1961-01-01

The solar aspect sensor described herein performs the analog-to-digital conversion of data optically. To accomplish this, it uses a binary "Gray code" light mask to produce a digital indication, in vehicle-fixed coordinates, of the elevation and azimuth angles of incident light from the sun. This digital solar aspect sensor system, in Explorer X, provided measurements of both elevation and azimuth angles to +/- 2 degrees at a distance of over 140,000 statute miles.

Polymer bulk heterojunction solar cells with PEDOT:PSS bilayer structure as hole extraction layer.

PubMed

Kim, Wanjung; Kim, Namhun; Kim, Jung Kyu; Park, Insun; Choi, Yeong Suk; Wang, Dong Hwan; Chae, Heeyeop; Park, Jong Hyeok

2013-06-01

A high current density obtained in a limited, nanometer-thick region is important for high efficiency polymer solar cells (PSCs). The conversion of incident photons to charge carriers only occurs in confined active layers; therefore, charge-carrier extraction from the active layer within the device by using solar light has an important impact on the current density and the related to power conversion efficiency. In this study, we observed a surprising result, that is, extracting the charge carrier generated in the active layer of a PSC device, with a thickness-controlled PEDOT:PSS bilayer that acted as a hole extraction layer (HEL), yielded a dramatically improved power conversion efficiency in two different model systems (P3HT:PC₆₀BM and PCDTBT:PC₇₀BM). To understand this phenomenon, we conducted optical strength simulation, photocurrent-voltage measurements, incident photon to charge carrier efficiency measurements, ultraviolet photoelectron spectroscopy, and AFM studies. The results revealed that approximately 60 nm was the optimum PEDOT:PSS bilayer HEL thickness in PSCs for producing the maximum power conversion efficiency. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid renewable energy system using doubly-fed induction generator and multilevel inverter

NASA Astrophysics Data System (ADS)

Ahmed, Eshita

The proposed hybrid system generates AC power by combining solar and wind energy converted by a doubly-fed induction generator (DFIG). The DFIG, driven by a wind turbine, needs rotor excitation so the stator can supply a load or the grid. In a variable-speed wind energy system, the stator voltage and its frequency vary with wind speed, and in order to keep them constant, variable-voltage and variable-frequency rotor excitation is to be provided. A power conversion unit supplies the rotor, drawing power either from AC mains or from a PV panel depending on their availability. It consists of a multilevel inverter which gives lower harmonic distortion in the stator voltage. Maximum power point tracking techniques have been implemented for both wind and solar power. The complete hybrid renewable energy system is implemented in a PSIM-Simulink interface and the wind energy conversion portion is realized in hardware using dSPACE controller board.

Design of dual-diameter nanoholes for efficient solar-light harvesting

PubMed Central

2014-01-01

A dual-diameter nanohole (DNH) photovoltaic system is proposed, where a top (bottom) layer with large (small) nanoholes is used to improve the absorption for the short-wavelength (long-wavelength) solar incidence, leading to a broadband light absorption enhancement. Through three-dimensional finite-element simulation, the core device parameters, including the lattice constant, nanohole diameters, and nanohole depths, are engineered in order to realize the best light-matter coupling between nanostructured silicon and solar spectrum. The designed bare DNH system exhibits an outstanding absorption capability with a photocurrent density (under perfect internal quantum process) predicted to be 27.93 mA/cm2, which is 17.39%, 26.17%, and over 100% higher than the best single-nanohole (SNH) system, SNH system with an identical Si volume, and equivalent planar configuration, respectively. Considering the fabrication feasibility, a modified DNH system with an anti-reflection coating and back silver reflector is examined by simulating both optical absorption and carrier transport in a coupled way in frequency and three-dimensional spatial domains, achieving a light-conversion efficiency of 13.72%. PACS 85.60.-q; Optoelectronic device; 84.60.Jt; Photovoltaic conversion PMID:25258605

Stacbeam 2

NASA Astrophysics Data System (ADS)

Adams, L. R.; Vonroos, A.

1985-04-01

An investigation being conducted by Astro Aerospace Corporation (Astro) for Jet Propulsion Laboratory in which efficient structures for geosynchronous spacecraft solar arrays are being developed is discussed. Recent developments in solar blanket technology, including the introduction of ultrathin (50 micrometer) silicon solar cells with conversion efficiencies approaching 15 percent, have resulted in a significant increase in blanket specific power. System specific power depends not only on blanket mass but also on the masses of the support structure and deployment mechanism. These masses must clearly be reduced, not only to minimize launch weight, but also to increase array natural frequency. The solar array system natural frequency should be kept high in order to reduce the demands on the attitude control system. This goal is approached by decreasing system mass, by increasing structural stiffness, and by partitioning the blanket. As a result of this work, a highly efficient structure for deploying a solar array was developed.

Solar-thermal conversion and thermal energy storage of graphene foam-based composites.

PubMed

Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

2016-08-14

Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

Development of a practical photochemical energy storage system. Quarterly report. [Interconversion between norbornadiene and quadricyclene for thermochemical heat storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hautala, R.R.; Kutal, C.R.

1977-06-15

Research on polymeric organic sensitizers and polymeric inorganic sensitizers for the conversion of norbornadine to quadricyclene and catalysts for the conversion of quadricyclene to norbornadine is described. The interconversion of norbornadine and quadricyclene is studied for its possible use for thermochemical solar energy storage. (WHK)

Phase 1 of the First Small Power System Experiment (engineering Experiment No. 1). Volume 5: Supporting Analyses and Trade Studies. [development and testing of a solar thermal power plant

NASA Technical Reports Server (NTRS)

Holl, R. J.

1979-01-01

The development and design of a modular solar thermal power system for application in the 1 to 10 MWe range is described. The system is used in remote utility applications, small communities, rural areas, and for industrial uses. Thermal and stress analyses are performed on the collector subsystem, energy storage subsystem, energy transport subsystem, the power conversion subsystem, and the plant control subsystem.

High voltage systems (tube-type microwave)/low voltage system (solid-state microwave) power distribution

NASA Technical Reports Server (NTRS)

Nussberger, A. A.; Woodcock, G. R.

1980-01-01

SPS satellite power distribution systems are described. The reference Satellite Power System (SPS) concept utilizes high-voltage klystrons to convert the onboard satellite power from dc to RF for transmission to the ground receiving station. The solar array generates this required high voltage and the power is delivered to the klystrons through a power distribution subsystem. An array switching of solar cell submodules is used to maintain bus voltage regulation. Individual klystron dc voltage conversion is performed by centralized converters. The on-board data processing system performs the necessary switching of submodules to maintain voltage regulation. Electrical power output from the solar panels is fed via switch gears into feeder buses and then into main distribution buses to the antenna. Power also is distributed to batteries so that critical functions can be provided through solar eclipses.

Recent Advances in Solar Cell Technology

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Bailey, Sheila G.; Piszczor, Michael F., Jr.

1996-01-01

The advances in solar cell efficiency, radiation tolerance, and cost over the last decade are reviewed. Potential performance of thin-film solar cells in space are discussed, and the cost and the historical trends in production capability of the photovoltaics industry are considered with respect to the requirements of space power systems. Concentrator cells with conversion efficiency over 30%, and nonconcentrating solar cells with efficiency over 25% are now available, and advanced radiation-tolerant cells and lightweight, thin-film arrays are both being developed. Nonsolar applications of solar cells, including thermophotovoltaics, alpha- and betavoltaics, and laser power receivers, are also discussed.

Direct conversion of solar energy to thermal energy

NASA Astrophysics Data System (ADS)

Sizmann, Rudolf

1986-12-01

Selective coatings (cermets) were produced by simultaneous evaporation of copper and silicon dioxide, and analyzed by computer assisted spectral photometers and ellipsometers; hemispherical emittance was measured. Steady state test procedures for covered and uncovered collectors were investigated. A method for evaluating the transient behavior of collectors was developed. The derived transfer functions describe their transient behavior. A stochastic approach was used for reducing the meteorological data volume. Data sets which are statistically equivalent to the original data can be synthesized. A simulation program for solar systems using analytical solutions of differential equations was developed. A large solar DHW system was optimized by a detailed modular simulation program. A microprocessor assisted data aquisition records the four characteristics of solar cells and solar cell systems in less than 10 msec. Measurements of a large photovoltaic installation (50 sqm) are reported.

Improving Si solar cell performance using Mn:ZnSe quantum dot-doped PLMA thin film

PubMed Central

2013-01-01

Poly(lauryl methacrylate) (PLMA) thin film doped with Mn:ZnSe quantum dots (QDs) was spin-deposited on the front surface of Si solar cell for enhancing the solar cell efficiency via photoluminescence (PL) conversion. Significant solar cell efficiency enhancements (approximately 5% to 10%) under all-solar-spectrum (AM0) condition were observed after QD-doped PLMA coatings. Furthermore, the real contribution of the PL conversion was precisely assessed by investigating the photovoltaic responses of the QD-doped PLMA to monochromatic and AM0 light sources as functions of QD concentration, combined with reflectance and external quantum efficiency measurements. At a QD concentration of 1.6 mg/ml for example, among the efficiency enhancement of 5.96%, about 1.04% was due to the PL conversion, and the rest came from antireflection. Our work indicates that for the practical use of PL conversion in solar cell performance improvement, cautions are to be taken, as the achieved efficiency enhancement might not be wholly due to the PL conversion. PMID:23787125

Silicon Schottky photovoltaic diodes for solar energy conversion

NASA Technical Reports Server (NTRS)

Anderson, W. A.

1975-01-01

Various factors in Schottky barrier solar cell fabrication are evaluated in order to improve understanding of the current flow mechanism and to isolate processing variables that improve efficiency. Results of finger design, substrate resistivity, surface finishing and activation energy studies are detailed. An increased fill factor was obtained by baking of the vacuum system to remove moisture.

Where there is a wind, there is a way

NASA Technical Reports Server (NTRS)

Mosher, C. A.

1973-01-01

A shift in USA energy policy from oil or natural gases to thermonuclear fission and solar energy is predicted. A massive diversified energy research and development effort to productively harness the energy in the winds is outlined to develop commercially feasible wind energy conversion systems - considered a form of solar energy - in the near future.

Construction and characterization of spherical Si solar cells combined with SiC electric power inverter

NASA Astrophysics Data System (ADS)

Oku, Takeo; Matsumoto, Taisuke; Hiramatsu, Kouichi; Yasuda, Masashi; Shimono, Akio; Takeda, Yoshikazu; Murozono, Mikio

2015-02-01

Spherical silicon (Si) photovoltaic solar cell systems combined with an electric power inverter using silicon carbide (SiC) field-effect transistor (FET) were constructed and characterized, which were compared with an ordinary Si-based converter. The SiC-FET devices were introduced in the direct current-alternating current (DC-AC) converter, which was connected with the solar panels. The spherical Si solar cells were used as the power sources, and the spherical Si panels are lighter and more flexible compared with the ordinary flat Si solar panels. Conversion efficiencies of the spherical Si solar cells were improved by using the SiC-FET.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, Kenneth C.

1992-01-01

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, Kenneth C.

1990-01-01

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, K.C.

1992-12-08

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion. 16 figs.

The possibility of developing hybrid PV/T solar system

NASA Astrophysics Data System (ADS)

Dobrnjac, M.; Zivkovic, P.; Babic, V.

2017-05-01

An alternative and cost-effective solution to developing integrated PV system is to use hybrid photovoltaic/thermal (PV/T) solar system. The temperature of PV modules increases due to the absorbed solar radiation that is not converted into electricity, causing a decrease in their efficiency. In hybrid PV/T solar systems the reduction of PV module temperature can be combined with a useful fluid heating. In this paper we present the possibility of developing a new hybrid PV/T solar system. Hybrid PV/T system can provide electrical and thermal energy, thus achieving a higher energy conversion rate of the absorbed solar radiation. We developed PV/T prototype consisted of commercial PV module and thermal panel with our original solution of aluminium absorber with special geometric shapes. The main advantages of our combined PV/T system are: removing of heat from the PV panel; extending the lifetime of photovoltaic cells; excess of the removing heat from PV part is used to heat the fluid in the thermal part of the panel; the possibility of using on the roof and facade constructions because less weight.

ERDA/Lewis research center photovoltaic systems test facility

NASA Technical Reports Server (NTRS)

Forestieri, A. F.; Johnson, J. A.; Knapp, W. D.; Rigo, H.; Stover, J.; Suhay, R.

1977-01-01

A national photovoltaic power systems test facility (of initial 10-kW peak power rating) is described. It consists of a solar array to generate electrical power, test-hardware for several alternate methods of power conversion, electrical energy storage systems, and an instrumentation and data acquisition system.

A geopressured-geothermal, solar conversion system to produce potable water

NASA Astrophysics Data System (ADS)

Nitschke, George Samuel

A design is presented for recovering Geopressured-Geothermal (GPGT) reservoir brines for conversion into solar ponds to renewably power coastal seawater desalination. The hot, gas-cut, high-pressure GPGT brine is flowed through a well-bore to surface systems which concentrate the brine in multi-effect evaporators and recover the gas. The gas and distilled water are used for thermal enhanced oil recovery, and the concentrated brine is used to construct solar ponds. The thermal energy from the solar ponds is used to produce electricity, which is then used to renewably power coastal desalination plants for large-scale potable water production from the sea. The design is proposed for deployment in California and Texas, where the two largest U.S. GPGT basins exist. Projections show that the design fully deployed in California could provide 5 MAF/y (million acre-ft per year) while yielding a 45% Rate of Return (combined oil and water revenues); the California municipal water load is 10 MAF/y. The dissertation contains a feasibility study of the design approach, supported by engineering analyses and simulation models, included in the appendices. A range of systems configurations and GPGT flow conditions are modeled to illustrate how the approach lends itself to modular implementation, i.e., incrementally installing a single system, tens of systems, up to 1000 systems, which corresponds to full deployment in California for the scenario analyzed. The dissertation includes a method for launching and piloting the approach, starting from a single system installation.

Semiconducting Single-Walled Carbon Nanotubes in Solar Energy Harvesting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blackburn, Jeffrey L.

Semiconducting single-walled carbon nanotubes (s-SWCNTs) represent a tunable model one-dimensional system with exceptional optical and electronic properties. High-throughput separation and purification strategies have enabled the integration of s-SWCNTs into a number of optoelectronic applications, including photovoltaics (PVs). In this Perspective, we discuss the fundamental underpinnings of two model PV interfaces involving s-SWCNTs. We first discuss s-SWCNT-fullerene heterojunctions where exciton dissociation at the donor-acceptor interface drives solar energy conversion. Next, we discuss charge extraction at the interface between s-SWCNTs and a photoexcited perovskite active layer. In each case, the use of highly enriched semiconducting SWCNT samples enables fundamental insights into themore » thermodynamic and kinetic mechanisms that drive the efficient conversion of solar photons into long-lived separated charges. As a result, these model systems help to establish design rules for next-generation PV devices containing well-defined organic semiconductor layers and help to frame a number of important outstanding questions that can guide future studies.« less

Semiconducting Single-Walled Carbon Nanotubes in Solar Energy Harvesting

DOE PAGES

Blackburn, Jeffrey L.

2017-06-14

Semiconducting single-walled carbon nanotubes (s-SWCNTs) represent a tunable model one-dimensional system with exceptional optical and electronic properties. High-throughput separation and purification strategies have enabled the integration of s-SWCNTs into a number of optoelectronic applications, including photovoltaics (PVs). In this Perspective, we discuss the fundamental underpinnings of two model PV interfaces involving s-SWCNTs. We first discuss s-SWCNT-fullerene heterojunctions where exciton dissociation at the donor-acceptor interface drives solar energy conversion. Next, we discuss charge extraction at the interface between s-SWCNTs and a photoexcited perovskite active layer. In each case, the use of highly enriched semiconducting SWCNT samples enables fundamental insights into themore » thermodynamic and kinetic mechanisms that drive the efficient conversion of solar photons into long-lived separated charges. As a result, these model systems help to establish design rules for next-generation PV devices containing well-defined organic semiconductor layers and help to frame a number of important outstanding questions that can guide future studies.« less

Experimental Results From a 2kW Brayton Power Conversion Unit

NASA Technical Reports Server (NTRS)

Hervol, David; Mason, Lee; Birchenough, Arthur

2003-01-01

This paper presents experimental test results from operation of a 2 kWe Brayton power conversion unit. The Brayton converter was developed for a solar dynamic power system flight experiment planned for the Mir Space Station in 1997. The flight experiment was cancelled, but the converter was tested at Glenn Research Center as part of the Solar Dynamic Ground Test Demonstration system which included a solar concentrator, heat receiver, and space radiator. In preparation for the current testing, the heat receiver was removed and replaced with an electrical resistance heater, simulating the thermal input of a steady-state nuclear source. The converter was operated over a full range of thermal input power levels and rotor speeds to generate an overall performance map. The converter unit will serve as the centerpiece of a Nuclear Electric Propulsion Testbed at Glenn. Future potential uses for the Testbed include high voltage electrical controller development, integrated electric thruster testing and advanced radiator demonstration testing to help guide high power Brayton technology development for Nuclear Electric Propulsion (NEP).

New Multijunction Design Leads to Ultra-Efficient Solar Cell; Highlights in Research & Development, NREL (National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-09-01

NREL has demonstrated a 45.7% conversion efficiency for a four-junction solar cell at 234 suns concentration. This achievement represents one of the highest photovoltaic research cell efficiencies ever achieved across all types of solar cells. NREL's new solar cell, which is designed for operation in a concentrator photovoltaic (CPV) system where it can receive more than 1,000 suns of concentrated sunlight, greatly improves earlier designs by adding an additional high quality absorber layer to achieve an ultra-high efficiency.

Military markets for solar thermal electric power systems

NASA Technical Reports Server (NTRS)

Hauger, J. S.

1980-01-01

The Department of Defense maintains an inventory of over 1,800 MW of engine-generators 15 KW and larger, with an estimated procurement rate of over 140 MW/year. Nearly the entire requirement could be met by advanced heat engines of the types being developed as point-focussing, distributed receiver power plants. A conceptual system consisting of a heat engine which efficiently burns liquid fossil or synthetic fuels, with a 'solarization kit' for conversion to hybrid solar operation could meet existing DOD requirements for new systems which are quieter, lighter, and multi-fueled. An estimated 24 percent (33 MW/year) or more could operationally benefit from the solar option. Baseline cost projections indicate levelized energy cost goals of 210 to 120 mills/KWh (15 to 1000 KW systems). Fuel cost escalation is the major factor affecting the value of the solar option. A baseline calculation for fuel at $0.59/gal in spring, 1979, escalating at 8 percent above general inflation indicates a value of $2700/KWe for a solarization kit.

Performance characteristics of solar-photovoltaic flywheel-storage systems

NASA Astrophysics Data System (ADS)

Jarvinen, P. O.; Brench, B. L.; Rasmussen, N. E.

A solar photovoltaic energy flywheel storage and conversion system for residential applications was tested. Performance and efficiency measurements were conducted on the system, which utilizes low loss magnetic bearings, maximum power point tracking of the photovoltaic array, integrated permanent magnet motor generator, and output power conditioning sections of either the stand alone cycloconverter or utility interactive inverter type. The overall in/out electrical storage efficiency of the flywheel system was measured along with the power transfer efficiencies of the individual components and the system spin down tare losses. The system compares favorably with systems which use batteries and inverters.

An initial comparative assessment of orbital and terrestrial central power systems

NASA Technical Reports Server (NTRS)

Caputo, R.

1977-01-01

Orbital solar power plants, which beam power to earth by microwave, are compared with ground-based solar and conventional baseload power plants. Candidate systems were identified for three types of plants and the selected plant designs were then compared on the basis of economic and social costs. The representative types of plant selected for the comparison are: light water nuclear reactor; turbines using low BTU gas from coal; central receiver with steam turbo-electric conversion and thermal storage; silicon photovoltaic power plant without tracking and including solar concentration and redox battery storage; and silicon photovoltaics.

Contribution to solving the energy crisis - Simulating the prospects for low cost energy through silicon solar cells

NASA Technical Reports Server (NTRS)

Kran, A.

1978-01-01

PECAN (Photovoltaic Energy Conversion Analysis) is a highly interactive decision analysis and support system. It simulates the prospects for widespread use of solar cells for the generation of electrical power. PECAN consists of a set of integrated APL functions for evaluating the potential of terrestrial photovoltaics. Specifically, the system is a deterministic simulator, which translates present and future manufacturing technology into economic and financial terms, using the production unit concept. It guides solar cell development in three areas: tactical decision making, strategic planning, and the formulation of alternative options.

MHD conversion of solar energy. [space electric power system

NASA Technical Reports Server (NTRS)

Lau, C. V.; Decher, R.

1978-01-01

Low temperature plasmas wherein an alkali metal vapor is a component are uniquely suited to simultaneously absorb solar radiation by coupling to the resonance lines and produce electrical power by the MHD interaction. This work is an examination of the possibility of developing space power systems which take advantage of concentrated solar power to produce electricity. It is shown that efficient cycles in which expansion work takes place at nearly constant top cycle temperature can be devised. The power density of the solar MHD generator is lower than that of conventional MHD generators because of the relatively high seed concentration required for radiation absorption and the lower flow velocity permitted to avoid total pressure losses due to heating.

A simplified solar cell array modelling program

NASA Technical Reports Server (NTRS)

Hughes, R. D.

1982-01-01

As part of the energy conversion/self sufficiency efforts of DSN engineering, it was necessary to have a simplified computer model of a solar photovoltaic (PV) system. This article describes the analysis and simplifications employed in the development of a PV cell array computer model. The analysis of the incident solar radiation, steady state cell temperature and the current-voltage characteristics of a cell array are discussed. A sample cell array was modelled and the results are presented.

Air Brayton Solar Receiver, phase 1

NASA Technical Reports Server (NTRS)

Zimmerman, D. K.

1979-01-01

A six month analysis and conceptual design study of an open cycle Air Brayton Solar Receiver (ABSR) for use on a tracking, parabolic solar concentrator are discussed. The ABSR, which includes a buffer storage system, is designed to provide inlet air to a power conversion unit. Parametric analyses, conceptual design, interface requirements, and production cost estimates are described. The design features were optimized to yield a zero maintenance, low cost, high efficiency concept that will provide a 30 year operational life.

Silicon nanowires for photovoltaic solar energy conversion.

PubMed

Peng, Kui-Qing; Lee, Shuit-Tong

2011-01-11

Semiconductor nanowires are attracting intense interest as a promising material for solar energy conversion for the new-generation photovoltaic (PV) technology. In particular, silicon nanowires (SiNWs) are under active investigation for PV applications because they offer novel approaches for solar-to-electric energy conversion leading to high-efficiency devices via simple manufacturing. This article reviews the recent developments in the utilization of SiNWs for PV applications, the relationship between SiNW-based PV device structure and performance, and the challenges to obtaining high-performance cost-effective solar cells.

Solar-energy conversion system provides electrical power and thermal control for life-support systems

NASA Technical Reports Server (NTRS)

Davis, B. K.

1974-01-01

System utilizes Freon cycle and includes boiler turbogenerator with heat exchanger, regenerator and thermal-control heat exchangers, low-pressure and boiler-feed pumps, and condenser. Exchanger may be of interest to engineers and scientists investigating new energy sources.

Pluri-energy analysis of livestock systems--a comparison of dairy systems in different territories.

PubMed

Vigne, Mathieu; Vayssières, Jonathan; Lecomte, Philippe; Peyraud, Jean-Louis

2013-09-15

This paper introduces a generic assessment method called pluri-energy analysis. It aims to assess the types of energy used in agricultural systems and their conversion efficiencies. Four types of energy are considered: fossil energy, gross energy contained in the biomass, energy from human and animal labor and solar energy. The method was applied to compare smallholder low-input dairy-production systems, which are common in developing countries, to the high-input systems encountered in OECD countries. The pluri-energy method is useful for analyzing the functioning of agricultural systems by highlighting their modes of energy management. Since most dairy systems in South Mali (SM) are low-input systems, they are primarily based on solar and labor energy types and do not require substantial fossil-energy inputs to produce milk. Farms in Poitou-Charentes (PC) and Bretagne (BR) show intermediate values of fossil-energy use for milk production, similar to that found in the literature for typical European systems. However, fossil-energy use for milk production is higher on PC than BR farms because of a higher proportion of maize silage in the forage area; grazing pastures are more common on BR farms. Farms on Reunion Island (RI) require a relatively large amount of fossil energy to produce milk, mainly because the island context limits the amount of arable land. Consequently, milk production is based on large imports of concentrated feed with a high fossil-energy cost. The method also enables assessment of fossil-energy-use efficiency in order to increase the performance of biological processes in agricultural systems. Comparing the low-input systems represented by SM to the high-input systems represented by RI, PC and BR, an increase in solar-energy conversion, and thus land productivity, was observed due to intensification via increased fossil-energy use. Conversely, though fossil-energy use at the herd level increased milk productivity, its effect on gross-energy conversion by the herd was less evident. Partitioning the total on-farm gross energy produced among animal co-products (milk, meat and manure) highlights the major functions of SM herds, which are managed to produce organic crop fertilizers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Proceedings: Panel on Information Dissemination for Wind Energy

NASA Astrophysics Data System (ADS)

Weis, P.

1980-04-01

A program for coordinating and strengthening technical information activities related to the commercialization of solar energy research and development results is described. The program contains a project for each of the following technologies: biomass; ocean thermal energy conversion; photovoltaics; solar thermal power; and wind energy conversion systems. In addition to the production and dissemination of several types of information materials, the wind energy project aims to support efforts of others in the field. The meeting is the first attempt to acquaint people with the information activities of others, to discuss information needs as an aid to planning, and to promote cooperation in disseminating information on wind energy.

Significant enhancement in the power-conversion efficiency of chlorophyll co-sensitized solar cells by mimicking the principles of natural photosynthetic light-harvesting complexes.

PubMed

Wang, Xiao-Feng; Koyama, Yasushi; Kitao, Osamu; Wada, Yuji; Sasaki, Shin-Ich; Tamiaki, Hitoshi; Zhou, Haoshen

2010-04-15

Dye-sensitized solar cells (DSSCs) are similar to natural photosynthesis in the initial processes involving in light-harvesting and charge separation. In order to mimic those natural photosynthetic systems mainly containing multiple pigments, six different chlorophyllous sensitizers have been isolated from natural photosynthetic organism or synthesized based on natural photosynthetic precursors, and used for fabricating DSSCs. These dye sensitizers can be placed into three classes, i.e., a-type, b-type, or c-type, based on the structural similarity to their analogs of the natural photosynthesis pigments chlorophylls a, b, and c. We succeeded in demonstrating homogeneous co-sensitization among these analogues when these were present together on mesoporous TiO2 films, and we measured the photovoltaic performance of the resulting chlorophyll-sensitized solar cells. Significantly enhanced power-conversion efficiencies (eta) were achieved with DSSCs based on co-sensitization of a chlorophyll a derivative with a chlorophyll b or c derivative. A highest power-conversion efficiency of up to 5.4% has been obtained. These results suggest that it is possible to apply multiple pigments and the energy transfer mechanism from natural photosynthetic systems in fabricating high-efficiency DSSCs. 2010 Elsevier B.V. All rights reserved.

Early Results from Solar Dynamic Space Power System Testing

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Mason, Lee S.

1996-01-01

A government/industry team designed, built and tested a 2-kWe solar dynamic space power system in a large thermal vacuum facility with a simulated Sun at the NASA Lewis Research Center. The Lewis facility provides an accurate simulation of temperatures, high vacuum and solar flux as encountered in low-Earth orbit. The solar dynamic system includes a Brayton power conversion unit integrated with a solar receiver which is designed to store energy for continuous power operation during the eclipse phase of the orbit. This paper reviews the goals and status of the Solar Dynamic Ground Test Demonstration project and describes the initial testing, including both operational and performance data. System testing to date has accumulated over 365 hours of power operation (ranging from 400 watts to 2.0-W(sub e)), including 187 simulated orbits, 16 ambient starts and 2 hot restarts. Data are shown for an orbital startup, transient and steady-state orbital operation and shutdown. System testing with varying insolation levels and operating speeds is discussed. The solar dynamic ground test demonstration is providing the experience and confidence toward a successful flight demonstration of the solar dynamic technologies on the Space Station Mir in 1997.

Solar Energy Economics Revisited: The Promise and Challenge of Orbiting Reflectors for World Energy Supply

NASA Technical Reports Server (NTRS)

Billman, Kenneth W.; Gilbreath, William P.; Bowen, Stuart W.

1978-01-01

A system of orbiting, large-area, low mass density reflector satellites which provide nearly continuous solar energy to a world-distributed set of conversion sites is examined under the criteria for any potential new energy system: technical feasibility, significant and renewable energy impact, economic feasibility and social/political acceptability. Although many technical issues need further study, reasonable advances in space technology appear sufficient to implement the system. The enhanced insolation is shown to greatly improve the economic competitiveness of solar-electric generation to circa 1995 fossil/nuclear alternatives. The system is shown to have the potential for supplying a significant fraction of future domestic and world energy needs. Finally, the environmental and social issues, including a means for financing such a large shift to a world solar energy dependence, is addressed.

Parabolic dish test site: History and operating experience

NASA Technical Reports Server (NTRS)

Selcuk, M. K. (Compiler)

1985-01-01

The parabolic dish test site (PDTS) was established for testing point-focusing solar concentrator systems operating at temperatures approaching 1650 C. Among tests run were evaluation and performance characterization of parabolic dish concentrators, receivers, power conversion units, and solar/fossil-fuel hybrid systems. The PDTS was fully operational until its closure in June, 1984. The evolution of the test program, a chronological listing of the experiments run, and data summaries for most of the tests conducted are presented.

Theoretical Analysis of Two Novel Hybrid Thermoelectric-Photovoltaic Systems Based on Cu₂ZnSnS₄ Solar Cells.

PubMed

Lorenzi, Bruno; Contento, Gaetano; Sabatelli, Vincenzo; Rizzo, Antonella; Narducci, Dario

2017-03-01

The development and commercialization of Photovoltaic (PV) cells with good cost-efficiency trade-off not using critical raw materials (CRMs) is one of the strategies chosen by the European Community (EC) to address the Energy Roadmap 2050. In this context Cu2ZnSnS4 (CZTS) solar cells are attracting a major interest since they have the potential to combine low price with relatively high conversion efficiencies. Although a ≈9% lab scale efficiency has already been reported for CZTS this technology is still far from being competitive in terms of cost per peak-power (€/Wp) with other common materials. One possible near-future solution to increase the CZTS competiveness comes from thermoelectrics. Actually it has already been shown that Hybrid Thermoelectric-Photovoltaic Systems (HTEPVs) based on CIGS, another kesterite very similar to CZTS, can lead to a significant efficiency improvement. However it has been also clarified how the optimal hybridization strategy cannot come from the simple coupling of solar cells with commercial TEGs, but special layouts have to be implemented. Furthermore, since solar cell performances are well known to decrease with temperature, thermal decoupling strategies of the PV and TEG sections have to be taken. To address these issues, we developed a model for two different HTEPV solutions, both coupled with CZTS solar cells. In the first case we considered a Thermally-Coupled HTEPV device (TC-HTEPV) in which the TEG is placed underneath the solar cell and in thermal contact with it. The second system consists instead of an Optically-Coupled but thermally decoupled device (OC-HTEPV) in which part of the solar spectrum is focused by a non-imaging optical concentrator on the TEG hot side. For both solutions the model returns conversion efficiencies higher than that of the CZTS solar cell alone. Specifically, increases of ≈30% are predicted for both kind of systems considered.

High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

1992-01-01

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

Optimization of Norbornadiene Compounds for Solar Thermal Storage by First-Principles Calculations.

PubMed

Kuisma, Mikael; Lundin, Angelica; Moth-Poulsen, Kasper; Hyldgaard, Per; Erhart, Paul

2016-07-21

Molecular photoswitches capable of storing solar energy are interesting candidates for future renewable energy applications. Here, using quantum mechanical calculations, we carry out a systematic screening of crucial optical (solar spectrum match) and thermal (storage energy density) properties of 64 such compounds based on the norbornadiene-quadricyclane system. Whereas a substantial number of these molecules reach the theoretical maximum solar power conversion efficiency, this requires a strong red-shift of the absorption spectrum, which causes undesirable absorption by the photoisomer as well as reduced thermal stability. These compounds typically also have a large molecular mass, leading to low storage densities. By contrast, single-substituted systems achieve a good compromise between efficiency and storage density, while avoiding competing absorption by the photo-isomer. This establishes guiding principles for the future development of molecular solar thermal storage systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solar-Powered Plasmon-Enhanced Heterogeneous Catalysis

NASA Astrophysics Data System (ADS)

Naldoni, Alberto; Riboni, Francesca; Guler, Urcan; Boltasseva, Alexandra; Shalaev, Vladimir M.; Kildishev, Alexander V.

2016-06-01

Photocatalysis uses semiconductors to convert sunlight into chemical energy. Recent reports have shown that plasmonic nanostructures can be used to extend semiconductor light absorption or to drive direct photocatalysis with visible light at their surface. In this review, we discuss the fundamental decay pathway of localized surface plasmons in the context of driving solar-powered chemical reactions. We also review different nanophotonic approaches demonstrated for increasing solar-to-hydrogen conversion in photoelectrochemical water splitting, including experimental observations of enhanced reaction selectivity for reactions occurring at the metalsemiconductor interface. The enhanced reaction selectivity is highly dependent on the morphology, electronic properties, and spatial arrangement of composite nanostructures and their elements. In addition, we report on the particular features of photocatalytic reactions evolving at plasmonic metal surfaces and discuss the possibility of manipulating the reaction selectivity through the activation of targeted molecular bonds. Finally, using solar-to-hydrogen conversion techniques as an example, we quantify the efficacy metrics achievable in plasmon-driven photoelectrochemical systems and highlight some of the new directions that could lead to the practical implementation of solar-powered plasmon-based catalytic devices.

The impact of surface chemistry on the performance of localized solar-driven evaporation system

PubMed Central

Yu, Shengtao; Zhang, Yao; Duan, Haoze; Liu, Yanming; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2015-01-01

This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation. PMID:26337561

The impact of surface chemistry on the performance of localized solar-driven evaporation system.

PubMed

Yu, Shengtao; Zhang, Yao; Duan, Haoze; Liu, Yanming; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2015-09-04

This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation.

Current matching using CdSe quantum dots to enhance the power conversion efficiency of InGaP/GaAs/Ge tandem solar cells.

PubMed

Lee, Ya-Ju; Yao, Yung-Chi; Tsai, Meng-Tsan; Liu, An-Fan; Yang, Min-De; Lai, Jiun-Tsuen

2013-11-04

A III-V multi-junction tandem solar cell is the most efficient photovoltaic structure that offers an extremely high power conversion efficiency. Current mismatching between each subcell of the device, however, is a significant challenge that causes the experimental value of the power conversion efficiency to deviate from the theoretical value. In this work, we explore a promising strategy using CdSe quantum dots (QDs) to enhance the photocurrent of the limited subcell to match with those of the other subcells and to enhance the power conversion efficiency of InGaP/GaAs/Ge tandem solar cells. The underlying mechanism of the enhancement can be attributed to the QD's unique capacity for photon conversion that tailors the incident spectrum of solar light; the enhanced efficiency of the device is therefore strongly dependent on the QD's dimensions. As a result, by appropriately selecting and spreading 7 mg/mL of CdSe QDs with diameters of 4.2 nm upon the InGaP/GaAs/Ge solar cell, the power conversion efficiency shows an enhancement of 10.39% compared to the cell's counterpart without integrating CdSe QDs.

A Deep Space Power System Option Based on Synergistic Power Conversion Technologies

NASA Technical Reports Server (NTRS)

Schreiber, Jeffrey G.

2000-01-01

Deep space science missions have typically used radioisotope thermoelectric generator (RTG) power systems. The RTG power system has proven itself to be a rugged and highly reliable power system over many missions, however the thermal-to-electric conversion technology used was approximately 5% efficient. While the relatively low efficiency has some benefits in terms of system integration, there are compelling reasons why a more efficient conversion system should be pursued. The cost savings alone that are available as a result of the reduced isotope inventory are significant. The Advanced Radioisotope Power System (ARPS) project was established to fulfill this goal. Although it was not part of the ARPS project, Stirling conversion technology is being demonstrated with a low level of funding by both NASA and DOE. A power system with Stirling convertors. although intended for use with an isotope heat source. can be combined with other advanced technologies to provide a novel power system for deep space missions. An inflatable primary concentrator would be used in combination with a refractive secondary concentrator (RSC) as the heat source to power the system. The inflatable technology as a structure has made great progress for a variety of potential applications such as communications reflectors, radiators and solar arrays. The RSC has been pursued for use in solar thermal propulsion applications, and it's unique properties allow some advantageous system trades to be made. The power system proposed would completely eliminate the isotope heat source and could potentially provide power for science missions to planets as distant as Uranus. This paper will present the background and developmental status of the technologies and will then describe the power system being proposed.

Thin film solar cells grown by organic vapor phase deposition

NASA Astrophysics Data System (ADS)

Yang, Fan

Organic solar cells have the potential to provide low-cost photovoltaic devices as a clean and renewable energy resource. In this thesis, we focus on understanding the energy conversion process in organic solar cells, and improving the power conversion efficiencies via controlled growth of organic nanostructures. First, we explain the unique optical and electrical properties of organic materials used for photovoltaics, and the excitonic energy conversion process in donor-acceptor heterojunction solar cells that place several limiting factors of their power conversion efficiency. Then, strategies for improving exciton diffusion and carrier collection are analyzed using dynamical Monte Carlo models for several nanostructure morphologies. Organic vapor phase deposition is used for controlling materials crystallization and film morphology. We improve the exciton diffusion efficiency while maintaining good carrier conduction in a bulk heterojunction solar cell. Further efficiency improvement is obtained in a novel nanocrystalline network structure with a thick absorbing layer, leading to the demonstration of an organic solar cell with 4.6% efficiency. In addition, solar cells using simultaneously active heterojunctions with broad spectral response are presented. We also analyze the efficiency limits of single and multiple junction organic solar cells, and discuss the challenges facing their practical implementations.

Optimization of a point-focusing, distributed receiver solar thermal electric system

NASA Technical Reports Server (NTRS)

Pons, R. L.

1979-01-01

This paper presents an approach to optimization of a solar concept which employs solar-to-electric power conversion at the focus of parabolic dish concentrators. The optimization procedure is presented through a series of trade studies, which include the results of optical/thermal analyses and individual subsystem trades. Alternate closed-cycle and open-cycle Brayton engines and organic Rankine engines are considered to show the influence of the optimization process, and various storage techniques are evaluated, including batteries, flywheels, and hybrid-engine operation.

Power output and carrier dynamics studies of perovskite solar cells under working conditions.

PubMed

Yu, Man; Wang, Hao-Yi; Hao, Ming-Yang; Qin, Yujun; Fu, Li-Min; Zhang, Jian-Ping; Ai, Xi-Cheng

2017-08-02

Perovskite solar cells have emerged as promising photovoltaic systems with superb power conversion efficiency. For the practical application of perovskite devices, the greatest concerns are the power output density and the related dynamics under working conditions. In this study, the working conditions of planar and mesoscopic perovskite solar cells are simulated and the power output density evolutions with the working voltage are highlighted. The planar device exhibits higher capability of outputting power than the mesoscopic one. The transient photoelectric conversion dynamics are investigated under the open circuit, short circuit and working conditions. It is found that the power output and dynamic processes are correlated intrinsically, which suggests that the power output is the competitive result of the charge carrier recombination and transport. The present work offers a unique view to elucidating the relationship between the power output and the charge carrier dynamics for perovskite solar cells in a comprehensive manner, which would be beneficial to their future practical applications.

Research opportunities to advance solar energy utilization.

PubMed

Lewis, Nathan S

2016-01-22

Major developments, as well as remaining challenges and the associated research opportunities, are evaluated for three technologically distinct approaches to solar energy utilization: solar electricity, solar thermal, and solar fuels technologies. Much progress has been made, but research opportunities are still present for all approaches. Both evolutionary and revolutionary technology development, involving foundational research, applied research, learning by doing, demonstration projects, and deployment at scale will be needed to continue this technology-innovation ecosystem. Most of the approaches still offer the potential to provide much higher efficiencies, much lower costs, improved scalability, and new functionality, relative to the embodiments of solar energy-conversion systems that have been developed to date. Copyright © 2016, American Association for the Advancement of Science.

Fresnel Concentrators for Space Solar Power and Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Bradford, Rodney; Parks, Robert W.; Craig, Harry B. (Technical Monitor)

2001-01-01

Large deployable Fresnel concentrators are applicable to solar thermal propulsion and multiple space solar power generation concepts. These concentrators can be used with thermophotovoltaic, solar thermionic, and solar dynamic conversion systems. Thin polyimide Fresnel lenses and reflectors can provide tailored flux distribution and concentration ratios matched to receiver requirements. Thin, preformed polyimide film structure components assembled into support structures for Fresnel concentrators provide the capability to produce large inflation-deployed concentrator assemblies. The polyimide film is resistant to the space environment and allows large lightweight assemblies to be fabricated that can be compactly stowed for launch. This work addressed design and fabrication of lightweight polyimide film Fresnel concentrators, alternate materials evaluation, and data management functions for space solar power concepts, architectures, and supporting technology development.

A Question and Answer Guide to Astronomy

NASA Astrophysics Data System (ADS)

Christian, Carol; Roy, Jean-René

2017-03-01

Preface; 1. The sky viewed from Earth; 2. The Earth and Moon system; 3. The Solar System; 4. Stars and stellar systems; 5. Galaxies and the Universe; 6. Life in the Universe; 7. Amateur astronomy; 8. Telescopes and instruments; Unit conversion and basic physical and astronomical measurements; References; Bibliography; Index.

Power system requirements and definition for lunar and Mars outposts

NASA Technical Reports Server (NTRS)

Petri, D. A.; Cataldo, R. L.; Bozek, J. M.

1990-01-01

Candidate power systems being considered for outpost facilities (stationary power systems) and vehicles (mobile systems) are discussed, including solar, chemical, isotopic, and reactor. The current power strategy was an initial outpost power system composed of photovoltaic arrays for daytime energy needs and regenerative fuel cells for power during the long lunar night. As day and night power demands grow, the outpost transitions to nuclear-based power generation, using thermoelectric conversion initially and evolving to a dynamic conversion system. With this concept as a guideline, a set of requirements has been established, and a reference definition of candidate power systems meeting these requirements has been identified.

Workshop proceedings: Photovoltaic conversion of solar energy for terrestrial applications. Volume 1: Working group and panel reports

NASA Technical Reports Server (NTRS)

1973-01-01

Technological aspects of solar energy conversion by photovoltaic cells are considered. The advantage of the single crystal silicon solar cell approach is developed through comparisons with polycrystalline silicon, cadmium sulfide/copper sulfide thin film cells, and other materials and devices.

A Silicon–Singlet Fission Tandem Solar Cell Exceeding 100% External Quantum Efficiency with High Spectral Stability

PubMed Central

2017-01-01

After 60 years of research, silicon solar cell efficiency saturated close to the theoretical limit, and radically new approaches are needed to further improve the efficiency. The use of tandem systems raises this theoretical power conversion efficiency limit from 34% to 45%. We present the advantageous spectral stability of using voltage-matched tandem solar cells with respect to their traditional series-connected counterparts and experimentally demonstrate how singlet fission can be used to produce simple voltage-matched tandems. Our singlet fission silicon–pentacene tandem solar cell shows efficient photocurrent addition. This allows the tandem system to benefit from carrier multiplication and to produce an external quantum efficiency exceeding 100% at the main absorption peak of pentacene. PMID:28261671

Critical areas: Satellite power systems concepts

NASA Technical Reports Server (NTRS)

1975-01-01

Critical Areas are defined and discussed in the various areas pertinent to satellite power systems. The presentation is grouped into five areas (General, Space Systems, Solar Energy Conversion, Microwave Systems, and Environment/Ecology) with a sixth area (Power Relay) considered separately in an appendix. Areas for Future Consideration as critical areas are discussed in a second appendix.

A solar simulator-pumped atomic iodine laser

NASA Technical Reports Server (NTRS)

Lee, J. H.; Weaver, W. R.

1981-01-01

An atomic iodine laser, a candidate for the direct solar-pumped gas laser, was excited with a 4-kW beam from a xenon arc solar simulator. Continuous lasing at 1.315 micron for over 10 ms was obtained for static filling of n-C3F7I vapor. By momentarily flowing the lasant, a 30-Hz pulsed output was obtained for about 200 ms. The peak laser power observed was 4 W for which the system efficiency reached 0.1%. These results indicate that direct solar pumping of a gas laser for power conversion in space is indeed feasible.

Control system development for an organic Ranking cycle engine

NASA Technical Reports Server (NTRS)

Bergthold, F. M., Jr.; Fulton, D. G.; Haskins, H. J.

1981-01-01

An organic Rankine cycle engine is used as part of a solar thermal power conversion assembly (PCA). The PCA, including a direct-heated cavity receiver and a shaft-mounted alternator, is mounted at the focal point of a parabolic dish concentrator. The engine controls are required to maintain approximately constant values of turbine inlet temperature and shaft speed, despite variation in the concentrated solar power input to the receiver. The controls design approach, system models, and initial stability and performance analysis results are presented herein.

NASA-OAST photovoltaic energy conversion program

NASA Technical Reports Server (NTRS)

Mullin, J. P.; Loria, J. C.

1984-01-01

The NASA program in photovoltaic energy conversion research is discussed. Solar cells, solar arrays, gallium arsenides, space station and spacecraft power supplies, and state of the art devices are discussed.

Integrated Photoelectrochemical Solar Energy Conversion and Organic Redox Flow Battery Devices.

PubMed

Li, Wenjie; Fu, Hui-Chun; Li, Linsen; Cabán-Acevedo, Miguel; He, Jr-Hau; Jin, Song

2016-10-10

Building on regenerative photoelectrochemical solar cells and emerging electrochemical redox flow batteries (RFBs), more efficient, scalable, compact, and cost-effective hybrid energy conversion and storage devices could be realized. An integrated photoelectrochemical solar energy conversion and electrochemical storage device is developed by integrating regenerative silicon solar cells and 9,10-anthraquinone-2,7-disulfonic acid (AQDS)/1,2-benzoquinone-3,5-disulfonic acid (BQDS) RFBs. The device can be directly charged by solar light without external bias, and discharged like normal RFBs with an energy storage density of 1.15 Wh L -1 and a solar-to-output electricity efficiency (SOEE) of 1.7 % over many cycles. The concept exploits a previously undeveloped design connecting two major energy technologies and promises a general approach for storing solar energy electrochemically with high theoretical storage capacity and efficiency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface Plasmon-Assisted Solar Energy Conversion.

PubMed

Dodekatos, Georgios; Schünemann, Stefan; Tüysüz, Harun

2016-01-01

The utilization of localized surface plasmon resonance (LSPR) from plasmonic noble metals in combination with semiconductors promises great improvements for visible light-driven photocatalysis, in particular for energy conversion. This review summarizes the basic principles of plasmonic photocatalysis, giving a comprehensive overview about the proposed mechanisms for enhancing the performance of photocatalytically active semiconductors with plasmonic devices and their applications for surface plasmon-assisted solar energy conversion. The main focus is on gold and, to a lesser extent, silver nanoparticles in combination with titania as semiconductor and their usage as active plasmonic photocatalysts. Recent advances in water splitting, hydrogen generation with sacrificial organic compounds, and CO2 reduction to hydrocarbons for solar fuel production are highlighted. Finally, further improvements for plasmonic photocatalysts, regarding performance, stability, and economic feasibility, are discussed for surface plasmon-assisted solar energy conversion.

Systems definition space based power conversion systems: Executive summary

NASA Technical Reports Server (NTRS)

1977-01-01

Potential space-located systems for the generation of electrical power for use on earth were investigated. These systems were of three basic types: (1) systems producing electrical power from solar energy; (2) systems producing electrical power from nuclear reactors; (3) systems for augmenting ground-based solar power plants by orbital sunlight reflectors. Configurations implementing these concepts were developed through an optimization process intended to yield the lowest cost for each. A complete program was developed for each concept, identifying required production rates, quantities of launches, required facilities, etc. Each program was costed in order to provide the electric power cost appropriate to each concept.

Solar photovoltaic power systems: an electric utility R & d perspective.

PubMed

Demeo, E A; Taylor, R W

1984-04-20

Solar photovoltaic technology is receiving increasing attention as a prospective source of bulk, electric utility power within the next 10 to 20 years. Successful development will require solar energy conversion efficiencies of about 15 percent for photovoltaic flat-plate modules, or about 25 percent for photovoltaic cells using highly concentrated sunlight. Three different cell technologies have a better than even chance of achieving these target efficiencies with costs and operating lifetimes that would allow significant use by electric utilities. The challenge for the next decade is to push photovoltaic technology to its physical limits while expanding markets and user confidence with currently available systems.

Nature-Inspired Design of Artificial Solar-to-Fuel Conversion Systems based on Copper Phosphate Microflowers.

PubMed

Wang, Jing; Zhu, Ting; Ho, Ghim Wei

2016-07-07

Phosphates play significant roles in plant photosynthesis by mediating electron transportation and furnishing energy for CO2 reduction. Motivated by this, we demonstrate herein an artificial solar-to-fuel conversion system, involving versatile copper phosphate microflowers as template and titanium dioxide nanoparticles as host photocatalyst. The elaborate flowerlike architectures, coupled with a unique proton-reduction cycle from interchangeability of different species of orthophosphate ions, not only offer a 2D nanosheet platform for an optimal heterostructure interface but also effectively augment charge-carrier transfer, thereby contributing to enhanced photoactivity and hydrogen generation. These nature-inspired, phosphate-derived nanocomposites advance the synthesis of a large variety of functional materials, which holds great potential for photochemical, photoelectric and catalytic applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Papaya drying and waste conversion system. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-02-12

This project, performed under United States Department of Energy Small-scale Appropriate Energy Technology Grant, involves demonstration of an integrated system using solar energy to process off-grade or reject fruit into marketable food products. The integrated system consists of three phases: (1) solar dehydration of usable fruit; (2) solar vacuum distillation of fermented wastes (peelings, rinds, skins, and seeds) to produce an ethanol fuel to use as a backup source of heat for dehydration; and (3) land reclamation by mixing stillage and compost with volcanic cinder and ash to produce on marginal land a rich soil suitable for growing more cropsmore » to dry. Although the system is not 100% complete the investigators have demonstrated that a small business can efficiently use solar energies in an integrated fashion to process waste into food, improve the quality of the land, and provide meaningful jobs in a region of very high unemployment.« less

Papago Indians Light the Way.

ERIC Educational Resources Information Center

D'Alessandro, Bill

1979-01-01

Describes the world's only solar electric village power system, a photovoltaic conversion installation in a remote Papago Indian Reservation village. Notes comparative costs, electric output, and potential applications of the system, a prototype for remote rural communities and developing nations. Notes outstanding questions and key issues in…

Hydrophobic Light-to-Heat Conversion Membranes with Self-Healing Ability for Interfacial Solar Heating.

PubMed

Zhang, Lianbin; Tang, Bo; Wu, Jinbo; Li, Renyuan; Wang, Peng

2015-09-02

Self-healing hydrophobic light-to-heat conversion membranes for interfacial solar heating are fabricated by deposition of light-to-heat conversion material of polypyrrole onto a porous stainless-steel mesh, followed by hydrophobic fluoroalkylsilane modification. The mesh-based membranes spontaneously stay at the water-air interface, collect and convert solar light into heat, and locally heat only the water surface for enhanced evaporation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of the DSSC photoanode area based on TiO2/Ag on the conversion efficiency of solar energy into electrical energy

NASA Astrophysics Data System (ADS)

Ibrayev, N.; Serikov, T.; Zavgorodniy, A.; Sadykova, A.

2018-01-01

A module based on dye-sensitized solar cells with Ag/TiO2 structure was developed. It is shown that the addition of the core-shell structure to the semiconductor film of titanium dioxide, where the nanoparticle Ag serves as the core, and the TiO2 is shell, increases the coefficient of solar energy conversion into electrical energy. The effect of the photoanode area on the efficiency of conversion of solar energy into electrical energy is studied. It is shown that the density of the photocurrent decreases with increasing of the photoanode area, which leads to a drop in the efficiency of solar cells.

NOMINAL VALUES FOR SELECTED SOLAR AND PLANETARY QUANTITIES: IAU 2015 RESOLUTION B3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prša, Andrej; Harmanec, Petr; Torres, Guillermo

In this brief communication we provide the rationale for and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIXth General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature, and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the timemore » of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary, and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion.« less

Nominal Values for Selected Solar and Planetary Quantities: IAU 2015 Resolution B3

NASA Astrophysics Data System (ADS)

Prša, Andrej; Harmanec, Petr; Torres, Guillermo; Mamajek, Eric; Asplund, Martin; Capitaine, Nicole; Christensen-Dalsgaard, Jørgen; Depagne, Éric; Haberreiter, Margit; Hekker, Saskia; Hilton, James; Kopp, Greg; Kostov, Veselin; Kurtz, Donald W.; Laskar, Jacques; Mason, Brian D.; Milone, Eugene F.; Montgomery, Michele; Richards, Mercedes; Schmutz, Werner; Schou, Jesper; Stewart, Susan G.

2016-08-01

In this brief communication we provide the rationale for and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIXth General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature, and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the time of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary, and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion.

Laser annealing of ion implanted CZ silicon for solar cell junction formation

NASA Technical Reports Server (NTRS)

Katzeff, J. S.

1981-01-01

The merits of large spot size pulsed laser annealing of phosphorus implanted, Czochralski grown silicon for function formation of solar cells are evaluated. The feasibility and requirements are also determined to scale-up a laser system to anneal 7.62 cm diameter wafers at a rate of one wafer/second. Results show that laser annealing yields active, defect-free, shallow junction devices. Functional cells with AM 1 conversion efficiencies up to 15.4% for 2 x 2 cm and 2 x 4 cm sizes were attained. For larger cells, 7.62 cm dia., conversion efficiencies ranged up to 14.5%. Experiments showed that texture etched surfaces are not compatible with pulsed laser annealing due to the surface melting caused by the laser energy. When compared with furnace annealed cells, the laser annealed cells generally exhibited conversion efficiencies which were equal to or better than those furnace annealed. In addition, laser annealing has greater throughput potential.

Space-based solar power conversion and delivery systems study. Volume 5: Economic analysis

NASA Technical Reports Server (NTRS)

1977-01-01

Space-based solar power conversion and delivery systems are studied along with a variety of economic and programmatic issues relevant to their development and deployment. The costs, uncertainties and risks associated with the current photovoltaic Satellite Solar Power System (SSPS) configuration, and issues affecting the development of an economically viable SSPS development program are addressed. In particular, the desirability of low earth orbit (LEO) and geosynchronous (GEO) test satellites is examined and critical technology areas are identified. The development of SSPS unit production (nth item), and operation and maintenance cost models suitable for incorporation into a risk assessment (Monte Carlo) model (RAM) are reported. The RAM was then used to evaluate the current SSPS configuration expected costs and cost-risk associated with this configuration. By examining differential costs and cost-risk as a function of postulated technology developments, the critical technologies, that is, those which drive costs and/or cost-risk, are identified. It is shown that the key technology area deals with productivity in space, that is, the ability to fabricate and assemble large structures in space, not, as might be expected, with some hardware component technology.

Revised congressional budget request, FY 1982. Conservation and renewable energy program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-03-01

Programs dealing with conservation and renewable energy are reprinted from the Revised Congressional Budget Request FY 1982. From Volume 7, Energy Conservation, information is presented on: buildings and community systems; industrial programs; transportation programs; state and local programs; inventor's program energy conversion technology; energy impact assistance; and residential/commercial retrofit. From Volume 2, Energy Supply Research and Development, information and data are presented on: solar building applications; solar industrial applications; solar power applications; solar information systems; SERI facility; solar international activities; alcohol fuels; geothermal; and hydropower. From Volume 6, Energy Production, Demonstration, and Distribution, information and data on solar energy production,more » demonstration, and distribution are presented. From Volume 3, Energy Supply and R and D Appropriation, information and data on electric energy systems and energy storage systems are included. From Volume 4, information and data are included on geothermal resources development fund. In Volume 5, Power Marketing Administrations, information and data are presented on estimates by appropriations, positions and staff years by appropriation, staffing distribution, and power marketing administrations. Recissions and deferrals for FY 1981 are given. (MCW)« less

Current challenges in organic photovoltaic solar energy conversion.

PubMed

Schlenker, Cody W; Thompson, Mark E

2012-01-01

Over the last 10 years, significant interest in utilizing conjugated organic molecules for solid-state solar to electric conversion has produced rapid improvement in device efficiencies. Organic photovoltaic (OPV) devices are attractive for their compatibility with low-cost processing techniques and thin-film applicability to flexible and conformal applications. However, many of the processes that lead to power losses in these systems still remain poorly understood, posing a significant challenge for the future efficiency improvements required to make these devices an attractive solar technology. While semiconductor band models have been employed to describe OPV operation, a more appropriate molecular picture of the pertinent processes is beginning to emerge. This chapter presents mechanisms of OPV device operation, based on the bound molecular nature of the involved transient species. With the intention to underscore the importance of considering both thermodynamic and kinetic factors, recent progress in elucidating molecular characteristics that dictate photovoltage losses in heterojunction organic photovoltaics is also discussed.

The influence of the push-pull effect and a π-conjugated system in conversion efficiency of bis-chalcone compounds in a dye sensitized solar cell

NASA Astrophysics Data System (ADS)

Teo, Kien Yung; Tiong, Mee Hing; Wee, Hung Yee; Jasin, Nornadia; Liu, Zhi-Qiang; Shiu, Ming Yang; Tang, Jyun Yang; Tsai, Jenn-Kai; Rahamathullah, Rafizah; Khairul, Wan M.; Tay, Meng Guan

2017-09-01

Chalcone and its related compounds are known to be π-conjugated compounds, which can be potentially used in different electronic areas include dye sensitized solar cell (DSSC). A total of six bis-chalcone compounds (1-6) have been synthesized using a Claisen-Schmidt condensation method under basic conditions. The compounds were used as the dye in DSSC to test their solar conversion efficiency. In the process of solar cell fabrication, titanium(II) oxide (TiO2) coated glass was used as the working electrode, whereas the mixture of iodine (I2), lithium iodide (LiI), 4-tertbutylpyridine (4-TBP) and 1,2-dimethyl-3-propylimidazolium (DMPII) in 3-methoxypropionitrile were used as the electrolyte. The DSSC was fabricated by immersing the TiO2 glass into the respective bis-chalcone compound solution and dried into the oven at 45 °C for 120 min. Lastly, the working electrode and counter electrode were sealed using surlyn of 60 μm thickness. The efficiency test was conducted under AM 1.5G illumination with the incident light intensity of 100 mW/cm2. Among the six bis-chalcone derivatives, compound 2, namely 1,4-bis-2-hydroxychalcone, was recorded with the highest efficiency (0.054%) compared to the others (0.022-0.035%). The presence of a π-conjugated system and the push-pull effect in the molecule were found to enhance the conversion efficiency of DSSC. Details of the results are discussed in the present paper.

Methods and analysis of factors impact on the efficiency of the photovoltaic generation

NASA Astrophysics Data System (ADS)

Tianze, Li; Xia, Zhang; Chuan, Jiang; Luan, Hou

2011-02-01

First of all, the thesis elaborates two important breakthroughs which happened In the field of the application of solar energy in the 1950s.The 21st century the development of solar photovoltaic power generation will have the following characteristics: the continued high growth of industrial development, the significantly reducing cost of the solar cell, the large-scale high-tech development of photovoltaic industries, the breakthroughs of the film battery technology, the rapid development of solar PV buildings integration and combined to the grids. The paper makes principles of solar cells the theoretical analysis. On the basis, we study the conversion efficiency of solar cells, find the factors impact on the efficiency of the photovoltaic generation, solve solar cell conversion efficiency of technical problems through the development of new technology, and open up new ways to improve the solar cell conversion efficiency. Finally, the paper connecting with the practice establishes policies and legislation to the use of encourage renewable energy, development strategy, basic applied research etc.

Research and Technology Activities Supporting Closed-Brayton-Cycle Power Conversion System Development

NASA Technical Reports Server (NTRS)

Barrett, Michael J.

2004-01-01

The elements of Brayton technology development emphasize power conversion system risk mitigation. Risk mitigation is achieved by demonstrating system integration feasibility, subsystem/component life capability (particularly in the context of material creep) and overall spacecraft mass reduction. Closed-Brayton-cycle (CBC) power conversion technology is viewed as relatively mature. At the 2-kWe power level, a CBC conversion system Technology Readiness Level (TRL) of six (6) was achieved during the Solar Dynamic Ground Test Demonstration (SD-GTD) in 1998. A TRL 5 was demonstrated for 10 kWe-class CBC components during the development of the Brayton Rotating Unit (BRU) from 1968 to 1976. Components currently in terrestrial (open cycle) Brayton machines represent TRL 4 for similar uses in 100 kWe-class CBC space systems. Because of the baseline component and subsystem technology maturity, much of the Brayton technology task is focused on issues related to systems integration. A brief description of ongoing technology activities is given.

Alternative Architecture for Commercial Space Solar Power

NASA Technical Reports Server (NTRS)

Potter, Seth

2000-01-01

This presentation discuss the space solar power (SSP) concept. It takes us step by step through the process: the use of sunlight and solar cells to create power, the conversion of the sunlight into electricity, the conversion of electricity to microwaves, and finally the from microwaves back to electricity by the Rectennas on Earth.

Supported black phosphorus nanosheets as hydrogen-evolving photocatalyst achieving 5.4% energy conversion efficiency at 353 K.

PubMed

Tian, Bin; Tian, Bining; Smith, Bethany; Scott, M C; Hua, Ruinian; Lei, Qin; Tian, Yue

2018-04-11

Solar-driven water splitting using powdered catalysts is considered as the most economical means for hydrogen generation. However, four-electron-driven oxidation half-reaction showing slow kinetics, accompanying with insufficient light absorption and rapid carrier combination in photocatalysts leads to low solar-to-hydrogen energy conversion efficiency. Here, we report amorphous cobalt phosphide (Co-P)-supported black phosphorus nanosheets employed as photocatalysts can simultaneously address these issues. The nanosheets exhibit robust hydrogen evolution from pure water (pH = 6.8) without bias and hole scavengers, achieving an apparent quantum efficiency of 42.55% at 430 nm and energy conversion efficiency of over 5.4% at 353 K. This photocatalytic activity is attributed to extremely efficient utilization of solar energy (~75% of solar energy) by black phosphorus nanosheets and high-carrier separation efficiency by amorphous Co-P. The hybrid material design realizes efficient solar-to-chemical energy conversion in suspension, demonstrating the potential of black phosphorus-based materials as catalysts for solar hydrogen production.

Efficient Solar-Thermal Energy Harvest Driven by Interfacial Plasmonic Heating-Assisted Evaporation.

PubMed

Chang, Chao; Yang, Chao; Liu, Yanming; Tao, Peng; Song, Chengyi; Shang, Wen; Wu, Jianbo; Deng, Tao

2016-09-07

The plasmonic heating effect of noble nanoparticles has recently received tremendous attention for various important applications. Herein, we report the utilization of interfacial plasmonic heating-assisted evaporation for efficient and facile solar-thermal energy harvest. An airlaid paper-supported gold nanoparticle thin film was placed at the thermal energy conversion region within a sealed chamber to convert solar energy into thermal energy. The generated thermal energy instantly vaporizes the water underneath into hot vapors that quickly diffuse to the thermal energy release region of the chamber to condense into liquids and release the collected thermal energy. The condensed water automatically flows back to the thermal energy conversion region under the capillary force from the hydrophilic copper mesh. Such an approach simultaneously realizes efficient solar-to-thermal energy conversion and rapid transportation of converted thermal energy to target application terminals. Compared to conventional external photothermal conversion design, the solar-thermal harvesting device driven by the internal plasmonic heating effect has reduced the overall thermal resistance by more than 50% and has demonstrated more than 25% improvement of solar water heating efficiency.

Luminescent Spectral Conversion to Improve the Performance of Dye-Sensitized Solar Cells.

PubMed

Hosseini, Zahra; Taghavinia, Nima; Wei-Guang Diau, Eric

2017-12-06

Relative to the broadband solar spectrum, a narrow range of spectral absorption of photovoltaic (PV) devices is considered an important determinant that the efficiency of light harvesting of these devices is less than unity. Having the narrowest spectral response to solar radiation among all PV devices, dye-sensitized solar cells (DSSCs) suffer severely from this loss. Luminescent spectral conversion provides a mechanism to manipulate and to adapt the incident solar spectrum by converting, through photoluminescence, the energies of solar photons into those that are more effectively captured by a PV device. This mechanism is particularly helpful for DSSCs because there is much flexibility in both the choice of the light-harvesting materials and the architecture of the DSSC. Here we review and discuss recent advances in the field of luminescent spectral conversion for DSSCs. The focus is on the architectural design of DSSCs, and the complications, advantages and new functionalities offered by each of their configurations are discussed. The loss mechanisms are examined and important parameters governing the spectral conversion mechanism of a DSSC are introduced. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A program for the calculation of paraboloidal-dish solar thermal power plant performance

NASA Technical Reports Server (NTRS)

Bowyer, J. M., Jr.

1985-01-01

A program capable of calculating the design-point and quasi-steady-state annual performance of a paraboloidal-concentrator solar thermal power plant without energy storage was written for a programmable calculator equipped with suitable printer. The power plant may be located at any site for which a histogram of annual direct normal insolation is available. Inputs required by the program are aperture area and the design and annual efficiencies of the concentrator; the intercept factor and apparent efficiency of the power conversion subsystem and a polynomial representation of its normalized part-load efficiency; the efficiency of the electrical generator or alternator; the efficiency of the electric power conditioning and transport subsystem; and the fractional parasitic loses for the plant. Losses to auxiliaries associated with each individual module are to be deducted when the power conversion subsystem efficiencies are calculated. Outputs provided by the program are the system design efficiency, the annualized receiver efficiency, the annualized power conversion subsystem efficiency, total annual direct normal insolation received per unit area of concentrator aperture, and the system annual efficiency.

Determination of unique power conversion efficiency of solar cell showing hysteresis in the I-V curve under various light intensities.

PubMed

Cojocaru, Ludmila; Uchida, Satoshi; Tamaki, Koichi; Jayaweera, Piyankarage V V; Kaneko, Shoji; Nakazaki, Jotaro; Kubo, Takaya; Segawa, Hiroshi

2017-09-18

Energy harvesting at low light intensities has recently attracted a great deal of attention of perovskite solar cells (PSCs) which are regarded as promising candidate for indoor application. Anomalous hysteresis of the PSCs a complex issue for reliable evaluation of the cell performance. In order to address these challenges, we constructed two new evaluation methods to determinate the power conversion efficiencies (PCEs) of PSCs. The first setup is a solar simulator based on light emitting diodes (LEDs) allowing evaluation of the solar cells at wider range of light intensities, ranging from 10 2  to 10 -3  mW·cm -2 . As the overestimate error, we found that the PCEs of dye sensitized solar cell (DSC) and PSCs increase dramatically at low light intensities conditions. Due to the internal capacitance at the interfaces on hybrid solar cells, the measurement of current below 10 -2  mW·cm -2 shows constant value given high PCE, which is related to the capacitive current and origin of the hysteresis. The second setup is a photovoltaic power analyzing system, designed for tracking the maximum power (P max ) with time. The paper suggests the combination of the LED solar simulator and P max tracking technique as a standard to evaluate the PCE of capacitive solar cells.

The OAST space power program

NASA Technical Reports Server (NTRS)

Bennett, Gary L.

1991-01-01

The NASA Office of Aeronautics and Space Technology (OAST) space power program was established to provide the technology base to meet power system requirements for future space missions, including the Space Station, earth orbiting spacecraft, lunar and planetary bases, and solar system exploration. The program spans photovoltaic energy conversion, chemical energy conversion, thermal energy conversion, power management, thermal management, and focused initiatives on high-capacity power, surface power, and space nuclear power. The OAST space power program covers a broad range of important technologies that will enable or enhance future U.S. space missions. The program is well under way and is providing the kind of experimental and analytical information needed for spacecraft designers to make intelligent decisions about future power system options.

Low cost solar array project 1: Silicon material

NASA Technical Reports Server (NTRS)

Jewett, D. N.; Bates, H. E.; Hill, D. M.

1980-01-01

The low cost production of silicon by deposition of silicon from a hydrogen/chlorosilane mixture is described. Reactor design, reaction vessel support systems (physical support, power control and heaters, and temperature monitoring systems) and operation of the system are reviewed. Testing of four silicon deposition reactors is described, and test data and consequently derived data are given. An 18% conversion of trichlorosilane to silicon was achieved, but average conversion rates were lower than predicted due to incomplete removal of byproduct gases for recycling and silicon oxide/silicon polymer plugging of the gas outlet. Increasing the number of baffles inside the reaction vessel improved the conversion rate. Plans for further design and process improvements to correct the problems encountered are outlined.

High-Temperature-Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells.

PubMed

Kim, Minjin; Kim, Gi-Hwan; Oh, Kyoung Suk; Jo, Yimhyun; Yoon, Hyun; Kim, Ka-Hyun; Lee, Heon; Kim, Jin Young; Kim, Dong Suk

2017-06-27

Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm 2 active area and 18% over a 1 cm 2 active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

Lunar power systems

NASA Technical Reports Server (NTRS)

1986-01-01

The findings of a study on the feasibility of several methods of providing electrical power for a permanently manned lunar base are provided. Two fundamentally different methods for lunar electrical power generation are considered. One is the use of a small nuclear reactor and the other is the conversion of solar energy to electricity. The baseline goal was to initially provide 300 kW of power with growth capability to one megawatt and eventually to 10 megawatts. A detailed, day by day scenario for the establishment, build-up, and operational activity of the lunar base is presented. Also presented is a conceptual approach to a supporting transportation system which identifies the number, type, and deployment of transportation vehicles required to support the base. An approach to the use of solar cells in the lunar environment was developed. There are a number of heat engines which are applicable to solar/electric conversions, and these are examined. Several approaches to energy storage which were used by the electric power utilities were examined and those which could be used at a lunar base were identified.

Stretched Lens Array (SLA) for Collection and Conversion of Infrared Laser Light: 45% Efficiency Demonstrated for Near-Term 800 W/kg Space Power System

NASA Technical Reports Server (NTRS)

O'Neill, Mark; Howell, Joe; Fikes, John; Fork, Richard; Phillips, Dane; Aiken, Dan; McDanal, A. J.

2006-01-01

For the past 2% years, our team has been developing a unique photovoltaic concentrator array for collection and conversion of infrared laser light. This laser-receiving array has evolved from the solar-receiving Stretched Lens Array (SLA). The laser-receiving version of SLA is being developed for space power applications when or where sunlight is not available (e.g., the eternally dark lunar polar craters). The laser-receiving SLA can efficiently collect and convert beamed laser power from orbiting spacecraft or other sources (e.g., solar-powered lasers on the permanently illuminated ridges of lunar polar craters). A dual-use version of SLA can produce power from sunlight during sunlit portions of the mission, and from beamed laser light during dark portions of the mission. SLA minimizes the cost and mass of photovoltaic cells by using gossamer-like Fresnel lenses to capture and focus incoming light (solar or laser) by a factor of 8.5X, thereby providing a cost-effective, ultra-light space power system.

Space-based solar power conversion and delivery systems study. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Hazelrigg, G. A., Jr.

1976-01-01

The technical and economic aspects of satellite solar power systems are presented with a focus on the current configuration 5000 MW system. The technical studies include analyses of the orbital system structures, control and stationkeeping, and the formulation of program plans and costs for input to the economic analyses. The economic analyses centered about the development and use of a risk analysis model for a system cost assessment, identification of critical issues and technologies, and to provide information for programmatic decision making. A preliminary economic examination of some utility interface issues is included. Under the present state-of-knowledge, it is possible to formulate a program plan for the development of a satellite solar power system that can be economically justified. The key area of technological uncertainty is man's ability to fabricate and assemble large structures in space.

Integrated solar thermochemical reaction system for steam methane reforming

DOE PAGES

Zheng, Feng; Diver, Rich; Caldwell, Dustin D.; ...

2015-06-05

Solar-aided upgrade of the energy content of fossil fuels, such as natural gas, can provide a near-term transition path towards a future solar-fuel economy and reduce carbon dioxide emission from fossil fuel consumption. Both steam and dry reforming a methane-containing fuel stream have been studied with concentrated solar power as the energy input to drive the highly endothermic reactions but the concept has not been demonstrated at a commercial scale. Under a current project with the U.S. Department of Energy, PNNL is developing an integrated solar thermochemical reaction system that combines solar concentrators with micro- and meso-channel reactors and heatmore » exchangers to accomplish more than 20% solar augment of methane higher heating value. The objective of our three-year project is to develop and prepare for commercialization such solar reforming system with a high enough efficiency to serve as the frontend of a conventional natural gas (or biogas) combined cycle power plant, producing power with a levelized cost of electricity less than 6¢/kWh, without subsidies, by the year 2020. In this paper, we present results from the first year of our project that demonstrated a solar-to-chemical energy conversion efficiency as high as 69% with a prototype reaction system.« less

Renewable and high efficient syngas production from carbon dioxide and water through solar energy assisted electrolysis in eutectic molten salts

NASA Astrophysics Data System (ADS)

Wu, Hongjun; Liu, Yue; Ji, Deqiang; Li, Zhida; Yi, Guanlin; Yuan, Dandan; Wang, Baohui; Zhang, Zhonghai; Wang, Peng

2017-09-01

Over-reliance on non-renewable fossil fuel leads to steadily increasing concentration of atmospheric CO2, which has been implicated as a critical factor contributing to global warming. The efficient conversion of CO2 into useful product is highly sought after both in academic and industry. Herein, a novel conversion strategy is proposed to one-step transform CO2/H2O into syngas (CO/H2) in molten salt with electrolysis method. All the energy consumption in this system are contributed from sustainable energy sources: concentrated solar light heats molten salt and solar cell supplies electricity for electrolysis. The eutectic Li0.85Na0.61K0.54CO3/nLiOH molten electrolyte is rationally designed with low melting point (<450 °C). The synthesized syngas contains very desirable content of H2 and CO, with tuneable molar ratios (H2/CO) from 0.6 to 7.8, and with an efficient faradaic efficiency of ∼94.5%. The synthesis of syngas from CO2 with renewable energy at a such low electrolytic temperature not only alleviates heat loss, mitigates system corrosion, and heightens operational safety, but also decreases the generation of methane, thus increases the yield of syngas, which is a remarkable technological breakthrough and this work thus represents a stride in sustainable conversion of CO2 to value-added product.

Optical Analysis of Transparent Polymeric Material Exposed to Simulated Space Environment

NASA Technical Reports Server (NTRS)

Edwards, David L.; Finckenor, Miria M.

1999-01-01

Transparent polymeric materials are being designed and utilized as solar concentrating lenses for spacecraft power and propulsion systems. These polymeric lenses concentrate solar energy onto energy conversion devices such as solar cells and thermal energy systems. The conversion efficiency is directly related to the transmissivity of the polymeric lens. The Environmental Effects Group of the Marshall Space Flight Center's Materials, Processes, and Manufacturing Department exposed a variety of materials to a simulated space environment and evaluated them for an, change in optical transmission. These materials include Lexan(TM), polyethylene terephthalate (PET). several formulations of Tefzel(TM). and Teflon(TM), and silicone DC 93-500. Samples were exposed to a minimum of 1000 Equivalent Sun Hours (ESH) of near-UV radiation (250 - 400 nm wavelength). Data will be presented on materials exposed to charged particle radiation equivalent to a five-year dose in geosynchronous orbit. These exposures were performed in MSFC's Combined Environmental Effects Test Chamber, a unique facility with the capability to expose materials simultaneously or sequentially to protons, low-energy electrons, high-energy electrons, near UV radiation and vacuum UV radiation.Prolonged exposure to the space environment will decrease the polymer film's transmission and thus reduce the conversion efficiency. A method was developed to normalize the transmission loss and thus rank the materials according to their tolerance to space environmental exposure. Spectral results and the material ranking according to transmission loss are presented.

Status of NASA's Advanced Radioisotope Power Conversion Technology Research and Development

NASA Technical Reports Server (NTRS)

Wong, Wayne A.; Anderson, David J.; Tuttle, Karen L.; Tew, Roy C.

2006-01-01

NASA s Advanced Radioisotope Power Systems (RPS) development program is funding the advancement of next generation power conversion technologies that will enable future missions that have requirements that can not be met by either the ubiquitous photovoltaic systems or by current Radioisotope Power Systems (RPS). Requirements of advanced radioisotope power systems include high efficiency and high specific power (watts/kilogram) in order to meet mission requirements with less radioisotope fuel and lower mass. Other Advanced RPS development goals include long-life, reliability, and scalability so that these systems can meet requirements for a variety of future space applications including continual operation surface missions, outer-planetary missions, and solar probe. This paper provides an update on the Radioisotope Power Conversion Technology Project which awarded ten Phase I contracts for research and development of a variety of power conversion technologies consisting of Brayton, Stirling, thermoelectrics, and thermophotovoltaics. Three of the contracts continue during the current Phase II in the areas of thermoelectric and Stirling power conversion. The accomplishments to date of the contractors, project plans, and status will be summarized.

Enhanced Conversion Efficiency of III–V Triple-junction Solar Cells with Graphene Quantum Dots

PubMed Central

Lin, Tzu-Neng; Santiago, Svette Reina Merden S.; Zheng, Jie-An; Chao, Yu-Chiang; Yuan, Chi-Tsu; Shen, Ji-Lin; Wu, Chih-Hung; Lin, Cheng- An J.; Liu, Wei-Ren; Cheng, Ming-Chiang; Chou, Wu-Ching

2016-01-01

Graphene has been used to synthesize graphene quantum dots (GQDs) via pulsed laser ablation. By depositing the synthesized GQDs on the surface of InGaP/InGaAs/Ge triple-junction solar cells, the short-circuit current, fill factor, and conversion efficiency were enhanced remarkably. As the GQD concentration is increased, the conversion efficiency in the solar cell increases accordingly. A conversion efficiency of 33.2% for InGaP/InGaAs/Ge triple-junction solar cells has been achieved at the GQD concentration of 1.2 mg/ml, corresponding to a 35% enhancement compared to the cell without GQDs. On the basis of time-resolved photoluminescence, external quantum efficiency, and work-function measurements, we suggest that the efficiency enhancement in the InGaP/InGaAs/Ge triple-junction solar cells is primarily caused by the carrier injection from GQDs to the InGaP top subcell. PMID:27982073

A home-made system for IPCE measurement of standard and dye-sensitized solar cells.

PubMed

Palma, Giuseppina; Cozzarini, Luca; Capria, Ennio; Fraleoni-Morgera, Alessandro

2015-01-01

A home-made system for incident photon-to-electron conversion efficiency (IPCE) characterization, based on a double-beam UV-Vis spectrophotometer, has been set up. In addition to its low cost (compared to the commercially available apparatuses), the double-beam configuration gives the advantage to measure, autonomously and with no need for supplementary equipment, the lamp power in real time, compensating possible variations of the spectral emission intensity and quality, thus reducing measurement times. To manage the optical and electronic components of the system, a custom software has been developed. Validations carried out on a common silicon-based photodiode and on a dye-sensitized solar cell confirm the possibility to adopt this system for determining the IPCE of solar cells, including dye-sensitized ones.

Thermodynamics, Entropy, Information and the Efficiency of Solar Cells

NASA Astrophysics Data System (ADS)

Abrams, Zeev R.

For well over 50 years, the limits to photovoltaic energy conversion have been known and codified, and have played a vital role in the push for technological breakthroughs to reach—and even attempt to surpass—those limits. This limit, known as the Shockley-Queisser detailed-balance limit, was found by using only the most basic of thermodynamic assumptions, and therefore provides an upper bound that is difficult to contest without violating the laws of thermodynamics. Many different schemes have been devised to improve a solar cell's efficiency beyond this limit, with various benefits and drawbacks for each method. Since the field of solar cell research has been analyzed and dissected for so long by a large variety of researchers, it is quite hard to say or discover anything new without repeating the work of the past. The approach taken in this work is to analyze solar cells from the joint perspective of thermodynamics and information theory. These two subjects have recently been appreciated to be highly interrelated, and using the formalism of Missing Information, we can differentiate between different novel technologies, as well as devise new limits for new and existing methodologies. In this dissertation, the fundamentals of photovoltaic conversion are analyzed from the most basic of principles, emphasizing the thermodynamic parameters of the photovoltaic process. In particular, an emphasis is made on the voltage of the device, as opposed to the current. This emphasis is made since there is a direct relation between the open-circuit voltage of a solar cell and the fundamental equations of thermodynamics and the Free Energy of the system. Moreover, this relation extends to the entropy of the system, which subsequently relates to the field of Information Theory. By focusing on the voltage instead of the current, realizations are made that are not obvious to the majority or researchers in the field, and in particular to efforts of surpassing the Shockley-Queisser limit, known as "3rd generation" concepts. After analyzing the standard single-junction cell, other forms of surpassing the detailed-balance limit are presented and discussed, from the viewpoint of entropy and its relation to the amount of information lost or produced in the photovoltaic conversion process. In addition to the well-known 3rd generation methods: up- and down-conversion, carrier multiplication and intermediate band solar cells, other ideas are discussed such as using Feedback to shift the optimal bandgap of the cell, and the use of spectral splitting to completely utilize the solar spectrum. The focus on entropy (and the open-circuit voltage) as the primary variable of interest uncovers new limitations to these processes, and denotes preferences of certain technologies over others. Using this parallel approach provides insights into the field that were either neglected or not realized. This work thus provides a new set of guidelines for searching for and analyzing innovative techniques to maximize the power conversion efficiency from solar cells.

Preliminary designs for 25 kWe advanced Stirling conversion systems for dish electric applications

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Schreiber, Jeffrey G.

1990-01-01

Under the Department of Energy's (DOE) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for terrestrial Solar Distributed Heat Receivers. The Stirling engine has been identified by Sandia as one of the most promising engines for terrestrial applications. The Stirling engine also has the potential to meet DOE's performance and cost goals. The NASA Lewis Research Center is conducting Stirling engine technology development activities directed toward a dynamic power source for space applications. Space power systems requirements include high reliability, very long life, low vibration and high efficiency. The free-piston Stirling engine has the potential for future high power space conversion systems, either nuclear or solar powered. Although both applications appear to be quite different, their requirements complement each other. Preliminary designs feature a free-piston Stirling engine, a liquid metal heat transport system, and a means to provide nominally 25 kW electric power to a utility grid while meeting DOE's performance and long term cost goals. The Cummins design incorporates a linear alternator to provide the electrical output, while the STC design generates electrical power indirectly through a hydraulic pump/motor coupled to an induction generator. Both designs for the ASCS's will use technology which can reasonably be expected to be available in the early 1990's.

Preliminary designs for 25 kWe advanced Stirling conversion systems for dish electric applications

NASA Astrophysics Data System (ADS)

Shaltens, Richard K.; Schreiber, Jeffrey G.

Under the Department of Energy's (DOE) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for terrestrial Solar Distributed Heat Receivers. The Stirling engine has been identified by Sandia as one of the most promising engines for terrestrial applications. The Stirling engine also has the potential to meet DOE's performance and cost goals. The NASA Lewis Research Center is conducting Stirling engine technology development activities directed toward a dynamic power source for space applications. Space power systems requirements include high reliability, very long life, low vibration and high efficiency. The free-piston Stirling engine has the potential for future high power space conversion systems, either nuclear or solar powered. Although both applications appear to be quite different, their requirements complement each other. Preliminary designs feature a free-piston Stirling engine, a liquid metal heat transport system, and a means to provide nominally 25 kW electric power to a utility grid while meeting DOE's performance and long term cost goals. The Cummins design incorporates a linear alternator to provide the electrical output, while the STC design generates electrical power indirectly through a hydraulic pump/motor coupled to an induction generator. Both designs for the ASCS's will use technology which can reasonably be expected to be available in the early 1990's.

Preliminary designs for 25 kWe advanced Stirling conversion systems for dish electric applications

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Schreiber, Jeffrey G.

1990-01-01

Under the Department of Energy's (DOE) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for terrestrial Solar Distributed Heat Receivers. The Stirling engine has been identified by Sandia as one of the most promising engines for terrestrial applications. The Stirling engine also has the potential to meet DOE's performance and cost goals. The NASA Lewis Research Center is conducting Stirling engine technology development activities directed toward a dynamic power source for space applications. Space power systems requirements include high reliability, very long life, low vibration and high efficiency. The free-piston Stirling engine has the potential for future high power space conversion systems, either nuclear or solar powered. Although both applications appear to be quite different, their requirements complement each other. Preliminary designs feature a free-piston Stirling engine, a liquid metal heat transport system, and a means to provide nominally 25 kW electric power to a utility grid while meeting DOE's performance and long term cost goals. The Cummins design incorporates a linear alternator to provide the electrical output, while the STC design generates electrical power indirectly through a hydraulic pump/motor coupled to an induction generator. Both designs for the ASCS's will use technology which can reasonably be expected to be available in the early 1990's

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion

NASA Technical Reports Server (NTRS)

Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.;

Application of Ce3+ single-doped complexes as solar spectral downshifters for enhancing photoelectric conversion efficiencies of a-Si-based solar cells

NASA Astrophysics Data System (ADS)

Song, Pei; Jiang, Chun

2013-05-01

The effect on photoelectric conversion efficiency of an a-Si-based solar cell by applying a solar spectral downshifter of rare earth ion Ce3+ single-doped complexes including yttrium aluminum garnet Y3Al5O12 single crystals, nanostructured ceramics, microstructured ceramics and B2O3-SiO2-Gd2O3-BaO glass is studied. The photoluminescence excitation spectra in the region 360-460 nm convert effectively into photoluminescence emission spectra in the region 450-550 nm where a-Si-based solar cells exhibit a higher spectral response. When these Ce3+ single-doped complexes are placed on the top of an a-Si-based solar cell as precursors for solar spectral downshifting, theoretical relative photoelectric conversion efficiencies of nc-Si:H and a-Si:H solar cells approach 1.09-1.13 and 1.04-1.07, respectively, by means of AMPS-1D numerical modeling, potentially benefiting an a-Si-based solar cell with a photoelectric efficiency improvement.

Theoretical analysis of improved efficiency of silicon-wafer solar cells with textured nanotriangular grating structure

NASA Astrophysics Data System (ADS)

Zhang, Yaoju; Zheng, Jun; Zhao, Xuesong; Ruan, Xiukai; Cui, Guihua; Zhu, Haiyong; Dai, Yuxing

2018-03-01

A practical model of crystalline silicon-wafer solar cells is proposed in order to enhance the light absorption and improve the conversion efficiency of silicon solar cells. In the model, the front surface of the silicon photovoltaic film is designed to be a textured-triangular-grating (TTG) structure, and the ITO contact film and the antireflection coating (ARC) of glass are coated on the TTG surface of silicon solar cells. The optical absorption spectrum of solar cells are simulated by applying the finite difference time domain method. Electrical parameters of the solar cells are calculated using two models with and without carrier loss. The effect of structure parameters on the performance of the TTG cell is discussed in detail. It is found that the thickness (tg) of the ARC, period (p) of grating, and base angle (θ) of triangle have a crucial influence on the conversion efficiency. The optimal structure of the TTG cell is designed. The TTG solar cell can produce higher efficiency in a wide range of solar incident angle and the average efficiency of the optimal TTG cell over 7:30-16:30 time of day is 8% higher than that of the optimal plane solar cell. In addition, the study shows that the bulk recombination of carriers has an influence on the conversion efficiency of the cell, the conversion efficiency of the actual solar cell with carrier recombination is reduced by 20.0% of the ideal cell without carrier recombination.

Rapid Conversion from Carbohydrates to Large-Scale Carbon Quantum Dots for All-Weather Solar Cells.

PubMed

Tang, Qunwei; Zhu, Wanlu; He, Benlin; Yang, Peizhi

2017-02-28

A great challenge for state-of-the-art solar cells is to generate electricity in all weather. We present here the rapid conversion of carbon quantum dots (CQDs) from carbohydrates (including glucose, maltol, sucrose) for an all-weather solar cell, which comprises a CQD-sensitized mesoscopic titanium dioxide/long-persistence phosphor (m-TiO 2 /LPP) photoanode, a I - /I 3 - redox electrolyte, and a platinum counter electrode. In virtue of the light storing and luminescent behaviors of LPP phosphors, the generated all-weather solar cells can not only convert sunlight into electricity on sunny days but persistently realize electricity output in all dark-light conditions. The maximized photoelectric conversion efficiency is as high as 15.1% for so-called all-weather CQD solar cells in dark conditions.

One-dimension-based spatially ordered architectures for solar energy conversion.

PubMed

Liu, Siqi; Tang, Zi-Rong; Sun, Yugang; Colmenares, Juan Carlos; Xu, Yi-Jun

2015-08-07

The severe consequences of fossil fuel consumption have resulted in a need for alternative sustainable sources of energy. Conversion and storage of solar energy via a renewable method, such as photocatalysis, holds great promise as such an alternative. One-dimensional (1D) nanostructures have gained attention in solar energy conversion because they have a long axis to absorb incident sunlight yet a short radial distance for separation of photogenerated charge carriers. In particular, well-ordered spatially high dimensional architectures based on 1D nanostructures with well-defined facets or anisotropic shapes offer an exciting opportunity for bridging the gap between 1D nanostructures and the micro and macro world, providing a platform for integration of nanostructures on a larger and more manageable scale into high-performance solar energy conversion applications. In this review, we focus on the progress of photocatalytic solar energy conversion over controlled one-dimension-based spatially ordered architecture hybrids. Assembly and classification of these novel architectures are summarized, and we discuss the opportunity and future direction of integration of 1D materials into high-dimensional, spatially organized architectures, with a perspective toward improved collective performance in various artificial photoredox applications.

Evidence of significant down-conversion in a Si-based solar cell using CuInS2/ZnS core shell quantum dots

NASA Astrophysics Data System (ADS)

Gardelis, Spiros; Nassiopoulou, Androula G.

2014-05-01

We report on the increase of up to 37.5% in conversion efficiency of a Si-based solar cell after deposition of light-emitting Cd-free, CuInS2/ZnS core shell quantum dots on the active area of the cell due to the combined effect of down-conversion and the anti- reflecting property of the dots. We clearly distinguished the effect of down-conversion from anti-reflection and estimated an enhancement of up to 10.5% in the conversion efficiency due to down-conversion.

Methods for the photochemical utilization of solar energy

NASA Technical Reports Server (NTRS)

Schwerzel, R. E.

1978-01-01

The paper considers the 'ground rules' which govern the efficiency of photochemical solar energy conversion and then summarizes the most promising approaches in each of three categories: photochemically assisted thermal systems for the heating and/or cooling of structures; photogalvanic systems for the production of electrical power in applications, such as photorechargeable batteries or inexpensive 'solar cells'; and photochemical formation of fuels for combustion and for use as chemical feedstocks or foods. Three concepts for the photochemical utilization of solar energy in space are found to be particularly promising: (1) photochemical trans-cis isomerization of indigold dyes for photoassisted heating or cooling, (2) the redox stabilized photoelectrolysis cell for the production of hydrogen (and/or oxygen or other useful chemicals), and (3) the liquid-junction photovoltaic cell for the production of electrical power.

An inverter/controller subsystem optimized for photovoltaic applications

NASA Technical Reports Server (NTRS)

Pickrell, R. L.; Merrill, W. C.; Osullivan, G.

1978-01-01

Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. This paper discusses the optimization of the inverter/controller design as part of an overall Photovoltaic Power System (PPS) designed for maximum energy extraction from the solar array. The special design requirements for the inverter/controller include: (1) a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and (2) an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy. It must be capable of operating connected to the utility line at a level set by an external controller (PSC).

CdSe quantum dot-fullerene hybrid nanocomposite for solar energy conversion: electron transfer and photoelectrochemistry.

PubMed

Bang, Jin Ho; Kamat, Prashant V

2011-12-27

The development of organic/inorganic hybrid nanocomposite systems that enable efficient solar energy conversion has been important for applications in solar cell research. Nanostructured carbon-based systems, in particular C(60), offer attractive strategies to collect and transport electrons generated in a light harvesting assembly. We have assembled CdSe-C(60) nanocomposites by chemically linking CdSe quantum dots (QDs) with thiol-functionalized C(60). The photoinduced charge separation and collection of electrons in CdSe QD-C(60) nanocomposites have been evaluated using transient absorption spectroscopy and photoelectrochemical measurements. The rate constant for electron transfer between excited CdSe QD and C(60) increased with the decreasing size of the CdSe QD (7.9 × 10(9) s(-1) (4.5 nm), 1.7 × 10(10) s(-1) (3.2 nm), and 9.0 × 10(10) s(-1) (2.6 nm)). Slower hole transfer and faster charge recombination and transport events were found to dominate over the forward electron injection process, thus limiting the deliverance of maximum power in CdSe QD-C(60)-based solar cells. The photoinduced charge separation between CdSe QDs and C(60) opens up new design strategies for developing light harvesting assemblies.

The dish-Rankine SCSTPE program (Engineering Experiment no. 1). [systems engineering and economic analysis for a small community solar thermal electric system

NASA Technical Reports Server (NTRS)

Pons, R. L.; Grigsby, C. E.

1980-01-01

Activities planned for phase 2 Of the Small Community Solar Thermal Power Experiment (PFDR) program are summarized with emphasis on a dish-Rankine point focusing distributed receiver solar thermal electric system. Major design efforts include: (1) development of an advanced concept indirect-heated receiver;(2) development of hardware and software for a totally unmanned power plant control system; (3) implementation of a hybrid digital simulator which will validate plant operation prior to field testing; and (4) the acquisition of an efficient organic Rankine cycle power conversion unit. Preliminary performance analyses indicate that a mass-produced dish-Rankine PFDR system is potentially capable of producing electricity at a levelized busbar energy cost of 60 to 70 mills per KWh and with a capital cost of about $1300 per KW.

In silico designing of power conversion efficient organic lead dyes for solar cells using todays innovative approaches to assure renewable energy for future

NASA Astrophysics Data System (ADS)

Kar, Supratik; Roy, Juganta K.; Leszczynski, Jerzy

2017-06-01

Advances in solar cell technology require designing of new organic dye sensitizers for dye-sensitized solar cells with high power conversion efficiency to circumvent the disadvantages of silicon-based solar cells. In silico studies including quantitative structure-property relationship analysis combined with quantum chemical analysis were employed to understand the primary electron transfer mechanism and photo-physical properties of 273 arylamine organic dyes from 11 diverse chemical families explicit to iodine electrolyte. The direct quantitative structure-property relationship models enable identification of the essential electronic and structural attributes necessary for quantifying the molecular prerequisites of 11 classes of arylamine organic dyes, responsible for high power conversion efficiency of dye-sensitized solar cells. Tetrahydroquinoline, N,N'-dialkylaniline and indoline have been least explored classes under arylamine organic dyes for dye-sensitized solar cells. Therefore, the identified properties from the corresponding quantitative structure-property relationship models of the mentioned classes were employed in designing of "lead dyes". Followed by, a series of electrochemical and photo-physical parameters were computed for designed dyes to check the required variables for electron flow of dye-sensitized solar cells. The combined computational techniques yielded seven promising lead dyes each for all three chemical classes considered. Significant (130, 183, and 46%) increment in predicted %power conversion efficiency was observed comparing with the existing dye with highest experimental %power conversion efficiency value for tetrahydroquinoline, N,N'-dialkylaniline and indoline, respectively maintaining required electrochemical parameters.

Solar heating system final design package

NASA Technical Reports Server (NTRS)

1979-01-01

The system is composed of a warm air collector, a logic control unit and a universal switching and transport unit. The collector was originally conceived and designed as an integrated roof/wall system and therefore provides a dual function in the structure. The collector serves both as a solar energy conversion system and as a structural weather resistant skin. The control unit provides totally automatic control over the operation of the system. It receives input data from sensor probes in collectors, storage and living space. The logic was designed so as to make maximum use of solar energy and minimize use of conventional energy. The transport and switching unit is a high-efficiency air-handling system equipped with gear motor valves that respond to outputs from the control system. The fan unit was designed for maximum durability and efficiency in operation, and has permanently lubricated ball bearings and excellent air-handling efficiency.

Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties.

PubMed

Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

2016-12-01

Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer.

Photovoltaic test and demonstration project for the National Photovoltaic Conversion program

NASA Technical Reports Server (NTRS)

Deyo, J. N.

1975-01-01

Proposed are photovoltaic system tests and demonstrations covering a wide range of applications in order to develop low cost photovoltaic cells suitable for terrestrial applications. Program objectives are: (1) tests and model system demonstrations; (2) device performance and diagnostics; and (3) endurance of solar cell modules and arrays.

Hybrid chromophore/template nanostructures: a customizable platform material for solar energy storage and conversion.

PubMed

Kolpak, Alexie M; Grossman, Jeffrey C

2013-01-21

Challenges with cost, cyclability, and/or low energy density have largely prevented the development of solar thermal fuels, a potentially attractive alternative energy technology based on molecules that can capture and store solar energy as latent heat in a closed cycle. In this paper, we present a set of novel hybrid photoisomer/template solar thermal fuels that can potentially circumvent these challenges. Using first-principles computations, we demonstrate that these fuels, composed of organic photoisomers bound to inexpensive carbon-based templates, can reversibly store solar energy at densities comparable to Li-ion batteries. Furthermore, we show that variation of the template material in combination with the photoisomer can be used to optimize many of the key performance metrics of the fuel-i.e., the energy density, the storage lifetime, the temperature of the output heat, and the efficiency of the solar-to-heat conversion. Our work suggests that the solar thermal fuels concept can be translated into a practical and highly customizable energy storage and conversion technology.

High-performance flat-panel solar thermoelectric generators with high thermal concentration

NASA Astrophysics Data System (ADS)

Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J. Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

2011-07-01

The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m-2) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity.

Carbon Nitride-Aromatic Diimide-Graphene Nanohybrids: Metal-Free Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion with 0.2% Efficiency.

PubMed

Kofuji, Yusuke; Isobe, Yuki; Shiraishi, Yasuhiro; Sakamoto, Hirokatsu; Tanaka, Shunsuke; Ichikawa, Satoshi; Hirai, Takayuki

2016-08-10

Solar-to-chemical energy conversion is a challenging subject for renewable energy storage. In the past 40 years, overall water splitting into H2 and O2 by semiconductor photocatalysis has been studied extensively; however, they need noble metals and extreme care to avoid explosion of the mixed gases. Here we report that generating hydrogen peroxide (H2O2) from water and O2 by organic semiconductor photocatalysts could provide a new basis for clean energy storage without metal and explosion risk. We found that carbon nitride-aromatic diimide-graphene nanohybrids prepared by simple hydrothermal-calcination procedure produce H2O2 from pure water and O2 under visible light (λ > 420 nm). Photoexcitation of the semiconducting carbon nitride-aromatic diimide moiety transfers their conduction band electrons to graphene and enhances charge separation. The valence band holes on the semiconducting moiety oxidize water, while the electrons on the graphene moiety promote selective two-electron reduction of O2. This metal-free system produces H2O2 with solar-to-chemical energy conversion efficiency 0.20%, comparable to the highest levels achieved by powdered water-splitting photocatalysts.

Analysis of the reflective multibandgap solar cell concept

NASA Technical Reports Server (NTRS)

Stern, T. G.

1983-01-01

A new and unique approach to improving photovoltaic conversion efficiency, the reflective multiband gap solar cell concept, was examined. This concept uses back surface reflectors and light trapping with several physically separated cells of different bandgaps to make more effective use of energy from different portions of the solar spectrum. Preliminary tests performed under General Dynamics Independent Research and Development (IRAD) funding have demonstrated the capability for achieving in excess of 20% conversion efficiency with aluminum gallium arsenide and silicon. This study analyzed the ultimate potential for high conversion efficiency with 2, 3, 4, and 5 different bandgap materials, determined the appropriate bandgaps needed to achieve this optimized efficiency, and identified potential problems or constraints. The analysis indicated that an improvement in efficiency of better than 40% could be attained in this multibandgap approach, compared to a single bandgap converter under the same assumptions. Increased absorption loss on the back surface reflector was found to incur a minimal penalty on efficiency for two and three bandgap systems. Current models for bulk absorption losses in 3-5 materials were found to be inadequate for explaining laboratory observed transmission losses. Recommendations included the continued development of high bandgap back surface reflector cells and basic research on semiconductor absorption mechanisms.

Design of a photovoltaic system for a southwest all-electric residence

NASA Astrophysics Data System (ADS)

Mehalick, E. M.; Obrien, G.; Tully, G. F.; Johnson, J.; Parker, J.

1980-04-01

The grid connected residential photovoltaic system for the Southwest is designed to meet both space conditioning requirements and all conventional electrical load requirements for an all-electric residence. The system is comprised of two major subsystems, the solar array and the power conditioning subsystem (PCS). An 8 kW peak photovoltaic array been designed for the house. The 93 square meters solar array uses a shingle solar cell module in a highly redundant series/parallel matrix. The photovoltaic generated power is supplied to a 10kVA power conversion subsystem which is controlled to track the solar array maximum power operating point and feed the 240 Vac output power directly to the house loads or back to the utility when excess power is generated. The photovoltaic power is isolated from the utility by a 15 kVA transformer. The house design and subsystem specifications are given in detail.

Solar selective performance of metal nitride/oxynitride based magnetron sputtered thin film coatings: a comprehensive review

NASA Astrophysics Data System (ADS)

Ibrahim, Khalil; Taha, Hatem; Mahbubur Rahman, M.; Kabir, Humayun; Jiang, Zhong-Tao

2018-03-01

Since solar-thermal collectors are considered to be the most direct way of converting solar energy into usable forms, in the last few years growing attention has been paid to the development of transition metal nitride and metal oxynitride based thin film selective surfaces for solar-thermal collectors, in order to harvest more solar energy. A solar-thermal energy system, generally, shows very high solar absorption of incident solar radiation from the solar-thermal collectors in the visible range (0.3 to 2.5 μm) and extremely low thermal losses through emission (or high reflection) in the infrared region (≥2.5 μm). The efficiency of a solar-thermal energy conversion system can be improved by the use of solar selective surfaces consisting of novel metallic nanoparticles embedded in metal nitride/oxynitride systems. In order to enhance the effectiveness of solar-thermal devices, solar selective surfaces with high thermal stability are a prerequisite. Over the years, substantial efforts have been made in the field of solar selective surfaces to attain higher solar absorptance and lower thermal emittance in high temperature (above 400 °C) applications. In this article, we review the present state-of-the-art transition metal nitride and/or oxynitride based vacuum sputtered nanostructured thin film coatings, with respect to their optical and solar selective surface applications. We have also summarized the solar selectivity data from recently published investigations, including discussion on some potential applications for these materials.

Photoelectrochemistry of III-V epitaxial layers and nanowires for solar energy conversion

NASA Astrophysics Data System (ADS)

Parameshwaran, Vijay; Enck, Ryan; Chung, Roy; Kelley, Stephen; Sampath, Anand; Reed, Meredith; Xu, Xiaoqing; Clemens, Bruce

2017-05-01

III-V materials, which exhibit high absorption coefficients and charge carrier mobility, are ideal templates for solar energy conversion applications. This work describes the photoelectrochemistry research in several IIIV/electrolyte junctions as an enabler for device design for solar chemical reactions. By designing lattice-matched epitaxial growth of InGaP and GaP on GaAs and Si, respectively, extended depletion region electrodes achieve photovoltages which provide an additional boost to the underlying substrate photovoltage. The InGaP/GaAs and GaP/Si electrodes drive hydrogen evolution currents under aqueous conditions. By using nanowires of InN and InP under carefully controlled growth conditions, current and capacitance measurements are obtained to reveal the nature of the nanowire-electrolyte interface and how light is translated into photocurrent for InP and a photovoltage in InN. The materials system is expanded into the III-V nitride semiconductors, in which it is shown that varying the morphology of GaN on silicon yields insights to how the interface and light conversion is modulated as a basis for future designs. Current extensions of this work address growth and tuning of the III-V nitride electrodes with doping and polarization engineering for efficient coupling to solar-driven chemical reactions, and rapid-throughput methods for III-V nanomaterials synthesis in this materials space.

Microencapsulated Phase Change Materials in Solar-Thermal Conversion Systems: Understanding Geometry-Dependent Heating Efficiency and System Reliability.

PubMed

Zheng, Zhaoliang; Chang, Zhuo; Xu, Guang-Kui; McBride, Fiona; Ho, Alexandra; Zhuola, Zhuola; Michailidis, Marios; Li, Wei; Raval, Rasmita; Akhtar, Riaz; Shchukin, Dmitry

2017-01-24

The performance of solar-thermal conversion systems can be improved by incorporation of nanocarbon-stabilized microencapsulated phase change materials (MPCMs). The geometry of MPCMs in the microcapsules plays an important role for improving their heating efficiency and reliability. Yet few efforts have been made to critically examine the formation mechanism of different geometries and their effect on MPCMs-shell interaction. Herein, through changing the cooling rate of original emulsions, we acquire MPCMs within the nanocarbon microcapsules with a hollow structure of MPCMs (h-MPCMs) or solid PCM core particles (s-MPCMs). X-ray photoelectron spectroscopy and atomic force microscopy reveals that the capsule shell of the h-MPCMs is enriched with nanocarbons and has a greater MPCMs-shell interaction compared to s-MPCMs. This results in the h-MPCMs being more stable and having greater heat diffusivity within and above the phase transition range than the s-MPCMs do. The geometry-dependent heating efficiency and system stability may have important and general implications for the fundamental understanding of microencapsulation and wider breadth of heating generating systems.

Theoretical studies of thermionic conversion of solar energy with graphene as emitter and collector

NASA Astrophysics Data System (ADS)

Olawole, Olukunle C.; De, Dilip Kumar

2018-01-01

Thermionic energy conversion (TEC) using nanomaterials is an emerging field of research. It is known that graphene can withstand temperatures as high as 4600 K in vacuum, and it has been shown that its work function can be engineered from a high value (for monolayer/bilayer) of 4.6 eV to as low as 0.7 eV. Such attractive electronic properties (e.g., good electrical conductivity and high dielectric constant) make engineered graphene a good candidate as an emitter and collector in a thermionic energy converter for harnessing solar energy efficiently. We have used a modified Richardson-Dushman equation and have adopted a model where the collector temperature could be controlled through heat extraction in a calculated amount and a magnet can be attached on the back surface of the collector for future control of the space-charge effect. Our work shows that the efficiency of solar energy conversion also depends on power density falling on the emitter surface, and that a power conversion efficiency of graphene-based solar TEC as high as 55% can be easily achieved (in the absence of the space-charge effect) through proper choice of work functions, collector temperature, and emissivity of emitter surfaces. Such solar energy conversion would reduce our dependence on silicon solar panels and offers great potential for future renewable energy utilization.

Thermal energy storage for organic Rankine cycle solar dynamic space power systems

NASA Astrophysics Data System (ADS)

Heidenreich, G. R.; Parekh, M. B.

An organic Rankine cycle-solar dynamic power system (ORC-SDPS) comprises a concentrator, a radiator, a power conversion unit, and a receiver with a thermal energy storage (TES) subsystem which charges and discharges energy to meet power demands during orbital insolation and eclipse periods. Attention is presently given to the criteria used in designing and evaluating an ORC-SDPS TES, as well as the automated test facility employed. It is found that a substantial data base exists for the design of an ORC-SDPS TES subsystem.

Applications of novel effects derived from Si ingot growth inside Si melt without contact with crucible wall using noncontact crucible method to high-efficiency solar cells

NASA Astrophysics Data System (ADS)

Nakajima, Kazuo; Ono, Satoshi; Kaneko, Yuzuru; Murai, Ryota; Shirasawa, Katsuhiko; Fukuda, Tetsuo; Takato, Hidetaka; Jensen, Mallory A.; Youssef, Amanda; Looney, Erin E.; Buonassisi, Tonio; Martel, Benoit; Dubois, Sèbastien; Jouini, Anis

2017-06-01

The noncontact crucible (NOC) method was proposed for obtaining Si single bulk crystals with a large diameter and volume using a cast furnace and solar cells with high conversion efficiency and yield. This method has several novel characteristics that originate from its key feature that ingots can be grown inside a Si melt without contact with a crucible wall. Si ingots for solar cells were grown by utilizing the merits resulting from these characteristics. Single ingots with high quality were grown by the NOC method after furnace cleaning, and the minority carrier lifetime was measured to investigate reduction of the number of impurities. A p-type ingot with a convex growth interface in the growth direction was also grown after furnace cleaning. For p-type solar cells prepared using wafers cut from the ingot, the highest and average conversion efficiencies were 19.14% and 19.0%, respectively, which were obtained using the same solar cell structure and process as those employed to obtain a conversion efficiency of 19.1% for a p-type Czochralski (CZ) wafer. Using the cast furnace, solar cells with a conversion efficiency and yield as high as those of CZ solar cells were obtained by the NOC method.

Heat Transfer Phenomena in Concentrating Solar Power Systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Armijo, Kenneth Miguel; Shinde, Subhash L.

Concentrating solar power (CSP) utilizes solar thermal energy to drive a thermal power cycle for the generation of electricity. CSP systems are facilitated as large, centralized power plants , such as power towers and trough systems, to take advantage of ec onomies of scale through dispatchable thermal energy storage, which is a principle advantage over other energy generation systems . Additionally, the combination of large solar concentration ratios with high solar conversion efficiencies provides a strong o pportunity of employment of specific power cycles such as the Brayton gas cycle that utilizes super critical fluids such as supercritical carbon dioxidemore » (s CO 2 ) , compared to other sola r - fossil hybrid power plants. A comprehensive thermal - fluids examination is provided by this work of various heat transfer phenomena evident in CSP technologies. These include sub - systems and heat transfer fundamental phenomena evident within CSP systems , which include s receivers, heat transfer fluids (HTFs), thermal storage me dia and system designs , thermodynamic power block systems/components, as well as high - temperature materials. This work provides literature reviews, trade studies, and phenomenological comparisons of heat transfer media (HTM) and components and systems, all for promotion of high performance and efficient CSP systems. In addition, f urther investigations are also conducted that provide advanced heat transfer modeling approaches for gas - particle receiver systems , as well as performance/efficiency enhancement re commendations, particularly for solarized supercritical power systems .« less

All silicon electrode photocapacitor for integrated energy storage and conversion.

PubMed

Cohn, Adam P; Erwin, William R; Share, Keith; Oakes, Landon; Westover, Andrew S; Carter, Rachel E; Bardhan, Rizia; Pint, Cary L

2015-04-08

We demonstrate a simple wafer-scale process by which an individual silicon wafer can be processed into a multifunctional platform where one side is adapted to replace platinum and enable triiodide reduction in a dye-sensitized solar cell and the other side provides on-board charge storage as an electrochemical supercapacitor. This builds upon electrochemical fabrication of dual-sided porous silicon and subsequent carbon surface passivation for silicon electrochemical stability. The utilization of this silicon multifunctional platform as a combined energy storage and conversion system yields a total device efficiency of 2.1%, where the high frequency discharge capability of the integrated supercapacitor gives promise for dynamic load-leveling operations to overcome current and voltage fluctuations during solar energy harvesting.

CNRS interdisciplinary research program for solar energy development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The contributions of CNRS to the French national solar energy R and D program are reviewed. The three principal processes in which solar radiation is converted into other, directly usable energy forms are discussed in detail. These include thermodynamic conversion, photovoltaic conversion, and bioconversion to produce a substitute fuel. Related research on insolation and the weather is mentioned and relations with the industrial sector are considered. French collaboration with other countries in solar energy is discussed.

Superficial photoluminescence and PV conversion of nanoscale Si-layered systems at 400 nm

NASA Astrophysics Data System (ADS)

Kuznicki, Zbigniew T.; Meyrueis, Patrick; Sarrabayrouse, Gérard; Rousset, Bernard

2006-04-01

A surprising photovoltaic (PV) conversion at 400 nm has been observed in nanoscale Si-layered systems (ns-Si-ls) during spectral response measurements. In conventional solar cells the UV and blue PV conversion may be poor because of the surface recombination within a thin superficial layer. In multi-interface novel devices (MIND) containing ns-Si-ls this conversion is always negligible within an even thicker surface dead zone from which practically no free-carriers can be collected. So the measured 400 nm band PV conversion in MIND cells is totally inconsistent with usually observed effects. Another CE paradox concerns its inversely proportional variation versus incident flux intensity, lower the intensity higher the CE, which value can even exceed unity. This new effect is also localized at the superficial nanostratum and originates from postimplantation defects and nanostructures formed during the implantation process. A similar low energy free-carrier generation has been observed recently in MIND cells with buried ns-Si-ls having a relatively very thin superficial stratum because of an excellent electronic passivation. No available publication mentions such an effect despite extensive investigations on the subject of structural and optical properties of Si nanoparticles, Si nanolayers, new Si-based materials such as semiconductor silicides and the luminescence-center doped Si materials. In this work, the carrier collection properties of the superficial Si nanostratum are reported and discussed in detail in relation to incident flux intensity. An additional low energy generation was observed experimentally. The effect could have capital importance for a breakthrough in the PV conversion efficiency in Si solar cells with nanotransformations.

Spectral reflectance properties of electroplated and converted zinc for use as a solar selective coating

NASA Technical Reports Server (NTRS)

Mcdonald, G. E.; Curtis, H. B.; Gianelos, L.

1975-01-01

The spectral reflectance properties of electroplated and chemically converted zinc were measured for both chromate and chloride conversion coatings. The reflectance properties were measured for various times of conversion and for conversion at various chromate concentrations. The values of absorptance, integrated over the solar spectrum, and of infrared emittance, integrated over black body radiation at 250 F were then calculated from the measured reflectance values. The interdependent variations of absorptance and infrared emittance were plotted. The results indicate that the optimum combination of the highest absorptance in the solar spectrum and the lowest emittance in the infrared of the converted electroplated zinc is produced by chromate conversion at 1/2 concentration of the standard NEOSTAR chromate black solution for 0.50 minute or by chloride conversion for 0.50 minute.

Spectral reflectance properties of electroplated and converted zinc for use as a solar selective coating

NASA Technical Reports Server (NTRS)

Mcdonald, G. E.; Curtis, H. B.; Gianelos, L.

1975-01-01

The spectral reflectance properties of electroplated and chemically converted zinc were measured for both chromate and chloride conversion coatings. The reflectance properties were measured for various times of conversion and for conversion at various chromate concentrations. The values of absorptance, alpha, integrated over the solar spectrum, and of infrared emittance, epsilon, integrated over black body radiation at 250 F were then calculated from the measured reflectance values. The interdependent variations of alpha and epsilon were plotted. The results indicate that the optimum combination of the highest absorptance in the solar spectrum and the lowest emittance in the infrared of the converted electroplated zinc is produced by chromate conversion at 1/2 concentration of the standard NEOSTAR chromate black solution for 0.50 minute or by chloride conversion for 0.50 minute.

Antireflective Paraboloidal Microlens Film for Boosting Power Conversion Efficiency of Solar Cells.

PubMed

Fang, Chaolong; Zheng, Jun; Zhang, Yaoju; Li, Yijie; Liu, Siyuan; Wang, Weiji; Jiang, Tao; Zhao, Xuesong; Li, Zhihong

2018-06-21

Microlens arrays can improve light transmittance in optical devices or enhance the photoelectrical conversion efficiency of photovoltaic devices. Their surface morphology (aspect ratio and packed density) is vital to photon management in solar cells. Here, we report a 100% packed density paraboloidal microlens array (PMLA), with a large aspect ratio, fabricated by direct-write UV laser photolithography coupled with soft imprint lithography. Optical characterization shows that the PMLA structure can remarkably decrease the front-side reflectance of solar cell device. The measured electrical parameters of the solar cell device clearly and consistently demonstrate that the PMLA film can considerably improve the photoelectrical conversion efficiency. In addition, the PMLA film has superhydrophobic properties, verified by measurement of a large water contact angle, and can enhance the self-cleaning capability of solar cell devices.

Theoretical studies of solar pumped lasers

NASA Technical Reports Server (NTRS)

Harries, Wynford L.

1990-01-01

One concept for collecting solar energy is to use large solar collectors and then use lasers as energy converters whose output beams act as transmission lines to deliver the energy to a destination. The efficiency of the process would be improved if the conversion could be done directly using solar pumped lasers, and the possibility of making such lasers is studied. There are many applications for such lasers, and these are examined. By including the applications first, the requirements for the lasers will be more evident. They are especially applicable to the Space program, and include cases where no other methods of delivering power seem possible. Using the lasers for conveying information and surveillance is also discussed. Many difficulties confront the designer of an efficient system for power conversion. These involve the nature of the solar spectrum, the method of absorbing the energy, the transfer of power into laser beams, and finally, the far field patterns of the beams. The requirements of the lasers are discussed. Specific laser configurations are discussed. The thrust is into gas laser systems, because for space applications, the laser could be large, and also the medium would be uniform and not subject to thermal stresses. Dye and solid lasers are treated briefly. For gas lasers, a chart of the various possibilities is shown, and the various families of gas lasers divided according to the mechanisms of absorbing solar radiation and of lasing. Several specific models are analyzed and evaluated. Overall conclusions for the program are summarized, and the performances of the lasers related to the requirements of various applications.

Modeling and simulation of temperature effect in polycrystalline silicon PV cells

NASA Astrophysics Data System (ADS)

Marcu, M.; Niculescu, T.; Slusariuc, R. I.; Popescu, F. G.

2016-06-01

Due to the human needs of energy, there is a need to apply new technologies in energy conversion to supply the demand of clean and cheap energy in the context of environmental issues. Renewable energy sources like solar energy has one of the highest potentials. In this paper, solar panel is the key part of a photovoltaic system which converts solar energy to electrical energy. The purpose of this paper is to give a MATLAB/ Simulink simulation for photovoltaic module based on the one-diode model of a photovoltaic cell made of polycrystalline silicon. This model reveals the effect of the ambient temperature and the heating of the panel due to the solar infrared radiation. Also the measurements on the solar cell exposed to solar radiation can confirm the simulation.

Solar power satellites - Heat engine or solar cells

NASA Technical Reports Server (NTRS)

Oman, H.; Gregory, D. L.

1978-01-01

A solar power satellite is the energy-converting element of a system that can deliver some 10 GW of power to utilities on the earth's surface. We evaluated heat engines and solar cells for converting sunshine to electric power at the satellite. A potassium Rankine cycle was the best of the heat engines, and 50 microns thick single-crystal silicon cells were the best of the photovoltaic converters. Neither solar cells nor heat engines had a clear advantage when all factors were considered. The potassium-turbine power plant, however, was more difficult to assemble and required a more expensive orbital assembly base. We therefore based our cost analyses on solar-cell energy conversion, concluding that satellite-generated power could be delivered to utilities for around 4 to 5 cents a kWh.

Embedding solar cell materials with on-board integrated energy storage for load-leveling and dark power delivery (Presentation Recording)

NASA Astrophysics Data System (ADS)

Pint, Cary L.; Westover, Andrew S.; Cohn, Adam P.; Erwin, William R.; Share, Keith; Metke, Thomas; Bardhan, Rizia

2015-10-01

This work will discuss our recent advances focused on integrating high power energy storage directly into the native materials of both conventional photovoltaics (PV) and dye-sensitized solar cells (DSSCs). In the first case (PV), we demonstrate the ability to etch high surface-area porous silicon charge storage interfaces directly into the backside of a conventional polycrystalline silicon photovoltaic device exhibiting over 14% efficiency. These high surface area materials are then coupled with solid-state ionic liquid-polymer electrolytes to produce solid-state fully integrated devices where the PV device can directly inject charge into an on-board supercapacitor that can be separately discharged under dark conditions with a Coulombic efficiency of 84%. In a similar manner, we further demonstrate that surface engineered silicon materials can be utilized to replace Pt counterelectrodes in conventional DSSC energy conversion devices. As the silicon counterelectrodes rely strictly on surface Faradaic chemical reactions with the electrolyte on one side of the wafer electrode, we demonstrate double-sided processing of electrodes that enables dual-function of the material for simultaneous energy storage and conversion, each on opposing sides. In both of these devices, we demonstrate the ability to produce an all-silicon coupled energy conversion and storage system through the common ability to convert unused silicon in solar cells into high power silicon-based supercapacitors. Beyond the proof-of-concept design and performance of this integrated solar-storage system, this talk will conclude with a brief discussion of the hurdles and challenges that we envision for this emerging area both from a fundamental and technological viewpoint.

The evolution of complex and higher organisms

NASA Technical Reports Server (NTRS)

Milne, D. (Editor); Raup, D. (Editor); Billingham, J. (Editor); Niklaus, K. (Editor); Padian, K. (Editor)

1985-01-01

The evolution of Phanerozoic life has probably been influenced by extraterrestrial events and properties of the Earth-Moon system that have not, until now, been widely recognized. Tide range, gravitational strength, the Earth's axial tilt, and other planetary properties provide background conditions whose effects on evolution may be difficult to distinguish. Solar flares, asteroid impacts, supernovae, and passage of the solar system through galactic clouds can provide catastrophic changes on the Earth with consequent characteristic extinctions. Study of the fossil record and the evolution of complex Phanerozoic life can reveal evidence of past disturbances in space near the Earth. Conversely, better understanding of environmental influences caused by extraterrestrial factors and properties of the solar system can clarify aspects of evolution, and may aid in visualizing life on other planets with different properties.

Self-reverse-biased solar panel optical receiver for simultaneous visible light communication and energy harvesting.

PubMed

Shin, Won-Ho; Yang, Se-Hoon; Kwon, Do-Hoon; Han, Sang-Kook

2016-10-31

We propose a self-reverse-biased solar panel optical receiver for energy harvesting and visible light communication. Since the solar panel converts an optical component into an electrical component, it provides both energy harvesting and communication. The signal component can be separated from the direct current component, and these components are used for communication and energy harvesting. We employed a self-reverse-biased receiver circuit to improve the communication and energy harvesting performance. The reverse bias on the solar panel improves the responsivity and response time. The proposed system achieved 17.05 mbps discrete multitone transmission with a bit error rate of 1.1 x 10^-3 and enhanced solar energy conversion efficiency.

Solar pumped lasers: Work in progress at the University of Chicago

NASA Astrophysics Data System (ADS)

Winston, Roland

Of the variety of solar energy conversion schemes that have been explored, the conversion of solar flux to coherent laser radiation is relatively new. Solar flux at sufficiently high concentrations to overcome threshold for the really important laser materials has not been available. This technological inhibition has recently been overcome through the application of nonimaging optics through the demonstration of concentration levels of 84,000 suns at the University of Chicago in a refractive medium (sapphire) and of over 20,000 suns in air at the Solar Energy Research Institute High Flux Facility. A thermodynamic overview is presented of solar lasers including solid state lasers and dye lasers.

Plasmon-enhanced solar energy conversion in organic bulk heterojunction photovoltaics

NASA Astrophysics Data System (ADS)

Morfa, Anthony J.; Rowlen, Kathy L.; Reilly, Thomas H.; Romero, Manuel J.; van de Lagemaat, Jao

2008-01-01

Plasmon-active silver nanoparticle layers were included in solution-processed bulk-heterojunction solar cells. Nanoparticle layers were fabricated using vapor-phase deposition on indium tin oxide electrodes. Owing to the increase in optical electrical field inside the photoactive layer, the inclusion of such particle films lead to increased optical absorption and consequently increased photoconversion at solar-conversion relevant wavelengths. The resulting solar energy conversion efficiency for a bulk heterojunction photovoltaic device of poly(3-hexylthiophene)/[6,6]-phenyl C61 butyric acid methyl ester was found to increase from 1.3%±0.2% to 2.2%±0.1% for devices employing thin plasmon-active layers. Based on six measurements, the improvement factor of 1.7 was demonstrated to be statistically significant.

Impact of spectral irradiance distribution and temperature on the outdoor performance of concentrator photovoltaic system

NASA Astrophysics Data System (ADS)

Husna, Husyira Al; Shibata, Naoki; Sawano, Naoki; Ueno, Seiya; Ota, Yasuyuki; Minemoto, Takashi; Araki, Kenji; Nishioka, Kensuke

2013-09-01

Multi-junction solar cell is designed to have considerable effect towards the solar spectrum distribution so that the maximum solar radiation could be absorbed hence, enhancing the energy conversion efficiency of the cell. Due to its application in CPV system, the system's characteristics are more sensitive to environmental factor in comparison to flat-plate PV system which commonly equipped with Si-based solar cell. In this paper, the impact of environmental factors i.e. average photon energy (APE) and temperature of solar cell (Tcell) towards the performance of the tracking type CPV system were discussed. A year data period of direct spectral irradiance, cell temperature, and power output which recorded from November 2010 to October 2011 at a CPV system power generator plant located at Miyazaki, Japan was used in this study. The result showed that most frequent condition during operation was at APE = 1.87±0.005eV, Tcell = 65±2.5°C with performance ratio of 83.9%. Furthermore, an equivalent circuit simulation of a CPV subsystem in module unit was conducted in order to investigate the influence of environmental factors towards the performance of the module.

Advances in graphene-based semiconductor photocatalysts for solar energy conversion: fundamentals and materials engineering.

PubMed

Xie, Xiuqiang; Kretschmer, Katja; Wang, Guoxiu

2015-08-28

Graphene-based semiconductor photocatalysis has been regarded as a promising technology for solar energy storage and conversion. In this review, we summarized recent developments of graphene-based photocatalysts, including preparation of graphene-based photocatalysts, typical key advances in the understanding of graphene functions for photocatalytic activity enhancement and methodologies to regulate the electron transfer efficiency in graphene-based composite photocatalysts, by which we hope to offer enriched information to harvest the utmost fascinating properties of graphene as a platform to construct efficient graphene-based composite photocatalysts for solar-to-energy conversion.

Integration of dye-sensitized solar cells, thermoelectric modules and electrical storage loop system to constitute a novel photothermoelectric generator.

PubMed

Chang, Ho; Yu, Zhi-Rong

2012-08-01

This study self-develops a novel type of photothermoelectric power generation modules. Dye-sensitized solar cells (DSSCs) serve as the photoelectric conversion system and a copper (Cu) heat-transfer nanofilm coating on both sides of the thermoelectric generator (TEG) acts as a thermoelectric conversion system. Thus module assembly absorbs light and generates electricity by DSSCs, and also recycles waste heat and generates power by the TEG. In addition, a set of pulsating heat pipes (PHP) filled with Cu nanofluid is placed on the cooling side to increase cooling effects and enhance the power generation efficiency. Results show that when the heat source of thermoelectric modules reaches 90 degrees C, TEG power output is increased by 85.7%. Besides, after thermoelectric modules are heated by additional heat source at 80 degrees C, the electrical energy generated by them can let a NiMH cell (1.25 V) be sufficiently charged in about 30 minutes. When photothermoelectric modules is illumined by simulated light, the temperature difference of two sides of TEG can reach 7 degrees C and the thermoelectric conversion efficiency is 2.17%. Furthermore, the power output of the thermoelectric modules is 11.48 mW/cm2, enhancing 1.4 % compared to merely using DSSCs module.

Ground-Based and Space-Based Laser Beam Power Applications

NASA Technical Reports Server (NTRS)

Bozek, John M.

1995-01-01

A space power system based on laser beam power is sized to reduce mass, increase operational capabilities, and reduce complexity. The advantages of laser systems over solar-based systems are compared as a function of application. Power produced from the conversion of a laser beam that has been generated on the Earth's surface and beamed into cislunar space resulted in decreased round-trip time for Earth satellite electric propulsion tugs and a substantial landed mass savings for a lunar surface mission. The mass of a space-based laser system (generator in space and receiver near user) that beams down to an extraterrestrial airplane, orbiting spacecraft, surface outpost, or rover is calculated and compared to a solar system. In general, the advantage of low mass for these space-based laser systems is limited to high solar eclipse time missions at distances inside Jupiter. The power system mass is less in a continuously moving Mars rover or surface outpost using space-based laser technology than in a comparable solar-based power system, but only during dust storm conditions. Even at large distances for the Sun, the user-site portion of a space-based laser power system (e.g., the laser receiver component) is substantially less massive than a solar-based system with requisite on-board electrochemical energy storage.

Low Molecular Weight Norbornadiene Derivatives for Molecular Solar-Thermal Energy Storage.

PubMed

Quant, Maria; Lennartson, Anders; Dreos, Ambra; Kuisma, Mikael; Erhart, Paul; Börjesson, Karl; Moth-Poulsen, Kasper

2016-09-05

Molecular solar-thermal energy storage systems are based on molecular switches that reversibly convert solar energy into chemical energy. Herein, we report the synthesis, characterization, and computational evaluation of a series of low molecular weight (193-260 g mol(-1) ) norbornadiene-quadricyclane systems. The molecules feature cyano acceptor and ethynyl-substituted aromatic donor groups, leading to a good match with solar irradiation, quantitative photo-thermal conversion between the norbornadiene and quadricyclane, as well as high energy storage densities (396-629 kJ kg(-1) ). The spectroscopic properties and energy storage capability have been further evaluated through density functional theory calculations, which indicate that the ethynyl moiety plays a critical role in obtaining the high oscillator strengths seen for these molecules. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Solar-pumped gas laser development

NASA Technical Reports Server (NTRS)

Wilson, J. W.

1981-01-01

The direct conversion of solar radiation into an inverted population for extraction in an optical cavity holds promise as a relatively simple system design. Broad-band photoabsorption in the visible or near-UV range is required to excite large volumes of gas and to ensure good solar absorption efficiency. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than approximately 10 A. The system should show chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. A search of electronic-vibrational transitions in diatomic molecules satisfying these conditions is now in progress. A photodissociation-pumped atomic iodine laser is now being tested under solar pumping conditions. Photodissociation studies for thallium spin-flip metastable formation will begin in the near future.

CARBON DIOXIDE FIXATION.

DOE Office of Scientific and Technical Information (OSTI.GOV)

FUJITA,E.

2000-01-12

Solar carbon dioxide fixation offers the possibility of a renewable source of chemicals and fuels in the future. Its realization rests on future advances in the efficiency of solar energy collection and development of suitable catalysts for CO{sub 2} conversion. Recent achievements in the efficiency of solar energy conversion and in catalysis suggest that this approach holds a great deal of promise for contributing to future needs for fuels and chemicals.

Performance and economic risk evaluation of dispersed solar thermal power systems by Monte Carlo simulation

NASA Technical Reports Server (NTRS)

Manvi, R.; Fujita, T.

1978-01-01

A preliminary comparative evaluation of dispersed solar thermal power plants utilizing advanced technologies available in 1985-2000 time frame is under way at JPL. The solar power plants of 50 KWe to 10 MWe size are equipped with two axis tracking parabolic dish concentrator systems operating at temperatures in excess of 1000 F. The energy conversion schemes under consideration include advanced steam, open and closed cycle gas turbines, stirling, and combined cycle. The energy storage systems include advanced batteries, liquid metal, and chemical. This paper outlines a simple methodology for a probabilistic assessment of such systems. Sources of uncertainty in the development of advanced systems are identified, and a computer Monte Carlo simulation is exercised to permit an analysis of the tradeoffs of the risk of failure versus the potential for large gains. Frequency distribution of energy cost for several alternatives are presented.

Photovoltaic concepts inspired by coherence effects in photosynthetic systems

NASA Astrophysics Data System (ADS)

Brédas, Jean-Luc; Sargent, Edward H.; Scholes, Gregory D.

2017-01-01

The past decade has seen rapid advances in our understanding of how coherent and vibronic phenomena in biological photosynthetic systems aid in the efficient transport of energy from light-harvesting antennas to photosynthetic reaction centres. Such coherence effects suggest strategies to increase transport lengths even in the presence of structural disorder. Here we explore how these principles could be exploited in making improved solar cells. We investigate in depth the case of organic materials, systems in which energy and charge transport stand to be improved by overcoming challenges that arise from the effects of static and dynamic disorder -- structural and energetic -- and from inherently strong electron-vibration couplings. We discuss how solar-cell device architectures can evolve to use coherence-exploiting materials, and we speculate as to the prospects for a coherent energy conversion system. We conclude with a survey of the impacts of coherence and bioinspiration on diverse solar-energy harvesting solutions, including artificial photosynthetic systems.

Satellite Power System (SPS) concept definition study (Exhibit D). Volume 2: Systems/subsystems analyses

NASA Technical Reports Server (NTRS)

Hanley, G. M.

1981-01-01

Modifications to the reference concept were studied and the best approaches defined. The impact of the high efficiency multibandgap solar array on the reference concept design is considered. System trade studies for several solid state concepts, including the sandwich concept and a separate antenna/solar concept, are described. Two solid state concepts were selected and a design definition is presented for each. Magnetrons as an alternative to the reference klystrons for dc/RF conversion are evaluated. System definitions are presented for the preferred klystron and solid state concepts. Supporting systems are analyzed, with major analysis in the microwave, structures, and power distribution areas. Results of studies for thermal control, attitude control, stationkeeping, and details of a multibandgap solar cell study are included. Advanced laser concepts and the meteorological effects of a laser beam power transmission concept are considered.

Systems definition space-based power conversion systems. [for satellite power transmission to earth

NASA Technical Reports Server (NTRS)

1976-01-01

Potential space-located systems for the generation of electrical power for use on Earth are discussed and include: (1) systems producing electrical power from solar energy; (2) systems producing electrical power from nuclear reactors; and (3) systems for augmenting ground-based solar power plants by orbital sunlight reflectors. Systems (1) and (2) would utilize a microwave beam system to transmit their output to Earth. Configurations implementing these concepts were developed through an optimization process intended to yield the lowest cost for each. A complete program was developed for each concept, identifying required production rates, quantities of launches, required facilities, etc. Each program was costed in order to provide the electric power cost appropriate to each concept.

Advanced solar energy conversion. [solar pumped gas lasers

NASA Technical Reports Server (NTRS)

Lee, J. H.

1981-01-01

An atomic iodine laser, a candidate for the direct solar pumped lasers, was successfully excited with a 4 kW beam from a xenon arc solar simulator, thus proving the feasibility of the concept. The experimental set up and the laser output as functions of operating conditions are presented. The preliminary results of the iodine laser amplifier pumped with the HCP array to which a Q switch for giant pulse production was coupled are included. Two invention disclosures - a laser driven magnetohydrodynamic generator for conversion of laser energy to electricity and solar pumped gas lasers - are also included.

Common Data Format: New XML and Conversion Tools

NASA Astrophysics Data System (ADS)

Han, D. B.; Liu, M. H.; McGuire, R. E.

2002-12-01

Common Data Format (CDF) is a self-describing platform-independent data format for storing, accessing, and manipulating scalar and multidimensional scientific data sets. Significant benefit has accrued to specific science communities from their use of standard formats within those communities. Examples include the International Solar Terrestrial Physics (ISTP) community in using CDF for traditional space physics data (fields, particles and plasma, waves, and images), the worldwide astronomical community in using FITS (Flexible Image Transport System) for solar data (primarily spectral images), the NASA Planetary community in using Planetary Data System (PDS) Labels, and the earth science community in using Hierarchical Data Format (HDF). Scientific progress in solar-terrestrial physics continues to be impeded by the multiplicity of available standards for data formats and dearth of general data format translators. As a result, scientists today spend a significant amount of time translating data into the format they are familiar with for their research. To minimize this unnecessary data translation time and to allow more research time, the CDF office located at GSFC National Space Science Data Center (NSSDC) has developed HDF-to-CDF and FITS-to-CDF translators, and employed the eXtensible Markup Language (XML) technology to facilitate and promote data interoperability within the space science community. We will present the current status of the CDF work including the conversion tools that have been recently developed, conversion tools that are planned in the near future, share some of the XML experiences, and use the discussion to gain community feedback to our planned future work.

2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion.

PubMed

Collins, Gillian; Armstrong, Eileen; McNulty, David; O'Hanlon, Sally; Geaney, Hugh; O'Dwyer, Colm

2016-01-01

This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems. Strategies for using 2D as well as 3D structures, ordered macroporous materials such as inverse opals are summarized and recent work on plasmonic-photonic coupling in metal nanoparticle-infiltrated wide band gap inverse opals for enhanced photoelectrochemistry are provided.

2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion

PubMed Central

Collins, Gillian; Armstrong, Eileen; McNulty, David; O’Hanlon, Sally; Geaney, Hugh; O’Dwyer, Colm

2016-01-01

Abstract This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems. Strategies for using 2D as well as 3D structures, ordered macroporous materials such as inverse opals are summarized and recent work on plasmonic–photonic coupling in metal nanoparticle-infiltrated wide band gap inverse opals for enhanced photoelectrochemistry are provided. PMID:27877904

Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging.

PubMed

Liao, Shichao; Zong, Xu; Seger, Brian; Pedersen, Thomas; Yao, Tingting; Ding, Chunmei; Shi, Jingying; Chen, Jian; Li, Can

2016-05-04

Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge injection, our device shows an optimal solar-to-chemical conversion efficiency of ∼5.9% and an overall photon-chemical-electricity energy conversion efficiency of ∼3.2%, which, to our knowledge, outperforms previously reported SRFCs. The proposed SRFC can be self-photocharged to 0.8 V and delivers a discharge capacity of 730 mAh l(-1). Our work may guide future designs for highly efficient solar rechargeable devices.

FOCUSing on Innovative Solar Technologies

ScienceCinema

Rohlfing, Eric; Holman, Zak, Angel, Roger

2018-06-22

Many of ARPA-E’s technology programs seek to break down silos and build new technological communities around a specific energy challenge. In this video, ARPA-E’s Deputy Director for Technology Eric Rohlfing, discusses how the Full-Spectrum Optimized Conversion and Utilization of Sunlight (FOCUS) program is bringing together the photovoltaic (PV) and concentrated solar power (CSP) communities to develop hybrid solar energy systems. This video features interviews with innovators from the FOCUS project team made up by Arizona State University and the University of Arizona, and showcases how the FOCUS program is combining.

High-performance flat-panel solar thermoelectric generators with high thermal concentration.

PubMed

Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

2011-05-01

The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m(-2)) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity. © 2011 Macmillan Publishers Limited. All rights reserved

Embedded vertically aligned cadmium telluride nanorod arrays grown by one-step electrodeposition for enhanced energy conversion efficiency in three-dimensional nanostructured solar cells.

PubMed

Wang, Jun; Liu, Shurong; Mu, Yannan; Liu, Li; A, Runa; Yang, Jiandong; Zhu, Guijie; Meng, Xianwei; Fu, Wuyou; Yang, Haibin

2017-11-01

Vertically aligned CdTe nanorods (NRs) arrays are successfully grown by a simple one-step and template-free electrodeposition method, and then embedded in the CdS window layer to form a novel three-dimensional (3D) heterostructure on flexible substrates. The parameters of electrodeposition such as deposition potential and pH of the solution are varied to analyze their important role in the formation of high quality CdTe NRs arrays. The photovoltaic conversion efficiency of the solar cell based on the 3D heterojunction structure is studied in detail. In comparison with the standard planar heterojunction solar cell, the 3D heterojunction solar cell exhibits better photovoltaic performance, which can be attributed to its enhanced optical absorption ability, increased heterojunction area and improved charge carrier transport. The better photoelectric property of the 3D heterojunction solar cell suggests great application potential in thin film solar cells, and the simple electrodeposition process represents a promising technique for large-scale fabrication of other nanostructured solar energy conversion devices. Copyright © 2017 Elsevier Inc. All rights reserved.

Device physics of Cu(In,Ga)Se2 solar cells for long-term operation

NASA Astrophysics Data System (ADS)

Nishinaga, J.; Shibata, H.

2017-02-01

The degradation mechanism of Cu(In,Ga)Se2 (CIGS) solar cells on exposure to air has been investigated. Exposure to air at room temperature slightly reduces the conversion efficiency of CIGS solar cells, and the conversion efficiency decreases significantly under damp heat testing at 85 °C and 85% relative humidity due to low shunt resistance. On the other hand, shunt resistance increases after dry nitrogen heating. Therefore, oxygen and humidity should degenerate the solar cell performance. The low shunt resistance and conversion efficiency are completely recovered after removing the side edges of the CIGS solar cells by mechanical scribing. These results suggest that low-resistive layers are formed on the sidewalls of the solar cells during damp heat testing. The low-resistive layers on the sidewalls are identified to be molybdenum oxides and sodium molybdate by Auger electron spectroscopy. After etching the oxides on the sidewalls by alkaline solution, the saturation current density and ideality factor are confirmed to be improved. These results suggest that metal oxides on the sidewalls of CIGS solar cells may act as recombination centers.

Microfabrication of microsystem-enabled photovoltaic (MEPV) cells

NASA Astrophysics Data System (ADS)

Nielson, Gregory N.; Okandan, Murat; Cruz-Campa, Jose L.; Resnick, Paul J.; Wanlass, Mark W.; Clews, Peggy J.; Pluym, Tammy C.; Sanchez, Carlos A.; Gupta, Vipin P.

2011-02-01

Microsystem-Enabled Photovoltaic (MEPV) cells allow solar PV systems to take advantage of scaling benefits that occur as solar cells are reduced in size. We have developed MEPV cells that are 5 to 20 microns thick and down to 250 microns across. We have developed and demonstrated crystalline silicon (c-Si) cells with solar conversion efficiencies of 14.9%, and gallium arsenide (GaAs) cells with a conversion efficiency of 11.36%. In pursuing this work, we have identified over twenty scaling benefits that reduce PV system cost, improve performance, or allow new functionality. To create these cells, we have combined microfabrication techniques from various microsystem technologies. We have focused our development efforts on creating a process flow that uses standard equipment and standard wafer thicknesses, allows all high-temperature processing to be performed prior to release, and allows the remaining post-release wafer to be reprocessed and reused. The c-Si cell junctions are created using a backside point-contact PV cell process. The GaAs cells have an epitaxially grown junction. Despite the horizontal junction, these cells also are backside contacted. We provide recent developments and details for all steps of the process including junction creation, surface passivation, metallization, and release.

Techno-economic projections for advanced small solar thermal electric power plants to years 1990-2000

NASA Technical Reports Server (NTRS)

Fujita, T.; Manvi, R.; Roschke, E. J.; El-Gabalawi, N.; Herrera, G.; Kuo, T. J.; Chen, K. H.

1979-01-01

Advanced technologies applicable to solar thermal electric power systems in the 1990-200 time-frame are delineated for power applications that fulfill a wide spectrum of small power needs with primary emphasis on power ratings less than 10MWe. Projections of power system characteristics (energy and capital costs as a function of capacity factor) are made based on development of identified promising technologies and are used as the basis for comparing technology development options and combinations of these options to determine developmental directions offering potential for significant improvements. Stirling engines, Brayton/Rankine combined cycles and storage/transport concepts encompassing liquid metals, and reversible-reaction chemical systems are considered for two-axis tracking systems such as the central receiver or power tower concept and distributed parabolic dish receivers which can provide efficient low-cost solar energy collection while achieving high temperatures for efficient energy conversion. Pursuit of advanced technology across a broad front can result in post-1985 solar thermal systems having the potential of approaching the goal of competitiveness with conventional power systems.

Solar Array Hysteresis and its Interaction with the MPPT System

NASA Astrophysics Data System (ADS)

Fernandez, A.; Baur, C.; Gomez-Carpintero, F.

2014-08-01

It is well known that solar cells have a capacitance in parallel which value changes with the voltage. Depending on the section arrangement on the Solar Array, the power conversion unit connected to it will see a smaller or larger capacitance value and will have to cope with its adverse effects. In the case of converters with an MPPT, this capacitance gives place to an hysteresis effect that might shift the tracking point, reducing the power extracted from the Solar Array. This paper explores the different sides of this issue, from capacitance modelling to the effects on the MPPT. Additionally, this paper analyses a similar interaction between MPPTs and commercial SAS.

Achieving Simultaneous CO2 and H2 S Conversion via a Coupled Solar-Driven Electrochemical Approach on Non-Precious-Metal Catalysts.

PubMed

Ma, Weiguang; Wang, Hong; Yu, Wei; Wang, Xiaomei; Xu, Zhiqiang; Zong, Xu; Li, Can

2018-03-19

Carbon dioxide (CO 2 ) and hydrogen sulfide (H 2 S) are generally concomitant with methane (CH 4 ) in natural gas and traditionally deemed useless or even harmful. Developing strategies that can simultaneously convert both CO 2 and H 2 S into value-added products is attractive; however it has not received enough attention. A solar-driven electrochemical process is demonstrated using graphene-encapsulated zinc oxide catalyst for CO 2 reduction and graphene catalyst for H 2 S oxidation mediated by EDTA-Fe 2+ /EDTA-Fe 3+ redox couples. The as-prepared solar-driven electrochemical system can realize the simultaneous conversion of CO 2 and H 2 S into carbon monoxide and elemental sulfur at near neutral conditions with high stability and selectivity. This conceptually provides an alternative avenue for the purification of natural gas with added economic and environmental benefits. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development status of the small community solar power system

NASA Technical Reports Server (NTRS)

Pons, R. L.

1982-01-01

The development status and test results for the Small Community Solar Thermal Power Experiment are presented. Activities on the phase 2 power module development effort are presented with emphasis on the receiver, the plant control subsystem, and the energy transport subsystem. The components include a single prototype power module consisting of a parabolic dish concentrator, a power conversion assembly (PCA), and a multiple-module plant control subsystem. The PCA consists of a cavity receiver coupled to an organic Rankine cycle engine-alternator unit defined as the power conversion subsystem; the PCA is mounted at the focus of a parabolic dish concentrator. At a solar insolation of 100 W/sq m and ambient temperature of 28 C (82 F), the power module produces approximately 20 kW of 3-phase, 3 kHz ac power, depending on the concentrator employed. A ground-mounted rectifier to the central collection site where it is supplied directly to the common dc bus which collects the power from all modules in the plant.

Improving Photocatalytic Activity through Electrostatic Self-Assembly: Polyelectrolytes as Tool for Solar Energy Conversion?

NASA Astrophysics Data System (ADS)

Groehn, Franziska

2015-03-01

With regard to the world's decreasing energy resources, developing strategies to exploit solar energy become more and more important. One approach is to take advantage of photocatalysis. Inspired by natural systems such as assemblies performing photosynthesis, it is highly promising to self-assemble synthetic functional species to form more effective or tailored supramolecular units. In this contribution, a new type of photocatalytically active self-assembled nanostructures in aqueous solution will be presented: supramolecular nano-objects obtained through self-assembly of macroions and multivalent organic or inorganic counterions. Polyelectrolyte-porphyrin nanoscale assemblies exhibit up to 10-fold higher photocatalytic activity than the corresponding porphyrins without polymeric template. Other self-assembled catalysts based on polyelectrolytes can exhibit expressed selectivity in a photocatalytic model reaction or even allow catalytic reactions in solution that are not possible with the building blocks only. Further, current results on combining different functional units at the polyelectrolyte template represent a next step towards more complex supramolecular structures for solar energy conversion.

Comparison of reconnection in magnetosphere and solar corona

NASA Astrophysics Data System (ADS)

Imada, Shinsuke; Hirai, Mariko; Isobe, Hiroaki; Oka, Mitsuo; Watanabe, Kyoko; Minoshima, Takashi

One of the most famous rapid energy conversion mechanisms in space is a magnetic reconnec-tion. The general concept of a magnetic reconnection is that the rapid energy conversion from magnetic field energy to thermal energy, kinetic energy or non-thermal particle energy. The understanding of rapid energy conversion rates from magnetic field energy to other energy is the fundamental and essential problem in the space physics. One of the important goals for studying magnetic reconnection is to answer what plasma condition/parameter controls the energy conversion rates. Earth's magnetotail has been paid much attention to discuss a mag-netic reconnection, because we can discuss magnetic reconnection characteristics in detail with direct in-situ observation. Recently, solar atmosphere has been focused as a space laboratory for magnetic reconnection because of its variety in plasma condition. So far considerable effort has been devoted toward understanding the energy conversion rates of magnetic reconnection, and various typical features associated with magnetic reconnection have been observed in the Earth's magnetotail and the solar corona. In this talk, we first introduce the variety of plasma condition/parameter in solar corona and Earth's magnetotail. Later, we discuss what plasma condition/parameter controls the energy conversion from magnetic field to especially non-thermal particle. To compare non-thermal electron and ion acceleration in magnetic reconnection, we used Hard X-ray (electron) /Neu-tron monitor (ion) for solar corona and Geotail in-situ measurement (electron and ion) for magnetoatil. We found both of electron and ion accelerations are roughly controlled by re-connection electric field (reconnection rate). However, some detail points are different in ion and electron acceleration. Further, we will discuss what is the major difference between solar corona and Earth's magnetotail for particle acceleration.

Harmonic analysis and suppression in hybrid wind & PV solar system

NASA Astrophysics Data System (ADS)

Gupta, Tripti; Namekar, Swapnil

2018-04-01

The growing demand of electricity has led to produce power through non-conventional source of energy such as solar energy, wind energy, hydro power, energy through biogas and biomass etc. Hybrid system is taken to complement the shortcoming of either sources of energy. The proposed system is grid connected hybrid wind and solar system. A 2.1 MW Doubly fed Induction Generator (DFIG) has been taken for analysis of wind farm whose rotor part is connected to two back-to-back converters. A 250 KW Photovoltaic (PV) array taken to analyze solar farm where inverter is required to convert power from DC to AC since electricity generated through solar PV is in the form of DC. Stability and reliability of the system is very important when the system is grid connected. Harmonics is the major Power quality issue which degrades the quality of power at load side. Harmonics in hybrid system arise through the use of power conversion unit. The other causes of harmonics are fluctuation in wind speed and solar irradiance. The power delivered to grid must be free from harmonics and within the limits specified by Indian grid codes. In proposed work, harmonic analysis of the hybrid system is performed in Electrical Transient Analysis program (ETAP) and single tuned harmonic filter is designed to maintain the utility grid harmonics within limits.

2015 Materials Research Society Spring Meeting

DTIC Science & Technology

2016-05-12

State University, Raleigh, NC 27695  Eicke R. Weber, Fraunhofer Institute for  Solar  Energy Systems, Freiburg, Germany    Symposium Highlights:  The...emission from fossil fuels.  Materials hold the key to  advanced renewable energy technologies including  solar  cells, batteries, fuel cells, and catalysis...systems. For example, among renewable energy technologies,  solar  energy is  a limitless source of energy, and photovoltaic energy conversion is one of the

NREL Pyrheliometer Comparisons: September 26-October 7, 2016 (NPC-2016)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reda, Ibrahim; Dooraghi, Mike; Andreas, Afshin

Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for developing and deploying solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations that are traceable to an international standard is the first step in producing research-quality solar irradiance measurements. National Renewable Energy Laboratory (NREL) pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) inmore » Golden, Colorado. Open to all pyrheliometer owners and operators, each NPC provides an opportunity to determine the unique World Radiometric Reference transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR. NPC-2016 was September 26 through October 7, 2016. Participants operated 45 absolute cavity radiometers and 27 conventional thermopile-based pyrheliometers to simultaneously measure clear-sky, direct normal solar irradiance during this period.« less

Comparative Ab-Initio Study of Substituted Norbornadiene-Quadricyclane Compounds for Solar Thermal Storage.

PubMed

Kuisma, Mikael J; Lundin, Angelica M; Moth-Poulsen, Kasper; Hyldgaard, Per; Erhart, Paul

2016-02-25

Molecular photoswitches that are capable of storing solar energy, so-called molecular solar thermal storage systems, are interesting candidates for future renewable energy applications. In this context, substituted norbornadiene-quadricyclane systems have received renewed interest due to recent advances in their synthesis. The optical, thermodynamic, and kinetic properties of these systems can vary dramatically depending on the chosen substituents. The molecular design of optimal compounds therefore requires a detailed understanding of the effect of individual substituents as well as their interplay. Here, we model absorption spectra, potential energy storage, and thermal barriers for back-conversion of several substituted systems using both single-reference (density functional theory using PBE, B3LYP, CAM-B3LYP, M06, M06-2x, and M06-L functionals as well as MP2 calculations) and multireference methods (complete active space techniques). Already the diaryl substituted compound displays a strong red-shift compared to the unsubstituted system, which is shown to result from the extension of the conjugated π-system upon substitution. Using specific donor/acceptor groups gives rise to a further albeit relatively smaller red-shift. The calculated storage energy is found to be rather insensitive to the specific substituents, although solvent effects are likely to be important and require further study. The barrier for thermal back-conversion exhibits strong multireference character and as a result is noticeably correlated with the red-shift. Two possible reaction paths for the thermal back-conversion of diaryl substituted quadricyclane are identified and it is shown that among the compounds considered the path via the acceptor side is systematically favored. Finally, the present study establishes the basis for high-throughput screening of norbornadiene-quadricyclane compounds as it provides guidelines for the level of accuracy that can be expected for key properties from several different techniques.

Augmentation of Solar Thermal Propulsion Systems Via Phase Change Thermal Energy Storage and Thermal Electric Conversion

DTIC Science & Technology

2012-04-01

vapor infiltration on erosion and thermal properties of porous carbon/carbon composite on thermal insulation . Carbon, (38):441– 449, 2000. [14] J. Mueller...Thermal Energy Storage and Thermal Electric Conversion 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...with thermo-acoustic instabilities. Results will be reported on the flame structure, liquid core length and spreading rate, and comparison with data

Enhancing the power conversion efficiency of dye-sensitized solar cells via molecular plasmon-like excitations.

PubMed

Li, Jian-Hao; Gryn'ova, Ganna; Prlj, Antonio; Corminboeuf, Clémence

2017-02-21

We introduce a tactic for employing molecular plasmon-like excitations to enhance solar-to-electric power conversion efficiency of dye-sensitized solar cells. We offer general design principles of dimeric dyes, in which a strong plasmonic interaction between two π-conjugated moieties is promoted. The π-stacked conformations of these dimeric dyes result in a desirable broadened absorption and a longer absorption onset wavelength.

Efficiency enhancement of organic solar cells using transparent plasmonic Ag nanowire electrodes.

PubMed

Kang, Myung-Gyu; Xu, Ting; Park, Hui Joon; Luo, Xiangang; Guo, L Jay

2010-10-15

Surface plasmon enhanced photo-current and power conversion efficiency of organic solar cells using periodic Ag nanowires as transparent electrodes are reported, as compared to the device with conventional ITO electrodes. External quantum efficiencies are enhanced about 2.5 fold around the peak solar spectrum wavelength of 560 nm, resulting in 35% overall increase in power conversion efficiency than the ITO control device under normal unpolarized light.

Key techniques for space-based solar pumped semiconductor lasers

NASA Astrophysics Data System (ADS)

He, Yang; Xiong, Sheng-jun; Liu, Xiao-long; Han, Wei-hua

2014-12-01

In space, the absence of atmospheric turbulence, absorption, dispersion and aerosol factors on laser transmission. Therefore, space-based laser has important values in satellite communication, satellite attitude controlling, space debris clearing, and long distance energy transmission, etc. On the other hand, solar energy is a kind of clean and renewable resources, the average intensity of solar irradiation on the earth is 1353W/m2, and it is even higher in space. Therefore, the space-based solar pumped lasers has attracted much research in recent years, most research focuses on solar pumped solid state lasers and solar pumped fiber lasers. The two lasing principle is based on stimulated emission of the rare earth ions such as Nd, Yb, Cr. The rare earth ions absorb light only in narrow bands. This leads to inefficient absorption of the broad-band solar spectrum, and increases the system heating load, which make the system solar to laser power conversion efficiency very low. As a solar pumped semiconductor lasers could absorb all photons with energy greater than the bandgap. Thus, solar pumped semiconductor lasers could have considerably higher efficiencies than other solar pumped lasers. Besides, solar pumped semiconductor lasers has smaller volume chip, simpler structure and better heat dissipation, it can be mounted on a small satellite platform, can compose satellite array, which can greatly improve the output power of the system, and have flexible character. This paper summarizes the research progress of space-based solar pumped semiconductor lasers, analyses of the key technologies based on several application areas, including the processing of semiconductor chip, the design of small and efficient solar condenser, and the cooling system of lasers, etc. We conclude that the solar pumped vertical cavity surface-emitting semiconductor lasers will have a wide application prospects in the space.

Integration of CdSe/CdSexTe1−x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion

PubMed Central

Lee, Sangheon; Flanagan, Joseph C.; Kang, Joonhyeon; Kim, Jinhyun; Shim, Moonsub; Park, Byungwoo

2015-01-01

Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSexTe1−x type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSexTe1−x heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO2 interface. Additional ~32% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO2 electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials. PMID:26638994

Solar to fuels conversion technologies: a perspective.

PubMed

Tuller, Harry L

2017-01-01

To meet increasing energy needs, while limiting greenhouse gas emissions over the coming decades, power capacity on a large scale will need to be provided from renewable sources, with solar expected to play a central role. While the focus to date has been on electricity generation via photovoltaic (PV) cells, electricity production currently accounts for only about one-third of total primary energy consumption. As a consequence, solar-to-fuel conversion will need to play an increasingly important role and, thereby, satisfy the need to replace high energy density fossil fuels with cleaner alternatives that remain easy to transport and store. The solar refinery concept (Herron et al. in Energy Environ Sci 8:126-157, 2015), in which captured solar radiation provides energy in the form of heat, electricity or photons, used to convert the basic chemical feedstocks CO 2 and H 2 O into fuels, is reviewed as are the key conversion processes based on (1) combined PV and electrolysis, (2) photoelectrochemically driven electrolysis and (3) thermochemical processes, all focused on initially converting H 2 O and CO 2 to H 2 and CO. Recent advances, as well as remaining challenges, associated with solar-to-fuel conversion are discussed, as is the need for an intensive research and development effort to bring such processes to scale.

Integration of CdSe/CdSexTe1-x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion.

PubMed

Lee, Sangheon; Flanagan, Joseph C; Kang, Joonhyeon; Kim, Jinhyun; Shim, Moonsub; Park, Byungwoo

2015-12-07

Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSe(x)Te(1-x) type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSe(x)Te(1-x) heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO(2) interface. Additional ~31% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO(2) electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials.

Solar power satellite rectenna design study: Directional receiving elements and parallel-series combining analysis

NASA Technical Reports Server (NTRS)

Gutmann, R. J.; Borrego, J. M.

1978-01-01

Rectenna conversion efficiencies (RF to dc) approximating 85 percent were demonstrated on a small scale, clearly indicating the feasibility and potential of efficiency of microwave power to dc. The overall cost estimates of the solar power satellite indicate that the baseline rectenna subsystem will be between 25 to 40 percent of the system cost. The directional receiving elements and element extensions were studied, along with power combining evaluation and evaluation extensions.

Mesoporous TiO2 Yolk-Shell Microspheres for Dye-sensitized Solar Cells with a High Efficiency Exceeding 11%

PubMed Central

Li, Zhao-Qian; Chen, Wang-Chao; Guo, Fu-Ling; Mo, Li-E; Hu, Lin-Hua; Dai, Song-Yuan

2015-01-01

Yolk-shell TiO2 microspheres were synthesized via a one-pot template-free solvothermal method building on the aldol condensation reaction of acetylacetone. This unique structure shows superior light scattering ability resulting in power conversion efficiency as high as 11%. This work provided a new synthesis system for TiO2 microspheres from solid to hollow and a novel material platform for high performance solar cells. PMID:26384004

Mushrooms as Efficient Solar Steam-Generation Devices.

PubMed

Xu, Ning; Hu, Xiaozhen; Xu, Weichao; Li, Xiuqiang; Zhou, Lin; Zhu, Shining; Zhu, Jia

2017-07-01

Solar steam generation is emerging as a promising technology, for its potential in harvesting solar energy for various applications such as desalination and sterilization. Recent studies have reported a variety of artificial structures that are designed and fabricated to improve energy conversion efficiencies by enhancing solar absorption, heat localization, water supply, and vapor transportation. Mushrooms, as a kind of living organism, are surprisingly found to be efficient solar steam-generation devices for the first time. Natural and carbonized mushrooms can achieve ≈62% and ≈78% conversion efficiencies under 1 sun illumination, respectively. It is found that this capability of high solar steam generation is attributed to the unique natural structure of mushroom, umbrella-shaped black pileus, porous context, and fibrous stipe with a small cross section. These features not only provide efficient light absorption, water supply, and vapor escape, but also suppress three components of heat losses at the same time. These findings not only reveal the hidden talent of mushrooms as low-cost materials for solar steam generation, but also provide inspiration for the future development of high-performance solar thermal conversion devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photothermal conversion of CO₂ into CH₄ with H₂ over Group VIII nanocatalysts: an alternative approach for solar fuel production.

PubMed

Meng, Xianguang; Wang, Tao; Liu, Lequan; Ouyang, Shuxin; Li, Peng; Hu, Huilin; Kako, Tetsuya; Iwai, Hideo; Tanaka, Akihiro; Ye, Jinhua

2014-10-20

The photothermal conversion of CO2 provides a straightforward and effective method for the highly efficient production of solar fuels with high solar-light utilization efficiency. This is due to several crucial features of the Group VIII nanocatalysts, including effective energy utilization over the whole range of the solar spectrum, excellent photothermal performance, and unique activation abilities. Photothermal CO2 reaction rates (mol h(-1) g(-1)) that are several orders of magnitude larger than those obtained with photocatalytic methods (μmol h(-1) g(-1)) were thus achieved. It is proposed that the overall water-based CO2 conversion process can be achieved by combining light-driven H2 production from water and photothermal CO2 conversion with H2. More generally, this work suggests that traditional catalysts that are characterized by intense photoabsorption will find new applications in photo-induced green-chemistry processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A theoretical analysis of the current-voltage characteristics of solar cells. [and their energy conversion efficiency

NASA Technical Reports Server (NTRS)

Dunbar, P. M.; Hauser, J. R.

1976-01-01

Various mechanisms which limit the conversion efficiency of silicon solar cells were studied. The effects of changes in solar cell geometry such as layer thickness on performance were examined. The effects of various antireflecting layers were also examined. It was found that any single film antireflecting layer results in a significant surface loss of photons. The use of surface texturing techniques or low loss antireflecting layers can enhance by several percentage points the conversion efficiency of silicon cells. The basic differences between n(+)-p-p(+) and p(+)-n-n(+) cells are treated. A significant part of the study was devoted to the importance of surface region lifetime and heavy doping effects on efficiency. Heavy doping bandgap reduction effects are enhanced by low surface layer lifetimes, and conversely, the reduction in solar cell efficiency due to low surface layer lifetime is further enhanced by heavy doping effects. A series of computer studies is reported which seeks to determine the best cell structure and doping levels for maximum efficiency.

Can quantum coherent solar cells break detailed balance?

NASA Astrophysics Data System (ADS)

Kirk, Alexander P.

2015-07-01

Carefully engineered coherent quantum states have been proposed as a design attribute that is hypothesized to enable solar photovoltaic cells to break the detailed balance (or radiative) limit of power conversion efficiency by possibly causing radiative recombination to be suppressed. However, in full compliance with the principles of statistical mechanics and the laws of thermodynamics, specially prepared coherent quantum states do not allow a solar photovoltaic cell—a quantum threshold energy conversion device—to exceed the detailed balance limit of power conversion efficiency. At the condition given by steady-state open circuit operation with zero nonradiative recombination, the photon absorption rate (or carrier photogeneration rate) must balance the photon emission rate (or carrier radiative recombination rate) thus ensuring that detailed balance prevails. Quantum state transitions, entropy-generating hot carrier relaxation, and photon absorption and emission rate balancing are employed holistically and self-consistently along with calculations of current density, voltage, and power conversion efficiency to explain why detailed balance may not be violated in solar photovoltaic cells.

Harnessing surface plasmons for solar energy conversion

NASA Technical Reports Server (NTRS)

Anderson, L. M.

1983-01-01

NASA research on the feasibility of solar-energy conversion using surface plasmons is reviewed, with a focus on inelastic-tunnel-diode techniques for power extraction. The need for more efficient solar converters for planned space missions is indicated, and it is shown that a device with 50-percent efficiency could cost up to 40 times as much per sq cm as current Si cells and still be competitive. The parallel-processing approach using broadband carriers and tunable diodes is explained, and the physics of surface plasmons on metal surfaces is outlined. Technical problems being addressed include phase-matching sunlight to surface plasmons, minimizing ohmic losses and reradiation in energy transport, coupling into the tunnels by mode conversion, and gaining an understanding of the tunnel-diode energy-conversion process. Diagrams illustrating the design concepts are provided.

Carbon-doped BN nanosheets for metal-free photoredox catalysis

PubMed Central

Huang, Caijin; Chen, Cheng; Zhang, Mingwen; Lin, Lihua; Ye, Xinxin; Lin, Sen; Antonietti, Markus; Wang, Xinchen

2015-01-01

The generation of sustainable and stable semiconductors for solar energy conversion by photoredox catalysis, for example, light-induced water splitting and carbon dioxide reduction, is a key challenge of modern materials chemistry. Here we present a simple synthesis of a ternary semiconductor, boron carbon nitride, and show that it can catalyse hydrogen or oxygen evolution from water as well as carbon dioxide reduction under visible light illumination. The ternary B–C–N alloy features a delocalized two-dimensional electron system with sp2 carbon incorporated in the h-BN lattice where the bandgap can be adjusted by the amount of incorporated carbon to produce unique functions. Such sustainable photocatalysts made of lightweight elements facilitate the innovative construction of photoredox cascades to utilize solar energy for chemical conversion. PMID:26159752

Performance comparison investigation on solar photovoltaic-thermoelectric generation and solar photovoltaic-thermoelectric cooling hybrid systems under different conditions

NASA Astrophysics Data System (ADS)

Wu, Shuang-Ying; Zhang, Yi-Chen; Xiao, Lan; Shen, Zu-Guo

2018-07-01

The performance of solar photovoltaic-thermoelectric generation hybrid system (PV-TGS) and solar photovoltaic-thermoelectric cooling hybrid system (PV-TCS) under different conditions were theoretically analysed and compared. To test the practicality of these two hybrid systems, the performance of stand-alone PV system was also studied. The results show that PV-TGS and PV-TCS in most cases will result in the system with a better performance than stand-alone PV system. The advantage of PV-TGS is emphasised in total output power and conversion efficiency which is even poorer in PV-TCS than that in stand-alone PV system at the ambient wind speed uw being below 3 m/s. However, PV-TCS has obvious advantage on lowering the temperature of PV cell. There is an obvious increase in tendency on the performance of PV-TGS and PV-TCS when the cooling capacity of two hybrid systems varies from around 0.06 to 0.3 W/K. And it is also proved that not just a-Si in PV-TGS can produce a better performance than the stand-alone PV system alone at most cases.

Matter effects on the flavor conversions of solar neutrinos and high-energy astrophysical neutrinos

NASA Astrophysics Data System (ADS)

Huang, Guo-yuan; Liu, Jun-Hao; Zhou, Shun

2018-06-01

Can we observe the solar eclipses in the neutrino light? In principle, this is possible by identifying the lunar matter effects on the flavor conversions of solar neutrinos when they traverse the Moon before reaching the detectors at the Earth. Unfortunately, we show that the lunar matter effects on the survival probability of solar 8B neutrinos are suppressed by an additional factor of 1.2%, compared to the day-night asymmetry. However, we point out that the matter effects on the flavor conversions of high-energy astrophysical neutrinos, when they propagate through the Sun, can be significant. Though the flavor composition of high-energy neutrinos can be remarkably modified, it is quite challenging to observe such effects even in the next-generation of neutrino telescopes.

REDOX electrochemical energy storage

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1980-01-01

Reservoirs of chemical solutions can store electrical energy with high efficiency. Reactant solutions are stored outside conversion section where charging and discharging reactions take place. Conversion unit consists of stacks of cells connected together in parallel hydraulically, and in series electrically. Stacks resemble fuel cell batteries. System is 99% ampere-hour efficient, 75% watt hour efficient, and has long projected lifetime. Applications include storage buffering for remote solar or wind power systems, and industrial load leveling. Cost estimates are $325/kW of power requirement plus $51/kWh storage capacity. Mass production would reduce cost by about factor of two.

Work Began on Contracts for Radioisotope Power Conversion Technology Research and Development

NASA Technical Reports Server (NTRS)

Wong, Wayne A.

2005-01-01

NASA has had a history of successful space flight missions that depended on radioisotope-fueled power systems. These Radioisotope Power Systems (RPSs) converted the heat generated from the decay of radioisotope material into useful electrical power. An RPS is most attractive in applications where photovoltaics are not optimal, such as deep-space applications where the solar flux is too low or extended applications on planets such as Mars where the day/night cycle, settling of dust, and life requirements limit the usefulness of photovoltaics. NASA s Radioisotope Power Conversion Technology (RPCT) Program is developing next-generation power-conversion technologies that will enable future missions that have requirements that cannot be met by the two RPS flight systems currently being developed by the Department of Energy for NASA: the Multi-Mission Radioisotope Thermoelectric Generator and the Stirling Radioisotope Generator (SRG).

Exploring Interfacial Events in Gold-Nanocluster-Sensitized Solar Cells: Insights into the Effects of the Cluster Size and Electrolyte on Solar Cell Performance.

PubMed

Abbas, Muhammad A; Kim, Tea-Yon; Lee, Sang Uck; Kang, Yong Soo; Bang, Jin Ho

2016-01-13

Gold nanoclusters (Au NCs) with molecule-like behavior have emerged as a new light harvester in various energy conversion systems. Despite several important strides made recently, efforts toward the utilization of NCs as a light harvester have been primarily restricted to proving their potency and feasibility. In solar cell applications, ground-breaking research with a power conversion efficiency (PCE) of more than 2% has recently been reported. Because of the lack of complete characterization of metal cluster-sensitized solar cells (MCSSCs), however, comprehensive understanding of the interfacial events and limiting factors which dictate their performance remains elusive. In this regard, we provide deep insight into MCSSCs for the first time by performing in-depth electrochemical impedance spectroscopy (EIS) analysis combined with physical characterization and density functional theory (DFT) calculations of Au NCs. In particular, we focused on the effect of the size of the Au NCs and electrolytes on the performance of MCSSCs and reveal that they are significantly influential on important solar cell characteristics such as the light absorption capability, charge injection kinetics, interfacial charge recombination, and charge transport. Besides offering comprehensive insights, this work represents an important stepping stone toward the development of MCSSCs by accomplishing a new PCE record of 3.8%.

Boeing's High Voltage Solar Tile Test Results

NASA Astrophysics Data System (ADS)

Reed, Brian J.; Harden, David E.; Ferguson, Dale C.; Snyder, David B.

2002-10-01

Real concerns of spacecraft charging and experience with solar array augmented electrostatic discharge arcs on spacecraft have minimized the use of high voltages on large solar arrays despite numerous vehicle system mass and efficiency advantages. Boeing's solar tile (patent pending) allows high voltage to be generated at the array without the mass and efficiency losses of electronic conversion. Direct drive electric propulsion and higher power payloads (lower spacecraft weight) will benefit from this design. As future power demand grows, spacecraft designers must use higher voltage to minimize transmission loss and power cable mass for very large area arrays. This paper will describe the design and discuss the successful test of Boeing's 500-Volt Solar Tile in NASA Glenn's Tenney chamber in the Space Plasma Interaction Facility. The work was sponsored by NASA's Space Solar Power Exploratory Research and Technology (SERT) Program and will result in updated high voltage solar array design guidelines being published.

Boeing's High Voltage Solar Tile Test Results

NASA Technical Reports Server (NTRS)

Reed, Brian J.; Harden, David E.; Ferguson, Dale C.; Snyder, David B.

2002-01-01

Real concerns of spacecraft charging and experience with solar array augmented electrostatic discharge arcs on spacecraft have minimized the use of high voltages on large solar arrays despite numerous vehicle system mass and efficiency advantages. Boeing's solar tile (patent pending) allows high voltage to be generated at the array without the mass and efficiency losses of electronic conversion. Direct drive electric propulsion and higher power payloads (lower spacecraft weight) will benefit from this design. As future power demand grows, spacecraft designers must use higher voltage to minimize transmission loss and power cable mass for very large area arrays. This paper will describe the design and discuss the successful test of Boeing's 500-Volt Solar Tile in NASA Glenn's Tenney chamber in the Space Plasma Interaction Facility. The work was sponsored by NASA's Space Solar Power Exploratory Research and Technology (SERT) Program and will result in updated high voltage solar array design guidelines being published.

Parabolic Dish Solar Thermal Power Annual Program Review Proceedings

NASA Technical Reports Server (NTRS)

Holbeck, H. J.

1981-01-01

The development and testing of concentrators, receivers, and power conversion units are reported. System design and development for engineering experiments are described. Economic analysis and market assessments for advanced development activities are discussed. Technology development issues and application/user needs are highlighted.

Photovoltaic test and demonstration project. [residential energy program

NASA Technical Reports Server (NTRS)

Forestieri, A. F.; Brandhorst, H. W., Jr.; Deyo, J. N.

1976-01-01

The considered project consists of three subprojects related to applications, device performance and diagnostics, and endurance testing. The objectives of the applications subproject include the determination of the operating characteristics for a variety of photovoltaic conversion systems. A system test facility is being constructed in this connection and a prototype residence experiment is to be conducted. Market demand for solar cells is to be stimulated by demonstrating suitability of solar cells for specific near-term applications. Activities conducted in connection with device performance studies and diagnostics are also discussed along with developments in the area of endurance testing.

Thin film solar cells: research in an industrial perspective.

PubMed

Edoff, Marika

2012-01-01

Electricity generation by photovoltaic conversion of sunlight is a technology in strong growth. The thin film technology is taking market share from the dominant silicon wafer technology. In this article, the market for photovoltaics is reviewed, the concept of photovoltaic solar energy conversion is discussed and more details are given about the present technological limitations of thin film solar cell technology. Special emphasis is given for solar cells which employ Cu(In,Ga)Se(2) and Cu(2)ZnSn(S,Se)(4) as the sunlight-absorbing layer.

Particulate photocatalysts for overall water splitting

NASA Astrophysics Data System (ADS)

Chen, Shanshan; Takata, Tsuyoshi; Domen, Kazunari

2017-10-01

The conversion of solar energy to chemical energy is a promising way of generating renewable energy. Hydrogen production by means of water splitting over semiconductor photocatalysts is a simple, cost-effective approach to large-scale solar hydrogen synthesis. Since the discovery of the Honda-Fujishima effect, considerable progress has been made in this field, and numerous photocatalytic materials and water-splitting systems have been developed. In this Review, we summarize existing water-splitting systems based on particulate photocatalysts, focusing on the main components: light-harvesting semiconductors and co-catalysts. The essential design principles of the materials employed for overall water-splitting systems based on one-step and two-step photoexcitation are also discussed, concentrating on three elementary processes: photoabsorption, charge transfer and surface catalytic reactions. Finally, we outline challenges and potential advances associated with solar water splitting by particulate photocatalysts for future commercial applications.

Solar sustained plasma/absorber conceptual design

NASA Technical Reports Server (NTRS)

Rodgers, R. J.; Krascella, N. L.; Kendall, J. S.

1979-01-01

A space power system concept was evaluated which uses concentrated solar energy to heat a working fluid to temperatures as high as 4000 K. The high temperature working fluid could be used for efficient electric power production in advanced thermal or magnetohydrodynamic conversion cycles. Energy absorber configurations utilizing particles or cesium vapor absorber material were investigaed. Results of detailed radiant heat transfer calculations indicated approximately 86 percent of the incident solar energy could be absorbed within a 12-cm-dia flowing stream of gas borne carbon particles. Calculated total energy absorption in the cesium vapor seeded absorber configuration ranged from 34 percent to 64 percent of the incident solar energy. Solar flux concentration ratios of between approximately 3000 and 10,000 will be required to sustain absorber temperatures in the range from 3000 K to 4000 K.

Designing interfaces of hydrogenase-nanomaterial hybrids for efficient solar conversion.

PubMed

King, Paul W

2013-01-01

The direct conversion of sunlight into biofuels is an intriguing alternative to a continued reliance on fossil fuels. Natural photosynthesis has long been investigated both as a potential solution, and as a model for utilizing solar energy to drive a water-to-fuel cycle. The molecules and organizational structure provide a template to inspire the design of efficient molecular systems for photocatalysis. A clear design strategy is the coordination of molecular interactions that match kinetic rates and energetic levels to control the direction and flow of energy from light harvesting to catalysis. Energy transduction and electron-transfer reactions occur through interfaces formed between complexes of donor-acceptor molecules. Although the structures of several of the key biological complexes have been solved, detailed descriptions of many electron-transfer complexes are lacking, which presents a challenge to designing and engineering biomolecular systems for solar conversion. Alternatively, it is possible to couple the catalytic power of biological enzymes to light harvesting by semiconductor nanomaterials. In these molecules, surface chemistry and structure can be designed using ligands. The passivation effect of the ligand can also dramatically affect the photophysical properties of the semiconductor, and energetics of external charge-transfer. The length, degree of bond saturation (aromaticity), and solvent exposed functional groups of ligands can be manipulated to further tune the interface to control molecular assembly, and complex stability in photocatalytic hybrids. The results of this research show how ligand selection is critical to designing molecular interfaces that promote efficient self-assembly, charge-transfer and photocatalysis. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Photon up-conversion increases biomass yield in Chlorella vulgaris.

PubMed

Menon, Kavya R; Jose, Steffi; Suraishkumar, Gadi K

2014-12-01

Photon up-conversion, a process whereby lower energy radiations are converted to higher energy levels via the use of appropriate phosphor systems, was employed as a novel strategy for improving microalgal growth and lipid productivity. Photon up-conversion enables the utilization of regions of the solar spectrum, beyond the typical photosynthetically active radiation, that are usually wasted or are damaging to the algae. The effects of up-conversion of red light by two distinct sets of up-conversion phosphors were studied in the model microalgae Chlorella vulgaris. Up-conversion by set 1 phosphors led to a 2.85 fold increase in biomass concentration and a 3.2 fold increase in specific growth rate of the microalgae. While up-conversion by set 2 phosphors resulted in a 30% increase in biomass and 12% increase in specific intracellular neutral lipid, while the specific growth rates were comparable to that of the control. Furthermore, up-conversion resulted in higher levels of specific intracellular reactive oxygen species in C. vulgaris. Up-conversion of red light (654 nm) was shown to improve biomass yields in C. vulgaris. In principle, up-conversion can be used to increase the utilization range of the electromagnetic spectrum for improved cultivation of photosynthetic systems such as plants, algae, and microalgae. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A standard description and costing methodology for the balance-of-plant items of a solar thermal electric power plant. Report of a multi-institutional working group

NASA Technical Reports Server (NTRS)

1983-01-01

Standard descriptions for solar thermal power plants are established and uniform costing methodologies for nondevelopmental balance of plant (BOP) items are developed. The descriptions and methodologies developed are applicable to the major systems. These systems include the central receiver, parabolic dish, parabolic trough, hemispherical bowl, and solar pond. The standard plant is defined in terms of four categories comprising (1) solar energy collection, (2) power conversion, (3) energy storage, and (4) balance of plant. Each of these categories is described in terms of the type and function of components and/or subsystems within the category. A detailed description is given for the BOP category. BOP contains a number of nondevelopmental items that are common to all solar thermal systems. A standard methodology for determining the costs of these nondevelopmental BOP items is given. The methodology is presented in the form of cost equations involving cost factors such as unit costs. A set of baseline values for the normalized cost factors is also given.

Thermal storage requirements for parabolic dish solar power plants

NASA Technical Reports Server (NTRS)

Wen, L.; Steele, H.

1980-01-01

The cost effectiveness of a high temperature thermal storage system is investigated for a representative parabolic dish solar power plant. The plant supplies electrical power in accordance with a specific, seasonally varying demand profile. The solar power received by the plant is supplemented by power from fuel combustion. The cost of electricity generated by the solar power plant is calculated, using the cost of mass-producible subsystems (specifically, parabolic dishes, receivers, and power conversion units) now being designed for this type of solar plant. The trade-off between fuel and thermal storage is derived in terms of storage effectiveness, the cost of storage devices, and the cost of fuel. Thermal storage requirements, such as storage capacity, storage effectiveness, and storage cost are established based on the cost of fuel and the overall objective of minimizing the cost of the electricity produced by the system. As the cost of fuel increases at a rate faster than general inflation, thermal storage systems in the $40 to $70/kWthr range could become cost effective in the near future.

Thermo-electronic solar power conversion with a parabolic concentrator

NASA Astrophysics Data System (ADS)

Olukunle, Olawole C.; De, Dilip K.

2016-02-01

We consider the energy dynamics of the power generation from the sun when the solar energy is concentrated on to the emitter of a thermo-electronic converter with the help of a parabolic mirror. We use the modified Richardson-Dushman equation. The emitter cross section is assumed to be exactly equal to the focused area at a height h from the base of the mirror to prevent loss of efficiency. We report the variation of output power with solar insolation, height h, reflectivity of the mirror, and anode temperature, initially assuming that there is no space charge effect. Our methodology allows us to predict the temperature at which the anode must be cooled in order to prevent loss of efficiency of power conversion. Novel ways of tackling the space charge problem have been discussed. The space charge effect is modeled through the introduction of a parameter f (0 < f < 1) in the thermos-electron emission equation. We find that the efficiency of the power conversion depends on solar insolation, height h, apart from radii R of the concentrator aperture and emitter, and the collector material properties. We have also considered solar thermos electronic power conversion by using single atom-layer graphene as an emitter.

Microgravity fluid management requirements of advanced solar dynamic power systems

NASA Technical Reports Server (NTRS)

Migra, Robert P.

1987-01-01

The advanced solar dynamic system (ASDS) program is aimed at developing the technology for highly efficient, lightweight space power systems. The approach is to evaluate Stirling, Brayton and liquid metal Rankine power conversion systems (PCS) over the temperature range of 1025 to 1400K, identify the critical technologies and develop these technologies. Microgravity fluid management technology is required in several areas of this program, namely, thermal energy storage (TES), heat pipe applications and liquid metal, two phase flow Rankine systems. Utilization of the heat of fusion of phase change materials offers potential for smaller, lighter TES systems. The candidate TES materials exhibit large volume change with the phase change. The heat pipe is an energy dense heat transfer device. A high temperature application may transfer heat from the solar receiver to the PCS working fluid and/or TES. A low temperature application may transfer waste heat from the PCS to the radiator. The liquid metal Rankine PCS requires management of the boiling/condensing process typical of two phase flow systems.

The application of simulation modeling to the cost and performance ranking of solar thermal power plants

NASA Technical Reports Server (NTRS)

Rosenberg, L. S.; Revere, W. R.; Selcuk, M. K.

1981-01-01

A computer simulation code was employed to evaluate several generic types of solar power systems (up to 10 MWe). Details of the simulation methodology, and the solar plant concepts are given along with cost and performance results. The Solar Energy Simulation computer code (SESII) was used, which optimizes the size of the collector field and energy storage subsystem for given engine-generator and energy-transport characteristics. Nine plant types were examined which employed combinations of different technology options, such as: distributed or central receivers with one- or two-axis tracking or no tracking; point- or line-focusing concentrator; central or distributed power conversion; Rankin, Brayton, or Stirling thermodynamic cycles; and thermal or electrical storage. Optimal cost curves were plotted as a function of levelized busbar energy cost and annualized plant capacity. Point-focusing distributed receiver systems were found to be most efficient (17-26 percent).

A search for space energy alternatives

NASA Technical Reports Server (NTRS)

Gilbreath, W. P.; Billman, K. W.

1978-01-01

This paper takes a look at a number of schemes for converting radiant energy in space to useful energy for man. These schemes are possible alternatives to the currently most studied solar power satellite concept. Possible primary collection and conversion devices discussed include the space particle flux devices, solar windmills, photovoltaic devices, photochemical cells, photoemissive converters, heat engines, dielectric energy conversion, electrostatic generators, plasma solar collectors, and thermionic schemes. Transmission devices reviewed include lasers and masers.

Efficient and Stable Photovoltaic Characteristics of Quasi-Solid State DSSC using Polymer Gel Electrolyte Based on Ionic Liquid in Organosiloxane Polymer Gels

NASA Astrophysics Data System (ADS)

Pujiarti, H.; Arsyad, W. S.; Shobih; Muliani, L.; Hidayat, R.

2018-04-01

Dye-Sensitized Solar Cell (DSSC) is still one of the promising solar cell types among the third generation of solar cells because of easiness of fabrication and variety of available materials. In this type of solar cell, the electrolyte is one of the important components for regenerating excited dyes and transporting electric charge carriers to the counter electrode. Indeed, the power conversion efficiency of DSSC can be then significantly affected by the chemical and physical properties of the electrolyte. The simplest electrolyte system of an I-/I3 - redox couple in an organic solvent, however, has some drawbacks due to corrosive properties, volatile and leakage problem. Use of solid phase or gel phase electrolyte may overcome those problems, but it is often considered to suppress the efficiency due to low ion diffusion. Here, we report the photovoltaic characteristics of DSSC using polymer gel electrolyte (PGE), which is composed of ionic liquid and an organosiloxane polymer gel. The better cell performance with power conversion efficiency of about 6% has been obtained by optimizing the mesoporous size of the TiO2 layer and the PGE viscosity.

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

PubMed Central

Hao, Yan; Yang, Wenxing; Zhang, Lei; Jiang, Roger; Mijangos, Edgar; Saygili, Yasemin; Hammarström, Leif; Hagfeldt, Anders; Boschloo, Gerrit

2016-01-01

Photoelectrochemical approach to solar energy conversion demands a kinetic optimization of various light-induced electron transfer processes. Of great importance are the redox mediator systems accomplishing the electron transfer processes at the semiconductor/electrolyte interface, therefore affecting profoundly the performance of various photoelectrochemical cells. Here, we develop a strategy—by addition of a small organic electron donor, tris(4-methoxyphenyl)amine, into state-of-art cobalt tris(bipyridine) redox electrolyte—to significantly improve the efficiency of dye-sensitized solar cells. The developed solar cells exhibit efficiency of 11.7 and 10.5%, at 0.46 and one-sun illumination, respectively, corresponding to a 26% efficiency improvement compared with the standard electrolyte. Preliminary stability tests showed the solar cell retained 90% of its initial efficiency after 250 h continuous one-sun light soaking. Detailed mechanistic studies reveal the crucial role of the electron transfer cascade processes within the new redox system. PMID:28000672

Solar cooling - comparative study between thermal and electrical use in industrial buildings

NASA Astrophysics Data System (ADS)

Badea, N.; Badea, G. V.; Epureanu, A.; Frumuşanu, G.

2016-08-01

The increase in the share of renewable energy sources together with the emphasis on the need for energy security bring to a spotlight the field of trigeneration autonomous microsystems, as a solution to cover the energy consumptions, not only for isolated industrial buildings, but also for industrial buildings located in urban areas. The use of solar energy for cooling has been taken into account to offer a cooling comfort in the building. Cooling and air- conditioned production are current applications promoting the use of solar energy technologies. Solar cooling systems can be classified, depending on the used energy, in electrical systems using mechanical compression chillers and systems using thermal compression by absorption or adsorption. This comparative study presents the main strengths and weaknesses of solar cooling obtained: i) through the transformation of heat resulted from thermal solar panels combined with adsorption chillers, and ii) through the multiple conversion of electricity - photovoltaic panels - battery - inverter - combined with mechanical compression chillers. Both solutions are analyzed from the standpoints of energy efficiency, dynamic performances (demand response), and costs sizes. At the end of the paper, experimental results obtained in the climatic condition of Galafi city, Romania, are presented.

Effective Charge Carrier Utilization in Photocatalytic Conversions.

PubMed

Zhang, Peng; Wang, Tuo; Chang, Xiaoxia; Gong, Jinlong

2016-05-17

Continuous efforts have been devoted to searching for sustainable energy resources to alleviate the upcoming energy crises. Among various types of new energy resources, solar energy has been considered as one of the most promising choices, since it is clean, sustainable, and safe. Moreover, solar energy is the most abundant renewable energy, with a total power of 173 000 terawatts striking Earth continuously. Conversion of solar energy into chemical energy, which could potentially provide continuous and flexible energy supplies, has been investigated extensively. However, the conversion efficiency is still relatively low since complicated physical, electrical, and chemical processes are involved. Therefore, carefully designed photocatalysts with a wide absorption range of solar illumination, a high conductivity for charge carriers, a small number of recombination centers, and fast surface reaction kinetics are required to achieve a high activity. This Account describes our recent efforts to enhance the utilization of charge carriers for semiconductor photocatalysts toward efficient solar-to-chemical energy conversion. During photocatalytic reactions, photogenerated electrons and holes are involved in complex processes to convert solar energy into chemical energy. The initial step is the generation of charge carriers in semiconductor photocatalysts, which could be enhanced by extending the light absorption range. Integration of plasmonic materials and introduction of self-dopants have been proved to be effective methods to improve the light absorption ability of photocatalysts to produce larger amounts of photogenerated charge carriers. Subsequently, the photogenerated electrons and holes migrate to the surface. Therefore, acceleration of the transport process can result in enhanced solar energy conversion efficiency. Different strategies such as morphology control and conductivity improvement have been demonstrated to achieve this goal. Fine-tuning of the morphology of nanostructured photocatalysts can reduce the migration distance of charge carriers. Improving the conductivity of photocatalysts by using graphitic materials can also improve the transport of charge carriers. Upon charge carrier migration, electrons and holes also tend to recombine. The suppression of recombination can be achieved by constructing heterojunctions that enhance charge separation in the photocatalysts. Surface states acting as recombination centers should also be removed to improve the photocatalytic efficiency. Moreover, surface reactions, which are the core chemical processes during the solar energy conversion, can be enhanced by applying cocatalysts as well as suppressing side reactions. All of these strategies have been proved to be essential for enhancing the activities of semiconductor photocatalysts. It is hoped that delicate manipulation of photogenerated charge carriers in semiconductor photocatalysts will hold the key to effective solar-to-chemical energy conversion.

Improved Nuclear Reactor and Shield Mass Model for Space Applications

NASA Technical Reports Server (NTRS)

Robb, Kevin

2004-01-01

New technologies are being developed to explore the distant reaches of the solar system. Beyond Mars, solar energy is inadequate to power advanced scientific instruments. One technology that can meet the energy requirements is the space nuclear reactor. The nuclear reactor is used as a heat source for which a heat-to-electricity conversion system is needed. Examples of such conversion systems are the Brayton, Rankine, and Stirling cycles. Since launch cost is proportional to the amount of mass to lift, mass is always a concern in designing spacecraft. Estimations of system masses are an important part in determining the feasibility of a design. I worked under Michael Barrett in the Thermal Energy Conversion Branch of the Power & Electric Propulsion Division. An in-house Closed Cycle Engine Program (CCEP) is used for the design and performance analysis of closed-Brayton-cycle energy conversion systems for space applications. This program also calculates the system mass including the heat source. CCEP uses the subroutine RSMASS, which has been updated to RSMASS-D, to estimate the mass of the reactor. RSMASS was developed in 1986 at Sandia National Laboratories to quickly estimate the mass of multi-megawatt nuclear reactors for space applications. In response to an emphasis for lower power reactors, RSMASS-D was developed in 1997 and is based off of the SP-100 liquid metal cooled reactor. The subroutine calculates the mass of reactor components such as the safety systems, instrumentation and control, radiation shield, structure, reflector, and core. The major improvements in RSMASS-D are that it uses higher fidelity calculations, is easier to use, and automatically optimizes the systems mass. RSMASS-D is accurate within 15% of actual data while RSMASS is only accurate within 50%. My goal this summer was to learn FORTRAN 77 programming language and update the CCEP program with the RSMASS-D model.

Suppression of Tla1 gene expression for improved solar conversion efficiency and photosynthetic productivity in plants and algae

DOEpatents

Melis, Anastasios; Mitra, Mautusi

2010-06-29

The invention provides method and compositions to minimize the chlorophyll antenna size of photosynthesis by decreasing TLA1 gene expression, thereby improving solar conversion efficiencies and photosynthetic productivity in plants, e.g., green microalgae, under bright sunlight conditions.

Analysis of S-band solid-state transmitters for the solar power satellite

NASA Technical Reports Server (NTRS)

Belohoubek, E. F.; Ettenberg, M.; Huang, H. C.; Nowogrodzki, M.; Sechi, F. N.

1979-01-01

The possibility of replacing the Reference System antenna in which thermionic devices are used for the dc-to-microwave conversion, with solid-state elements was explored. System, device, and antenna module tradeoff investigations strongly point toward the desirability of changing the transmitter concept to a distributed array of relatively low power elements, deriving their dc power directly from the solar cell array and whose microwave power outputs are combined in space. The approach eliminates the thermal, weight, and dc-voltage distribution problems of a system in which high power tubes are simply replaced with clusters of solid state amplifiers. The proposed approach retains the important advantages of a solid state system: greatly enhanced reliability and graceful degradation of the system.

Test results of an organic Rankine-cycle power module for a small community solar thermal power experiment

NASA Technical Reports Server (NTRS)

Clark, T. B.

1985-01-01

The organic Rankine-cycle (ORC) power conversion assembly was tested. Qualification testing of the electrical transport subsystem was also completed. Test objectives were to verify compatibility of all system elements with emphasis on control of the power conversion assembly, to evaluate the performance and efficiency of the components, and to validate operating procedures. After 34 hours of power generation under a wide range of conditions, the net module efficiency exceeded 18% after accounting for all parasitic losses.

Electron Transport Modeling of Molecular Nanoscale Bridges Used in Energy Conversion Schemes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunietz, Barry D

2016-08-09

The goal of the research program is to reliably describe electron transport and transfer processes at the molecular level. Such insight is essential for improving molecular applications of solar and thermal energy conversion. We develop electronic structure models to study (1) photoinduced electron transfer and transport processes in organic semiconducting materials, and (2) charge and heat transport through molecular bridges. We seek fundamental understanding of key processes, which lead to design new experiments and ultimately to achieve systems with improved properties.

Microalgal hydrogen production: prospects of an essential technology for a clean and sustainable energy economy.

PubMed

Bayro-Kaiser, Vinzenz; Nelson, Nathan

2017-09-01

Modern energy production is required to undergo a dramatic transformation. It will have to replace fossil fuel use by a sustainable and clean energy economy while meeting the growing world energy needs. This review analyzes the current energy sector, available energy sources, and energy conversion technologies. Solar energy is the only energy source with the potential to fully replace fossil fuels, and hydrogen is a crucial energy carrier for ensuring energy availability across the globe. The importance of photosynthetic hydrogen production for a solar-powered hydrogen economy is highlighted and the development and potential of this technology are discussed. Much successful research for improved photosynthetic hydrogen production under laboratory conditions has been reported, and attempts are underway to develop upscale systems. We suggest that a process of integrating these achievements into one system to strive for efficient sustainable energy conversion is already justified. Pursuing this goal may lead to a mature technology for industrial deployment.

Preparation of ultra-thin and high-quality WO{sub 3} compact layers and comparision of WO{sub 3} and TiO{sub 2} compact layer thickness in planar perovskite solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jincheng; Shi, Chengwu, E-mail: shicw506@foxmail.com; Chen, Junjun

2016-06-15

In this paper, the ultra-thin and high-quality WO{sub 3} compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO{sub 3} and TiO{sub 2} compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO{sub 2} compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO{sub 3} and TiO{sub 2} compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO{submore » 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. - Graphical abstract: The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. Display Omitted - Highlights: • Preparation of ultra-thin and high-quality WO{sub 3} compact layers. • Perovskite solar cell with 15 nm-thick WO{sub 3} compact layer achieved PCE of 10.14%. • Perovskite solar cell with 60 nm-thick TiO{sub 2} compact layer achieved PCE of 12.64%.« less

Performance of conversion efficiency of a crystalline silicon solar cell with base doping density

NASA Astrophysics Data System (ADS)

Sahin, Gokhan; Kerimli, Genber; Barro, Fabe Idrissa; Sane, Moustapha; Alma, Mehmet Hakkı

In this study, we investigate theoretically the electrical parameters of a crystalline silicon solar cell in steady state. Based on a one-dimensional modeling of the cell, the short circuit current density, the open circuit voltage, the shunt and series resistances and the conversion efficiency are calculated, taking into account the base doping density. Either the I-V characteristic, series resistance, shunt resistance and conversion efficiency are determined and studied versus base doping density. The effects applied of base doping density on these parameters have been studied. The aim of this work is to show how short circuit current density, open circuit voltage and parasitic resistances are related to the base doping density and to exhibit the role played by those parasitic resistances on the conversion efficiency of the crystalline silicon solar.

The spectroscopic characterization of newly developed emissive materials and the effects of environment on their photophysical properties

NASA Astrophysics Data System (ADS)

McNamara, Louis Edward, III

The development of new materials capable of efficient charge transfer and energy storage has become increasingly important in many areas of modern chemical research. This is especially true for the development of emissive optoelectronic devices and in the field of solar to electric energy conversion. The characterization of the photophysical properties of new molecular systems for these applications has become critical in the design and development of these materials. Many molecular building blocks have been developed and understanding the properties of these molecules at a fundamental level is essential for their successful implementation and future engineering. This dissertation focuses on the characterization of some of these newly-developed molecular systems. The spectroscopic studies focus on the characterization of newly-developed molecules based on perylene and indolizine derivatives for solar to electric energy conversion, thienopyrazine derivatives for near infrared (NIR) emissive applications, an SCS pincer complex for blue emissive materials and a fluorescent probe for medical applications. The effects of noncovalent interactions are also investigated on these systems and a benchmark biological molecule trimethylamine N-oxide (TMAO).

Organic electronics on fibers for energy conversion applications

NASA Astrophysics Data System (ADS)

O'Connor, Brendan T.

Currently, there is great demand for pollution-free and renewable sources of electricity. Solar cells are particularly attractive from the standpoint of sunlight abundance. However, truly widespread adoption of solar cells is impeded by the high cost and poor scalability of existing technologies. For example, while 53,000 mi2 of 10% efficient solar cell modules would be required to supply the current U.S. energy demand, only about 50 mi2 have been installed worldwide. Organic semiconductors potentially offer a route to realizing low-cost solar cell modules, but currently suffer from low conversion efficiency. For organic-based solar cells to become commercially viable, further research is required to improve device performance, develop scalable manufacturing methods, and reduce installation costs via, for example, novel device form factors. This thesis makes several contributions to the field of organic solar cells, including the replacement of costly and brittle indium tin oxide (ITO) electrodes by inexpensive and malleable, thin metal films, and the application of external dielectric coatings to improve power conversion efficiency. Furthermore, we show that devices with non-planar geometries (e.g. organic solar cells deposited onto long fibers) can have higher efficiencies than conventional planar devices. Building on these results, we demonstrate novel fiber-based organic light emitting devices (OLEDs) that offer substantially improved color quality and manufacturability as a next-generation solid-state lighting technology. An intriguing possibility afforded by the fiber-based device architectures is the ability to integrate energy conversion and lighting functionalities with textiles, a mature, commodity-scale technology.

Thermodynamic power stations at low temperatures

NASA Astrophysics Data System (ADS)

Malherbe, J.; Ployart, R.; Alleau, T.; Bandelier, P.; Lauro, F.

The development of low-temperature thermodynamic power stations using solar energy is considered, with special attention given to the choice of the thermodynamic cycle (Rankine), working fluids (frigorific halogen compounds), and heat exchangers. Thermomechanical conversion machines, such as ac motors and rotating volumetric motors are discussed. A system is recommended for the use of solar energy for irrigation and pumping in remote areas. Other applications include the production of cold of fresh water from brackish waters, and energy recovery from hot springs.

Comparing solar energy alternatives

NASA Astrophysics Data System (ADS)

White, J. R.

1984-03-01

This paper outlines a computational procedure for comparing the merits of alternative processes to convert solar radiation to heat, electrical power, or chemical energy. The procedure uses the ratio of equipment investment to useful work as an index. Comparisons with conversion counterparts based on conventional fuels are also facilitated by examining this index. The procedure is illustrated by comparisons of (1) photovoltaic converters of differing efficiencies; (2) photovoltaic converters with and without focusing concentrators; (3) photovoltaic conversion plus electrolysis vs photocatalysis for the production of hydrogen; (4) photovoltaic conversion plus plasma arcs vs photocatalysis for nitrogen fixation. Estimates for conventionally-fuelled processes are included for comparison. The reasons why solar-based concepts fare poorly in such comparisons are traced to the low energy density of solar radiation and its low stream time factor resulting from the limited number of daylight hours available and clouds obscuring the sun.

Systems Analysis of GPS Electrical Power System Redesign

DTIC Science & Technology

1995-12-01

Table 8 - System Efficiencies & Multipliers for Solar Direct Model (12:102; 15:864) Component Efficiency AMTEC 0.180 Receiver and Thermal Energy Storage...and low temperatures of the working fluid. Extreme high and low temperatures provide a greater efficiency , but require extensive thermal control and...direct conversion category. The Alkali Metal Thermal -to-Electric Converter ( AMTEC ) shows mass and cost savings due to efficiencies significantly higher

Reformulation of the relativistic conversion between coordinate time and atomic time

NASA Technical Reports Server (NTRS)

Thomas, J. B.

1975-01-01

The relativistic conversion between coordinate time and atomic time is reformulated to allow simpler time calculations relating analysis in solar system barycentric coordinates (using coordinate time) with earth-fixed observations (measuring 'earth-bound' proper time or atomic time). After an interpretation in terms of relatively well-known concepts, this simplified formulation, which has a rate accuracy of about 10 to the minus 15th, is used to explain the conventions required in the synchronization of a worldwide clock network and to analyze two synchronization techniques - portable clocks and radio interferometry. Finally, pertinent experimental tests of relativity are briefly discussed in terms of the reformulated time conversion.

Space Solar Power: Satellite Concepts

NASA Technical Reports Server (NTRS)

Little, Frank E.

1999-01-01

Space Solar Power (SSP) applies broadly to the use of solar power for space related applications. The thrust of the NASA SSP initiative is to develop concepts and demonstrate technology for applying space solar power to NASA missions. Providing power from satellites in space via wireless transmission to a receiving station either on earth, another celestial body or a second satellite is one goal of the SSP initiative. The sandwich design is a satellite design in which the microwave transmitting array is the front face of a thin disk and the back of the disk is populated with solar cells, with the microwave electronics in between. The transmitter remains aimed at the earth in geostationary orbit while a system of mirrors directs sunlight to the photovoltaic cells, regardless of the satellite's orientation to the sun. The primary advantage of the sandwich design is it eliminates the need for a massive and complex electric power management and distribution system for the satellite. However, it requires a complex system for focusing sunlight onto the photovoltaic cells. In addition, positioning the photovoltaic array directly behind the transmitting array power conversion electronics will create a thermal management challenge. This project focused on developing designs and finding emerging technology to meet the challenges of solar tracking, a concentrating mirror system including materials and coatings, improved photovoltaic materials and thermal management.

Novel Integration of Perovskite Solar Cell and Supercapacitor Based on Carbon Electrode for Hybridizing Energy Conversion and Storage.

PubMed

Liu, Zhiyong; Zhong, Yan; Sun, Bo; Liu, Xingyue; Han, Jinghui; Shi, Tielin; Tang, Zirong; Liao, Guanglan

2017-07-12

Power packs integrating both photovoltaic parts and energy storage parts have gained great scientific and technological attention due to the increasing demand for green energy and the tendency for miniaturization and multifunctionalization in electronics industry. In this study, we demonstrate novel integration of perovskite solar cell and solid-state supercapacitor for power packs. The perovskite solar cell is integrated with the supercapacitor based on common carbon electrodes to hybridize photoelectric conversion and energy storage. The power pack achieves a voltage of 0.84 V when the supercapacitor is charged by the perovskite solar cell under the AM 1.5G white light illumination with a 0.071 cm 2 active area, reaching an energy storage proportion of 76% and an overall conversion efficiency of 5.26%. When the supercapacitor is precharged at 1.0 V, an instant overall output efficiency of 22.9% can be achieved if the perovskite solar cell and supercapacitor are connected in series, exhibiting great potential in the applications of solar energy storage and flexible electronics such as portable and wearable devices.

Molecular approaches to solar energy conversion: the energetic cost of charge separation from molecular-excited states.

PubMed

Durrant, James R

2013-08-13

This review starts with a brief overview of the technological potential of molecular-based solar cell technologies. It then goes on to focus on the core scientific challenge associated with using molecular light-absorbing materials for solar energy conversion, namely the separation of short-lived, molecular-excited states into sufficiently long-lived, energetic, separated charges capable of generating an external photocurrent. Comparisons are made between different molecular-based solar cell technologies, with particular focus on the function of dye-sensitized photoelectrochemical solar cells as well as parallels with the function of photosynthetic reaction centres. The core theme of this review is that generating charge carriers with sufficient lifetime and a high quantum yield from molecular-excited states comes at a significant energetic cost-such that the energy stored in these charge-separated states is typically substantially less than the energy of the initially generated excited state. The role of this energetic loss in limiting the efficiency of solar energy conversion by such devices is emphasized, and strategies to minimize this energy loss are compared and contrasted.

PVMirror: A New Concept for Tandem Solar Cells and Hybrid Solar Converters

DOE PAGES

Yu, Zhengshan J.; Fisher, Kathryn C.; Wheelwright, Brian M.; ...

2015-08-25

As the solar electricity market has matured, energy conversion efficiency and storage have joined installed system cost as significant market drivers. In response, manufacturers of flatplate silicon photovoltaic (PV) cells have pushed cell efficiencies above 25%—nearing the 29.4% detailed-balance efficiency limit— and both solar thermal and battery storage technologies have been deployed at utility scale. This paper introduces a new tandem solar collector employing a “PVMirror” that has the potential to both increase energy conversion efficiency and provide thermal storage. A PVMirror is a concentrating mirror, spectrum splitter, and light-to-electricity converter all in one: It consists of a curved arrangementmore » of PV cells that absorb part of the solar spectrum and reflect the remainder to their shared focus, at which a second solar converter is placed. A strength of the design is that the solar converter at the focus can be of a radically different technology than the PV cells in the PVMirror; another is that the PVMirror converts a portion of the diffuse light to electricity in addition to the direct light. Here, we consider two case studies—a PV cell located at the focus of the PVMirror to form a four-terminal PV–PV tandem, and a thermal receiver located at the focus to form a PV–CSP (concentrating solar thermal power) tandem—and compare the outdoor energy outputs to those of competing technologies. PVMirrors can outperform (idealized) monolithic PV–PV tandems that are under concentration, and they can also generate nearly as much energy as silicon flat-plate PV while simultaneously providing the full energy storage benefit of CSP.« less

Refractive Secondary Concentrators for Solar Thermal Applications

NASA Technical Reports Server (NTRS)

Wong, Wayne A.; Macosko, Robert P.

1999-01-01

The NASA Glenn Research Center is developing technologies that utilize solar energy for various space applications including electrical power conversion, thermal propulsion, and furnaces. Common to all of these applications is the need for highly efficient, solar concentration systems. An effort is underway to develop the innovative single crystal refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. The refractive secondary offers very high throughput efficiencies (greater than 90%), and when used in combination with advanced primary concentrators, enables very high concentration ratios (10,0(X) to 1) and very high temperatures (greater than 2000 K). Presented is an overview of the refractive secondary concentrator development effort at the NASA Glenn Research Center, including optical design and analysis techniques, thermal modeling capabilities, crystal materials characterization testing, optical coatings evaluation, and component testing. Also presented is a discussion of potential future activity and technical issues yet to be resolved. Much of the work performed to date has been in support of the NASA Marshall Space Flight Center's Solar Thermal Propulsion Program. The many benefits of a refractive secondary concentrator that enable efficient, high temperature thermal propulsion system designs, apply equally well to other solar applications including furnaces and power generation systems such as solar dynamics, concentrated thermal photovoltaics, and thermionics.

Energy Transfer Kinetics in Photosynthesis as an Inspiration for Improving Organic Solar Cells.

PubMed

Nganou, Collins; Lackner, Gerhard; Teschome, Bezu; Deen, M Jamal; Adir, Noam; Pouhe, David; Lupascu, Doru C; Mkandawire, Martin

2017-06-07

Clues to designing highly efficient organic solar cells may lie in understanding the architecture of light-harvesting systems and exciton energy transfer (EET) processes in very efficient photosynthetic organisms. Here, we compare the kinetics of excitation energy tunnelling from the intact phycobilisome (PBS) light-harvesting antenna system to the reaction center in photosystem II in intact cells of the cyanobacterium Acaryochloris marina with the charge transfer after conversion of photons into photocurrent in vertically aligned carbon nanotube (va-CNT) organic solar cells with poly(3-hexyl)thiophene (P3HT) as the pigment. We find that the kinetics in electron hole creation following excitation at 600 nm in both PBS and va-CNT solar cells to be 450 and 500 fs, respectively. The EET process has a 3 and 14 ps pathway in the PBS, while in va-CNT solar cell devices, the charge trapping in the CNT takes 11 and 258 ps. We show that the main hindrance to efficiency of va-CNT organic solar cells is the slow migration of the charges after exciton formation.

Superlattice photonic crystal as broadband solar absorber for high temperature operation.

PubMed

Rinnerbauer, Veronika; Shen, Yichen; Joannopoulos, John D; Soljačić, Marin; Schäffler, Friedrich; Celanovic, Ivan

2014-12-15

A high performance solar absorber using a 2D tantalum superlattice photonic crystal (PhC) is proposed and its design is optimized for high-temperature energy conversion. In contrast to the simple lattice PhC, which is limited by diffraction in the short wavelength range, the superlattice PhC achieves solar absorption over broadband spectral range due to the contribution from two superposed lattices with different cavity radii. The superlattice PhC geometry is tailored to achieve maximum thermal transfer efficiency for a low concentration system of 250 suns at 1500 K reaching 85.0% solar absorptivity. In the high concentration case of 1000 suns, the superlattice PhC absorber achieves a solar absorptivity of 96.2% and a thermal transfer efficiency of 82.9% at 1500 K, amounting to an improvement of 10% and 5%, respectively, versus the simple square lattice PhC absorber. In addition, the performance of the superlattice PhC absorber is studied in a solar thermophotovoltaic system which is optimized to minimize absorber re-emission by reducing the absorber-to-emitter area ratio and using a highly reflective silver aperture.

Concept of the solar-pumped laser-photovoltaics combined system and its application to laser beam power feeding to electric vehicles

NASA Astrophysics Data System (ADS)

Motohiro, Tomoyoshi; Takeda, Yasuhiko; Ito, Hiroshi; Hasegawa, Kazuo; Ikesue, Akio; Ichikawa, Tadashi; Higuchi, Kazuo; Ichiki, Akihisa; Mizuno, Shintaro; Ito, Tadashi; Yamada, Noboru; Nath Luitel, Hom; Kajino, Tsutomu; Terazawa, Hidetaka; Takimoto, Satoshi; Watanabe, Kemmei

2017-08-01

We have developed a compact solar-pumped laser (µSPL) employing an off-axis parabolic mirror with an aperture of 76.2 mm diameter and an yttrium aluminum garnet (YAG) ceramic rod of φ1 mm × 10 mm doped with 1% Nd and 0.1% Cr as a laser medium. The laser oscillation wavelength of 1.06 µm, just below the optical absorption edge of Si cells, is suitable for photoelectric conversion with minimal thermal loss. The concept of laser beam power feeding to an electric vehicle equipped with a photovoltaic panel on the roof was proposed by Ueda in 2010, in which the electricity generated by solar panels over the road is utilized to drive a semiconductor laser located on each traffic signal along the road. By substituting this solar-electricity-driven semiconductor laser with a solar-pumped laser, the energy loss of over 50% in converting the solar electricity to a laser beam can be eliminated. The overall feasibility of this system in an urban area such as Tokyo was investigated.

Real-time and accelerated outdoor endurance testing of solar cells

NASA Technical Reports Server (NTRS)

Forestieri, A. F.; Anagnostou, E.

1977-01-01

Real-time and accelerated outdoor endurance testing was performed on a variety of samples of interest to the National Photovoltaic Conversion Program. The real-time tests were performed at seven different sites and the accelerated tests were performed at one of those sites in the southwestern United States. The purpose of the tests were to help evaluate the lifetime of photovoltaic systems. Three types of samples were tested; transmission samples of possible cover materials, sub-modules constructed using these materials attached to solar cells, and solar cell modules produced by the manufacturers for the ERDA program. Results indicate that suitable cover materials are glass, FEP-A and PFA. Dirt accumulation and cleanability are important factors in the selection of solar cell module covers and encapsulants.

Down-conversion emission of Ce3+-Tb3+ co-doped CaF2 hollow spheres and application for solar cells

NASA Astrophysics Data System (ADS)

Cheng, Yufei; Wang, Yongbo; Teng, Feng; Dong, Hua; Chen, Lida; Mu, Jianglong; Sun, Qian; Fan, Jun; Hu, Xiaoyun; Miao, Hui

2018-03-01

Luminescent downconversion is a promising way to harvest ultraviolet sunlight and transform it into visible light that can be absorbed by solar cells, and has potential to improve their photoelectric conversion efficiency. In this work, the uniform hollow spheres and well dispersed CaF2 phosphors doped with rare-earth Ce3+ and Tb3+ ions are prepared by a one-step hydrothermal synthesis method. Benefiting from the stronger ability of absorption and emission and excellent transparency property, we demonstrate that the application of the doped nanocrystals can efficiently improve visible light transmittance. The chosen phosphors are added in the SiO2 sols so as to get the anti-reflection coatings with wavelength conversion bi-functional films, promoting the optical transmittance in the visible and near-infrared range which matches with the range of the band gap energy of silicon semiconductor. Optimized photoelectric conversion efficiency of 14.35% and the external quantum efficiency over 70% from 450 to 950 nm are obtained through the silicon solar cells with 0.10 g phosphors coating. Compared with the pure glass devices, the photoelectric conversion efficiency is enhanced by 0.69%. This work indicates that fluorescent downconversion not only can serve as proof of principles for improving photoelectric conversion efficiency of solar cells but also may be helpful to practical application in the future.

Thermodynamic limits to the efficiency of solar energy conversion by quantum devices

NASA Technical Reports Server (NTRS)

Buoncristiani, A. M.; Byvik, C. E.; Smith, B. T.

1981-01-01

The second law of thermodynamics imposes a strict limitation to the energy converted from direct solar radiation to useful work by a quantum device. This limitation requires that the amount of energy converted to useful work (energy in any form other than heat) can be no greater than the change in free energy of the radiation fields. Futhermore, in any real energy conversion device, not all of this available free energy in the radiation field can be converted to work because of basic limitations inherent in the device itself. A thermodynamic analysis of solar energy conversion by a completely general prototypical quantum device is presented. This device is completely described by two parameters, its operating temperature T sub R and the energy threshold of its absorption spectrum. An expression for the maximum thermodynamic efficiency of a quantum solar converter was derived in terms of these two parameters and the incident radiation spectrum. Efficiency curves for assumed solar spectral irradiance corresponding to air mass zero and air mass 1.5 are presented.

Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging

PubMed Central

Liao, Shichao; Zong, Xu; Seger, Brian; Pedersen, Thomas; Yao, Tingting; Ding, Chunmei; Shi, Jingying; Chen, Jian; Li, Can

2016-01-01

Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge injection, our device shows an optimal solar-to-chemical conversion efficiency of ∼5.9% and an overall photon–chemical–electricity energy conversion efficiency of ∼3.2%, which, to our knowledge, outperforms previously reported SRFCs. The proposed SRFC can be self-photocharged to 0.8 V and delivers a discharge capacity of 730 mAh l−1. Our work may guide future designs for highly efficient solar rechargeable devices. PMID:27142885

New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells

PubMed Central

Wang, DongLin; Su, Gang

2014-01-01

Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350 nm–800 nm, the conversion efficiency of solar cells can be further enhanced. PMID:25418477

Enhancing the Efficiency of Bulk Heterojunction Solar Cells via Templated Self Assembly

NASA Astrophysics Data System (ADS)

Pan, Cheng; Li, Hongfei; Akgun, Bulent; Satijia, Sushil; Gersappe, Dilip; Zhu, Yimei; Rafailovich, Miriam

2013-03-01

Bulk Heterojunction (BHJ) polymer solar cells are an area of intense interest due to their flexibility and relatively low cost. The mixture of polythiophene derivatives (donor) and fullerenes (acceptor) is spin coated on substrate as the active layer, and are phase-separated into interconnected domains. However, due to the disordered inner structures in the active layer, donor or acceptor domains isolated from electrodes and long path conduction, the power conversion efficiency (PCE) of BHJ solar cell is low. Therefore, morphology control in bulk heterojunction (BHJ) solar cell is considered to be critical for the power conversion efficiency (PCE). Here, we present a novel approach that introduces non-photoactive polymer that organizes the poly(3-hexylthiophene) (P3HT) into columnar phases decorated by [6,6]-phenyl C61-butyric acid methyl ester (PCBM) at the interface. This structure represents a realization of an idealized morphology of an organic solar cell, in which, both exiciton dissociation and the carrier transport are optimized leading to increased power conversion efficiency.

Recent advances in visible-light-responsive photocatalysts for hydrogen production and solar energy conversion--from semiconducting TiO2 to MOF/PCP photocatalysts.

PubMed

Horiuchi, Yu; Toyao, Takashi; Takeuchi, Masato; Matsuoka, Masaya; Anpo, Masakazu

2013-08-28

The present perspective describes recent advances in visible-light-responsive photocatalysts intended to develop novel and efficient solar energy conversion technologies, including water splitting and photofuel cells. Water splitting is recognized as one of the most promising techniques to convert solar energy as a clean and abundant energy resource into chemical energy in the form of hydrogen. In recent years, increasing concern is directed to not only the development of new photocatalytic materials but also the importance of technologies to produce hydrogen and oxygen separately. Photofuel cells can convert solar energy into electrical energy by decomposing bio-related compounds and livestock waste as fuels. The advances of photocatalysts enabling these solar energy conversion technologies have been going on since the discovery of semiconducting titanium dioxide materials and have extended to organic-inorganic hybrid materials, such as metal-organic frameworks and porous coordination polymers (MOF/PCP).

Modeling and simulation of InGaN/GaN quantum dots solar cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aissat, A., E-mail: sakre23@yahoo.fr; LASICOMLaboratory, Faculty of Sciences, University of Blida 1; Benyettou, F.

2016-07-25

Currently, quantum dots have attracted attention in the field of optoelectronics, and are used to overcome the limits of a conventional solar cell. Here, an In{sub 0.25}Ga{sub 0.75}N/GaN Quantum Dots Solar Cell has been modeled and simulated using Silvaco Atlas. Our results show that the short circuit current increases with the insertion of the InGaN quantum dots inside the intrinsic region of a GaN pin solar cell. In contrary, the open circuit voltage decreases. A relative optimization of the conversion efficiency of 54.77% was achieved comparing a 5-layers In{sub 0.25}Ga{sub 0.75}N/GaN quantum dots with pin solar cell. The conversion efficiencymore » begins to decline beyond 5-layers quantum dots introduced. Indium composition of 10 % improves relatively the efficiency about 42.58% and a temperature of 285 K gives better conversion efficiency of 13.14%.« less