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A combined photovoltaic/thermal collector has been built and is now being tested. Initial tests have concentrated on evaluating the thermal efficiency of the collector before and after the silicon cells are mounted. With likely improvements in bonding between cells and receiver and in the absorptivity of the cells, thermal efficiencies greater than 50% can be expected for the combined receiver operating at 100 C.
Various techniques to increase the open circuit voltage are being explored. It had been previously observed that cells made on CdS deposited from a single source gave a consistently higher V sub oc. Further tests have now shown that this effect may in fact relate to differences in source and substrate temperatures. The resulting differences in CdS structure and crystallinity are being documented. Deposits of mixed CdS and ZnS are being produced and will be initially made into cells using the conventional barriering technique. Analysis of I-V characteristics at temperatures between 25 and 110 C is being perfected to provide nondestructive analysis of the Cu2S. Changes due to vacuum heat treatments and exposure to oxygen are also being monitored by the same technique. Detailed spectral response measurements are being made.
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(Previously announced in STAR as N82-29354)
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.
Solar-thermionic energy conversion system design using mathematical simulation relating characteristics of solar collector and cavity absorber
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.
Radiation resistant silicon cells for solar energy conversion
Recent parametric studies of alternate SPS design concepts have shown that the concept appears technically feasible. The parametric studies were based on the use of advanced technology silicon solar cells for solar energy conversion. Solar array blanket unit masses of 0.31 to 0.46 kg/sq m were investigated. Conversion efficiencies of 15 to 17 percent air mass zero (AMO at 247 K) with a concentration ratio of two were considered. The systems were sized for a ground power output of 10 GW. To the level of detail studied, no design or operational problems were encountered that did not appear amenable to solution; however, the economic viability of the SPS concepts studied is obviously dependent upon a combination of technology advancement and/or the costs of competitive sources.
Thermoelectric flat plates, thermionic systems, and uncooled silicon solar cells for solar direct-energy conversion
Mathematical model simulation of solar-thermal energy conversion systems and collectors
Results obtained from studies of a (1) solar concentrator, (2) solar energy receiver - thermionic converter system, and (3) solar thermionic topping system are described. Peripheral subsystems, which are required for any solar energy conversion system, are also discussed.
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.
Since the energy input to solar thermal conversion systems is both time variant and probabilistic, it is unlikely that simple steady-state methods for estimating lifetime performance will provide satisfactory results. The work described here uses dynamic modeling to begin identifying what must be known about input radiation and system dynamic characteristics to estimate performance reliably. Daily operation of two conceptual solar energy systems was simulated under varying operating strategies with time-dependent radiation intensity ranging from smooth input of several magnitudes to input of constant total energy whose intensity oscillated with periods from 1/4 hour to 6 hours. Integrated daily system output and efficiency were functions of both level and dynamic characteristics of insolation. Sensitivity of output to changes in total input was greater than one.
500-electrical-watt solar energy thermionic conversion system for a mars spacecraft
Analysis, design, and development of flat plate solar thermoelectric energy conversion panel
Analysis, design, and development of flat plate solar thermoelectric energy conversion panel
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.