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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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This paper presents an overview of photovoltaic systems applications since the initiation of the U.S. National Photovoltaic Program in 1975. Experiences with these applications are summarized and some conclusions are drawn. Implications for future research, technology development and application experiments are drawn from the experiences to date.
The historical progression of efficiency improvements, cost reductions, and performance improvements in modules and photovoltaic systems are described. The potential for future improvements in photovoltaic device efficiencies and cost reductions continues as device concepts, designs, processes, and automated production capabilities mature. Additional step-function improvements can be made as today's simpler devices are replaced by more sophisticated devices.
This handbook will permit the user to design a low-cost structure for a variety of photovoltaic system applications under 10 kW. Any presently commercially available photovoltaic modules may be used. Design alternatives are provided for different generic structure types, structural materials, and electric interfaces. The use of a hand-held calculator is sufficient to perform the necessary calculations for the array designs.
Report presents results of field tests of solar-cell-powered refrigerator/freezers for vaccines. Covers following topics: explanation of project; descriptions of refrigerator/freezer systems; account of installation experiences; performance data for 22 systems for which field-test data reported; summary of operational reliability; comments of users of some systems tested; and recommendations for design and future use. Photovoltaic systems store vaccines in remote regions where powerlines unavailable.
The development of a solar dynamic electric power generation system as part of the Space Station Freedom Program is documented. The solar dynamic power system includes a solar concentrator, which collects sunlight; a receiver, which accepts and stores the concentrated solar energy and transfers this energy to a gas; a Brayton turbine, alternator, and compressor unit, which generates electric power; and a radiator, which rejects waste heat. Solar dynamic systems have greater efficiency and lower maintenance costs than photovoltaic systems and are being considered for future growth of Space Station Freedom. Solar dynamic development managed by the NASA Lewis Research Center from 1986 to Feb. 1991 is covered. It summarizes technology and hardware development, describes 'lessons learned', and, through an extensive bibliography, serves as a source list of documents that provide details of the design and analytic results achieved. It was prepared by the staff of the Solar Dynamic Power System Branch at the NASA Lewis Research Center in Cleveland, Ohio. The report includes results from the prime contractor as well as from in-house efforts, university grants, and other contracts. Also included are the writers' opinions on the best way to proceed technically and programmatically with solar dynamic efforts in the future, on the basis of their experiences in this program.
The Federal Photovoltaics Program is reviewed with reference to price goals, program organization, technical developments, and various applications. The immediate goals of the program are: (1) to develop the Federal market by encouraging Government agencies to incorporate photovoltaic systems, and (2) to provide marketing support to commercial solar cell and system manufacturers whose growth is crucial to the ultimate success of the photovoltaic program. The program will initially provide for procurement of the smaller remote types of systems and will be broadened to include residential and intermediate load systems.
As original evaluation of a space solar energy source coupled with Alkali Metal Thermoelectric Conversion (AMTEC) is presented here. This study indicates that an AMTEC system would have 30 percent of the mass of a photovoltaic system and 70 percent of the mass of a Stirling cycle system at the 35-kWe level of power generation modules typical of the baseline for the U.S. Space Station. The operating temperatures and sodium heat pipe components for solar receiver/TES hardware (currently being developed by NASA) integrate well with AMTEC power conversion. AMTEC is therefore an attractive alternative specifically for space solar power generation.
An analysis of the solar power satellite system is presented. Performance, cost, and operational characteristics are assessed. The photovoltaic system is described and investigated. Alternative construction concepts are discussed. The structural bay configuration is presented along with the antenna structure options.
The current status of NASA R&D programs for space power systems is reviewed and illustrated with drawings and diagrams. Topics addressed include photovoltaic systems, energy-storage technology, solar-dynamic systems, the SP-100 Advanced Technology Program, Stirling engine technology, and thermal management. Consideration is given to power management and distribution, power-system autonomy, high-Tc superconductor technology, space power materials, and environmental interactions.
Many studies have been conducted to develop a thermal control system that can operate under the extreme thermal environments found on the lunar surface. While these proposed heat rejection systems use different methods to reject heat, each system contains a similar component, a thermal radiator system. These studies have always considered pristine thermal control system components and have overlooked the possible deleterious effects of lunar dust contamination. Since lunar dust has a high emissivity and absorptivity (greater than 0.9) and is opaque, dust accumulation on a surface should radically alter its optical properties and therefore alter its thermal response compared to ideal conditions. In addition, the non-specular nature of the dust particles will alter the performance of systems that employ specular surfaces to enhance heat rejection. To date, few studies have examined the effect of dust deposition on the normal control system components. These studies only focused on a single heat rejection or photovoltaic system. These studies did show that lunar dust accumulations alter the optical properties of any lunar base hardware, which in turn affects component temperatures, and heat rejection. Therefore, a new study was conducted to determine the effect of lunar dust contamination on heat rejection systems. For this study, a previously developed dust deposition model was incorporated into the Thermal Synthesizer System (TSS) model. This modeling scheme incorporates the original method of predicting dust accumulation due to vehicle landings by assuming that the thin dust layer can be treated as a semitransparent surface slightly above and in thermal contact with the pristine surface. The results of this study showed that even small amounts of dust deposits can radically alter the performance of the heat rejection systems. Furthermore. this study indicates that heat rejection systems be either located far from any landing sites or be protected from dust producing mechanisms.
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.
The Photovoltaic and Electrochemical Systems Branch (LEX) at the NASA Glenn Research Center (GRC) supports a wide variety of space and aeronautics missions, through research, development, evaluation, and oversight.Solar cells, thermal energy conversion, advanced array components, and novel array conceptsLow TRL R&D to component evaluation & flight experimentsSupports NASA missions through PV expertise and facilitiesManagement of SBIR/STTR Topics, Subtopics, and individual efforts.LEX works closely with other NASA organizations, academic institutions, commercial partners, and other Government entities.
The potential market of photovoltaic systems in remote village applications in developing countries is assessed. It is indicated that photovoltaic technology is cost-competitive with diesel generators in many remote village applications. The major barriers to development of this market are the limited financial resources on the part of developing countries, and lack of awareness of photovoltaics as a viable option in rural electrification. A comprehensive information, education and demonstration program should be established as soon as possible to convince the potential customer countries and the various financial institutions of the viability of photovoltaics as an electricity option for developing countries.
42-page report describes facilities capable of testing complete photovoltaic systems, subsystems, or components. Compilation includes facilities and capabilities of five field centers of national photovoltaics program, two state-operated agencies, and five private testing laboratories.
Pyroelectric conversion in space deserves a close look as preliminary calculations indicate that a system specific power of 350 to 850 watts per kilogram will be feasible. This power-to-weight ratio far exceeds state-of-the-art photovoltaic systems (40 to 66 watts/kg) and surpasses proposed thin blanket photovoltaics (about 300 watts/kg). In addition to its high specific power, the pyroelectric approach promises to be far less expensive than photovoltaics.
The satellite power system is assessed in comparison to six alternative technologies. The alternatives are: central-station terrestrial photovoltaic systems, conventional coal-fired power plants, coal-gasification/combined-cycle power plants, light water reactor power plants, liquid-metal fast-breeder reactors, and fusion. The comparison is made regarding issues of cost and performance, health and safety, environmental effects, resources, socio-economic factors, and institutional issues. The criteria for selecting the issues and the alternative technologies are given, and the methodology of the comparison is discussed. Brief descriptions of each of the technologies considered are included.
A 1 kW preprototype redox storage system underwent characterization tests and was operated as the storage device for a 5 kW (peak) photovoltaic array. The system is described and performance data are presented. Loss mechanisms are discussed and simple design changes leading to significant increases in efficiency are suggested. The effects on system performance of nonequilibrium between the predominant species of complexed chromic ion in the negative electrode reactant solution are indicated.
The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.