Showing papers on "Photovoltaic thermal hybrid solar collector published in 1990"

Solar collectors, energy storage, and materials

Abstract: This volume was prepared as an extended, annotated bibliography in the solar thermal energy collection field, documenting the state-of-the-art in the late 1980s. It covers collectors of solar thermal energy, including salt gradient solar ponds, flat plate collectors, compound parabolic concentrators, and other stationary and tracking collection systems. Collectors that are used for building applications are emphasized since power and industrial applications are considered in other volumes.

Physical limitations to photovoltaic energy conversion

Abstract: Contributions to a seminar on the physical limits of efficiency of solar cells are presented. An introductory chapter analyses the efficiency of a solar cell showing that, at least in theory, the use of cells of several bandgaps is the most effective way to increase the efficiency substantially. Other chapters deal with: the physical bounds of the concentration of light; the limits of absorption of light by a given cell volume; a fundamental treatment of the thermodynamics of an ideal solar cell; limits of efficiency of cells under radiative recombination; the mechanics of recombination in solar cells; surface recombination, particularly in the interface Si-SiO{sub 2}. (author).

Solar powered swimming pool skimmer

Abstract: A swimming pool skimmer includes a paddle wheel that directs fluid and debris into a debris catcher. The paddle wheel is turned by a motor that is powered from an array of solar cells. A solar concentrator focuses solar energy onto the solar cells, and an alarm circuit includes a strain gauge on the debris catcher. The strain gauge forms one leg of a bridge circuit that is connected to a comparator having a feedback loop. The output of the comparator is connected to an alarm element either directly or remotely.

A twenty percent efficient photovoltaic concentrator module

Abstract: A solar-to-electric efficiency greater than 200% has been achieved using a silicon-based photovoltaic concentrator module. The module uses 12 point-focus cells and has a total lens aperture area of 1875 cm/sup 2/. Results of outdoor testing of the full module are given. The cells and cell mounts of the module were designed for the commercial-prototype Sandia Baseline Module 3, and it is expected that concentrator modules with efficiencies of 20% will be available commercially within a few years. >

Solar collectors, energy storage, and materials

Abstract: "Solar Collectors, Energy Storage, and Materials "covers the materials and basic components needed for solar thermal energy systems. Using thermal performance and durability as the major criteria, the twenty six chapters emphasize the modeling and assessment of devices rather than their application or cost. Each part begins with an overview and concludes with an assessment of current issues and opportunities. The contributors have been careful to document failures as well as successes in materials research. This is the fifth volume in a series that distills the results of the intensive research on and development of solar thermal energy conversion technologies from 1975 to 1986.Contents: Solar Collectors. Collector Concepts and Designs. Optical Theory and Modeling of Solar Collectors. Thermal Theory and Modeling of Solar Collectors. Testing and Evaluation of Stationary Collectors. Testing and Evaluation of Tracking Collectors. Optical Research and Development. Collector Thermal Research and Development. Collector Engineering Research and Development. Solar Pond Research and Development. Reliability and Durability of Solar Collectors. Environmental Degradation of Low-Cost Solar Collectors. Energy Storage for Solar Systems. Storage Concepts and Design. Analytical and Numerical Modeling of Thermal Conversion Systems. Testing and Evaluation of Thermal Energy Storage Systems. Storage Research and Development. Materials for Solar Technologies. Materials for Solar Collector Concepts and Designs. Theory and Modeling of Solar Materials. Testing and Evaluation of Solar Materials. Exposure Testing and Evaluation of Performance Degradation. Solar Materials Research and Development.

Thermal storage module for solar dynamic receivers

Abstract: A thermal energy storage system comprising a germanium phase change material and a graphite container

Techno-economic model of a solar still coupled with a solar flat-plate collector

Abstract: In this paper, a techno-economic model has been developed for a solar still coupled with a flat-plate collector through a heat-exchanger. The model is based on the establishment of periodic steady-state conditions. The economic criterion used in the model is based on the least cost of a unit mass of distilled water evaluated from the life-cycle costing of the system. To evaluate the model, numerical calculations have been made corresponding to the climate of Delhi (India). It is concluded that the addition of a solar collector enhances the distillate yield; however, this is not always economical. This system therefore needs careful and economic system design.

Nonsolar photovoltaic cells

Abstract: For several interesting photovoltaic (PV) applications, the incident radiation is not sunlight (although it may be derived from sunlight). These nonsolar applications and the principles guiding cell design are reviewed. It is shown that much of the experience gained in designing and optimizing solar cells can be used. Cell design for luminescent sources, activated by thermal or chemical means, and for illumination by lasers is discussed. These special applications can have high conversion efficiency, in some cases over 50%. >

Seasonal performance of three grid-connected PV systems

Abstract: The one-year performances of three grid-connected photovoltaic (PV) power systems located at the Florida Solar Energy Center are compared. Three different photovoltaic cell technologies are presented: (1) single junction amorphous silicon (ARCO G4000 modules); (2) tandem junction amorphous silicon (Sovonics P-201 modules), and (3) crystalline silicon (Mobil Ra 180 modules). For the amorphous silicon PV arrays, their operating efficiencies were higher in the summer than in the winter. This is because their efficiency is affected only slightly by operating temperature, the warmer summer months improved the efficiency through annealing, and the spectral irradiance conditions are generally more favorable. Changes in the monthly operating efficiencies of the crystalline silicon PV array were almost entirely dependent on module operating temperatures. Consequently, the operating efficiencies of this PV array were higher in the winter than in the summer. >

Solar thermal power generating device

Abstract: PURPOSE: To increase power generating efficiency remarkably by providing a hot heater for further heating vapor produced by heat of collected light, a solar light collector for heating the hot heater, and a re-generative heat exchanger for pre-heating water supply for vapor. CONSTITUTION: In a solar thermal power generating plant, vapor is generated from water by collecting solar light 1 injected onto a light collector 22 and a steam turbine 5 is rotated by the vapor to generate power by a power generator 6. Then the vapor is cooled and condensed by cooling water 8 in a condensor 7 to return it back to water. In this case, a re-generative heat exchanger 9 for heating water supply by exhaust gas from the steam turbine 5 is provided, the water heated by the exchanger 9 is fed to an evaporator 31 by a water supply pump 4 and is heated and vaporized by solar light 1 collected by a light collector 21. Saturated vapor in a hot heater 32 is heated by the solar light 1 collected by a parabolic light collector 22 to supply it to the steam turbine 5. COPYRIGHT: (C)1992,JPO&Japio

Analysis of a Porous-Medium Solar Collector

Abstract: The porous-medium flat-plate solar collector is an interesting alternative to conventional fin-and-tube designs if higher pumping power requirements do not offset collector efficiency gains. In this paper, complementary to a transient two-phase heat transfer study where Darcy's law had been used, a non-Darcy flow equation and the convection-conduction heat transfer equation are solved numerically. The coupled fluid flow and heat transfer mechanisms are analyzed for a porous-medium solar collector, and its high-performance efficiency is compared with advanced tubular-type collectors.

Space proven GaAs solar cells-main power generation for CS-3

Abstract: GaAs solar cells were used for the main solar array to satisfy the power requirement for the Japanese domestic communications satellite-3 (CS-3). The authors review the GaAs solar cell performance, reliability, and array assembly for CS-3 and present the on-orbit performance of CS-3 after launch in 1988. The annual radiation degradation rate of the CS03 GaAs solar array was found to be one fourth or one fifth that of the ETS-V and BS-2b Si solar arrays. It was clear from the flight data that the radiation hardness of GaAs solar cells was excellent in comparison with that of Si solar cells. >

Requirements of Electrical Contacts to Photovoltaic Solar Cells

Abstract: The importance of contacts to photovoltaic solar cells is often underrated mainly because the required values of specific contact resistance and metal resistivity are often thought to be relatively modest compared with those associated with very large scale integration (VLSI) applications. However, due to the adverse environmental conditions experienced by solar cells, and since many of the more efficient cells are economically advantageous only when operated under solar concentration, the requirements for solar cell contacts are sometimes more severe. For example, at one-sun operation, the upper limit in specific contact resistance is usually taken to be 10−2 Ω-cm2. However, at several hundred suns, this value should be reduced to less than 10−4 Ω-cm2. Additionally, since grid line fabrication often relies on economical plating processes, porosity and contamination issues can be expected to cause reliability and stability problems once the device is fabricated. It is shown that, in practice, these metal resistivity issues can be much more important than issues relating to specific contact resistance and that the problem is similar to that of providing stable, low resistance interconnects in VLSI. This paper is concerned with the design and fabrication of collector grids on the front of the solar cells and, although the discussion is fairly general, it will center on the particular material indium phosphide. This III-V material is currently of great importance for space application because of its resistance to the damaging radiation experienced in space.

Design considerations for Mars photovoltaic systems

Abstract: Considerations for operation of a photovoltaic power system on Mars are discussed with reference to Viking Lander data. The average solar insolation on Mars is 590 W/m/sup 2/, which is reduced yet further by atmospheric dust. Of major concern are dust storms, which have been observed to occur on local as well as on global scales, and their effect on solar array output. While atmospheric opacity may rise to values ranging from three to nine, depending on storm severity, there is still an appreciable large diffuse illumination, even at high opacities so that photovoltaic operation is still possible. If the power system is to continue to generate power even on high-optical-opacity (i.e. dusty atmosphere) days, it is important that the photovoltaic system be designed to collect diffuse irradiance as well as direct. Energy storage will be required for operation during the night. Temperature and wind provide additional considerations for array design. >

Retractable planar space photovoltaic array

Abstract: An advanced array design based on the recently developed HS-601 oriented flatplate array is described. The advanced design incorporates the use of high-efficiency gallium arsenide on germanium dual-junction solar cells that have BOL (beginning-of-life) efficiencies of greater than 22%. Reflections off deployable flatplate shutters increase the sunlight concentration on the planar solar cell panels, resulting in a 30% increase in power from the solar cells. Each solar cell panel, 2.16*2.54 m/sup 2/ in size, has a BOL output power of 1667 W at the operating temperature of 81 degrees C. The full-size array, consisting of two wings with three panels/wing, has a BOL output of 10.0 kW and a projected end-of-life (e.g.. 1*10/sup 15/ e/cm/sup 2/, 1 MeV) output of about 7.7 kW. This advanced solar power structure provides a novel approach for utilizing high-efficiency multibandgap solar cells in a retractable array configuration, thus providing higher efficiency and a more versatile operational design. >

Solar-operated absorber refrigeration appts. - has driver within refrigeration circuit incorporated directly in solar collector

Abstract: The refrigeration appts. has an integrated solar collector (11) designed for use with diffuse solar radiation. It operates in a temp. range of between 80 and 120 degrees C. The refrigeration medium flows through a driver (2) which is incorporated in the solar collector with variable throttle points (4,5) on either side of it, adjusted in dependence on the level of solar radiation. The outputs from the throttle points (4,5) are fed to an absorber and heat exchanger (7) and to a condenser (3). USE - For food storage or room air-conditioning applications.

The potential performance of GaAs-based mechanically stacked multijunction solar concentrator cells

Abstract: The potential performance of GaAs-based mechanically stacked, multijunction (MSMJ) solar concentrator cells in 500X and 1000X concentrator modules is analyzed. A description of the concentrator module and the MSMJ concentrator cell is presented. A thermal analysis of the MSMJ cell assembly in the module is given, and implications of the module operating conditions for the design of the MSMJ cell are considered. The normal operating cell temperature of MSMJ cells in a concentrator module is higher than that of single-junction cells due to the stacked cell construction, which reduces the expected performance advantages of MSMJ versus single-junction cells. >