Showing papers on "Photovoltaic system published in 1975"

Apparatus for enhancing the output of photovoltaic solar cells

Abstract: An array of photovoltaic cells and a parabolic concentrator for concentrating solar energy onto the cells. A watertight chamber including a solar energy pervious window adjacent the focus of the parabolic concentrator. The solar cell array is disposed within the chamber in alignment with the window. A quantity of water disposed in the chamber, the quantity being sufficient to absorb heat energy so as to limit the temperature rise of the solar cell array during periods of solar energy impingement thereon. The watertight chamber has sufficient external surface area that the heat energy stored therein is transferred away during non-solar energy producing periods of the diurnal cycle.

High efficiency converter of solar energy to electricity

Abstract: Apparatus is disclosed which permits the use of a large proportion of the solar spectrum in the coversion of solar energy to electricity by means of photovoltaic cells. The apparatus comprises a collecting element which concentrates the incident radiation, a collimating element which forms the concentrated incident radiation into a beam of parallel photons, a spectral separation element, such as a prism, prism plate or diffraction grating which spectrally separates the solar radiation in the collimated beam and a plurality of photovoltaic cells disposed in the separated spectrum, the energy gap of the cells being matched to the energy of the photons in that portion of the spectrum in which the cells are located.

Solar energy converter with waste heat engine

Abstract: A solar energy converter uses gallium arsenide photovoltaic cells to convert light to direct current. Optical concentrators reduce the needed area of cells. Gallium arsenide retains high conversion efficiency up to several hundred degrees, so the waste heat may be used to produce mechanical power in a Rankine cycle engine.

Cadmium sulfide solar cells

Abstract: Development, fabrication and applications of CdS solar cells are reviewed in detail. The suitability of CdS cells for large solar panels and microcircuitry, and their low cost, are emphasized. Developments are reviewed by manufacturer-developer. Vapor phase deposition of thin-film solar cells, doping and co-evaporation, sputtering, chemical spray, and sintered layers are reviewed, in addition to spray deposition, monograin layer structures, and silk screening. Formation of junctions by electroplating, evaporation, brushing, CuCl dip, and chemiplating are discussed, along with counterelectrode fabrication, VPD film structures, the Cu2S barrier layer, and various photovoltaic effects (contact photovoltage, light intensity variation, optical enhancement), and various other CdS topics.

Silicon solar cells for high concentration applications

Abstract: The use of solar concentrators can significantly reduce the cost of solar energy conversion, provided that the photovoltaic cells can be operated at high efficiencies under high illumination conditions. This paper describes the design, fabrication, and results of testing a cell with interdigitated p+and n+fingers on the unilluminated side of the solar cell. This design significantly reduces the problems of series resistance, contact grid shadowing, and voltage saturation which limit the performance of conventionally designed solar cells at high illumination intensities. The performance of such a cell at illumination intensities up to 22 watts/cm2is also presented.

Solar cooling system for an automobile

Abstract: A solar energy cell system is used as an electric supply source to operate an air conditioner or a fan ventilation system contained within the interior chamber of an automobile. The electrical circuit comprises a series circuit consisting of: the solar energy cells, a voltage regulator, a storage battery, a thermostatic temperature control and a ventilation fan or an automobile air conditioner.

Solar powered portable calculator

Abstract: A portable calculator utilizing a solar panel array which can be either slidably moved within the calculator's housing or pivotly connected to it and which when exposed to incident light provide power for the calculator.

Method of fabricating a photovoltaic device

Abstract: Solar radiation is concentrated on a solar cell of a photovoltaic device in the range of 500 to 1600 suns. the photovoltaic device includes a plurality of solar cells on a flat surface of a heat sink, and means for concentrating solar radiation on the solar cells. The solar cells have a surface on which the solar light is incident. This high concentration of solar energy on the solar cell will increase the solar cell operating temperature. The dimensions of the solar cells and the center to center spacing between solar cells is such that good thermal dissipation is maintained in the photovoltaic device.

Orbiting solar power station

Abstract: The invention described herein is an orbiting solar powered, energy collecting, storage and transmitting station. Initially, a large array of solar cells collects and transforms radiant solar energy into moderate amounts of electrical current. This electrical current is fed into a large superconducting coil where it is gradually built up to very high values. The electrical energy is thereby converted and stored in the resulting magnetic field. This magnetic energy is extracted by drawing off the current at very high rates and used to energize a laser or microwave generator for wireless power transmission. Since the discharge of the superconducting coil can proceed at rates many times greater than the charging rate, the resulting beamed power can, over short time intervals, be many times greater than the rate of solar radiation falling on the solar array. Alternatively, the energy can be stored gradually in rotating flywheels for fast rate beaming.

Review of Radiation Damage to Silicon Solar Cells

Abstract: This paper reviews a large number of silicon solar cell irradiation experiments performed over the last 10 years, including 1-MeV and energy spectrum electron studies, and low-(100-keV) and high-energy (up to 155-MeV) proton studies on bare and covered silicon solar cells of several types. The results of satellite flight experiments on individual solar cells are also presented, as well as data from complete solar arrays and data on the new high-efficiency solar cells. Experimental evidence indicates that the percentage of degradation is smaller in thin solar cells than in thick ones, and that cells with high resistivity (10 ?·cm) degrade less than cells with lower resistivity (1 ?·cm). It is shown that high-efficiency silicon solar cells produced at COMSAT Laboratories and pilot production groups of these cells retain most of their increased power output under irradiation. It is emphasized that all surfaces and edges of the solar cells must be completely shielded from the large flux protons in the space environment. Insufficiencies in the published data are noted in certain areas, and recommendations for additional research are presented. Finally, an extensive bibliography is included.

Chemical Storage of Solar Energy and Photochemical Fuel Formation

Abstract: Recent advances in the quantum utilization of solar energy will be surveyed. The efficiency of photovoltaic devices in combination with electrical storage will be compared with photogalvanic and photochemical systems. Photochemical formation of fuel (including hydrogen) in homogeneous and heterogeneous devices will be discussed in detail.

Solar electric power plant and an improved thermal collector of solar energy

Abstract: A thermal collector of solar energy includes an elemental semiconductor material to absorb a substantial portion of the energy of solar radiation that is incident upon the material. At longer wavelengths, such material reradiates absorbed energy at a substantially reduced rate, whereby the efficiency of energy collection at high temperatures is improved. In a solar electric power plant collected heat is transferred from such collectors to a motive fluid, which drives a turbine-generator. The high operating temperature of the energy-absorbing material permits efficient conversion of the collected energy to electrical energy, while a required number of solar collectors is correspondingly reduced by the improved collection efficiency.

Solar‐energy materials preparation techniques

Abstract: The application of materials to the thermal control of structures, photothermal/electrical conversion, and photovoltaic conversion are reviewed. Applications include solar and infrared reflectors, optical filters, transparent conductors, bulk semiconductor materials, semiconductor films, and selective solar absorbers. The use of thin films in many conservation and photothermal applications is presently economical, but the economics of photothermal/electrical and photovoltaic conversion is still being investigated. The means of obtaining selective solar absorbers which have a high solar absorptance and low ir emittance are discussed, and specific data on an electrodeposited black‐chrome selective absorber is presented. It is shown that solar–electric generating plants must be constructed at a cost of about $50/m2 to be competitive with other electrical generating plants, and that a meaningful impact on the electrical energy economy will require a fabrication rate of greater than 1.8 × 108 m2 (50 square miles) per year. Present high‐volume deposition capabilities are reviewed, and it is shown that for some types of deposition, namely electrodeposition, e‐beam vacuum evaporation, and possibly sputter deposition, facilities exist which approach the desired volumes.

Outlook for Si photovoltaic devices for terrestrial solar‐energy utilization

Abstract: The feasibility of silicon solar cells for large scale energy conversion is examined In this context the availability of silicon and the cost of fabrication of devices are discussed It is proposed that a complete rethinking of solar array processing is necessary to achieve large reduction in production costs (AIP)

Terrestrial solar cell generator

Abstract: A terrestrial solar cell generator including a plurality of solar cells mounted in a housing and interconnected by a plurality of leads with the solar cells being protected against adverse environmental conditions. The housing is entirely formed of the same radiation resistant material and encloses the solar cells and the connecting leads on all sides.

Integrated Power/Attitude Control System (IPACS)

Abstract: An integrated power and attitude control system (IPACS) for spacecraft is described. The system utilizes energy wheels for electrical energy storage as well as attitude control. Results from the feasibility studies of this concept are summarized and indicate potential weight and cost savings up to 30% over conventional power and control systems. The IP ACS advantage is particularly significant for the longer duration missions which have a large number of energy charge-discharge cycles and higher power requirements. A system for a shuttle-launched Research and Applications Module (RAM) free-flying observatory spacecraft is described. The system utilizes three gimbaled, control, and energy-momentum gyros in a planar array. Each gyro unit is rated at 2.4 kw and delivers 1095 w-hr of energy while maintaining control angular momentum above 1115 N-m-sec. Dynamic response of combined power and control functions was evaluated by digital simulations which included significant nonlinearities and a symmetrical energy distribution law. Simulation data indicate that spacecraft attitude control response is similar to that achieved without the superposition of energy wheel speed changes and is essentially uncoupled from that of the faster power control loop. Both power and control dynamics are well regulated. A NUMBER of spacecraft designs have been develxmoped for the missions of the shuttle era. Most of these require subsystems with lifetimes of 5-7 yr to meet cost effectiveness goals. Pointing requirements below 0.25° are common, with specific scientific missions requiring experiment pointing to 1 arc sec. Momentum storage devices normally are used to provide control torques for long-life missions where control thruster propellant weights and valve life test costs prove excessive. The choice of momentum storage is reinforced, or even required, in several missions where mass expulsion contaminants are prohibited by experiment viewing requirements or where fine pointing stability and slewing is required. The significant impact of the long-life requirement on the electrical power system design is in the sizing of components rather than in the type of system selected. This is because nearly all systems postulated utilize solar arrays for electrical power generation and secondary batteries for electrochemical energy storage. The batteries prove to be the heaviest components of advanced spacecraft solar power systems. The weight of the batteries is determined by the rated energy densities and their inherent characteristic of decreasing life with increased depth-of-discharge and charge-discharge rate. Thus, for a specific energy storage requirement, the designer's major option for increasing battery life is that of increasing the size or number of battery cells thereby decreasing the depth of discharge. As a result, batteries and their controllers commonly constitute 30-40% of an electrical power system weight. Developments of recent years1'2 have shown that flywheels designed to store energy can provide higher energy densities than can be expected from several conventional spacecraft electrochemical devices. In spacecraft applications, parity in energy density between the energy wheel and battery subsystems may result in significant advantage to the energy wheel system. This is because many spacecraft designs currently employ flywheels in momentum storage attitude control systems which approximate the weight of energy wheels.

Solar collector control system

Abstract: A system for controlling the movement in azimuth and elevation of a large mber of sun following solar energy collectors from a single central controller. The system utilizes servo signal generators, a modulator and a demodulator for transmitting the servo signals, and stepping motors for controlling remotely located solar collectors. The system allows precise tracking of the sun by a series of solar collectors without the necessity or expense of individualized solar trackers.

Solar energy—An overview

Abstract: A survey of the potential of solar energy as a viable alternative for fossil fuels is presented. The present status of the six classes of solar energy conversion systems— (1) heating and cooling of buildings, (2) solar‐thermal electric power, (3) photovoltaic power, (4) ocean thermal‐gradient power, (5) bioconversion, and (6) wind energy conversion—is discussed and projections of energy costs are presented for each of these areas of development. (AIP)

Maximum efficiency of direct utilization of radiation

Abstract: The author considers the thermodynamic efficiency limits associated with the direct conversion of solar energy into work (e.g., the photoelectric effect).