Showing papers on "Photovoltaic system published in 1976"

Thin‐film CuInSe2/CdS heterojunction solar cells

Abstract: The fabrication procedures and characteristics of several thin‐film p‐CuInSe2/n‐CdS heterojunction solar cells are presented. Two modes of operation (illumination through CuInSe2 or through CdS) are discussed. Efficiencies in the range of 4–5% are reported, under 100 mW/cm2 tungsten‐halogen illumination for 1.2‐cm2 devices. Included are the spectral response and J‐V characteristics for these photovoltaic junctions.

Transparent heat mirrors for solar-energy applications.

Abstract: Transparent heat-mirror films, which transmit solar radiation but reflect ir thermal radiation, have potentially important applications in solar/thermal/electric conversion, solar heating, solar photovoltaic conversion, and window insulation. We have used rf sputtering to prepare two types of films: TiO2/Ag/TiO2 and Sn-doped In2O3. To characterize the properties of heat-mirror films for solar-energy collection, we define the parameters αeff, the effective solar absorptivity, and ∊eff, the effective ir emissivity. For our Sn-doped In2O3 films, αeff/∊eff is comparable to the values of α/∊ reported for the leading selective absorbers. Even higher values of αeff/∊eff are obtained for the TiO2/Ag/TiO2 films.

Solar Heating and Cooling.

Abstract: We have adequate theory and engineering capability to design, install, and use equipment for solar space and water heating. Energy can be delivered at costs that are competitive now with such high-cost energy sources as much fuel-generated, electrical resistance heating. The technology of heating is being improved through collector developments, improved materials, and studies of new ways to carry out the heating processes. Solar cooling is still in the experimental stage. Relatively few experiments have yielded information on solar operation of absorption coolers, on use of night sky radiation in locations with clear skies, on the combination of a solar-operated Rankine engine and a compression cooler, and on open cycle, humidification-dehumidification systems. Many more possibilities for exploration exist. Solar cooling may benefit from collector developments that permit energy delivery at higher temperatures and thus solar operation of additional kinds of cycles. Improved solar cooling capability can open up new applications of solar energy, particularly for larger buildings, and can result in markets for retrofitting existing buildings. Solar energy for buildings can, in the next decade, make a significant contribution to the national energy economy and to the pocketbooks of many individual users. very large-aggregate enterprises in manufacture, sale, and installation of solar energy equipment can result, which can involve a spectrum of large and small businesses. In our view, the technology is here or will soon be at hand; thus the basic decisions as to whether the United States uses this resource will be political in nature.

Interface design considerations for terrestrial solar cell modules

Abstract: The need for increased solar array electrical efficiency and reliability in the achievement of future large-scale system cost goals is discussed. The relative performance of various array module designs currently on the market is evaluated, and further design improvements are suggested. The subjects of module efficiency, temperature control, and series/parallel reliability are analyzed. Applications for various combinations of array characteristics are considered.

Solar-radiation collection apparatus with tracking circuitry

Abstract: The invention contemplates improved apparatus for collecting solar radiation and directionally concentrating the same upon utilization means such as a photovoltaic cell system. In the form described, arrayed collecting devices are mounted for individual tracking of maximum solar-energy response at each such cell system, utilizing time-shared access to a microprocessor, and correctional-drive signals uniquely appropriate to the orientation of each collecting device are supplied by the microprocessor on a time-shared basis for the respective components of orientation correction drive means for each collecting device. Since each collecting device is thus automatically correctively positioned for maximum output of its own utilization device, there is an avoidance of precision requirements (a) as to mounting the several collecting devices with respect to each other and (b) as to basic drives to anticipate relative aspect of the sun, as a function of the time of day, or the day of the year, and whatever the earthbound location of the apparatus.

High intensity solar energy converter

Abstract: A photovoltaic energy converter for converting incident radiant energy, such as solar energy, to electrical energy. The converter comprises a cell formed from a plurality of integrally interconnected p-n junction-containing semiconductor wafers. The wafers are stacked end-to-end in the cell so that the respective junctions in each wafer are parallel to each other. The efficiency and performance of the cell is improved, particularly upon exposure to concentrated sunlight, by imposing various conditions on the cell fabrication and design. Improvements result, for example, by selecting a high resistivity semiconductor as the starting material in the fabrication of the cell, controlling the diffusion process to optimize the junction gradient and minimize the thickness of the base region in each wafer, orienting the wafers in the cell so that they are illuminated at a small angle relative to the plane of the respective junctions therein, and treating the exposed surfaces of the wafer to reduce reflectivity and surface recombination velocities.

Application of thin films to solar energy utilization

Abstract: The principal areas of utilization of thin films and coatings in the harnessing of solar energy are (1) thermal control of structures, where reflecting or partially reflecting coatings and antireflection coatings are used to control incident solar radiation or to retain thermal energy; (2) photothermal conversion where solar energy is converted to low grade heat (<150 °C) using reflector films, antireflection coatings, and selective solar absorber coatings; (3) = p i a i )=hotothermal/electrical conversion where solar energy is concentrated and converted to high‐grade heat which is used to power a turbine; and (4) photovoltaic conversion where solar energy is converted directly into electrical energy using semiconductor films and junctions, transparent conductors, antireflection coatings, and metal electrode films. Films may be used in all of these areas for environmental protection. Several thin film systems have applications rather unique to solar energy. These include selective solar absorbers which ha...

Solar tracking device

Abstract: A solar tracking system is disclosed, utilizing a photovoltaic device, for following the changing solar position. When the sun ceases to be the brightest object in the sky, such as during periods of partial cloud cover, and the system seeks to acquire the brightest spot in preference to the sun, the photovoltaic device is automatically overridden. The override system is clock-driven and moves the tracking system to approximate the solar position so that the sun can be immediately reacquired by the photovoltaic device when the sun re-energizes as the brightest object in the sky.

Four quadrant, two dimensional, linear solar concentration panels

Abstract: The four quadrant, deep concave, linear solar concentration panel has been evolved to meet the need for a practical, low-cost solar energy conversion system, for individual house power supplementation installations. This specific type of solar concentration panel is not designed for a solar photovoltaic conversion arrangement, but for a water steam and flash boiler pipe arrangement where the generated steam is used to drive a rotary steam engine and 110 VAC alternator with a minimum rating of 10 KW/hr. The advocated solar concentration panel has a panel width to flash boiler pipe diameter of about 18:1, which provides a solar concentration ratio of between 22:1 and 27:1, at this point in time. The concentration panel width to height cross-section ratio is approximately 2.5:1, and the base focal line distance to panel height ratio is 1:2.5.

Solid-dielectric compound parabolic concentrators: on their use with photovoltaic devices.

Abstract: Prototype solid dielectric compound parabolic concentrators have been made and tested. By means of the geometry and refractive properties of a transparent solid they provide a technique for increasing the power output of silicon solar cells exposed to the sun by an amount nearly equal to the increase in effective collecting area. The response is uniform over a large angle which eliminates the necessity of diurnal tracking of the sun. The technique can be applied to the construction of thin panels and has the potential for significantly reducing their cost per unit area.

Stable solar power source for portable electrical devices

Abstract: The stable solar power source consists of solar cells for converting sunlight into electrical energy and a large capacitor for providing a current reserve to satisfy peak current demands and offset the effects of sunlight variations. The solar cells are mounted beneath a light transmitting thermal shield to minimize thermal induced cell output variations.

Photovoltaic system including a lens structure

Abstract: A photovoltaic or solar cell generator includes a plurality of unit solar cells each having one or more p-n junctions. An optical light-focusing system, which includes an array of lens elements, focuses the incoming radiation into a series of preferably narrow beams that are incident on the surfaces of the unit solar cells at locations lying immediately adjacent but spaced from the p-n junctions.

Terrestrial concentrating photovoltaic power system studies

Abstract: Studies aimed at defining the role of sunlight concentration in reducing the cost of electrical energy generated by terrestrial photovoltaic systems are described. These studies use computer modelling to (a) compare silicon cells and gallium arsenide cells in concentrating systems, (b) investigate the operation of photovoltaic systems in low insolation locations and (c) evaluate the effect of wind dependent thermal conductances on performance of passively cooled systems. Optimum fixed energy costs occur at higher aperature to cell area ratios for GaAs systems compared to silicon systems due to the better high temperature performance and increased costs of GaAs. Results based on currently available data show that concentrating systems should not be ruled out relative to fixed flat unconcentrated arrays even for low solar irradiation locations such as Cleveland. The wind dependent thermal conductance studies show that for precise modeling the effect of wind speed should be considered in locations having large wind speed deviations from the yearly mean. However, with the present uncertainties in cost inputs, the use of average values is quite appropriate.

Solar collector and drive circuitry control means

Abstract: A control that will, when attached to a Solar Collector in a proper manner, allow said Solar Collector to track the sun as to azimuth and elevation automatically, without manual assistance, through the diurnal cycle without regard as to whether the sun is visible or not. Also controlling said Collector at sunset to return to an Easterly setting to await the following diurnal cycle.

Photovoltaic device and method of making same

Abstract: An integrated array of solar cells is produced in continuous layers of photovoltaic junction forming semiconductor materials. Adjacent solar cells are sufficiently isolated by virtue of a relatively high resistivity in the semiconductor layers. The solar cells are connected in series by shorting the junction at selected points.

Solar powered engine and tracking system

Abstract: A solar powered engine and tracking system comprises a piston working within a cylinder for turning a drive shaft for driving an electrical generator or performing other useful work, a solar concentrator comprising a plurality of mirrors, each reflecting Sun light on a common focal point on the end of the cylinder for heating a flash boiler located thereon, preheated water from a source is injected into the flash boiler by a pump powered by the drive shaft timed according to piston movement after operating the piston, the steam is then vented from the boiler by valve means operated from the drive shaft. A starter motor is provided to initially start the engine operating by rotating the drive shaft until the piston movement is self sustaining. The entire device is enclosed in a solar energy collector panel for elevating the temperature of the system so as to maintain the water at a sufficient temperature with a minimum of external heating. The collector may also be utilized for separate external heating purposes. Sensor controlled motors track the relative movement of the Sun and Earth and continually position the collector for maximum solar energy concentration.

Solar cell array design handbook, volume 1

Abstract: Twelve chapters discuss the following: historical developments, the environment and its effects, solar cells, solar cell filters and covers, solar cell and other electrical interconnections, blocking and shunt diodes, substrates and deployment mechanisms, material properties, design synthesis and optimization, design analysis, procurement, production and cost aspects, evaluation and test, orbital performance, and illustrative design examples. A comprehensive index permits rapid locating of desired topics. The handbook consists of two volumes: Volume 1 is of an expository nature while Volume 2 contains detailed design data in an appendix-like fashion. Volume 2 includes solar cell performance data, applicable unit conversion factors and physical constants, and mechanical, electrical, thermal optical, magnetic, and outgassing material properties. Extensive references are provided.

Tandem photovoltaic solar cells and increased solar energy conversion efficiency

Abstract: 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.

Solar heating and insulating apparatus

Abstract: A combined solar heating and insulating apparatus for use on existing buildings or in new construction. The apparatus is inexpensive to manufacture and provides for auxiliary solar heating during the day and insulation during the night, both of which result in a savings in fuel and increased efficiency of the standard heating system of the building. The apparatus takes the form of panels which can be affixed to existing vertical southern walls with little or no modification, thus allowing for the use of solar energy without expensive physical modifications to the building.

Plant for generating and accumulating electric energy with the aid of wind power or solar energy

Abstract: Electric solar or windpowerplant with flywheel battery in which the electric generator is in the form of a d.c. generator, electrically connected to brushless d.c. motors switched in parallel which can also act as generators and each of which is coupled to a flywheel.

Device for converting solar energy

Abstract: A device is described for converting solar energy into electric power for a load, which device is provided with photocells and electric accumulators. Switching means are provided which at least during starting of the load connect this load to the output terminals of the array of photocells so that during starting the current through the load is determined by the current supplied by the photocells. The device makes efficient use of the available solar radiation, is of simple design and is reliable.

Evolution of the satellite solar power station /SSPS/ concept

Abstract: Orbital solar power plants are considered from the viewpoint of technology and costs in terms of photovoltaic conversion, baseline configuration, microwave reception and power generation, transportation, assembly, and maintenance. The economics and development program for the OSPP are briefly discussed. (WDM)

The photovoltaic generation of electricity

Abstract: A review is presented on the physics, fabrication, and cost of solar cells. The economics of photovoltaic generation of electricity are discussed. (WDM)

Comparison of candidate solar array maximum power utilization approaches

Abstract: A study was made of five potential approaches that can be utilized to detect the maximum power point of a solar array while sustaining operations at or near maximum power and without endangering stability or causing array voltage collapse. The approaches studied included: (1) dynamic impedance comparator, (2) reference array measurement, (3) onset of solar array voltage collapse detection, (4) parallel tracker, and (5) direct measurement. The study analyzed the feasibility and adaptability of these approaches to a future solar electric propulsion (SEP) mission, and, specifically, to a comet rendezvous mission. Such missions presented the most challenging requirements to a spacecraft power subsystem in terms of power management over large solar intensity ranges of 1.0 to 3.5 AU. The dynamic impedance approach was found to have the highest figure of merit, and the reference array approach followed closely behind. The results are applicable to terrestrial solar power systems as well as to other than SEP space missions.