Showing papers on "Photovoltaic system published in 1980"

Solar engineering of thermal processes

Abstract: FUNDAMENTALS. Solar Radiation. Available Solar Radiation. Selected Heat Transfer Topics. Radiation Characteristics of Opaque Materials. Radiation Transmission Through Glazing: Absorbed Radiation. Flat--Plate Collectors. Concentrating Collectors. Energy Storage. Solar Process Loads. System Thermal Calculations. Solar Process Economics. APPLICATIONS. Solar Water Heating----Active and Passive. Building Heating----Active. Building Heating: Passive and Hybrid Methods. Cooling. Industrial Process Heat. Solar Thermal Power Systems. Solar Ponds: Evaporative Processes. THERMAL DESIGN METHODS. Simulations in Solar Process Design. Design of Active Systems by f--Chart. Design of Active Systems by Utilizability Methods. Design of Passive and Hybrid Heating Systems. Design of Photovoltaic Systems. Appendices. Author Index. Subject Index.

Detailed balance limit of the efficiency of tandem solar cells

Abstract: The fundamental (detailed balance) limit of the performance of a tandem structure is presented. The model takes into account the fact that a particular cell is not only illuminated by part of the solar irradiance but also by the electroluminescence of other cells of the set. Whereas, under 1 sun irradiance, a single solar cell only converts 30% of the solar energy, a tandem structure of two cells can convert 42%, a tandem structure of three cells can convert 49%, etc. Under the highest possible light concentration, these efficiencies are 40% (one cell), 55% (two cells), 63% (three cells), etc. The model also allows us to predict the ideal efficiency of a stack with an infinite number of solar cells. Such a tandem system can convert 68% of the unconcentrated sunlight, and 86% of the concentrated sunlight.

Solar-cell array design handbook

Abstract: Twelve-chapter two-volume compilation of solar cell design data is written from industrial, university, and governmental sources. Volumes contain tutorial descriptions of analytical methods, solar-cell characteristics, and cell material properties widely used in specifying solar-cell array performance and hardware design, as well as analysis, fabrication, and test methods.

Principles of photoelectrochemical, solar energy conversion

Abstract: Photoelectrochemical devices for conversion of solar energy into both electrical energy and chemical energy are discussed with emphasis on how the various material properties of the photoactive electrodes influence device efficiency and stability. The similarity between photoelectrochemical cells (PECs) and solid state devices is used to model their behaviour and optimize such parameters as band gap, doping level, minority carrier lifetime, etc. A model is presented which calculates the electron affinity of any semiconductor and allows the prediction of the open circuit voltage of wet photovoltaic cells and optimum biasing forchemical producing cells. The effects of absorbed ions at the semiconductor/electrolyte interface are reviewed. The temperature dependence of the energy levels in the semiconductor and the electrolyte are considered and the implications of these results to operation of PECs at elevated temperature are discussed. The major differences between PECs and solid state devices are the stability considerations. The thermodynamics of this problem is discussed. Other important degradation mechanisms and some solutions to these problems are reviewed. Finally, a prognosis of the future of this field is presented.

Thin film solar cells

Abstract: Until recently, photovoltaic cells were only used for specialised electricity generation such as power for spacecraft. With the prospect of advanced cells and mass-production techniques, large-scale production of electricity seems to be an economically viable prospect within the next decade

Solar Cell Array Design Handbook: The Principles and Technology of Photovoltaic Energy Conversion

Abstract: Photovoltaic solar cell array design and technology for ground-based and space applications are discussed from the user's point of view. Solar array systems are described, with attention given to array concepts, historical development, applications and performance, and the analysis of array characteristics, circuits, components, performance and reliability is examined. Aspects of solar cell array design considered include the design process, photovoltaic system and detailed array design, and the design of array thermal, radiation shielding and electromagnetic components. Attention is then given to the characteristics and design of the separate components of solar arrays, including the solar cells, optical elements and mechanical elements, and the fabrication, testing, environmental conditions and effects and material properties of arrays and their components are discussed.

Photovoltaic power generation

Abstract: A photovoltaic module is disclosed in the form of a shingle having an active portion containing photovoltaic cells and an inactive mounting portion. Flat flexible ribbon-like positive and negative leads extend from the terminals in the active portion. The individual modules are mounted on a surface by means of fasteners extending through the inactive portions of the modules. At the time of installation, the flexible leads are folded to provide a servicing loop and the ends of the leads are then connected into the electrical network of the system. Individual modules can be removed from the system by moving the modules in their own planes away from the array of modules with accompanying straightening of the loops so that modules can be replaced. Improved circuit arrangements for connecting modules in an array and improved installation methods are disclosed which take advantage of the flat flexible conductors extending from the modules.

Stacked multijunction photovoltaic converters

Abstract: Solar cells with different bandgaps are stacked to form a multijunction photovoltaic converter with a high conversion efficiency. By stacking the cells mechanically rather than by growing them all at one time, the most convenient combination of materials may be selected for the cells. The stacking is completed by means of a glass sealing layer with moats containing inter-cell contacts which are bonded to the cells.

Solar cell with corrugated bus

Abstract: The invention teaches an improved bus for current collection in photovoltaic solar cells. The bus is prefabricated from a highly conductive metal and is corrugated to compensate for differences in thermal coefficients of expansion between the bus and the solar cell body.

Photovoltaic device and method of manufacturing thereof

Abstract: A photovoltaic device comprises a light transmissive insulating substrate, on which a plurality of isolated transparent electrodes are formed. An amorphous silicon layer of a PIN structure, for example, is formed on the substrate continuously and in common to the respective transparent electrodes. Aluminum electrodes are formed on the surface of the amorphous silicon layer so as to correspond to the respective transparent electrodes. The transparent electrodes and the aluminum electrodes are electrically connected to the adjacent opponent electrodes to withdraw in a series fashion photovoltaic power generated at the respective photoelectric conversion regions.

Solar power system requiring no active control device

Abstract: A solar power system has a photovoltaic array having a locus of peak power points for various insolation levels, a voltage-dependent variable resistance load such as a water electrolysis unit electrically connected to the array, and a demand-dependent variable resistance load such as a DC to AC inverter connected in parallel with the electrolysis unit. The electrolysis unit or other voltage-dependent variable resistance load has a voltage-current characteristic in which the operating point is displaced from the array's peak power point for most insolation levels. The characteristic is displaced towards higher voltage-lower current operating points. The inverter may move the operating point of the photovoltaic array toward its peak power point when the load requires power. The system may be designed so that the array operates within about 5 percent of its peak power point over a wide range of inverter power demands. A fuel cell may be connected in parallel with the array to provide power to the inverter at low insolation levels, at night or in low sunlight. The fuel cell may use the hydrogen produced by the electrolysis unit for fuel. The total photovoltaic power made available by the system of this invention is generally greater than 95 percent and often greater than 98 percent of the maximum power which the photovoltaic array may produce for many insolation levels.

High efficiency thin-film multiple-gap photovoltaic device

Abstract: A photovoltaic device includes at least two solar cells made from Group IV elements or their alloys in the amorphous state mounted on a substrate. The outermost or first cell has a larger bandgap than the second cell. Various techniques are utilized to improve the efficiency of the device.

Solar power supply and battery charging circuit

Abstract: A photovoltaic power supply and battery charging system comprises a photovoltaic solar energy power supply panel connected through a blocking diode to a secondary storage battery which, in turn, is connected to a suitable load. A temperature sensitive reference voltage is supplied to one input of a voltage comparator, the other input to which is connected to the battery and thereby varies in accordance with the variations of charge on the battery. A short circuit shunt switch is connected directly across the photovoltaic panel; and this shunt switch is opened for varying periods of time by the output of a variable pulse width generator. The pulse width generator, in turn, is connected to and is controlled by the output of the voltage comparator to produce pulses of different widths. The charging current supplied to the battery then occurs in the form of high current pulses of varying widths depending upon the charge state of the battery.

Metal‐insulator‐semiconductor solar cells using amorphous Si:F:H alloys

Abstract: Metal‐insulator‐semiconductor‐type photovoltaic devices using amorphous Si:F:H alloys have been fabricated. Conversion efficiencies of up to 6.3% under AM:1 illumination have been observed. These represent the highest efficiencies yet reported for amorphous thin‐film solar cells.

Thin-film solar cells: A unified analysis of their potential

Abstract: The development and deployment of low-cost thin-film solar cells for the direct conversion of sunlight to electricity can be accelerated by the utilization of loss minimization and cost minimization methodologies. The solar cell is separated into its five constituent layers to provide a common basis for the development of these methodologies. Photovoltaic theory, materials science, and loss analysis are combined to develop the loss minimization methodology which can be used to systematically improve and optimize performance of any solar-cell material system. The techniques of the chemical process industry have been applied to achieve cost minimization. The loss-and cost-minimization methodologies have been combined into a generalized procedure for the accelerated development of all low-cost thin-film photovoltaic material systems.

Effect of soiling on solar mirrors and techniques used to maintain high reflectivity

Abstract: Solar mirrors are used to concentrate low-level solar radiation to power levels which are practical and efficient for consumption Any interference with the collection of that energy not only decreases the power level but also increases the cost of the energy available from a solar power system One of the most immediate and drastic effects of outdoor exposure is the reflectance loss due to the accumulation of foreign particles on the mirror surface Specular reflectance losses as great as 25% have been observed for mirrors exposed for only a few weeks The effect of the deposited particles is to reduce the reflected energy by both absorbing and scattering light The degree to which the particles reduce the collection of reflected energy depends on their composition, number and size distribution An additional factor is the optics of the collection system The angular acceptance aperture of the system, defined as the angle subtended by the receiver at the concentrator surface, determines the relative importance of the scattering due to dust accumulation For flat plate thermal and photovoltaic collectors which have essentially a 180/sup 0/ angular acceptance aperture, scattering of the incident light is not critical but absorption can be an important factor more » in the loss of energy For concentrating collection systems, such as line focus collectors and central receivers, angular acceptance apertures of a few degrees make scattering at the concentrator surface much more important and can result in severe energy losses Results of a study of each of these areas are presented and discussed (WHK) « less

A line interfaced inverter with active control of the output current waveform

Abstract: A line interfaced inverter for photovoltaic systems is presented. This inverter employs a high frequency dc-chopper for shaping the output current, providing unity power factor operation and minimizing the size of the output filter. The isolation of the solar array from the utility is accomplished with a high frequency transformer, eliminating the need for large, 60 Hz magnetics. The dynamics of the power circuit are analyzed to determine proper compensation of the output current control loop. This analysis shows that a minor loop is required to stabilize the power circuit and that system response varies during the 60 Hz cycle. A Parity Simulation of the power circuit/control system is performed to verify this analysis. The results of this simulation are presented and compared to waveforms from a test inverter. The special considerations required for properly loading a photovoltaic array with a line interfaced inverter are discussed.

Combined Photovoltaic and Thermal Hybrid Collector

Abstract: Hybrid collector which produces both electric and thermal energy is very effective system for heightening efficiency of solar energy collector. In order to obtain the fundamental characteristics of these systems, two liquid type flat plate thermal collectors with selective surface have been modified by attaching 3'' diameter silicon solar cells. The measured cell array efficiencies were 8.84% and 9.20% at 28°C, AM 1.15. The maximum thermal efficiencies of these hybrid systems were 72% and 77% using water as coolant.

Solar Cells Made by Chalcopyrite Materials

Abstract: After a discussion of the material characteristics, which are necessary for high efficiency solar cells, some chalcopyrite materials are indicated as promising photovoltaic absorbers. Among these, CuInSe2, CuInSe1.66 Te0.34 and CuGaSe0.65 Te1.35 from the I-II-VI group and CdSiAs2 from the II-IV-V group seem to have a greater probability of success owing to their good lattice matching with CdS or ZnCdS. A brief review of the results obtained to date on single crystals and thin film solar cells is given, and this is followed by a description of a new technique, called Quasi-Rheotaxy, which allows one to obtain large grain thin films on amorphous low cost substrates. Quasi-Rheotaxy, which we used to grow ~10 µm grain thin films of the above mentioned I-III-VI chalcopyrite materials could substancially contribute to achieving low cost high efficiency thin film solar cells.

Performance of Photovoltaic Cells in Undersea Environment

Abstract: : Photovoltaic solar cells can serve as a reliable source of electric power for electronic instrumentation in temporarily or permanently submerged marine systems in the form of bottom installations, buoys, or remotely controlled unmanned vehicles. The power output of submerged solar cells is a function of solar insolation intensity on the water surface, depth of submersion, optical properties of water, temperature, and the orientation of the cell surface with respect to the sun. Experimental data were generated by submerging solar cell panels in different bodies of water with a 2.5- to 95-ft visual contrast limit, as defined by the observation of a submerged, standard, 12-in Secchi disc, and measuring their performance under load. The power output of horizontally oriented, upward-facing, photovoltaic cells submerged to the visual contrast limit depth was found to be a constant, equal to approximately 5 to 10 percent of the power generated by upward-facing, horizontally oriented cells in an atmospheric environment. The power output of the cells increased at lesser depths, until in the splash zone the output was essentially the same or higher than in the atmospheric environment. Based on these findings it can be concluded that high-efficiency silicon solar cells can serve as a practical electrical power supply in electronic devices for marine applications, if their depth of submersion in less than the visual contrast limit at the dive location.

Measurement of concentrator solar cell series resistance by flash testing

Abstract: A simple technique for the measurement of series resistance of concentrator solar (photovoltaic) cells is described. This technique makes use of the fact that the ’’short circuit’’ current of a solar cell as a function of light intensity will begin to saturate at an intensity determined by the series resistance of the cell and circuit. In this region the series resistance of the cell can easily be found from a measurement which is relatively independent of illumination intensity and spectrum. Experimental data are presented that verify this result.

Turbine configurations using wind and solar power

Abstract: A power system comprises structures which capture wind and solar energy to drive turbines for generating power. The structures can assume different forms, some intended to operate only from wind power. All in common, however, have lower air intake means which can accept the wind from any direction, air passageways that conduct the air upward through turbines, and venturi-assisted upper air exhaust vents which discharge the air downwind. Structures intended to operate on solar power in addition to wind have generally transparent sun-facing outer surfaces to admit solar radiation into the air passageways, a heat absorbing and transferring means inside the air passageways, and sufficient height that the solar heated air will rise with adequate velocity to operate the turbines. The invention includes an air inlet louver configuration which permits free entry of normal winds, but restricts entry of winds that have excessive force.

Prediction of direct gain solar heating system performance

Abstract: General design methods for building-integrated (passive) solar heating systems are needed to evaluate the effects of design parameters on building energy needs. For collector-storage walls, the Resistance Network Method and the Solar Load Ratio Method are available. For direct gain systems, however, the Solar Load Ratio Method is limited in the scope of system parameters which can be considered; it does not allow the examination of the effects of house capacitance, allowable room temperature swing, or alternative high and low room thermostat set point temperatures. A more general design method for direct gain systems is presented.

Method of manufacturing a solar cell panel

Abstract: The photovoltaic cells (6) are retained and protected by a transparent elastomer layer (12) extruded when hot prior to vulcanization and applied against the cells with a slight pressure to cause it to go into the spaces between cells, and vulcanized by heating, for example at 110° C. or at 180° C., thanks to the presence of incorporated peroxides. Application in the production of electricity from solar energy.