Showing papers on "Photovoltaic system published in 1986"

Starting and Steady-State Characteristics of DC Motors Powered by Solar Cell Generators

Abstract: The performance of dc motors (series, separately-excited, and shunt motors) powered by a solar cell generator and loaded by two different types of loads, one a constant load and one a ventilator load, were analyzed with respect to the transient (starting) and steady state operation. Direct current motors are employed in photovoltaic water pumping systems; therefore, the understanding of the system operation and the matching of the system components (solar cells, dc motor type, and load type) are important factors of the system design. Since the solar cell generator in a nonlinear and time-dependent power supply with an output that varies with the insolation (hourly and daily), the performance characteristics of the dc motor are different when supplied by a solar cell generator than when supplied by a conventional constant voltage source. The transient solution was obtained by using an available computer program - SUPER SCEPTRE. The separately - excited (or permanent magnet) motor with a ventilator load was found to be the most suitable for the solar cell generator. The series motor is quite acceptable, but the shunt motor gives poor performance. In all cases the ventilator load is more compatible with the solar cell generator than with the constant load.

A Linear Programming Approach to the Design of Integrated Renewable Energy Systems for Developing Countries

Abstract: Integrated renewable energy systems (IRES) which utilize different manifestations of solar energy to satisfy various energy needs are well suited for the remote rural areas of developing countries By employing a linear programming approach, this paper develops a methodology for the design of IRES The method is quite general and it minimizes an objective function of total annual cost, subject to a set of energy and power constraints A numerical example is included to illustrate the design procedure

Photovoltaic cell cover for use with a primary optical concentrator in a solar energy collector

Abstract: A solar energy collector including a primary optical concentrator, one or more solar cells and an improved solar cell cover design is provided. Each of the solar cells includes a flexible cell cover which significantly reduces optical losses due to gridline obscuration of active cell area and also due to reflection from the cover itself. The cover comprises an optically clear, flexible material, such as a silicone polymer, placed over the illuminated surface of each solar cell, with prisms formed on the outer surface of the cover such that incident sunlight is refracted by the prisms onto active cell area rather than partially onto non-active gridlines or conducting elements. Each of the prisms has a predetermined shape depending on the type of primary optical concentrator used in the solar energy collector.

Modular solar generating system

Abstract: A modular solar generating system is disclosed. The system includes a plurality of self-contained solar modules which are interconnectedly disposed in an array about the perimeter of a rigid framework housing a sign, light, or other load means necessitating electrical power during the night time hours. The modules themselves consist of a photovoltaic plate sandwiched between two suitable cover plates, including in this arrangement one or more continuous conductors. The modules are linked together by way of male and female plug connectors whereby the array may then be electrically connected to a battery. When the modular system is arranged in this fashion and exposed to incident sunlight for an appropriate period of time, power may be provided to a sign, light or other electrical apparatus for nighttime use.

Solar collector, transmitter and heater

Abstract: A Solar Power collector, sunfollower, power transmitter and receiver is described. The Solar power collector is a Cassegrain Reflector optical system mounted on a carriage travelling on a semicircular track. A small photovoltaic cell and rechargeable battery provide the power to position the collector. A computer, sensors, electronic circuit and two servomotors provides accurate alignment of the collector with the sun's rays during the day, and returns it to follow the sun again the next morning. Sun-power is preferably transmitted from the collector via a light-pipe to a cavity where it is converted to heat-power. The heat-power may be stored as heat energy in a phase change material at a suitable temperature for cooking or other uses, such as heat-electric power generation. A plurality of collector-sunfollowers may transmit light-power to a single cavity heat storage depot, from which heat-power may be supplied on demand to various utilities.

Self-charging solar battery.

Abstract: A self-charging battery comprising a rechargeable nickel-cadmium cell and a solar electric panel. Sunlight passing through the transparent housing excites the solar panel which then supplies recharging current to the nickel-cadmium cell.

Physics, technology, and use of photovoltaics

Abstract: Photovoltaic solar energy conversion is a field that has been researched since the 1950s and which now offers one of the most promising methods for dealing with our future energy needs. It is hoped that by the 1990s, manufacturing costs will have decreased sufficiently enough to make photovoltaics an economical, large-scale source of energy. This text deals with all aspects of the subject, introducing the reader to the physics of photovoltaic solar energy conversion with general considerations applying to all types of cells. This is followed by consideration of the device physics of the most important types including crystalline silicon cells and various thin-film structures. Much of the book is devoted to the technology of the different cells, and gives a basis from which the reader should be able to compare the different solar cell technologies and also to design photovoltaic systems. It concludes with discussions on testing of solar cells and modules, photovoltaic systems and existing applications.

Stowable large area solar power module

Abstract: A large area solar photovoltaic power module (30) comprises a plurality of flexible large area solar panels (32, 34, 36, 38) interconnected by a flexible hinge (42). The module may thus be folded and subsequently rolled into a compact, stowable cylindrical configuration.

Simplified Calculation of Solar Cell Temperatures in Terrestrial Photovoltaic Arrays

Abstract: A simplified algorithm to predict the average steady-state temperature of the solar cells in a photovoltaic array has been developed. The methodology can be applied to arrays on the roof (or walls) of buildings as well as on the ground. It is intended primarily for residential buildings, although it can be used for any type of building, and considers all four-array mounting systems (rack, stand-off, direct, and integral). Input parameters in this development include weather (insolation, ambient temperature, wind speed, humidity, and sky cloud cover), as well as building construction and operation characteristics. The photovoltaic array's geometrical, optical, and thermal properties are used in the analysis as well. Natural or forced convection under the solar panels and/or in the building attic below can also be accounted for by this model. The model has been partially verified against limited measured data and found to be in very good agreement for wind speeds of 1m/s or more.

Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final Report. Volume III: Silicon sheet: wafers and ribbons

Abstract: The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development. The primary objective of the Silicon Sheet Task of the FSA Project was the development of one or more low-cost technologies for producing silicon sheet suitable for processing into cost-eompetitive solar cells. Silicon sheet refers to high-purity crystalline silicon of size and thickness for fabrication into solar cells. The Task effort began with state-of-the-art sheet technologies and then solicited and supported any new silicon sheet alternatives that had the potential to achieve the Project goals. A total of 48 contracts were awarded that covered work in the areas of ingot growth and casting, wafering, ribbon growth, other sheet technologies, and programs of supportive research. Periodic reviews of each sheet technology were held, assessing the technical progress and the long-range potential. Technologies that failed to achieve their promise, or seemed to have lower probabilities for success in comparison with others, were dropped. A series of workshops was initiated to assess the state of the art, to provide insights into problems remaining to be addressed, and to support technology transfer. The Task made and fostered significant improvements in silicon sheet including processing of both ingot and ribbon technologies. An additional important outcome was the vastly improved understanding of the characteristics associated with high-quality sheet, and the control of the parameters required for higher efficiency solar cells. Although significant sheet cost reductions were made, the technology advancements required to meet the Task cost goals were not achieved. This FSA Final Report (JPL Publication 86-31, 5101-289, DOE/JPL 1012-125, October 1986) is composed of eight volumes, consisting of an Executive Summary and seven technology reports: Volume I: Executive Summary. Volume II: Silicon Material. Volume III: Silicon Sheet: Wafers and Ribbons Volume IV: High-Efficiency Solar Celis. Volume V: Process Development. Volume VI: Engineering Sciences and Reliability. Volume VII: Module Encapsulation. Volume VIII: Project Analysis and Integration. Two supplemental reports included in the final report package are: FSA Project: 10 Years of Progress, JPL Document 400-279. 5101-279, October 1985. Summary of FSA Project Documentation: Abstracts of Published Documents, 1975 to 1986, JPL Publication 82-79 (Revision 1),5101-221, DOE/JPL-1 012-76, September 1986.

Photovoltaic power control system

Abstract: There is disclosed a photovoltaic power control system equipped with at least one inverter for inverting an output of a solar cell array to AC power, and having charge-and discharge control means for charging a surplus portion with respect to the power for expected use of the output of the solar cell array to a storage battery and discharging shortage portion with respect to the power for expected use of the output of the solar cell array from the storage battery by detecting the surplus or shortage produced between the output of the solar cell array and AC power for expected use inverted by the inverter, the improvement comprising weather fluctuation pattern selection means for selecting one weather pattern out of various kinds of weather patterns preset based on weather information at a time point when the weather is forecasted on the day when the power is generated by the solar cell array; and workable pattern selection means for selecting one actuation pattern of the inverter corresponding to the weather pattern selected by the weather fluctuation pattern selection means out of various actuation patterns of the inverter preset corresponding to the weather pattern.

Solar array with aluminum foil matrix

Abstract: The disclosure relates to a method of making solar cell arrays and modules and the arrays and modules wherein the arrays are formed of semiconductor spheres of P-type interior having an N-type skin housed in a pair of aluminum foil members which form the contacts to the P-type and N-type regions The foils are electrically insulated from each other and are flexible Multiple arrays can be interconnected to form a module of solar cell elements for converting light energy into electrical energy

A High-Power High-Voltage DC-DC Converter for Space Applications

Abstract: The design details of a modular dc-dc converter used to power the main anode supply of a mercury-iron motor are presented. This motor, the RIT-35 built by Messerschmitt-BolkowBlohm (MBB), Germany, is used as the propulsion unit of a future Asteroid Gravity Optical and Radar Analysis (AGORA) mission. The design selected to cope with the high-voltage high-power conversion for space applications is shown, as well as the requirement to operate from an unregulated solar array with a voltage excursion of from 150 V at beginning-of-mission (BOM) to 240 V at end-of-mission (EOM).

Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final report. Volume VII: Module encapsulation

Abstract: The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development. The objective of the Encapsulation Task was to develop, demonstrate, and qualify photovoltaic (PV) module encapsulation systems that would provide 20-year (later increased to 30-year) life expectancies in terrestrial environments, and which would be compatible with the cost and performance goals of the FSA Project. The scope of the Encapsulation Task included the identification, development, and evaluation of material systems and configurations required to support and protect the optically and electrically active solar cell circuit components in the PV module operating environment. Encapsulation material technologies summarized in this report include the development of low-cost ultraviolet protection techniques, stable low-cost pottants, soiling resistant coatings, electrical isolation criteria, processes for optimum interface bonding, and analytical and experimental tools for evaluating the long-term durability and structural adequacy of encapsulated modules. Field testing, accelerated stress testing, and design studies have demonstrated that encapsulation materials, processes, and configurations are available that will meet the FSA cost and performance goals. Thirty-year module life expectancies are anticipated based on accelerated stress testing results and on extrapolation of real-time field exposures in excess of 9 years.

Modeling and simulation of spacecraft solar array deployment

Abstract: This paper presents the dynamic and digital simulation of the deployment of rigid solar panels on INTELSAT-V and INS AT spacecraft. Each spacecraft is characterized by very distinct mechanisms for its solar array deployment. The arrays on INTELSAT-V are in a topological tree configuration, while the INSAT arrays are in a closed-loop configuration because of the four-bar linkage deployment mechanism. It is shown that the kinematic control rod on the INSAT has a synchronizing function very similar to that of the closed cable loop on the INTELSAT-V spacecraft. Practical aspects of the modeling and simulation of complex deployment mechanisms are emphasized. The use and limitations of the DISCOS multibody code for deployment dynamics simulations are discussed, and the need for developing specialized simulation tools emphasized.

Circuit arrangement for feeding an electrical load from a solar generator

Abstract: A circuit arrangement for feeding an electrical load, solar generator provides that the current output by the solar generator has a prescribed ratio to the measured value which is a measure for the short-circuit current of the solar generator. Such a circuit arrangement has an optimally-high efficiency. This is achieved with comparatively low expense in that the short-circuit current of the solar generator is measured pulse-wise. The circuit arrangement can be employed with particular advantage for charging batteries in solar systems.

On the Development of the Solar Photovoltaic and Thermal (PVT) Collector

Abstract: The solar photovoltaic and thermal (PVT) collector is a device which converts solar energy into thermal and electrical energies simultaneously. The PVT collector can be used whenever both electricity and hot water are required, for example, for domestic uses. It is a known fact that the efficiency of the solar (photovoltaic) cells decreases as operating temperatures increase. Therefore, a better and a more efficient use of these cells, calls for cooling the cells. One method for doing that is to use a heat exchange system, which cools the cells by means of a heat absorbing medium, such as water, flowing in pipes. The heat removed from the cells results in hot water. Another advantage of the PVT collector is its higher overall efficiency per unit area and lower packaging costs due to its compact design. In this paper a theoretical analysis of the PVT collector using a simulation model is presented. In this model the PVT collector is divided into a matrix of ``small'' PVT collector units, each one consisting of several layers. The energy balance of each ``small'' PVT collector unit is studied by analysis of the energies entering and leaving each one of its layers. Later, the process is applied to the PVT collector itself. A PVT collector was designed and constructed and putthru a series of experiments under varying load conditions, insolation levels and other climatological conditions.

Solar energy focusing assembly and storage unit

Abstract: A power system heat source applicable to spacecraft and the like is realized in a combination of an integrated solar absorber-thermal storage assembly 10 and a solar energy focusing unit 50. The focusing unit is capable of selectively functioning inflatable pie-shaped wedges 60 which form a cover for the solar energy focusing unit to control collected radiation effectively and reliably.

Flexible solar skin in combination with an airplane

Abstract: A flexible solar skin which absorbs radiant solar energy to convert it into electricity, made possible through a conductive plastic, which conceals a conductive fiber, whereby the fiber directs generated electricity to a terminal in the form of a contact strip hemmed or fused alongside the material. Additionally, an air vehicle covered with this photovoltaic material to collect solar radiant energy during flight which is converted into electricity to assist the propulsion system of the vehicle.

Novel type of high-frequency link inverter for photovoltaic residential applications

Abstract: The paper demonstrates the possibility of utilising resonant convertor technology in the high-frequency link inverter configuration. In this system, an amplitude modulated high-frequency sinusoidal waveform is generated by a novel type of series resonant inverter allowing electric isolation through a high-frequency transformer. A complete description of the system is presented along with its control technique for interfacing a solar photovoltaic array with the utility line. Experimental results are included.

Parallel hybrid system for generating power

Abstract: An intermitently operable non-fuel-consuming power generator, such as a photovoltaic array or a wind generator, is connected through a control circuit to a battery for charging the same and supplying current to a time-wise substantially constant electrical load. An electrical generator, connected to an intermitently operable prime mover, charges the battery and supplies current to the electrical load when the prime mover is operated. A sensor circuit senses at least one electrical parameter, such as a failure of the power generator to produce current, for controlling the operation of the primer mover (i.e., starting of the prime mover). The sensor circuit also senses a second electrical parameter, such as the charge level of the battery. The prime mover is made operational only if the battery capacity is less than a predetermined threshold level when the power generator fails to produce current.

Optimization of a combined wind and solar power plant

Abstract: The paper is concerned with determining the optimized active areas of a photo voltaic conversion system, of a group of electricity generating wind machines and the optimal capacity of a battery storage system for a combined power plant. Minimization of the total life-cycle cost of the system is the criterion to obtaining the optimized parameters of the system. The algorithm consists of generating the system costs corresponding to various values of the parameters and to use these costs in a search procedure to determine the minimum. Each point is generated by a simulation program describing the system behaviour The purpose of the work described in this paper is the optimization of a combined solar/wind power plant. Electricity is generated by photovoltaic panels, by wind generators and eventually by diesel sets. This combined use of the renewable energy sources has been applied on the Greek island Kythnos. The existing system is equipped with a lead-acid battery storage system and a number of diesel generators. Previous work has described the characteristics of the system and the development of a simulation program (Samarakou and Hennet, 1985). The data obtained from the simulation indicated that an improvement of the system dimension could lead to decreasing the total life-cycle cost of the installation. The problems of frequency disturbances and of temporary unreliability of some devices are not considered in this paper because their effect on the system efficiency cannot systematically be attributed to one or another particular system component. The proposed optimization technique is a pseudo-gradient type search procedure which allows the global minimal cost to be found after a limited number of iterations. Each simulation is run hour by hour over a period of one year. It is a simplified version of the Kythnos plant simulation, generalizing the application either to autonomous systems or to systems integrated with other energy sources.

Status of research on the light-induced effect in a-Si materials and a-Si solar cells

Abstract: The light-induced change that occurs in hydrogenated amorphous silicon material (the Staebler-Wronski effect) can be observed in solar cells when cell efficiency drops rapidly in the initial stage of optical exposure and then exhibits a much slower decay or no subsequent change. Because long-term stability is important to photovoltaic systems, the light-induced effect must be resolved. This paper reports on the history and current status of investigations into the stability of a-Si material and a-Si solar cells.