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Showing papers on "Solar energy published in 1988"


Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of roughness elements on the heat transfer rate and friction in a flat-plate solar air heater duct with small diameter protrusion wires on the absorber plate.

414 citations


Journal ArticleDOI
TL;DR: In this paper, the regression coefficients of Angstrom type correlations for predicting monthly mean daily global solar radiation on a horizontal surface were developed to estimate regression coefficients in terms of the latitude, elevation, and percent of possible sunshine.

187 citations


Journal ArticleDOI
TL;DR: In this article, the authors used a compound parabolic concentrator to increase the solar radiation coupled into the laser rod, and showed that existing laser materials with broadband absorption characteristics (e.g. alexandrite and Nd:Cr:GSGG) have a potential for better than 10% overall conversion efficiency when solar-pumped.
Abstract: Results are presented for direct solar pumping of a Nd:YAG rod laser. Stable CW output of more than 60 W was obtained with a slope efficiency exceeding 2%. A compound parabolic concentrator, designed to increase the solar radiation coupled into the laser rod, was used in these experiments. The results are consistent with predictions based on a single solar-pumped laser model, which is also presented. Using this model, it is shown that existing laser materials with broadband absorption characteristics (e.g. alexandrite and Nd:Cr:GSGG) have a potential for better than 10% overall conversion efficiency when solar-pumped. >

150 citations


Book
31 Dec 1988
TL;DR: Salinity-gradient solar ponds are of interest as a means for collecting solar energy and storing it as heat for such low-temperature applications as space heating, industrial water heating, and crop drying as discussed by the authors.
Abstract: Salinity-gradient solar ponds are of interest as a means for collecting solar energy and storing it as heat for such low-temperature applications as space heating, industrial water heating, and crop drying Used in such applications, solar ponds may be significantly lower in cost than other solar collectors; and they combine at the same time the capability of long term storage In favorable sites where conventional fuel costs are unusually high, it is possible to use solar ponds for solar thermal power generation By far the largest solar ponds operated to date are those at the 5MW peaking power station at the north end of the Dead Sea in Israel Their intrinsic storage capability distinguishes solar pond power stations from other solar-electric systems

111 citations


Journal ArticleDOI
TL;DR: In this paper, an attempt is made for the generation of such a representative data set for the city of Athens mainly by following a method that has been proposed by Hall et al. This data set, which includes global solar radiation data and six other meteorological parameters referring to temperature, dew point, and wind velocity, has been characterized by Hall as a typical Meteorological Year.

105 citations


Book ChapterDOI
Rüdiger Memming1
TL;DR: In this paper, the progress in the field of solar energy conversion for the production of electricity and storable chemical fuels during the last decade is reviewed and the current-potential behavior of regenerative photovoltaic cells are derived and related to charge transfer processes at the solid/liquid interface.
Abstract: In the present paper the progress in the field of solar energy conversion for the production of electricity and storable chemical fuels during the last decade is reviewed. The current-potential behavior of regenerative photovoltaic cells are derived and related to charge transfer processes at the solid/liquid interface. Various cells are critically analyzed in view of their stability and conversion efficiency. A number of factors limiting the photovoltage are discussed in terms of a stabilization mechanism, trapping of minority carriers at the interface and the forward dark current. Concerning the production of chemical fuels the photocleavage of water and hydrogen sulfide, the reduction of carbon dioxide and the formation of ammonia is evaluated. The main emphasis is laid here on catalytic processes at semiconductor electrodes and particles. The principle function of catalysts being deposited on extended electrodes and particles are discussed in detail.

105 citations


Journal ArticleDOI
TL;DR: In this article, a computer simulation model of amorphous silicon solar cells using a Scharfetter and Gummel solution of Poisson's equation and Taylor and Simmons occupancy statistics for dangling bond gap states (D states), has been developed.
Abstract: A computer simulation model of amorphous silicon solar cells using a Scharfetter and Gummel solution of Poisson’s equation and Taylor and Simmons occupancy statistics for the dangling bond gap states (D states), has been developed. With a suitable choice of parameters, the numerical results for solar cell collection efficiency and dark and illuminated I‐V characteristics agree well with experimental values. The model has been used specifically to study the influence of interface states at the TCO‐p (transparent conductive oxide), p‐i, i‐n, and n‐metal interfaces and to explain the beneficial role of a graded‐band‐gap layer at the p‐i interface.

102 citations


Patent
19 Sep 1988
TL;DR: In this article, the authors presented a method of and apparatus for producing power from solar energy wherein a solar collector heats gas supplied to a gas turbine; compressors compress the gas, the gas being compressed and stored gas during a first period of time, with the stored compressed gas being supplied to the gas turbine during a second period to produce power by driving an electric generator.
Abstract: The present invention provides a method of and apparatus for producing power from solar energy wherein a solar collector heats gas supplied to a gas turbine; compressors compress the gas, the gas being compressed and stored gas during a first period of time, with the stored compressed gas being supplied to the gas turbine during a second period of time to produce power by driving an electric generator Preferably, the first period of time is during periods of off-peak electricity, which normally occur at night The second period of time is during the day The solar collector preferably comprises tracking reflectors for focusing solar radiation and a receiver for receiving the focused solar radiation and also heating the gas The solar radiation receiver preferably comprises a rotating ceramic member Furthermore, a combustion chamber is preferably provided to heat the gas entering the gas turbine and is operated by a temperature sensing/control unit when the solar radiation received by the receiver is insufficient to heat the gas entering the gas turbine to the required temperature The electric motor used to operate the compressors preferably comprises the electric generator of the gas turbine Furthermore, heat generated during the compression of the gas and contained therein is transferred to another fluid in a heat exchanger which comprises part of waste heat converter for producing electrical power therefrom

78 citations


Patent
29 Apr 1988
TL;DR: In this paper, a solar cell is disclosed wherein both the emitter and the base electrical contacts for a solar cells are disposed on the back major surface, and antireflection coatings are deposited on the front major layer.
Abstract: A solar cell is disclosed wherein both the emitter and the base electrical contacts for a solar cell are disposed on the back major surface Holes extend through the back major surface and the base layer to the emitter layer The walls of the holes are doped to the same conductivity as the front emitter layer Emitter contacts are deposited on the back major surface of the cell and extend into the holes making electrical contact to the emitter layer for collecting light generated current carriers The base contacts are also disposed on the back major surface, and antireflection coatings are deposited on the emitter front major layer Consequently, the front of the solar cell can be made smooth and therefore, a specularly reflective (non-scattering) solar cell results

72 citations


Journal ArticleDOI
TL;DR: In this article, an analysis of the stationary and sequential properties of daily global horizontal solar radiation, on a discrete monthly basis, is presented for a number of locations of widely varying climatic conditions.

70 citations


Journal ArticleDOI
TL;DR: In this paper, the energy balance equation on a solar collector is presented, which can be used to derive the approximate optimum operating condition for solar collectors, and it can be shown that two different collectors, an evacuated tubular collector and a flat-plate collector, have both nearly equal capabilities in exergy gain despite large differences in technological efforts and expenses to produce them.
Abstract: This paper presents the energy balance equation on a solar collector which acts as the fundamental and principal expression for the solar thermal design. The equation fully explains the exergy loss processes and can be used to derive the approximate optimum operating condition for solar collectors. Furthermore, using the equation, it can be shown that two different collectors, an evacuated tubular collector and a flat-plate collector, have both nearly equal capabilities in exergy gain despite large differences in technological efforts and expenses to produce them. In addition, ways for improvement for a solar collector are also discussed here briefly.

Journal ArticleDOI
TL;DR: A synopsis of work conducted over a number of years at the Solar Energy Research Institute (SERI) related to the validation of building energy analysis simulation programs can be found in this article.

Journal ArticleDOI
TL;DR: In this article, side-by-side experiments were conducted at the National Bureau of Standards to quantitatively evaluate the influence of flow rates, both for direct domestic hot water (SDHW) systems and for systems that employ an external heat exchanger to transfer heat from the solar collector array to the potable water.

Journal ArticleDOI
TL;DR: In this article, a simple one-dimensional model was developed for calculating the development of thermal structure in water bodies under specified meteorological conditions, as a function of their inherent optical properties (spectral absorption coefficients, scattering coefficient).
Abstract: A simple one-dimensional model has been developed for calculating the development of thermal structure in water bodies under specified meteorological conditions, as a function of their inherent optical properties (spectral absorption coefficients, scattering coefficient). Penetration of radiant solar energy is modeled with a previously derived equation relating attenuation of irradiance in narrow wavebands to absorption coefficient, scattering coefficient and solar angle. Evaporative and other heat exchange processes at the surface are taken into account. Vertical heat transfer is calculated by making use of a recently published parameterization of the eddy diffusion coefficient. The calculations show marked changes in thermal structure as absorption and scattering are varied over a range of optical water types from coastal seawater to highly colored and turbid inland water. In general terms, increasing the color and/or turbidity shifts the zone of shortwave energy absorption more toward the surface and leads to warmer but shallower mixed layers.

Journal ArticleDOI
TL;DR: In this paper, the authors presented numerical optimization of different types of collectors for maximizing the net exergy flow gained within a solar collector, the collector configuration can be optimized with regard to high useful heat and low friction losses.

Journal ArticleDOI
TL;DR: In this paper, the performance of silicon solar cells based on a novel, laser grooved, buried contact approach is described, achieving energy conversion efficiency as high as 19.8% for cells of 12 cm2 area.
Abstract: Improvements in the performance of silicon solar cells based on a novel, laser grooved, buried contact approach are described. Independently confirmed energy conversion efficiencies as high as 19.8% are reported for cells of 12 cm2 area, as are the resistivity dependence of efficiency, spectral response data, and the results of laser beam induced current scans. The potential for further improvement is also discussed.

Journal ArticleDOI
W.A. Kamal1
TL;DR: In this paper, a single basin solar still is examined theoretically and experimentally, based on solving the time-dependent simultaneous energy equations for the water, basin and glass cover, proved to be accurate in predicting the effects of the saline water depth and insulation thickness, when the still cover angle is close to its annual optimum value.

Journal ArticleDOI
TL;DR: In this paper, perimeter recombination currents have been characterized for 0.5 cm square and 2 cm square p/n GaAs solar cells, and it was shown that perimeter recombinations dominates the n=2 dark current component of these high-efficiency solar cells.
Abstract: Perimeter recombination currents have been characterized for 0.5-cm-square and 2-cm-square p/n GaAs solar cells. Measurements show that perimeter recombination dominates the n=2 dark current component of these high-efficiency solar cells. The results also suggest that perimeter recombination will be substantial even in much-larger-area solar cells. Although little influence on open-circuit voltage is expected, perimeter recombination may adversely affect the cell's one-sun fill factor. Because of its importance to one-sun applications, recombination at the junction perimeter must be suppressed before GaAs solar cells approach their limiting conversion efficiencies. >

Patent
12 Dec 1988
TL;DR: In this article, the authors proposed an electronic system where a control circuit (RK) is provided between the solar collector, the consuming device, and an electrical energy storage device (C1).
Abstract: In order to provide the required electric power uninterruptedly to an electrical or electronic consuming device (M) powered by solar cells (1, 2, 3, 4), the supply of power to the consuming device must be assured even under inadequate illumination conditions and/or during brief failures of the solar collector (S), an electronic system is proposed wherein a control circuit (RK) is provided between the solar collector (S), the consuming device (M), and an electrical energy storage device (C1). The control circuit (RK) functions at least as a connecting and commutating switching device which, subject to the priority of maintaining the operational readiness of the consuming device (M); provides various interconnections of the solar collector (S), the storage device (C1), and the consuming device (M). The control circuit (RK) makes these various connections in dependence on (1) the voltage (U S ) at the solar collector (S), (2) the voltage (U M ) required for operation of the consuming device (M), and (3) the state of charge of the storage device (C1). In this way, it is possible to maintain desired conditions (i.e., operation of the consuming device) during brief failures of the solar collector (S) when the illumination is inadequate. At the same time a situation can be avoided wherein the consuming device (M) can only receive adequate electric power after the capacitor (C1) has been charged to the specified operating voltage (U M ) of the consuming device by the solar collector (S). Thus, the invention makes it possible to avoid the drawbacks of previously known solar power delivery circuits and at the same time enables optimum utilization of the incident light as an energy source for electrical consuming devices.

Journal ArticleDOI
TL;DR: A solar radiation measurement plan is being considered for New York State that seeks to minimize costs by deploying a network of rotating shadowband radiometers that perform three basis solar measurements with a single detector.

Proceedings ArticleDOI
01 Jan 1988
TL;DR: The best n/p cell achieved an efficiency of 28.1% around 400 suns, and the best p/n cell achieved a performance of 27.5% around 1000 suns as mentioned in this paper.
Abstract: AlGaAs/GaAs heteroface solar concentrator cells which exhibit efficiencies in excess of 27% at high solar concentrations (>400 suns, AM1.5D, 100 mW/cm/sup 2/) have been fabricated with both n/p and p/n configurations. The best n/p cell achieved an efficiency of 28.1% around 400 suns, and the best p/n cell achieved an efficiency of 27.5% around 1000 suns. The high performance of these GaAs concentrator cells compared to earlier high-efficiency cells was due to improved control of the metal-organic chemical vapor deposition growth conditions and improved cell fabrication procedures (gridline definition and edge passivation). The design parameters of the solar cell structures and optimized grid pattern were determined with a realistic computer modeling program. An evaluation of the device characteristics and a discussion of future GaAs concentrator cell development are presented. >

Patent
25 May 1988
TL;DR: A solar lighting device for garden or driveway according to this invention transforms solar energy into electric energy using a solar energy absorbing plate and stores the electric energy into an electric battery A light sensor turns on the lighting circuit during dark hours as discussed by the authors.
Abstract: A solar lighting device for garden or driveway according to this invention transforms solar energy into electric energy using a solar energy absorbing plate and stores the electric energy into an electric battery A light sensor turns on the lighting circuit during dark hours The solar lighting device of this invention comprises a solar energy absorbing plate, a shell, an electric battery, a focusing reflector, a lens, and a set of connecting links The shell has two openings, one opening is inclined with respect to the shell and adapted for the insertion of the solar energy absorbing plate The other opening is for inserting the lens The shell holds an electric battery, a board, and a focusing reflector Also the solar energy absorbing plate engages with the inclined opening of the shell using lugs formed on the rim of the plate, and the frame of the lens is pivotally mounted on the other opening of the shell

Journal ArticleDOI
TL;DR: The efficiency with which the two-stage solar concentrator concentrated 55 W of sunlight to a small spot suggests that the system would be an excellent candidate for solar pumping of solid state lasers.
Abstract: Measurements are reported of the irradiance produced by a two-stage solar concentrator designed to approach the thermodynamic limit. Sunlight is collected by a 40.6-cm diam parabolic primary which forms a 0.98-cm diam image. The image is reconcentrated by a nonimaging refracting secondary with index n = 1.53 to a final aperture 1.27 mm in diameter. Thus the geometrical concentration ratio is 102, 000. The highest irradiance value achieved was 4.4 +/- 0.2 kW cm(-2), or 56,000 +/- 5000 suns, relative to a solar disk insolation of 800 W m(-2). This is greater than the previous peak solar irradiance record by nearly a factor of 3, and it is 68% of that existing at the solar surface itself. The efficiency with which we concentrated 55 W of sunlight to a small spot suggests that our two-stage system would be an excellent candidate for solar pumping of solid state lasers.

Journal ArticleDOI
TL;DR: In this paper, the effect of oxygen, which is unintentionally incorporated into AlGaAs films during epitaxial growth, on solar cell characteristics was investigated using molecular beam epitaxy, and it was found that oxygen concentration strongly influences minority carrier diffusion length and that solar cell efficiency greatly decreases as oxygen concentration increases.
Abstract: The effect of oxygen, which is unintentionally incorporated into AlGaAs films during epitaxial growth, on AlGaAs solar cell characteristics is investigated using molecular‐beam epitaxy. It is found that oxygen concentration strongly influences minority‐carrier diffusion length and that solar cell efficiency greatly decreases as oxygen concentration increases. A model to describe the effect of oxygen on solar cell characteristics is suggested.

Patent
28 Nov 1988
TL;DR: In this article, an integrated combustor/heat exchanger is coupled to the power conversion unit for heating the working fluid during periods of solar eclipse and giving off a water combustion product in the form of water vapor.
Abstract: A solar power system includes a solar concentrator and a power conversion unit for converting direct solar energy from the concentrator to electrical energy to power appropriate loads. The power conversion unit operates through the medium of a working fluid, such as a turbo-generator. An integrated combustor/heat exchanger is coupled to the power conversion unit for heating the working fluid during periods of solar eclipse and giving off a water combustion product in the form of water vapor. An electrolyzer receives the water combustion product and regenerates the product to gaseous hydrogen and oxygen. The electrolyzer is coupled to the power conversion unit as to be powered thereby during the periods of excess electrical energy. The regenerated hydrogen and oxygen is used in the integrated combustor/heat exchanger during periods of solar eclipse.

Journal ArticleDOI
TL;DR: In this paper, the authors presented a model and computer simulation results of the distributed collectors field of a solar power plant located in Tabernas (Almeria - Spain) using 100 lumped parameter submodels.

Patent
21 Nov 1988
TL;DR: In this article, the authors describe a steam broiler as a part of a stationary electrical facility power plant or a vehicle propulsion system, which produces electric current which powers an electrolysis unit and a cryogenic cooling unit.
Abstract: Solar energy produces electric current which powers an electrolysis unit and a cryogenic cooling unit. Gaseous hydrogen and gaseous oxygen are liquified in the cooling unit and pumped into cryogenic transport vehicles (railroad cars or highway trailers). An end user of the liquids has a boiler and vaporizing equipment for burning the reactants (H 2 and O 2 ) to produce electrical energy or mechanical power. The broiler may be part of a stationary electrical facility power plant or part of a vehicle propulsion system.

Journal ArticleDOI
TL;DR: In this article, the results of a series of demonstrative laboratory experiments simulating the possible instabilities in density-gradient solar ponds that can be induced by absorption of sunlight on the sun-facing wall are reported.

Journal ArticleDOI
TL;DR: The Reverse Flat Plat Collector (RFPC) as mentioned in this paper is a low-power, stationary, nonevacuated, low-technology, medium-temperature solar collector that is a promising alternative for intermediate temperature thermal needs (100/sup 0/C).
Abstract: The design, analysis, construction and testing of a novel solar collector is reported. The Reverse Flat Plat Collector (RFPC) is intended to be a stationary, nonevacuated, low-technology, medium temperature solar collector - a promising alternative for intermediate temperature thermal needs (100/sup 0/C

Journal ArticleDOI
TL;DR: In this article, a detailed analysis of the heat transfer and fluid flows within direct thermosyphonic solar energy water heaters has been undertaken, and the collector energy equations were cast in a two-dimensional form in order that the heat and thermal capacitance effects can be simulated accurately at the small flow rates encountered commonly in these buoyancy-driven systems.
Abstract: A detailed analysis of the heat transfers and fluid flows within direct thermosyphonic solar energy water heaters has been undertaken. The collector energy equations were cast in a two-dimensional form in order that the heat transfer and thermal capacitance effects can be simulated accurately at the small flow rates encountered commonly in these buoyancy-driven systems. The use of an appropriate nonisothermal friction factor correlation when calculating energy losses in the collector's riser pipes, produced predicted flow rates which were corroborated to within 2 percent by the values measured under steady flow conditions. For the laminar flow rates and the store configuration investigated, relaxation of the thermocline was shown to be dominated by axial conduction in the store walls. An indoor test facility, monitored and controlled by a microcomputer, enabled ''real'' operating conditions to be simulated. The predicted responses of the system to identical conditions showed good agreement with the corresponding experimental observations, the predicted heat delivery being within 2.8 percent of that measured.