Showing papers on "Solar energy published in 1995"
TL;DR: In this article, a detailed physical model of a hybrid photovoltaic/thermal system is proposed, and algorithms for making quantitative predictions regarding the performance of the system are presented.
338 citations
TL;DR: In this paper, a mathematical model and solution procedure for predicting the thermal performance of single-pass solar air collectors is presented, where the surface temperatures of the walls surrounding the air streams were assumed uniform whereas the air temperatures were assumed to vary linearly along the collector.
209 citations
TL;DR: In this article, the authors present a system which combines thermal and photovoltaic systems in one unit, which is basically a conventional forced circulation type water heater, and the system equations are solved by a finite difference method.
201 citations
TL;DR: The fabrication and characteristics of a number of the thin-film solar cell structures are discussed with emphasis on the thin film CdS CdTe solar cell in this paper, where the use of ZnO, ZnSe, and Cd1 − xZnxS as the window and use of CdTE and Cc 1 − x ZnxTe as the absorber are reviewed.
Abstract: With the exception of HgSe and HgTe, II–VI compounds are direct gap semiconductors with sharp optical absorption edge and large absorption coefficients at above bandgap wavelengths. Device quality polycrystalline films of II–VI compounds can be prepared from inexpensive raw materials by a number of low-cost methods. They are well-suited for thin film solar cells and provide an economically viable approach to the terrestrial utilization of solar energy. Thin film II–VI solar cells are usually of the heterojunction type consisting of a high bandgap window (or collector) and a lower bandgap absorber. The grain boundary effects in polycrystalline II–VI films are considerably less pronounced than those in III–V films and can be passivated, at least partially, by chemical treatment. The use of CdS, ZnO, ZnSe and Cd1 − xZnxS as the window and the use of CdTe and Cd1 − xZnxTe as the absorber are reviewed in this paper. The fabrication and characteristics of a number of the thin film solar cell structures are discussed with emphasis on the thin film CdS CdTe solar cell.
185 citations
Patent•
14 Sep 1995
TL;DR: In this paper, a self-steering heliostat is used to concentrate solar radiation onto an absorbing surface such as, or including, a solar cell array 1511 capable of absorbing power from the radiation, meanwhile removing heat (such as from long-wave infra-red radiation or resistive losses) from the surface with fluid heat transfer means 1503, 1504, then making effective use of that low-grade heat.
Abstract: A solar concentrator for producing usable power as heat and/or electricity uses a self-steering heliostat 1502 to concentrate solar radiation 1509 onto an absorbing surface such as, or including, a solar cell array 1511 capable of absorbing power from the radiation, meanwhile removing heat (such as from long-wave infra-red radiation or resistive losses) from the surface with fluid heat transfer means 1503, 1504, then making effective use of that low-grade heat. Thus the solar cell array is kept relatively cool and a larger proportion of the solar energy incident on the reflector unit is used. The invention uses electricity 1506 from the solar cells to move a transporting fluid through a heat exchanger 1504. Excess electricity may be available for local storage or use 1510, or feeding 1512 to the power distribution grid. Applications include warming swimming pools 1501, heating hot-water supplies using excess electricity, or warming, lighting and ventilating open spaces.
164 citations
01 Jun 1995
TL;DR: In this article, the part-load behavior of a typical 30-MWe SEGS (solar electric generating systems) plant was studied using a detailed thermodynamic model, based on measurement results of an LS-2 Collector and accounting for various conditions of receiver tubes, lost mirrors and measured reflectivity.
Abstract: The part-load behavior of a typical 30-MWe SEGS (solar electric generating systems) plant was studied using a detailed thermodynamic model. As part of this analysis, a new solar field model was derived, based on measurement results of an LS-2 Collector and accounting for various conditions of receiver tubes, lost mirrors and measured reflectivity. A comparison was made of the model results to real plant conditions for a winter and summer day in order to test the accuracy of the model. The effects of bare tubes, different wind speeds, mirror reflectivity and other factors were studied showing, e.g., that heat losses due to wind are predicted to be very low. The comparison also shows that the model still lacks the capability to fully account for actual solar field conditions. The model was also compared to the SOLERGY model, showing differences between the assumptions used in both models. Finally different operating conditions of the plant were studied for a summer, fall, and winter day to provide a better understanding of how changing solar field outlet temperatures affect gross and net output of the plant. This clearly indicates that the lowest possible superheating temperature maximizes the gross electric output. On a net basis this conclusion is modified due to the high parasitics of the HTF (heat transfer fluid) pumps. It was found that the optimum operating strategy depends on the insolation conditions, e.g., different superheating temperatures should be chosen in summer, fall and winter. If the pressure drop in the solar field is reduced due to replacement of flex hoses with ball joints, increasing the HTF flow is more reasonable, so that at low isolation conditions the lowest possible superheating temperature also leads to the maximum net output.
150 citations
TL;DR: In this paper, a new integrated collector storage (ICS) concept for low-temperature solar heating of water is described, where solar energy is stored in a salt-hydrate phase change material (PCM) held in the collector and is discharged to cold water flowing through a surface heat exchanger located in a layer of stationary heat transfer liquid (SHTL), floating over an immiscible layer of PCM.
127 citations
TL;DR: In this paper, the combined thermal reduction of ZnO and reforming of CH4 has been thermodynamically and kinetically examined, and the reaction mechanism was found to be controlled by gas film diffusion in the Stokes regime.
127 citations
Patent•
03 Feb 1995
TL;DR: In this article, a solar energy concentrator is used to focus incident solar radiation upon both sides of a bifacial photovoltaic cell, which is designed to operate in conjunction with any one of the tracking systems currently available in the industry.
Abstract: A solar energy concentrator apparatus which simultaneously focuses incident solar radiation upon both sides of a bifacial photovoltaic cell. The concentrator apparatus includes a corrugated-shaped reflector sheet and an open-grid support structure. Bifacial photovoltaic cells are held in place by the open-grid support structure and are mounted either horizontally or vertically with respect to the plane of the reflector sheet. The cells are specifically positioned so as to receive solar radiation--either directly or by reflection--at 90° angles to their surfaces. The system is designed to operate in conjunction with any one of the tracking systems currently available in the industry whereby the apparatus is maintained at a 90° angle with respect to the angle of incidence of the sun.
104 citations
01 Jun 1995
TL;DR: In this paper, the authors present a user's manual that describes typical meteorological year (TMY) data sets derived from the 1961-1990 National Solar Radiation Data Base (NSRDB).
Abstract: This report is a user`s manual that describes typical meteorological year (TMY) data sets derived from the 1961-1990 National Solar Radiation Data Base. The TMY is a data set of hourly values of solar radiation and meteorological elements for a 1-year period. The intended use if for computer simulations of solar energy conversion systems and building systems. Section 1 of the manual provides general information about the TMYs; Section 2 lists the stations and provides station identifying information and classification; Section 3 details the contents of the TMY2 files and provides the hourly records of data values; Section 4 compares TMY2 with 30-year data sets; Appendices provide procedures used to develop TMYs and a table to convert SI data to other units.
98 citations
Patent•
18 Jan 1995
TL;DR: A fiber optical solar power generating system provides a tower outside a structure to be supplied with solar energy and on which a multiplicity of collectors is provided as mentioned in this paper, which carries the collected optical energy to the structure in which a photovoltaic and/or a light/heat transducing stack can be provided and to which light is distributed from the optical fiber trunk so that the transducers need not occupy large areas of the property.
Abstract: A fiber optical solar power generating system provides a tower outside a structure to be supplied with solar energy and on which a multiplicity of collectors is provided. An optical fiber trunk carries the collected optical energy to the structure in which a photovoltaic and/or a light/heat transducing stack can be provided and to which light is distributed from the optical fiber trunk so that the transducers need not occupy large areas of the property.
TL;DR: In this paper, a single basin solar still with galvanized iron sheets and an inclined glass cover was constructed for indoor steady state operation and the variation of basin temperature, glass temperature and evaporation rate were measured during both indoor and outdoor operation.
TL;DR: In this paper, a computer simulation model is presented for studying the steady-state performance of a multi-stage stacked tray solar still with a diffusion type, and the results obtained from the model using the modified heat and mass transfer relationships are in good agreement with the experiments.
TL;DR: In this paper, an experimental study was performed for a laboratory building in Trabzon, Turkey for space heating, and the results indicated that the dual-source system is the most convenient solar heat-pump configuration, but before installing a solar-assisted heatpum systems, a detailed economic analysis is needed.
TL;DR: In this paper, the seasonal changes in spectral solar radiation effects the output of photovoltaic modules, and the accumulated output of PV modules was confirmed as changing seasonally in the same way as seasonal solar radiation.
Patent•
24 Jul 1995
TL;DR: In this paper, an array of photovoltaic cells for converting solar energy to electrical energy located within the enclosure, and a plurality of interconnected heat collecting tubes was disposed on the same plane as the array.
Abstract: Apparatus for converting solar energy to thermal and electrical energy including a substantially unsealed enclosure, an array of photovoltaic cells for converting solar energy to electrical energy located within the enclosure, and a plurality of interconnected heat collecting tubes located within the enclosure and disposed on the same plane as the array of photovoltaic cells for converting solar energy to thermal energy in a fluid disposed within the heat collecting tubes.
Patent•
17 Feb 1995
TL;DR: In this article, a solar energy collecting device is mounted on an automobile for exposure to solar energy, and an energy supply mechanism that routes energy collected by the solar energy collection device to the auxiliary motor device.
Abstract: In an automobile having a primary engine fueled by a primary source of fossil fuel energy, the primary engine and an auxiliary motor device are drivably connected to one or more ground engagement wheels of the automobile. A solar energy collecting device is mounted on the automobile for exposure to solar energy, and has an energy supply mechanism that routes energy collected by the solar energy collecting device to the auxiliary motor device. A control mechanism operates so that either energy is routed from the energy supply device to the auxiliary motor device, or energy is prevented from being routed to the auxiliary motor device.
TL;DR: In this paper, the authors proposed a new method for calculating the Angstrom turbidity coefficient based on the ratio of direct solar radiation to global solar radiation on a horizontal surface and on the “C” model of Iqbal.
Patent•
TL;DR: In this paper, a solar collector includes a base having a fixed portion and a rotatable portion and having a movable housing mounted to the rotatable part of the base so that the solar collector housing can be rotated and moved up and down to aim the collector face towards the sun.
TL;DR: In this paper, a mathematical model and a solution procedure for predicting the thermal performance of four types of single-pass flat-plate solar air collectors were presented, instead of resorting to complicated algebraic manipulations to solve the energy equations a matrixinversion technique was employed.
Patent•
12 Apr 1995
TL;DR: In this article, an aqueous dispersion of carbonaceous material is injected into a reactor in the form of a shower or a jet of droplets, and the droplets are allowed to sink inside the reactor across a high-temperature focal zone projected into the reactor by means of a system for the concentration of solar radiation.
Abstract: Use of solar energy for the production of synthesis gas from carbonaceous material. An aqueous dispersion of carbonaceous material is injected into a reactor in the form of a shower or a jet of droplets, and the droplets are allowed to sink inside the reactor across a high-temperature focal zone projected into the reactor by means of a system for the concentration of solar radiation. The residence time inside the reactor is adjustable by means of a countercurrent gas flow or by the injection of two or more discrete droplet jets in an impinging jet arrangement.
Patent•
[...]
TL;DR: In this article, the authors proposed a simple solar energy system of simple construction capable of utilizing the photovoltaic source always at a high efficiency without being affected by environmental changes or yearly declination of photivoltaic cell, etc.
Abstract: The object of the prevent invention is to provide a solar energy system of simple construction capable of utilizing the photovoltaic source always at a high efficiency without being affected by environmental changes or yearly declination of photovoltaic cell, etc. A solar energy system S provided, between photovoltaic array P constructed by connecting at least two photovoltaic arrays PL, PR of identical characteristics in parallel and a lead L to which the electric energy of the photovoltaic array P is supplied, with a detecting circuit NC for detecting the operating point of the photovoltaic array P, characterized in that the detecting circuit MC is provided with current limiting elements DL, DR with different voltage drops in forward direction connected in series to each of the two photovoltaic arrays PL, PR and that the system calculates the power of the two photovoltaic arrays PL, PR by detecting the terminal voltages of the two photovoltaic arrays PL, PR by means of those current limiting elements DL, DR and detects the operating point of the photovoltaic array P from the difference of power (or differential current) between the two photovoltaic arrays PL, PR.
TL;DR: In this paper, the authors deal with the optimization of design and operational parameters of a rock bed thermal energy storage device coupled with a two pass single cover solar air heater, i.e., charging time (⊖), rock bed size (flow length, H), and cross-sectional area for square cross section (AR), rock size (DR), air mass velocity per unit bed crosssectional area (G), and void fraction (ϵ), and investigate the effects of the above parameters on the total energy stored and the cost per unit energy stored in the rock bed for
01 Dec 1995
TL;DR: In this paper, an analytical model for radiative heat loss was developed and compared with two other methods used to determine radiative Heat loss, including a proposed convective heat loss correlation, including effects of aperture size, receiver operating temperature, and receiver angle.
Abstract: Cavity type receivers are used extensively in concentrating solar thermal energy collecting systems. The Solar Total Energy Project (STEP) in Shenandoah, Georgia is a large scale field test for the collection of solar thermal energy. The STEP experiment consists of a large field array of solar collectors used to supplement the process steam, cooling and other electrical power requirements of an adjacent knitwear manufacturing facility. The purpose of the tests, conducted for this study, was to isolate and quantify the radiative, conductive, and convective components of total heat loss, and to determine the effects of operating temperature, receiver angle, and aperture size on cavity heat loss. An analytical model for radiative heat loss was developed and compared with two other methods used to determine radiative heat loss. A proposed convective heat loss correlation, including effects of aperture size, receiver operating temperature, and receiver angle is presented. The resulting data is a source to evaluate the STEP measurements.
TL;DR: In this article, the theoretical feasibility of a solar energy based desalination scheme is analyzed in terms of the vapor pressure difference between fluids of different salinities and temperatures to produce fresh water from seawater.
TL;DR: In this article, the authors evaluate the energy consumption in solar photovoltaic (SPV) module production in India and examine its implications for large-scale introduction of SPV plants in the country.
Abstract: The objective of this article is to evaluate the energy consumption in solar photovoltaic (SPV) module production in India and examine its implications for large-scale introduction of SPV plants in the country. Data on energy used in SPV production were collected from existing manufacturing facilities in the country. The energy payback period turns out to be approximately 4 years. This is comparable to energy payback periods of similar modules produced internationally. However, if an ambitious program of introducing SPV power production is undertaken to contribute substantially to the power scenario in the country, an annual growth rate beyond 21% will render the program an energy sink rather than an energy source, as borne out by dynamic energy analysis. Policy implications are also discussed in light of this analysis.
TL;DR: In this article, the authors investigated the effect of site, technological and economical parameters on the cost effectiveness of large solar desalination systems and found that only for very low specific solar field cost and/or high commercial electricity prices would the fully solar options be more cost competitive than the partial solar options.
TL;DR: In this paper, the effect of water turbidity on the thermal performance of a salt-gradient solar pond was studied using a one-dimensional theoretical model using an empirical correlation that includes the effects of water clarity on solar radiation penetration in water.
01 Mar 1995
TL;DR: In this article, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system and the properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation.
Abstract: A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorbances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient. The method has been applied to one of the most optically complex systems in common use, a venetian blind in combination with multiple glazings. A comparison between the scanner-based calculation method and direct system calorimetric measurements made on the LBL MoWiTT facility showed good agreement, and is a significant validation of the method accuracy and feasibility.
Patent•
30 Jan 1995
TL;DR: An improved solar energy collector comprising a heat absorber to take in radiant energy and transfer the radiant energy to a heat transfer fluid carried by a transparent jacket is described in this paper, where the jacket is used to hermetically seal the jacket and to form a chamber about the heat absorbing fluid.
Abstract: An improved solar energy collector comprising a heat absorber to take in radiant energy and transfer the radiant energy to a heat transfer fluid carried thereby A transparent jacket is to receive the heat absorber therein The jacket will allow the radiant energy to pass therethrough and reach the heat absorber Components are for hermetically sealing the jacket and to form a chamber about the heat absorber A facility is for allowing the heat transfer fluid to enter and exit from the heat absorber A structure is for exhausting air out of the chamber, so as to produce a vacuum between the jacket and the heat absorber and to insulate the heat absorber from an external environment