Showing papers on "Photovoltaic thermal hybrid solar collector published in 1993"

Hybrid solar central receiver for combined cycle power plant

Abstract: A hybrid combined cycle power plant including a solar central receiver for receiving solar radiation and converting it to thermal energy. The power plant includes a molten salt heat transfer medium for transferring the thermal energy to an air heater. The air heater uses the thermal energy to preheat the air from the compressor of the gas cycle. The exhaust gases from the gas cycle are directed to a steam turbine for additional energy production.

The production of hydrogen from solar radiation at high efficiency

Abstract: A method of producing hydrogen comprising, converting solar radiation into thermal energy and electrical energy, and using the thermal energy and the electrical energy for producing hydrogen and oxygen by electrolysis of water.

Solar Photovoltaic Air Conditioning of Residential Buildings

Abstract: The use of photovoltaics (PV) for residential air conditioning (AC) represents an attractive application due to the close match between the diurnal cooling load and the availability of solar radiation. Conventional wisdom suggests that air conditioning is a process too energy intensive to be addressed by PV. Previous investigations have concentrated on the feasibility of matching PV output to vapor-compres sion machines, and the cost effectiveness of other solar cooling options. Recently, Japanese manufacturers have introduced small (8,000 Btu/hr) grid-connected solar assisted AC systems. These small room-sized systems are inadequately sized to meet air conditioning peak demands in larger U.S. homes of conventional construction practice. Previous studies considering the use of PV for solar cooling have treated the building thermal load as a fixed quantity. However, the large initial cost of PV systems ($6-$10/W peak) makes minimization of the building loads highly desirable. This paper describes a novel approach whereby the building, air conditioning and PV systems are simultaneously optimized to provide maximum solar cooling fraction for a minimum array size. A detailed hourly building energy simulation in a hot-humid climate is used to assess methods of reducing the building sensible and latent cooling loads to a practical minimum. A detailed PV system simulation is used to determine the match of the array output to that of the building’s peak loads. The paper addresses several key elements that influence the concept’s feasibility and potential economic attractiveness.

The PV/hydrogen/oxygen-system of the self-sufficient solar house Freiburg

Abstract: Solar radiation is the only energy source to supply the inhabitants of the self-sufficient solar house (SSSH) with heat and electricity. The house has no grid connection, no auxiliary fossil fuels are used. The transparent insulation of the southern building walls is the solar space heating system. A bifacially illuminated flat plate collector provides the domestic hot water. A PV generator of 4.2 kW provides all the electrical power for appliances and the control system and indirectly hydrogen gas for cooking. For short-term energy storage there is a lead-acid battery. For long-term storage (summer to winter), an electrolyser is used, which produces hydrogen and oxygen. In winter the gases are either transformed into electricity for electrical appliances by a fuel cell or used directly for cooking. The household is equipped with commercially available energy-efficient electrical appliances for 230 V AC. The construction of the house was completed in October 1992 after 3 years of research, planning and design. The first results show a good agreement with the simulation results. >

Development and fabrication of a hybrid holographic solar concentrator for concurrent generation of electricity and thermal utilization

Abstract: The efficiency of photovoltaic generators that are based on different semiconductor materials with optimized band-gaps can achieve considerably higher values than those obtained from single junction devices, e.g. Si-based solar cells. Hence, the splitting of the solar spectrum for use with the different band-gap cells is a desired characteristic of the solar collector. An enhanced efficiency is realized with the concentration of the incident solar radiation onto the corresponding solar cell. The optical characteristics of the holographic solar concentrator satisfy these requirements. The undiffracted solar radiation should be collected by an absorber that also cools the solar cells. This is the concept of the hybrid collector for electricity and thermal utilization that is presented in this paper. It can achieve an electrical efficiency above 22% and a thermal efficiency of 35% with a temperature of 100 degree(s)C.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Apparatus for obtaining electricity and heat

Abstract: The invention relates to an apparatus (1) for obtaining electrical energy and heat, in which a solar collector (2) is combined with a photoelectrochemical cell (3) or a solar cell (3) to form a unit (4) and the heat obtained by the solar collector (2) can be supplied together with the heat obtained by a heat pump (5) to a heat accumulator (6). To control the heat pump (5), provision is made for a control device (7) which, together with the heat pump (5), receives its electric potential from the photoelectrochemical cell (3) or the solar cell (3).

On Second-Law Efficiency of Solar Collectors

Abstract: Traditionally, the performance of solar collectors has been examined from the standpoint of energy-balance approach (Hahne, 1985; Francy et al., 1985; Lund, 1985; Satyamurty, 1985; Proctor, 1984a; Proctor; 1984b; Proctor, 1984c). It is important to note that this approach gives a very poor indication of how well a particular energy resource is being utilized by a given system to accomplish a specific objective. For example, it is difficult to examine the performance of solar thermal collectors versus solar-photovoltaic panels, strictly based on the first law of thermodynamics. A photovoltaic panel having ten percent first-law efficiency may be better than a solar collector converting 50 percent of useful energy by raising the water temperature from 30 to 50 C. Thus, it has been necessary to resort to the second law of thermodynamics for evaluation of solar systems, particularly collection devices. The second-law efficiency addresses the quality of energy. The quality of energy may be defined as its available portion; that portion which may be used for producing shaft work. It is important to note that the energy be conserved, but the manner in which energy is used must be examined. To use high quality energy for low-quality energy tasks is wasteful.more » This type of indication can only be examined from the second-law point of view. In this paper, measurements obtained from an experimental solar collector test facility are presented. Analysis of the performance of two flat-plate thermal solar collectors and one photovoltaic panel are analyzed based on both the first and second law of thermodynamics. The measurements presented, indicate very low second-law efficiency (maximum of 17 percent for photovoltaic panel and 11 percent for solar thermal flat-plate collectors), but are merely used as a vehicle for discussion.« less

Coupling light to solar cells

Abstract: Efficiencies over 33% have been achieved today in the photovoltaic conversion of solar energy into electricity. Part of this achievement is due to a effective coupling of the sunlight to the solar cell. In particular three aspects of the light-cell coupling are studied here: (1) the achievement of high irradiance on the cell; that is, the study of concentration, (2) the increase of the absorption in the cell and (3) the matching of the sun spectrum to the cell, with the use of several cells or thermo-photovoltaic devices. Finally, the ultimate limits of the efficiency of solar cells and photovoltaic devices in general, are studied. It is found that efficiencies in the range of 85% (depending on the spectrum of the sun) are theoretically possible. Also the conditions for thermodynamically reversible operation are analyzed. Some laboratory results are presented and the role of the light-cell coupling in the achievement of this high efficiency is stressed. 70 refs., 30 figs., 6 tabs.

System for cultivating plant and generating electricity with solar light

Abstract: PURPOSE: To provide a plant-cultivating and solar power-generating system capable of combining a plant cultivating system with a solar power-generating system and muturally compensating between them. CONSTITUTION: A prescribed ground surface 6 is covered with a panel 2 comprising solar batteries 4 faced to the sun and diffusive lenses such as fresnel lenses 3 for diffusing the solar light, the solar batteries 4 and the diffusion lenses 3 being arranged in a prescribed area ratio. The area ratio of the solar batteries 4 to the diffusion lenses 3 in the panel 2 is determined by determining the arranging area of the diffusion lenses so that the quantity of the solar light reaching the ground becomes a quantity suitable for the photosynthesis of plants, and by arranging the solar batteries 4 in the remaining area. COPYRIGHT: (C)1994,JPO&Japio

Performance of a wickless heat pipe solar collector

Abstract: The wickless heat pipe solar collector has the advantage of high effective thermal conductance due to its exploitation of phase-change phenomena, and the advantage of solving the problems of flat-plate solar water heaters suck as scale formation (corrosion), cycle reversing (during the night), and freezing. The use of the heat pipe technology in solar collectors will not only solve these problems but also eliminate the effect of the daily and seasonal variation of the solar radiation on the collector performance. The purpose of this article is to obtain a comprehensive understanding of the thermal performance of a wickless heat pipe solar collector on the basis of heat-transfer analysis using R-11, acetone, or water as a working fluid at different charging pressures. Also the effect of angle of inclination and the effect of liquid fill on the performance of the wickless heat pipe solar collector were studied. The experimental results show that the maximum efficiency occurs at 45° tilt angle. The ...

Low-energy passive-solar students residences at Strathclyde University using transparent insulation

Abstract: This paper reports the monitoring of an innovative solar building in Glasgow. In particular the properties of the novel technology, transparent insulation (TI), and the use of electricity are quantified. A main result is that winter solar energy gain into the fabric of a building can be significant at higher latitudes, but only if other energy efficiency measures are taken, such as superinsulation and dense internal construction with large intrinsic thermal capacity. The successful demonstration of the novel and associated technologies has given much practical information for replication. In general the passive features for heat gain (eg the TI, orientation, insulation, thermal mass) are more effective than the active features (eg air-to-air heat recovery, automatically controlled blinds, heater controls).

Computer simulation and optimisation of solar heating systems for Cyprus

Abstract: This thesis reports the results of research into the modelling and simulation of solar water and space heating for Cyprus, and the investigation of the factors concerning the optimisation of such systems Further a number of design criteria, which can be used by consultants and designers of solar heating systems, have been established Five solar heating system configurations have been modelled using the component models of the TRNSYS programme They concern thermosyphon solar water heating systems, active solar water heating systems, solar space heating systems, combined solar water and space heating systems and solar assisted heat pump systems for space and water heating These models are used to simulate the thermal performance of the systems and investigate their cost effectiveness under the weather and socioeconomic conditions of Cyprus The results of the simulations have been used to identify the optimum design criteria for such systems in the Cyprus environment The design criteria that have been established are concerned mainly with the solar collector and the storage tank and they are key design factors for a solar heating system The design factors include the collector orientation and tilt angle, the collector to load factor which relates the collector surface area to the annual thermal load, the storage factor which relates the capacity of the storage tank to the collector size, the collector water flow flux, which relates the water flow rate through the collector with the collector area, and other criteria, which concern the auxiliary heat supply and the heat exchangers For space heating systems, in addition to the above factors, a new design criterion is introduced, the collector to floor area factor, which relates the collector area to the building floor area, while for domestic hot water systems, the collector to consumer factor is used to specify the collector surface area needed for each hot water consumer in the building This work has resulted in the publication of four papers in refereed International Journals and the presentation of three other papers at International Conferences A list of publications is included in the Appendices

Constant temperature solar water heater switch

Abstract: A constant temperature solar water heater switch, for operating a solar water heating element, using an electrical motor, and a water pump, the water pump pumping water from a water source to the solar water heating element, which uses the solar rays to heat the water, and then returning the water to the source. This system matches a solar PV panel to a compatible relay, using a variable resistance to adjust for desired operation of the system, in order to shut the system down when the sun is not shining directly, and sufficiently to heat the water in the solar heater element, in order to prevent cool water to re-enter the source. A manual electrical overide switch is provided for manual operation of the system, for manual operation, or, for preventative maintenance.

Performance and testing of large‐size solar water heater cum solar cooker

Abstract: The performance of a novel device has been tested. The device can be used as a collector cum storage type solar water heater during the winter, and, with minor adjustments, it can be used as a hot-box solar cooker. The device can provide hot water at 50–60°C in the evening, which can be maintained at 40–45°C until the following morning. It can also be used for cooking food for about 40 people. The efficiencies of the device as a solar water heater and as a solar cooker have been found to be 67.7% and 29.8%, respectively. The payback period varies between 1.64 to 5.90 years depending on the fuel it replaces. The payback periods are of increasing length with respect to the fuels firewood, coal, electricity, LPG and kerosene.

Concentrator arrangement for increasing efficiency when using solar power

Abstract: The invention describes novel techniques in the exploitation of solar power, which are specified by the following detials: a) The beams are deflected in the reflectors by an easily replaceable reflecting film. b) By using parabolic mirrors for concentrating virtually unlimited solar power on solar cells and/or solar collectors, their efficiency is considerably increased. c) By novel design and arrangement of the solar cells and solar collectors, which are each located at the focal points of the reflectors. d) Arrangement of a finite number of the reflectors on a mast with central solar tracking.

Energy Evaluation of Solar Photovoltaic Energy Systems.

Abstract: 太陽光発電の大規模導入を前提として, 多結晶シリコンとアモルファスシリコンの太陽光発電システムのエネルギー収支を検討した.本試算には, 開発中の技術の導入, 太陽電池セル製造プロセスの効率向上が仮定されている.系統連系することを仮定し, 蓄電設備を持たない集中配置型の発電所を建設する場合のエネルギーペイバックタイムは, 年間10MWの生産規模で, 多結晶では5.7年, アモルファスでは6.3年となった.100GWの場合は, さらに技術開発が進行すること, およびスケールアップ効果により, 多結晶で3.3年, アモルファスで3.0年となる.集中配置による太陽光発電システムでは, 発電所を建設するためのエネルギー投入量が大きく, 生産規模に応じた発電システムを構築することが重要である.

Simulation in High Efficiency Solar Cell Research

Abstract: The practical application of numerical device simulation in high efficiency silicon solar cell research is presented. Aspects of the design development and the characterization are discussed.

Strategies for solar fuel generation

Abstract: Solar production and use of fuels (hydrogen, reduced carbon compounds) is an integral part of any large scale solar energy strategy. Technically, the most promising pattern of implementation is the decentralised generation of photovoltaic energy on buildings, interconnection with the public electricity grid and centralized electrolytic generation of fuels. A complementary strategy could be solar electrochemical generation of simple inorganic energy carriers (e.g. Fe2+ from Fe3+) which serve as the energy source for bacteria (e.g.Thiobacillus ferrooxidans), which fix carbon dioxide via the Calvin cycle. Direct photo-electrochemical generation of solar fuels (in analogy to photosynthesis) is a complex frontier with many unsolved problems, some of which are discussed. The most promising route appears to be development of photoactive transition metal electrocatalysts, which are able to induce interfacial coordination chemical mechanisms. In addition it may be necessary to develop far-from-equilibrium electrochemical mechanisms to facilitate cooperative electron transfer processes during photocatalysis.

Evaluation of Photovoltaic Modules Considered Spectral Solar Radiation

Abstract: For optimum design of photovoltaic power systems, it is very important to estimate their annual maximum amount of output. In general, the annual maximum amount of output has been calculated by using photovoltaic module efficiency under irradiance of 1kW/m2 at AM 1.5 with solar cell temperature of 25°C. Since the spectral distribution of solar radiation changes with weather, season and time, the efficiency of solar cells is not always constant. This paper describs a method evaluating the maximum amount of output in photovoltaic modules, “the spectral method”, by using the measured annual spectral solar radiation and the spectral response of various photovoltaic modules.The calculated values using the spectral method agreed well with the measured values for amorphous silicon photovoltaic modules from March, 1991 to February, 1992. The spectral method proved most effective for optimum design of amorphous silicon photovoltaic power systems.

Optimal nonimaging integrated evacuated solar collector

Abstract: A non imaging integrated evacuated solar collector for solar thermal energy collection is discussed which has the lower portion of the tubular glass vacuum enveloped shaped and inside surface mirrored to optimally concentrate sunlight onto an absorber tube in the vacuum. This design uses vacuum to eliminate heat loss from the absorber surface by conduction and convection of air, soda lime glass for the vacuum envelope material to lower cost, optimal non imaging concentration integrated with the glass vacuum envelope to lower cost and improve solar energy collection, and a selective absorber for the absorbing surface which has high absorptance and low emittance to lower heat loss by radiation and improve energy collection efficiency. This leads to a very low heat loss collector with high optical collection efficiency, which can operate at temperatures up to the order of 250 degree(s)C with good efficiency while being lower in cost than current evacuated solar collectors. Cost estimates are presented which indicate a cost for this solar collector system which can be competitive with the cost of fossil fuel heat energy sources when the collector system is produced in sufficient volume. Non imaging concentration, which reduces cost while improving performance, and which allows efficient solar energy collection without tracking the sun, is a key element in this solar collector design.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High heat flux engineering in solar energy applications

Abstract: Solar thermal energy systems can produce heat fluxes in excess of 10,000 kW/m2. This paper provides an introduction to the solar concentrators that produce high heat flux, the receivers that convert the flux into usable thermal energy, and the instrumentation systems used to measure flux in the solar environment. References are incorporated to direct the reader to detailed technical information.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.