Showing papers on "Photovoltaic thermal hybrid solar collector published in 2001"

The potential of solar energy use in desiccant cooling cycles

Abstract: The use of heat produced by solar thermal collectors is an interesting option for thermal driven air conditioning processes A thermal driven cooling technique which fits well to non-tracking solar collectors is the desiccant cooling technique Recently several projects have been carried out which focus on the connection of desiccant cooling systems with solar thermal energy for regeneration of the sorbents This communication deals with three main topics: (1) experiences achieved in a realized system which is coupled to a solar collector are discussed, (2) a new concept is presented, in which a solar air collector is integrated into the desiccant cooling cycle as the only heat source and (3) a comparative study is presented which compares system performance for different system configurations and different climatic situations

PV/thermal solar power assembly

Abstract: A flexible solar power assembly ( 2 ) includes a flexible photovoltaic device ( 16 ) attached to a flexible thermal solar collector ( 4 ). The solar power assembly can be rolled up for transport and then unrolled for installation on a surface, such as the roof ( 20, 25 ) or side wall of a building or other structure, by use of adhesive and/or other types of fasteners ( 23 ).

Solar collector for solar energy systems

Abstract: A solar collection system and method having means for receiving solar radiation through a main refractive interface and means for internally reflecting at least once, at least a portion of the received solar radiation The refractive medium may be liquid, gel or solid The device may be integrated with a photovoltaic device, photohydrolytic device, a heat engine, a light pipe or a photothermal receptor

Net energy analysis of solar and conventional domestic hot water systems in Melbourne, Australia

Abstract: It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions. Very rarely has the life-cycle energy requirements of solar hot water systems been analysed, including their embodied energy. The extent to which solar hot water systems save energy compared to conventional systems in Melbourne, Australia, is shown through a comparative net energy analysis. The solar systems provided a net energy saving compared to the conventional systems after 0.5 to 2 years, for electricity and gas systems respectively.

Automation and control of solar air conditioning systems

Abstract: A solar powered air conditioning system includes an absorption machine coupled to three primary loops. A heat loop provides energy to the absorption machine. A cooling tower loop exhausts heat from the absorption machine. A chilled water loop is used to draw heat from a room or building. The heat loop provides energy from a boiler and/or from a number of solar collectors. In one mode of operation, the solar collectors circulate through a storage tank. The flow through the solar collectors is regulated to maximize energy collection.

Thermodynamic theory of thermophotovoltaic solar energy conversion

Abstract: The thermophotovoltaic (TPV) efficiency is maximized by using three optimization parameters, namely, the absorber and PV solar cell temperatures and the voltage across the cell. Various combinations of spherical and (disk) plane absorbers and solar cells are analyzed. The best performance is associated with a combination plane absorber–plane solar cell. The thermal design has a significant influence on the optimum PV cell band gap. In the case of a normal thermal design, the cell temperature is usually high and depends strongly on the band gap. When a very good thermal design is considered, the optimum cell temperature is less than 30 degrees higher than the ambient temperature and decreases with an increase in the band gap. Increasing the ratio rA/rc between the absorber and PV cell radii leads to increased TPV efficiency. The optimum absorber temperature (practically) does not depend on rA/rc.

High-uniformity solar concentrators for photovoltaic systems

Abstract: Advances in Photovoltaic technology using multijunction cells allow sunlight-to-electrical energy conversion efficiencies of 25 percent with the potential of reaching 30 percent. The main drawback with these cells is their high cost. By using a concentrating Photovoltaic (CPV) solar collector, the area/cost of the cells relative to the total system area/cost can be reduced substantially. The design of CPV systems has one constraint not found in standard thermal solar concentrators, namely the target is square and the irradiance uniformity goal is very tight. A novel two-stage solar collector system designed for the National Renewable Energy Laboratory (NREL) is presented here. By tailoring the radial profile of the primary mirror that is slightly non-parabolic and using a straight square tube secondary, designs for concentrations between 100-2,000 suns can achieve uniformity under 3 percent and greater than 95 percent efficiencies. A design using a non-rotationally symmetric primary design is also presented, which reduces the problems with shading by spiders that attach the secondary to the primary mirror.

Solar energy and desalination

Abstract: Solar energy is used for desalination purposes in two forms: directly and indirectly. Direct solar desalination (solar distillation) uses solar stills that simultaneously capture and store solar energy. Indirect methods (solar powered or driven desalination) consist of two separate systems: The solar collection system and a conventional desalination system, mainly of small or medium capacity. In this paper the direct and indirect solar desalination methods are described and analyzed. A brief historical background of both is discussed and the most recent mathematical models for solar distillation are given. An effort is made to describe existing solar distillation plants and comment on solar stills operation.

Optimum design for residential photovoltaic‐thermal binary utilization system by minimizing auxiliary energy

Abstract: Possible designs for a self-sufficient residential binary solar energy include a side-by-side system, a PVT hybrid system, and a side-by-side PVT hybrid system. We designed and performed an annual performance simulation of three systems: PV with flat plate collector (PV/FPC), photovoltaic-thermal hybrid (PVT), and PV with photovoltaic-thermal hybrid (PV/PVT) including an electrical auxiliary heat pump. In this paper, the solar energy fraction (SEF) or auxiliary energy fraction (AUX) is used as a figure of merit for system evaluation. These indices are shown to be affected by the COP (coefficient of performance) of AUX and by the ratio of the DHW (domestic hot water) load to the annual synthetic load. The best results were achieved by the side-by-side PV/PVT hybrid system. Using PVT with PV leads to an improvement of the SEF or AEF compared with the PVT system alone. Glazing is found to be indispensable for the PV/PVT system with an AUX COP of 1, but is unnecessary for a PV/PVT system with a higher COP. © 2001 Scripta Technica, Electr Eng Jpn, 137(1): 28–35, 2001

Concentrating Solar Power: Energy from Mirrors

Abstract: This fact sheet explains how concentrating solar power technology works and the three types of systems in development today: trough, dish, and central receiver.

A hybrid power generation system: solar‐driven Rankine engine–hydrogen storage

Abstract: This paper reports on the feasibility of a hybrid power generation system consisting of a solar energy-driven Rankine engine and a hydrogen storage unit. Solar energy, the power for the hybrid system, is converted into electrical power through a combination of a solar collector, a tracking device to maintain proper orientation with the sun and a Rankine cycle engine driving an electrical power generator. Excess electricity is utilized to produce hydrogen for storage through electrolysis of water. At the solar down time, the stored hydrogen can be used to produce high-quality steam in an aphodid burner to operate a turbine and with a field modulated generator to supplement electric power. Case studies are carried out on the optimum configuration of the hybrid system satisfying the energy demand. A numerical example based on the actual measured solar input is also included to demonstrate the design potential. Copyright © 2001 John Wiley & Sons, Ltd.

Remote Solar, Wind, and Hybrid Solar/Wind Energy Systems for Purifying Water

Abstract: Solar energy, wind energy, and a combination of wind and solar energy have been used successfully to power an UV (ultraviolet) water purification system. Five different solar and wind energy systems have been tested and although these renewable energy systems have been used for water purification, graphs contained in the paper can be used to determine the feasibility of powering other electrical loads. Combining a 100-W solar-PV system with a 500-W wind turbine resulted in pumping and purifying enough water to satisfy the potable water requirements of 4000 people (16000 liters/day) at an estimated equipment cost of $4630.

The Status and Trends of Solar Energy Utilization

Abstract: Having unique advantages of other kinds of energies, solar energy is a kind of ideal alternate energy of common energies, which utilization will ultimately resolve energy problems such as lack of energy, environment pollution and greenhouse effect etc. After analysing the status of solar energy heat utilizatoin and photovoltatic technology in the world, the authors summarized the trends of solar energy development.

Application of iii-v materials in space solar cell engineering

Abstract: The present paper is the review of current situation in space solar cell engineering. The comparison of the more popular GaAs, AlGaAs, InGaP and InP solar cell parameters, as well as tlleir variation with temperature rise, radiation treatments and improving design have been represented. The typical working conditions for solar cells on the space orbit and requirements for solar cells are analysed. The modern international space projects, applied new types of III-V material solar cells, have discussed as well.

Assessment of domestic evacuated tube direct solar water heater

Abstract: []: This work presents the first assessment results of an evacuated tube solar collector at the Christchurch Polytechnic Institute of Technology. The assessment includes, a quantification of the capacity of heated water that could be supplied at different solar conditions and the realized energy savings (kWh), an interpretation of the working efficiency of the collector at different solar radiation and ambient temperatures. This paper presents a summary of the results achieved to date and outlines possible future developments that may be necessary to allow this type of direct solar water heater to be deployed in NZ conditions.

High temperature solar radiation heat converter

Abstract: Method and apparatus for producing available thermal energy from the energy of the solar radiation. The solar radiation is concentrated to a sufficiently high intensity within a concentrator assembly (11). The concentrated radiation is caused to impinge on an absorber (14) capable of supporting high temperatures. The heat of the concentrated radiation is transferred by heat exchange to a fluid to reach high temperatures and flow rates, and the fluid is then used to actuate a generator of mechanical energy (33). The temperature which is created during the exchange of heat in the fluid may be of at least 400 °C. The pressure drop across the heat exchanger assembly may be selected to be low enough to facilitate turbo-compressor closed loop operation.

Solar Powered Refrigeration for Transport Applications: A Feasibility Study Final Report

Abstract: A feasibility study was conducted to determine if solar power could be used to offset or eliminate the diesel fuel powered refrigeration systems currently used in transport applications. This study focused on the technical feasibility and economic viability of solar for this application. A target application was selected and a moderately detailed mathematical model was constructed to predict the performance of the system based on hourly solar insolation and temperature data in four U.S. cities. An economic analysis is presented comparing the use of solar photovoltaics vs. diesel for this application.

Analysis of a roof-top combined photovoltaic / solar thermal plant at Christchurch

Abstract: []: This paper presents an economic perspective of rooftop solar systems consisting of a 1kWp grid-connected photovoltaic (GC-PV) and an evacuated tube solar collector (ETC) water heater (1.37m2 unit) as a case study at Christchurch, New Zealand. The study considers the case that both systems are partially covering the energy demand of a one-family house. According to the average availability of solar radiation at Christchurch the expected year ac energy yield of the 1kWp GC-PV system has been found to be 1018 kWh/year and that of the solar thermal collector 851 kWh/year. Economic analysis has been carried out on the basis that PV electricity is fully used, either directly at user premises or by feeding the utility grid whereas the thermal energy made available by the solar collector is assisting the usual electrical water heating system to supply the necessary hotwater demand. The assumption made in this analysis is that the energy provided by the solar water heater is entirely replacing the otherwise used electricity for heating water. The final electrical energy demand after installing the solar system is then calculated. The presented analysis can be applied for larger capacities for commercial and industrial users considering that repetitive units of the here presented modules can be considered.

Solar thermal power plants for hydrogen production

Abstract: Renewable power plants are needed, if a high amount of hydrogen shall be produced for the use in a climate-compatible energy market. Since the potentials of hydro and wind power are limited, solar electricity generation will take over an important part in the near future. Solar thermal power plants in the Mediterranean area are one promising option. After a short introduction to this technology, the potentials are pointed out. Solar powered desalination offers new opportunities for hydrogen production. The final cost estimation for hydrogen and solar electricity generation will show the potential of both technologies for a sustainable energy industry.