Showing papers on "Photovoltaic thermal hybrid solar collector published in 1999"

Performance analysis of a hybrid photovoltaic/thermal (PV/T) collector with integrated CPC troughs

Abstract: In the present investigation a theoretical analysis has been presented for the modelling of thermal and electrical processes of a hybrid PV/T air heating collector coupled with a compound parabolic concentrator (CPC) In this design, several CPC troughs are combined in a single PV/T collector panel The absorber of the hybrid PV/T collector under investigation consists of an array of solar cells for generation of electricity, while collector fluid circulating past the absorber provides useful thermal energy as in a conventional flat plate collector In the analysis, it is assumed that solar cell efficiency can be represented by a linear decreasing function of its temperature Energy balance equations have been developed for the various components of the system Based on the developed analysis, both thermal and electrical performance of the system as a function of system design parameters are presented and discussed Results have been presented to compare the performance of hybrid PV/T collector coupled with and without CPC Copyright © 1999 John Wiley & Sons, Ltd

Solar cell module and process for its production, and solar cell module installing method and solar electricity generation system

Abstract: A solar cell module comprises a photovoltaic device having a flexible substrate. The photovoltaic device has a strain at least partly in the planar direction of the flexible substrate, and the strain is not greater than a critical value at which the photovoltaic device cracks. The solar cell module may further comprise a strain holding means for holding the strain. A deformable region where the photovoltaic device can be deformed when a region embracing the photovoltaic device is worked is defined so that a great variety of solar cell modules having a high reliability, also taking account of manufacture, can be designed with good efficiency.

Solar thermal water pumping systems: a review

Abstract: A number of attempts have been made by scientists to utilize solar energy for irrigation water pumping. It is mainly a problem of conversion of heat energy available from the sun, to mechanical energy. Some ingenious methods have been devised to utilize the available energy at low temperatures. This paper reviews past efforts to develop solar thermal water pumping systems which employ either conventional pumps or unconventional pumps, and emphasizes how the system modifications were made to suit different pumping conditions and requirements.

Experimental study of thermal performance improvement of a solar air flat plate collector through the use of obstacles: application for the drying of ‘yellow onion’

Abstract: In the solar air flat plate collector, the insufficiency of the thermal exchange between the fluid and the absorber obliges the user to enhance their optimization. This low thermal exchange does not allow these systems to obtain their best performance or the best thermal efficiency. In our experimental study, which consists of a solar energy simulation, we have sought to improve the efficiency–temperature rise couple of the flat plate solar collector by considering several types of obstacles disposed in rows in the dynamic air vein of the collector. Thus, we have proceeded to the application of the best two systems (WDL1 and TL) for drying an agricultural product (Yellow Onion). By comparing with the collector without obstacles (WO), the thermal transfers and, consequently, the output temperature (TOC) and the collector efficiency (η) are clearly improved. The drying times obtained with the proposed systems are very interesting. The heat quantities obtained in the case of WDL1 are very important compared with the collector WO. However, the entry to the drying cupboard of this high temperature (TOC) in the vicinity of the solar midday must be limited to the maximal value demanded by the considered product. Copyright © 1999 John Wiley & Sons, Ltd.

Solar collector system

Abstract: A solar collector system for converting solar radiation to thermal energy and electricity has an upper cover with a material that is transparent to solar radiation. A solar energy absorbing structure is disposed under the upper cover and has a heat conducting material such as metal. In addition, a first heat transfer system is disposed in contact with the solar energy absorbing structure and has a material that transfers heat from the solar energy absorbing structure to a first substance flowing within the first heat transfer system. The solar collector system also has electric cells that absorb solar radiation and convert it into electricity. The cells are configured and disposed on at least a portion of the upper cover.

Energy analysis of solar water heating systems in india

Abstract: This analysis can be called energy accounting of solar water heating systems. Five types of solar water heating systems have been considered. With the help of material balance, energy content has been found in these systems. Yearly output of systems has been found by conducting transient simulations using hourly data of radiation and ambient temperature. Such analysis has been done separately for one representative city of each of six climatic zones of India. The energy payback for India ranges from 0.73 to 4.16 years for the thirty cases considered here.

Solar thermal production of zinc : Program strategy and status of research

Abstract: The solar thermal production of zinc is considered for the conversion of solar energy into storable and transportable chemical fuels. The ultimate objective is to develop a technically and economically viable technology that can produce solar zinc. The program strategy for achieving such goal involves research in two paths: a direct path via the solar thermal splitting of ZnO, and an indirect path via the solar carbothermal and CH 4 -thermal reduction of ZnO. The chemical thermodynamics and kinetics for both paths are briefly reviewed. A vortex-flow solar reactor for reducing ZnO with CH 4 is also described. Solar tests conducted at PSI solar fumaces in the temperature range 1000-1600 K yielded high chemical conversion to zinc.

Solar cell with a solar collector and storage elements

Abstract: Heat insulations in houses having cardboard lattice arranged behind a glass pane yield, in practice, a heat flow which is dependent on insolation. Said heat flow is lower at night and during weak insolation and begins to increase when the lattice is solar heated. The inventive solar cell (1) comprises a lattice (5) which is situated behind a rear-ventilated glass pane (2) and which exhibits durable storage properties. The solar cells characterize a solar energy yield (ξ') by an arrangement which selects for an angle of incidence. Said solar energy yield does not lead to overheating in the room interior (R) also when the sun is at a high position. A thermal time constant is obtained by means of heat insulations (11, 12, 13) which are connected in succession. Said time constant guarantees comfortable temperatures in the interior (R) of the house also in the case of low supplementary heating. The solar cell (1) considerably reduces heat requirements and can be optimally adapted to a wide range of local climate relationships.

Theoretical and experimental study of efficiency factor, heat transfer and thermal heat loss coefficients in solar air collectors with selective and nonselective absorbers

Abstract: The thermal heat performance of a solar air collector depends strongly on the thermal heat loss and the efficiency factor. In order to increase these performances, it is necessary to use a solar air collector which is well insulated and where the fluid flow is fully developed turbulent flow. It needs a high heat transfer between the absorber plate and the fluid to decrease the absorber-plate temperature and hence the heat loss by radiation from the absorber to the ambient. This increases the efficiency factor. In the present paper, the heat loss and efficiency factor are treated for solar air collectors with selective and nonselective absorber plate. It is shown that the selectivity of the absorber plate cannot play an important role in a well-insulated solar collector with a fanned system which permits a fully developed turbulent flow and, in consequence, high heat transfer. Copyright © 1999 John Wiley & Sons, Ltd.

Transient Thermal Analysis of a Refractive Secondary Solar Concentrator

Abstract: A secondary concentrator is an optical device that accepts solar energy from a primary concentrator and further intensifies and directs the solar flux. The refractive secondary is one such device; fabricated from an optically clear solid material that can efficiently transmit the solar energy by way of refraction and total internal reflection. When combined with a large state-of-the-art rigid or inflatable primary concentrator, the refractive secondary enables solar concentration ratios of 10,000 to 1. In support of potential space solar thermal power and propulsion applications, the NASA Glenn Research Center is developing a single-crystal refractive secondary concentrator for use at temperatures exceeding 2000K. Candidate optically clear single-crystal materials like sapphire and zirconia are being evaluated for this application. To support this evaluation, a three-dimensional transient thermal model of a refractive secondary concentrator in a typical solar thermal propulsion application was developed. This paper describes the model and presents thermal predictions for both sapphire and zirconia prototypes. These predictions are then used to establish parameters for analyzing and testing the materials for their ability to survive thermal shock and stress.

Decentralised solar energy installation

Abstract: The novel solar collector installation is characterised in that it is less expensive to install on the site of the consumer and in that the inventive simplified construction and combination of devices which have previously functioned separately in structural engineering terms (solar collector (1), solar modules (2), wind generator (3), heat pump (4), cooling or air conditioning system (5), heat pump storage device (6), reservoir for water for use (6), heating storage device (6), concentrated solar energy exploitation system (7), sun tracking system (8), etc) into a single, pre-assembled device reduces the total weight to below 25 %. The invention is also characterised by its process engineering advantages, for example the heat losses are reduced to a negligible minimum. A novel principle is used for the solar collector (1) which is characterised by a rotating absorption plate (9) that is impinged upon by water. The invention is used for generating and supplying energy (electricity, heat, cold) in the private, communal and industrial sectors and supplying energy to energetic and chemical processes.

Self-regulating thermal solar system for hot water heating

Abstract: The solar system includes solar pumps for transporting heat carrying liquid for thermal solar units. The pumps (4) are driven by solar-electric power to achieve power control and automatic on-off switching of the solar pumps in accordance with the amount of radiation available.

Solar plant which can be coupled to conventional heating system for supporting service water heating and/or heat carrier heating

Abstract: A solar plant which can be coupled to a conventional heating system for supporting the service water heating and/or heat carrier heating, has a collector subject to fluid flow for heating a heat carrier by solar radiation, a device for circulating the heat carrier in the collector circuit, a control unit for the solar plant and pipes to connect the individual plant components. The heat carrier can flow over out of the collector circuit via at least one check valve (5, 7) directly into the conventional heating medium circuit (6, 8). In the collector circuit is located a switchable emptying valve (15) and at least one temperature sensor (11-14) monitors the temperature in the collector circuit.

Cover for irradiation surface of solar collectors for photovoltaic cells

Abstract: The invention provides a combined unit of solar collector and integrated photovoltaic modules such that the transparent photovoltaic elements replace the security glass of the solar collector, thus integrating both energy generating systems onto the area of the solar collector.

A second law approach to characterizing thermally stratified hot water storage in solar water heaters

Abstract: This paper presents a method of characterizing the performance of hot water storage tanks in terms of their temperature distribution. The change in exergy from the stratified state to the delivery state depends on the stored energy and the stratification. It can thus be used to define the storage efficiency for sensible heat storage devices. The effect of temperature distribution, delivery temperature and tank cross section on exergy is investigated. The advantage that stratification offers over a mixed tank is examined in terms of the storage efficiency and overall solar water heating system performance. Exergy is used to assess the operation of mantle heat exchangers in solar water heating systems and it is shown that an exergy, rather than energy, should be used to ascertain the performance of such heat exchangers.