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A · B · C · D · E · F · G · H · I · J · K · L · M · N · O · P · Q · R · S · T · U · V · W · X · Y · Z   entire Web this site solar collector A device used to collect, absorb, and transfer solar energy to a working fluid, such as water or air. The solar heat can be used for heating water, to back up heating systems, or for heating swimming pools.The heart of a solar collector is the absorber, which is usually composed of several narrow metal strips. The carrier fluid for heat transfer flows through a heat-carrying pipe, which is connected to the absorber strip. In flate-plate absorbers, two sheets are sandwiched together allowing the medium to flow between the two sheets. Types of solar collector include: Glazed flat-plate collectors Unglazed flat-plate collectors Unglazed perforated plate collectors Batch collectors Evacuated-tube collectors Liquid-based collectors Air-based collectors Back-pass collectors Concentrating collectors Parabolic dish collectors Parabolic trough collectors Power towers Stationary concentrating collectors Solar cookers How much energy does a solar collector provide? Efficiency graph of solar collector performance The efficiency of a solar collector is defined as the quotient of usable thermal energy versus received solar energy. Besides thermal loss there alwas is optical loss as well. The conversion factor or optical efficiency h0 indicates the percentage of the solar rays penetrating the transparent cover of the collector (transmission) and the percentage being absorbed. Basically, it is the product of the rate of transmission of the cover and the absorption rate of the absorber. The heat loss is indicated by the thermal loss factor or k-value. This is given in watt per m2 collector surface and the particular temperature difference (in °C) between the absorber and its surroundings. The higher the temperature difference, the more heat is lost. Above a specific temperature difference, the amount of heat loss equals the energy yield of the collector, so that no energy at all is delivered to the solar circulation system. A good collector will have a high conversion factor and a low k-value. Type of collector Conversion factor Thermal loss factor (W/m2 °C) Temp. range (°C) uncovered absorber 0.82 - 0.97 10 - 30 up to 40 flat-plate 0.66 - 0.83 2.9 - 5.3 20 - 80 evacuated-plate 0.81 - 0.83 2.6 - 4.3 20 -120 evacuated-tube 0.62 - 0.84 0.7 - 2.0 50 - 120 reservoir collector about 0.55 about 2.4 20 - 70 air collector 0.75 - 0.90 8 - 30 20 - 50 Which collector is suitable for which situation? Graph of efficiency and temperature ranges of various types of collectors (radiation: 1000 W/m2) The desired temperature range of the material to be heated is the most important factor in choosing the correct type of collector. An uncovered absorber is certainly not suitable for producing process heat. The amount of radiation on that spot, exposure to storms, and the amount of space must all be carefully considered when planning a solar array. The specific costs of collectors are also important. Evacuated-tube collectors are substantially more expensive than flat-plate collectors or even plastic absorbers. However, a good collector does not guarantee a good solar system. Rather, all components should be of high quality and similar capacity and strength. Related category    • SOLAR ENERGY AND POWER Some of the text and illustrations used with the permission of the German Foundation for Solar Energy (Deutschen Gesellschaft für Sonnenenergie e.V.) SOLAR ENERGY PAGES ON THIS SITE absorber absorption coefficient absorptivity active solar energy system active solar heating system air-based collector amorphous photovoltaic cell annual solar savings angle of incidence angle of inclination aperture apparent day autonomous system azimuth back-pass solar collector batch solar collector beam radiation blackbody blocking diode briefcase solar panels buffer storage building-integrated PV bypass diode candela candle power collector efficiency collector fluid collector tilt community solar access compound paraboloid collector concentrating collector concentrator crystalline silicon photovoltaic cell current at maximum power declination differential thermostat diffuse insolation diffuse radiation direct beam radiation direct gain direct insolation direct solar water heater double wall heat exchanger elevation emissivity equinox ethylene vinyl acetate eutectic salts evacuated tube collector expansion tank fill factor flat plate photovoltaic flat plate pumped collector flat plate solar module flat plate solar thermal collector flow condition foot candle Fresnel lens full sun Glauber's salt global insolation ground reflection heat absorbing window glass heliochemical process heliodon heliostat heliothermal heliothermic heliothermometer heliotropic hemispherical bowl technology high-temperature collector hot spot I-V curve illuminance incident light incident solar radiation indirect solar gain system indirect solar water heater infrared radiation insolation instantaneous efficiency interconnect internal collector storage irradiance isolated solar gain system isolation diode junction box light-induced defect light trapping liquid-based active solar heating liquid-based solar collector local solar time low-flow solar water heating system low-temperature collector low emissivity glass lumen maximum power point maximum power point tracker medium-temperature collector mixing valve multijunction device normal operating cell 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solar chimney power station solar collector orientation and tilt solar constant solar cooker solar cooling solar day solar declination solar distillation solar electric system solar electricity site resource eval. solar energy solar energy for crop drying solar film solar fraction solar furnace solar gain solar heat gain coefficient solar heating solar heating for homes & buildings solar heating system solar hot water for agriculture solar hot water for aquaculture solar hot water system solar irradiation solar mass solar module solar noon Solar One solar oven solar panel solar photovoltaic device solar pond solar power system solar radiation solar simulator solar space heater solar spectrum solar swimming pool heating solar thermal electric system solar thermal parabolic dish solar thermal system solar time solar transmittance solar trough system Solar Two solar ventilation air heating solar voltaic device solar water heater cost estimation solar water heater economics solar water heater efficiency solar water heater freeze protection solar water heater maint. & repair solar water heater site resource eval. solar water heater sizing solar water heating system corrosion solar water heating sys. bldng codes solarium solar-grade silicon solar-powered vehicle solstice spectral energy distribution spectral irradiance spectral reflectance spectrally selective coating split-spectrum cell Staebler-Wronski effect stagnation temperature stand-off mounting standard operating conditions standard test conditions stationary concentarting collector sun path diagram sun tempered building sunspace swimming pool absorber temperature coefficient thermal storage wall thermo photovoltaic (TPV) device thermophotovoltaic cell thermosiphon thermosiphon system thin film cell tilt angle of a solar collector total incident radiation total internal reflection tracking array trickle (solar) collector Trombe wall true south tube-in-plate absorber tube-type collector two-axis tracking two-tank solar system ultraviolet unglazed perforated plate collector unglazed solar collector visible light transmittance visible radiation water wall Also on this site: Encyclopedia of Science Transport Concepts & Designs (partner site) BACK TO TOP