© Bosch Thermotechnology Ltd.Each solar collector type has its advantage in terms of price, efficiency and aesthetics. An evacuated tube collector is more efficient than a flat plate solar collector, but is more expensive. Both types of solar thermal panels are working with liquids for heat transportation and are usually used in solar water heating systems.
Solar collectors working with air are more often used for solar air heating systems. Solar collectors are not only suitable for new-build houses, but can also be installed on already existing buildings. Once installed, solar thermal panels are able to provide 40-50% of annual domestic hot water requirements.
Flat Plate Solar Collector
The flat plate collector uses a dark, heat absorbing layer that has coils of copper or aluminium tubing run through it, and energy loss is reduced on the heating side through insulative glazing. A circulating fluid is pumped through the tubing and absorbs the plate's heat. This can be either the hot water that is heated directly, or an isolated intermediary fluid that is used to heat water in a hot water tank. The flat plate style can be the least expensive to install, but its efficiencies are rather low compared to the evacuated tube solar collector style.
Evacuated Tube Solar Collectors
The evacuated tube solar collector has several variations, but they all share several commonalities. This solar collector consists of several evacuated (reduced to vacuum pressure) transparent tubes made from glass with low thermal conductivity. Contained in each tube is then a central glass tube with a dark heat absorbing coating. The central tube is where the solar collector system's heat exchange fluid is circulated and heated, and then transported to heat water in your storage vessel. Due to the vacuum separation between the collecting elements and the atmosphere, this style of collector is more expensive than the flat plate style but has better heat loss attributes. The higher insulation rating generally allows it to be effective year round.
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