Flat plate collector
Flat-plate collectors are to solar thermal energy what solar modules are to photovoltaics. They are mounted on the roof as flat, even surfaces. In addition to flat-plate collectors, there are also the more efficient, but more expensive evacuated tube collectors in solar thermal energy. Both are government subsidized as part of a solar thermal system.
The flat-plate collectors are made of a coated absorber sheet, which is protected by a solar glass cover plate that absorbs the solar radiation. On the front and back of the housing of the flat-plate collectors, there is thermal insulation that minimises heat loss. Solar fluid contained in the solar circuit is heated by the absorber and then transports the heat to the solar heat storage tank or directly to the withdrawal points or radiators. Due to the flat design, no lateral solar radiation can be absorbed. The heat loss is also higher than with evacuated tube collectors. The efficiency is about 55 to 60%, a good 30% below that of tube collectors. In addition, there should be plenty of space on the roof, as flat-plate collectors require more surface area for the same heat output.
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