Evacuated tube collector

Evacuated tube collectors, also known as tube collectors for short, are the equivalent of solar modules in photovoltaics. They are installed on the roof. In solar thermal energy, there are flat-plate and evacuated tube collectors.

Evacuated tube collectors consist of airless coated glass tubes placed side by side and a heat insulating vacuum between the tubes. Each tube is equipped with an absorber, which absorbs the solar energy. Due to the vacuum, the heat is reliably retained inside the tube collectors and the tube construction also makes use of solar radiation penetrating from the side. The efficiency of vacuum tube collectors is more than 90%. The heat warms up the circulating solar fluid or air and is transferred via a heat exchanger to heating and service water for immediate use or to solar heat storage tanks for later use.

Evacuated tube collectors need less space and work more efficiently than flat plate collectors, because they achieve higher temperatures. Although tube collectors are more expensive to purchase than flat-plate collectors, they are subsidised by the government as part of a solar thermal system.

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