The most widely applied flat-plate collectors consist of a blackened steel plate, covered with a couple of sheets of glass, that's heated via the sunlight slipping on it. This heat is then transferred to air or drinking water, called carrier fluids, that move past the back again with the plate. https://berallunterwegs.de/2024/08/08/werten-sie-ihren-raum-auf-die-vorteile-masgeschneiderter-treppenlosungen/