What is a flat plate collector?
It is the heart of a solar water heating system. It consists of an absorber plate which is coated on its sun facing surface with an absorbent coating, also called selective coating. The absorber consists of a grid of metallic tubes and sheets. Water flows through the tubes. Sheet absorbs the solar radiation falling on it and transfers it to water. The absorber plate is placed in a top open box to protect it from weather. The space between back and sides of the absorber and the box is filled with insulation to reduce heat losses. The front of the box is covered with a high transmittance glass plate. Flat plate collectors are specified on the basis of their area and are of commonly 1×2 m size.
