What are the two main types of solar collectors?
A – Flat panel collectors- operate by absorbing the sun rays through the surface of an absorber. The absorber is made of copper sheet, covered with absorption layer made usually of black chrome or titanium.To the bottom of absorber are soldered thin copper pipes, through which an unfreezable liquid goes. Under the absorber the collector is isolated with mineral wool and from upper side the collector is covered by a special, hardened glass resistant to hail and specially coated.The box of the collector is made of aluminium sheet. Evacuated Tube Collectors -are constructed of glass solar collector tubes, containing a second inner tube with a selective coating. The space between the outer tube and inner tube is evacuated and maintained at a high vacuum eliminating all heat loss by conduction and convection. Solar radiation passes through the highly transparent outer glass tube and reaches the solar selective coating on the outside of the inner tube. The solar selective coating absorbs the
