If you look at the scheme would comprise a full installation of the panels at the macroscopic level where the water is heated, the heat exchanger and a water pump. These panels consist of several layers, but the main one is a copper coil serĂ¡donde black-painted hot water to affect the sun's rays. To build a piece recilcada exchange grids are behind any refrigerator. Acts as the hot system. The pump is responsible for moving the hot water into the loop. We must control the flow of water decanted to not go too fast and can be heated conditions. Another trick to achieve this is as shown in the diagram the cold water enters through the bottom and warms as it rises by cirtuito. The third part is the exchange itself, where it joins the hot water that comes from the hot and cold water coming from the cold forum, which in this case can be the water heater or an open circuit either. Some simple systems of trade can be for example passing the cold water inside a pot of hot water or vice versa. For it is a bit complex to evaluate. It all depends on what you are able to get second hand and the imagination and the resources you have. I'm making one with the most recycled material and will not exceed $ 400, while in the market are worth about $ 3. 500 U. S. . Agradesco much the idea is very good, especially that you can use recyclable sunbeam refrigerator parts for the most difficult to construct than is the collector decalr, could improve the framework for understanding more. . . .