It is basically a very small, really overpriced, solar heater. Since the amount of heat you can get out of a solar heater goes by the size of the panel, and that thing is about 4 square feet, and most people have two or more 80 square foot panels, that thing really isn't going to do very much. For about half the price of a conventional panel you get one 1/20th the heat, not a good deal.