... consists of solar vacuum tube, heat pipe, water tank, stand, P/T valve. 2. It is very high efficiency that heat pipe ... tube is very high efficiency.5. The complete system doesn't need any power, green and economic.6. Easy install, easy ... , 20 degree, 25 degree, 30 degree, 38 degree, 45 degree.P.S. 1. Controller can display the temperature, water level, automatically ...