... .Simple installation 4.Anti-freez,No maintenance Balcony Solar Water Heater, Technical Parameters: Heat Pipe Solar Collector Spec.(mm) Φ47 ... ~ 2.0mm Material Aluminium alloy plate Accessories Workstation system, Electric heater, E-Parts box, thermostat, Switch, Anode magnesium bar, T/ ... heat pipe vacuum tubes3) Efficiency generated about 55% in summer and 42% in winter more than that of normal glass ...