... In sunny days, the water is heated by solar energy, while in cloudy or rainy days, the water ... is heated by air energy 2) Safe, high efficiency, energy-saving and environment protection 3) ... 1) 1KW electricity can generate 4KW heat energy from the air, only 1/4 electricity consumption ... , totally solving making heat problems in winter About solar water heater: 1) Vacuum tube size: Φ58x1 ...