... heater. In sunny days, the water is heated by solar energy, while in cloudy or rainy days, the water is heated ... source heat pump: 1) 1KW electricity can generate 4KW heat energy from the air, only 1/4 electricity consumption of electrical ... defrosting system, totally solving making heat problems in winter Solar Energy Vacuum Tubular Water Heater inner tank material: SS304_2B food grade ...