non-pressurized solar water heater

1) Inner water tank shell is made of SUS304-2B food grade stainless steel plates, and outer tank shell is made of color steel plates, welded by argon arc. 2) Heat insulation of water tanks adopts polyurethane foam and the thickness is 55mm 3) The life of the vacuum tubes is 5 years. 4) Absorption rate: =93%, thermal radiation rate: =6% 5) It resists 25mm hail and the using life of the whole system can last for 15 years 6) Temperature when exposed to sun without water: 250°C, 2.5 hours to boiling point if using single tube 7) If you use electrical appliances, it will begin to work when the temperature of the water is below 60°C, and will switch off automatically when the temperature reached 60°C.