Closed loop solar collector 1. Rockwool insulation, can resist 350c high temperature. 2. Anti-freeze heatpipe, can resist low temperature to -35c. 3. Sc vacuum tube, better coating with better efficiency. 4. Closed loop system, can bear pressure of 6 bar. 5. Can be connected directly to electric boiler or gas boiler. Much beautiful designed. 6. Full stainless steel outer shell, reflector and stand parts, can be avoid of corrosion.