Free-energy high pressure stand alone model is a new type of solar water heater which adopts advanced heat pipe and all glass vacuum tube technology.High efficient vacuum tube absorbs heat to the condenser end of itself. Condensor indirectly contacts with water through a copper cap and it boils water by releasing heat gained from vacuum tube. The available size of the tank ranges from 150l to 500l. It has the following features: 1. High pressure storage tangk ( testing pressure = 9bar ) 2. No vent and less heat loss as compared to low pressure model 3. Highly efficient heat pipe technology 4. No water introduced into vacuum tube 5. No sealing rubber is needed and hence no leaking problem 6. Easy plug-in installation 7. Freezing resistance Whole package We have solar keymark-en12976 certificate Whole package. 15 sets fit in a 20" container 30 sets fit in a 40" container