Solar Evacuated Tubes are made up of two layers of borosilicate glass. Borosilicate glass is a strong glass that can withstand h

Solar Evacuated Tubes are made up of two layers of borosilicate glass.Borosilicate glass is a strong glass which can withstand high internal pressure and external force.Vacuum tube's outer tube is transparent allowing UV rays to pass through with minimal reflection and the inner tube is coated with a thermal radiation absorbing film,aluminum nitride (AlN). With the vacuum space in place the evacuated tubes can work well even in cold weather as apposed to flat plat collectors which have poor performance under cold weather conditions.So evacuated tubes are widely used for solar water heater and solar collector and the related solar thermal heating system.