Seller Sue Li

the evacuated tube is made upof 2 layers of glass. the solar energy passes though the outer glass and isabsorbed by the selective coating on the inner glass, thus the inner tubebecomes hot. the water inside the tube is heated by the inner glass andnaturally rises up into the water tank above through thermosiphon flow, and thecold water inside the water tank drops down and is heated. therefore the waterinside the water tank is heated.