Solar evacuated tube,Solar vacuum tube Advantage: Reach high temperature Antifreeze No polution Compective price This kind of tube is made of two layers of borosilicate glass which is specially hard.Borosilicate glass 3.3 is an ideal material for solar evacuated glass tube because it has high transparency and can withstand high temperature as well as high pressure. The vacuum jacket which is of high vacuum degree is a kind of superior insulation.It reduces heat loss and protects the water in the tube from freezing, Solar evacuated glass tube can produce hot water even tough water.That's why it is suitable to be used in areas and regions where is very cold or always cloudy. If you wanna get more information about our products and our company,you can visit our website SENLIDE.COM or contact us directly.