In solar thermal systems, vacuum tubes are the component which actually converts the suns energy into heat. It is thus important to have the best tubes possible to maximize the efficiency of your system. Our All-glass vacuum tube is made of strong borosilicate glass, and we use two layers of glass in the tube in order to increase strength and to prevent heat losses to the environment. This makes for a longer lasting, more efficient tube. The outer layer of the glass is transparent, allowing light rays to pass through with minimal reflection. The inner layer is coated with a special selective coating (Al-N/Al) which features excellent solar radiation absorption when compared to conventional flat plate collector systems. The top of the two tubes are fused together and the air contained in the space between the two layers of glass is pumped out while exposing the tube to high temperatures.