All glass evacuated tubes are the key component of solar collectors. The evacuated tube is similar to a conventional Dewar flask and consists of two borosilicate glass tubes, a glass with high chemical and thermal shock resistance. The outer side of the inner tube is coated with a sputtered solar selective surface. This coated inner tube is closed at one end and sealed at the other end to the outer tube. The annular space between the outer tube and inner tube is evacuated to virtually eliminate heat loss by conduction and convection.
WHY EVACUATED TUBE
Compare to the flat solar panel, solar tube is designed to collect the energy from the daylight at all angles. Therefore, solar tube collector could more efficiently absorb solar energy with less radiation and provide more hot waters to millions of users.