Accoring to Dr.Pei's design, the Tian-En tubes are the key absorber of any SWH (solar water heater). They convert sunshine into heat, and heat the water.

The outer tube is transparent allowing light rays to pass through with minimal reflection. The inner tube is coated with a special selective coating (Al-N/Al) which features excellent solar radiation absorption and minimal reflection properties.

Please pay attention to the space between the two glass layers, it is evacuated. So the solar energy will be traped within it.

Someone would like to call it "twin-glass tube". They are widely used for its reliability, performance and low manufacturing cost.

During our manufacturing, in order to assure the vacuum between the two glass layers, a barium agent is placed inside ( just like any TV kinescope). In assembly line, Tian-En tube barium agent is exposed to high temperatures, so it can coat the inner surface with a mirror.

This barium layer is important. Because it can react with the very few airs left. And at the same time, the mirror is a very good visual indicator of the vacuum status.

Once you find the mirror turns white, then you'd better exchange the tube. We always call it "Cold Tube".

You can easily see the differents. Left one is in good condition, while the right one goes white and can't work.

Another key component for high efficient SWH, is SCHP (super-conductive heat pipe).

Simple idea about SCHP (Super-conductive Heat Pipe)

Tian-En SCHP is copper pipe, hollow with the space inside evacuated. Inside, a small amount of special working material is placed.

The working material can be easily vapourized in one end and recover to liquid at the another end. So the heat can be transfer 1000 times faster than best conductive material, such as copper.