Working principle: When the sun shines, the selective absorptive coating on the surface of inner tube transfers solar energy into heat energy, then the medium is heated into vapor, the vapor run fast to the condensation end with very high speed and is condensed into liquid, thus heat is released and transferred to water in tank. Eventually, heat medium is driven back to the bottom part by gravity, and repeats circulation continuously.

The full-glass heat tube mainly uses phase transition of the medium to transfer heat, with small thermal resistance and high heat conducting performance, the heat tube is fully vacuumed, boiling point of the medium is much lowered, and can get realize quick start. It also possesses the unidirectional heat conduction features of thermal diode, with high heat-preservation efficiency and supreme heat-collecting performance.