The design of this type uses the all-glass evacuated solar collector tubes as the heat-absorb element. The high vacuum degree of the clearance between the outer and inner tube can reduce the heat emission which caused by convection and conduction to a very low level.

All-glass evacuated tube transfers sun energy into heat energy by the high absorption rate and low emittance rate of layer films. Depend on the different density between the hot water and the cold water, a cycle can be created in the tube which hot water ascending and cold water descending status. Keeping natural circulation like this, the water in the tank will be heated.