"Metro Solar  glass evacuated solar energy water heater" use the vacuum tube which can absorb solar energy highly and lowly radiation. Change the radiation of sun to the energy of heat. Use the character of heat water has low density and cold water has low density and cold water has high density. In the vacuum tube, the cold water flow from up to down and the heat water flow down to up. Through this circulating, all the water in water tank will become heat gradually.

The vacuum tube has the capability of following the solar radiation. So long there is solar radiation, the vacuum tube will work. Even in high latitude of high mountain, it also can work normally all year round.