Compact solar water heater is a kind of solar water heating system that solar collector and storage are connected together with the cylinder storage on the top and collector panel on the bottom. There is no need of pump to push the fluid and no need of pipeline between the collector and storage. It is a simple and safe solution to get heat power from the sun.

The compact solar water heaters relies on the natural circulation of water between the collector and the tank or heat exchanger. Compact Solar Water Heater relies on warm water rising, a phenomenon known as natural convection, to circulate water through the collectors and to the tank. As water in the vacuum tubes is heated it rises naturally into the tank, while cooler water in the tank flows down to the bottom of the vacuum tubes, causing circulation throughout the system.