Compact pressurized solar water heater

Passive solar water heaters use vacuum tubes with heat pipes and an attached water tank for direct heating of potable water. Sunlight enters the tubes, converting into heat at ~94% efficiency, and is then carried up through the heat pipe to the manifold which heats the water inside of the attached water tank. Water is supplied at the inlet from city/well water, heated and then fed directly into the hot water plumbing of the building.


1. Integrative pressurized solar water heaters are all-glass evacuated tube solar domestic water systems combined with heat pipes inside the glass tube.

2. The selective coating on the inner tube converts solar energy into heat energy and transfers to the heat pipe by an aluminum fin.

3. The liquid in the heat pipe changes into vapor which rises to the condenser.

4. The heat conducts the water inside the tank and the vapor becomes liquid, returning to the base of the heat pipe.

5. This continuous circulation transfers heat from the heat pipe to the cold water in the tank as long as the sun is heating the collectors.

6. Hot water can be obtained by injecting cold water from the bottom of the tank.

This unit includes an electric backup water heating element and a solar controller. The passive solar water heater controller is used for timing of the backup water heating and display of the tank temperature. Settings on the controller help prevent heating water when hot water will not be needed, such as during 4 in the morning. This gives the user the ability to only use electrical backup heating when it may be needed, thus giving the sun a chance to replenish heat.