Solar

Solar hot water is water heated by the use of solar energy. Solar water heating systems are generally composed of solar thermal collectors, and a system of pipes to use or store the heated water. The system may use electricity or Solar PhotoVoltaic for pumping the fluid, and use a tank for heat storage and subsequent use. The systems may be used to heat water for a wide variety of uses, including home, business and industrial uses. Heating swimming pools, under floor heating or energy input for space heating are more specific examples.

Domestic solar systems usually consist of an existing primary heat source such as a gas boiler, a hot water tank and the solar system. The solar system will heat the tank during the day (depending on the insolation), and if the tank has not reached the desired temperature through solar energy then the primary energy source can top up the tank.

The solar collectors consist of multiple evacuated twin walled tubes, these tubes efficiently capture the energy from the sun and transfer it to the heat store or hot water tank. As the tubes are evacuated they allow minimal heat loss and can therefore reach much higher temperatures than most flat panel collectors.

The tubes are covered with a special light-modulating coating. Sunlight passing through the outer glass tube heats the absorber tube contained within it. The absorber can either consist of copper (glass-metal) or specially-coated glass tubing (glass-glass). The glass-metal evacuated tubes are typically sealed at the manifold end, and the absorber is actually sealed in the vacuum, thus the fact that the absorber and heat pipe are dissimilar metals creates no corrosion problems. The better quality systems use foam insulation in the manifold. Low iron glass is used in the higher quality evacuated tubes manufacture.