The operation of the solar water heater varies depending on its type & water circulation. If the boiler is mounted higher than the collectors then it operates according to the natural flow, where the hot water goes to the boiler as the mass of the hot water is lighter and therefore tends to rise above the cold water which mass is heavier.If the boiler is mounted lower than the collectors, a pump (forced circulation) is needed.
Each solar water heater consists of 2 basic parts. The collector where it collects energy from the sun’s rays & the boiler where the water is being stored.
Collector:
The solar panel consists of the absorber plate (which is always dark in color), the crystal that surrounds the absorber plate, and the pipes into which the water flows. Its operation is based essentially on the greenhouse effect. As the sun’s rays fall on the crystal and penetrate it, they end up in the absorption plate where due to its dark color and its material it heats up. This temperature then is trapped between the crystal (Greenhouse effect), maintains & transfer from the plate to the pipes where the water is heated, and then stored in the boiler.
About the kind, the boiler can be double energy, triple energy, or heat pump boiler as well as either open or closed circuit.
Boiler types are divided into categories:
A) Depending on how the water is heated.
Open or closed circuit boiler.
In an open circuit boiler, the water flows through a collector, is heated directly, and returns for storage in the boiler as well as use. While in the closed-circuit boiler the water remains stored in the boiler while the energy (heat) is transferred through a closed circuit in which there is different water combined with antifreeze liquid circulating through the collector, heats up and thus indirectly transfers the heat to the stored water.
B) Depending on the energy sources available for connection.
Double or triple energy boiler.
In the double energy boiler, the available sources are solar energy & electricity. Inside the boiler, there is an electrical resistance thanks to which it is possible to turn on the solar water heater using electricity and heat the water, for example during the winter months when the sunshine is less.
The above applies also to the triple energy boiler, however, there is also the possibility of connection to the central heating of the house thanks to the coil inside. Τhis coil circulates the hot water produced by the central heating boiler and then heats the water inside the boiler.
Heat Pump Boiler
Ιn heat pump boilers except for the solar & electrical power there is also the possibility for connection with the heat pump. Heat pump boilers contain large surface coils. This is required because heat pumps operate at a lower temperature than boilers so we use them so that energy can be exchanged at these low temperatures as well.
