In a simple way, the solar water heating system is composed of solar collectors (plates) and the thermal reservoir (Boiler).
The responsibility for absorbing solar radiation rests with the plates. The solar heat that is captured by them is transferred to the water that circulates inside their copper pipes.
Also called the Boiler, the thermal reservoir, is the place where the heated water is stored. It consists of copper, polypropylene or stainless steel cylinders that are thermally insulated with expanded polyurethane without CFC, but they do not harm the ozone layer. The water is kept warm until it is consumed.
In the solar water heating system, the rays pass through the glass of the collector's cover and they will heat the fins that are made of copper or aluminum and painted with a special dark paint that helps to achieve the maximum absorption of solar radiation.
The heat then crosses the fins to the tubes (coil) that are usually made of copper. After that, the water inside the coil gets hot and stops directly in the water heating system reservoir.
The function of the thermal reservoir in the solar water heating system is like a water tank. She is responsible for making the stored water always hot in the solar heater.