Плоские солнечные коллекторы
Flat collector
— it is a relatively inexpensive type of solar collector. It is the simplest type of such device, massively presented on the market. On the front of such a device, there is a transparent coating (made of special glass or plastic), under it there is an absorbing layer (absorber) with a heat-conducting system, and a thermal insulating layer is provided on the back side (to avoid heat losses).Theoretically, such systems are capable of heating the water inside to a temperature of about 200 °C. At a low cost, they have good efficiency in the warm season. On the other hand, flat-plate collectors have a low degree of thermal insulation, which significantly reduces their efficiency in the autumn-winter period. There are improved varieties of such devices — in particular, devices that use a deep vacuum instead of a heat-insulating layer (do not confuse them with vacuum collectors — see the relevant paragraph). They can work at low temperatures. However, they are more expensive, and the actual efficiency is still highly dependent on the angle of incidence of the sun's rays.
Also, note that flat-plate collectors can be difficult to install: the collector has to be lifted and installed as one unit, which in some conditions causes inconvenience. Yes, and in the event of a failure, you have to change such a device entirely.