We normally heat water by burning fossil fuels or using electricity. Solar hot water panels heat water by absorbing solar energy. The systems may be used to heat domestic hot water, swimming pool water, or for space heating. The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment.
A solar water heating system is usually comprised of solar collectors and a water tank. The solar collectors absorb the heat in solar radiation to heat up water, either directly or indirectly. The solar collector is by far the most widely used solar energy conversion device. The hot water so produced is stored in the storage tank for subsequent use. Usually a solar water heating system is designed to fulfill a major part of the hot water requirements with the rest being made up by electric or gas heating.