Normally forced circulation system is used for this purpose. A pump is used for circulating water through the collector system and a thermostat is used to control temperature. The fixed temperature controller and differential temperature controller are the two types of controlling the flow of water in the system. In the case of fixed controller system the system will deliver hot water at constant temperature, but the quantity of hot water delivered depends upon the level of solar insolation and ambient conditions in the differential temperature controller fixed quantity of hot water is delivered at varying temperature depending upon the solar installations.