Abstract: A solar hot water heating system is provided with solar collectors connected to a hot water storage tank with a recirculating pump to circulate the cooler water in the storage tank through the collector to absorb heat therefrom and to be returned to the storage tank. A plurality of temperature sensors are placed throughout the system to monitor various temperatures and to develop control signals for energizing or de-energizing the recirculating pump, for opening and closing solenoid valves to isolate the solar collectors from the storage tank and for opening and closing solenoid valves to permit supply water to circulate at a predetermined rate through the solar collectors. The storage tank is provided with inlet and outlet stratifier tubes which, while permitting water to be fed into and withdrawn from the tank, produces stratification of the water stored within the tank and increases the overall efficiency of the system.