Multi- water tanks solar energy-heat pump composite hot-water system and its operation control method

The invention relates to a multiple water tank solar-heat pump composite hot water system and a control method thereof. The system is provided with two to five parallel hot water storage tanks; an electromagnetic valve is arranged on a water supply/return main pipe of each hot water storage tank; an electromagnetic valve is also arranged on a water inlet/outlet branch pipe; the bottom of each hot water storage tank is provided with a temperature sensor; a hot water connecting pipe enters from the bottom of each hot water storage tank and comes out from the upper part of the hot water storage tank; the hot water storage tanks are connected in series by the hot water connecting pipes. A water supply/return pipe of a solar heat collector near one end of a cold water inlet is connected with the water supply/return main pipe of the parallel hot water storage tank; a supply/return water pipe of a heat pump in the other end of the water inlet is connected with the water supply/return main pipe of the parallel hot wa