Solar heat pump hot water system with automatic regulation of working fluid charge

The invention relates to a solar energy heat pump hot water system and a control method for automatically regulating the charging amount of working medium. Including heat pump unit, solar unit, circulating water unit and control unit; The heat pump unit comprises a compressor, a condenser, an electronic expansion valve, an evaporator, a liquid storage device for a heat pump, a three-way electromagnetic valve, and a solenoid valve; The solar unit comprises a solar collector, a solar energy storage device, a working medium pump; The circulating water unit comprises a water tank, a water pump and a heat storage tank; The control unit includes microcomputer, temperature sensor, pressure sensor and liquid level sensor. The utility model can make full use of heat energy and solar energy in the air when making hot water by using solar energy unit and heat pump unit. Through the control of the electromagnetic three-way valve, solenoid valve, compressor and other components, the liquid working medium in the two reservoirs can be maintained a certain amount, so as to ensure that the solar unit and heat pump unit can maintain the best working medium charging amount during the working process.