Abstract: With the increasingly tense situation of energy and environment, the use of new energy sources such as renewable energy is becoming more and more important. Solar energy is most widely used for its rich and clean features. This paper combines solar energy with a traditional heat pump system to explore the performance of solar heat pump water heaters at low temperatures. Research shows that the solar heat pump system can improve and expand the low temperature application range of the pure heat pump system, and the stronger the solar radiation, the better the system performance; the low temperature defrosting method should adopt naturalized frost to avoid the high energy consumption and easy of the forced defrosting the disadvantage of liquid hammer and reduced system performance.

Key words: Solar heat pump system, Clean energy, Low temperature performance, Defrosting