The evaporating side and condensing side were

In VX-11e solar water heating mode, the solar water tank worked as evaporator, the domestic water tank acted as condenser, and two operation strategies were carried out. In the first operation strategy, the water in both water tanks was heated by flat-plate collector at the initial stage. When the irradiation was insufficient, the temperature of the domestic water tank can't fulfill the living needs. Then the collector was turned off, and the domestic water tank was heated by the heat pump. In the other operation strategy, the osmoconformers domestic water tank was heated by the heat pump directly, and the solar water tank was heated by the flat-plate collector simultaneously, which would provide evaporating heat to the system. In both operation strategies, when the heat pump started up, the initial temperature in the solar water tank and domestic water tank was identical. The water in the domestic water tank was heated by the heat pump from the initial temperature to the final temperature of 50 °C.