To provide a stable energy supply from a solar heat pump heating system under different solar radiation intensities, this paper aims at developing a controllable nucleation method using a type of controlled phase-change energy storage material to improve the operating efficiency of the system. Sodium acetate trihydrate is a promising phase-change energy storage material, but it has a serious supercooling effect during solidification. The addition of nucleating agents is a common way to reduce the supercooling degree of sodium acetate trihydrate. The effect of electrode types and activating voltage on the nucleation of supercooled sodium acetate is investigated. The results showed that the copper anode, the silver anode and the silver-plated anode could trigger the nucleation of supercooled sodium acetate solution without adding any nucleating agents. The thickness of metal demonstrated a poor effect on the nucleation of supercooled solution. The rapid nucleation of supercooled solution was achieved by applying a voltage of 1.0 V to 1.8 V to the electrode. When the voltage exceeded 2.0 V, the anode resistance increased with the increasing number of operations, with the surface silver oxide, the trigger efficiency was decreased. This research is very useful to improve the operating performance of the solar heat pump heating system.