Heat storage phase change materials (PCM) has been widely used in various thermal energy systems, such as solar-heat pump. Harvesting solar energy requires low-cost and efficient PCM with proper melting points and high energy absorbing capacity. This paper proposed a novel Sodium acetate trihydrate (SAT) -Acetamide (AC) -micron/nano Aluminum nitride (AlN) composite phase change material (CPCM) with a melting point of 47.3 °C for solar-heat pump implementation. 10 wt% AC was selected as modifier to lower the melting point of SAT. The nano AlN or micron AlN was added to CPCM to suppress “supercooling” and improve its thermal conductivity. In order to determine the optimal ratio of mixture and examine the composite's thermal properties, DSC, SEM, XRD, FTIR and other characterization methods were implemented in this study. The results showed that 3 μm and 30 nm mixed AlN were the most effective nucleating agent and thermal conductivity filler. Also, the optimal composite with 5 wt% mixed AlN could reduce the “supercooling” degree to 0.27 °C and improve the thermal conductivity to 0.6484 W/m·K. After 100 heat absorbing and releasing cycles, the latent heat of CPCM maintained a respectable value of 226.8 kJ/kg.