Hexadecanol-palmitic acid/expanded graphite eutectic composite phase change material and its application in photovoltaic panel

High temperature will generate when photovoltaic (PV) panel works, which probably reduces circle life and conversion efficiency during working. Typical phase change materials (paraffin, non-paraffin organics or salt hydrates) are restricted due to low thermal conductivity and incongruent melting and super-cooling. Herein, hexadecanol-palmitic acid/expanded graphite (HA-PA/EG) eutectic composite phase change materials with excellent thermal conductivity, leakage property, thermal stability and cycling stability were successfully prepared. The phase change temperature and latent heat of corresponding HA-PA/EG are 43.2 °C and 182.3 kJ/kg, respectively. HA-PA/EG possessed excellent thermal stability, and can meet the temperature requirement of photovoltaic panel during running. Furthermore, HA-PA/EG PCM had stable phase change temperature and latent heat even after 100 cycle heating. When applied in photovoltaic panel, HA-PA/EG could absorb large amount of heat from solar radiation and photovoltaic panel during strong solar radiation. When the solar radiation intensity was 815.9 W/m2, the temperature of HA-PA/EG-modified photovoltaic panel was 5.1 °C lower than that of control, and the temperature control by HA-PA/EG had excellent stability in different position. Thanks to the huge heat absorption by HA-PA/EG, the output voltage and power of photovoltaic panel could be considerably improved to 5.7 % and 7.4 % higher than that of control at the solar radiation intensity as 815.9 W/m2. Our result demonstrates that HA-PA/EG PCM is promising in the heat management of PV. Our study provides a novel eutectic PCM with suitable phase change temperature and excellent thermal conductivity to control the temperature and improve the corresponding voltage and power performance of PV panel.