Numerical and experimental study on temperature control of solar panels with form-stable paraffin/expanded graphite composite PCM

•A passive cooling PV-PCM system was developed.•Form-stable paraffin/EG composite PCM with high thermal conductivity was utilized.•Numerical simulation on the temperature of PV-PCM panel was carried out.•Effects of density were studied under the given weather conditions. Performance of photovoltaic (PV) panels is greatly affected by its operating temperature. And traditional active and passive cooling methods usually suffer from the disadvantages of external energy consumption, uneven temperature distribution and low thermal conductivity of phase change materials (PCMs). In this work, a PV-PCM system was developed to control the temperature of a PV panel by applying high thermal conductive form-stable paraffin (ZDJN-28)/EG composite PCM. The temperature, output voltage and power of a conventional PV panel and the PV-PCM panel were measured and compared. A numerical simulation model established by CFD software FLUENT was used to simulate the temperature change process of the PV-PCM panel with different material densities under the same conditions as experiment. The experiment results showed that compared with the temperature of the conventional PV panel, the temperature of the PV-PCM panel is kept below 50°C for 200min extended by 146min with output power averagely increased by 7.28% in heating process. Simulated temperatures were in good agreement with experimental temperatures and indicated that the higher the density of the PCM is, the better the temperature management performance the PV panel could achieve. Besides, the PCM with density of 900kg/m3 was found sufficient to achieve a good temperature management performance when the average ambient temperature below 25°C with the highest solar irradiation of 901w/m2. In summary, this work is of great importance in the design of a PV-PCM system for temperature management of PV panels.