Razi University

   The increase in the operating temperature of photovoltaic (PV) cells is one of the main factors reducing the efficiency and power output of solar panels. Phase Change Materials (PCMs), owing to their ability to absorb and store thermal energy, provide an effective method for thermal management of photovoltaic panels. This study experimentally investigated the effects of PCM composition, macrocapsule geometry, and metallic powder additives on the thermal and electrical performance of a 10 W photovoltaic panel. Initially, the performance of an uncooled panel was compared with panels containing pure paraffin and different paraffin-Vaseline mixtures. After selecting the optimum PCM composition, the effects of spherical and cylindrical brass macrocapsules containing PCM were evaluated. Finally, different amounts of iron powder, copper powder, and their combination were added to the optimum PCM to improve its thermal conductivity. The experiments were conducted using a solar simulator equipped with five halogen lamps, and the panel surface temperature, PCM temperature, voltage, current, and output power were measured over a 120-minute period. The results showed that the mixture containing 75% paraffin and 25% Vaseline provided the best performance, increasing the maximum output power from 4.96 W to 5.504 W. The use of cylindrical macrocapsules containing paraffin further increased the maximum output power to 5.687 W, indicating better performance than the spherical configuration. Among the metallic additives, the addition of 0.15 wt.% copper powder produced the best result, increasing the maximum output power to 6.288 W, corresponding to a 26.77% increase compared with the reference panel without cooling. In addition, the output voltage increased from 17.7 V to 19.0 V, while the current increased from 0.49 A to 0.56 A. The optimized cooling system, consisting of 75 % paraffin, 25 % Vaseline, 30 cylindrical macrocapsules containing paraffin, and 0.15 wt.% copper powder, reduced the panel surface temperature from 64.42 °C to 51.93 °C, corresponding to a temperature reduction of 12.49 °C (19.39%). Overall, the results demonstrated that the simultaneous optimization of PCM composition, macrocapsule geometry, and thermal conductivity enhancement using copper powder can effectively improve the thermal and electrical performance of photovoltaic panels. The proposed passive cooling system provides a simple, cost-effective, and efficient approach for improving PV panel performance under hot climatic conditions.