An Experimental Comparative Study of Flat and Extended-Surface PCM Containers for Passive Cooling of Photovoltaic Panels

In this study, an experimental investigation was conducted to evaluate the thermal and electrical behavior of three photovoltaic panel configurations under controlled indoor solar irradiation of 600, 800, and 1000 W/m2, considering both natural and forced convection to the surrounding air. The tested configurations included an uncooled reference panel (PV-1), a PCM-cooled panel incorporating a flat rear container (PV-2), and a proposed PCM-cooled panel equipped with an extended-surface rear container (PV-3). A PCM characterized by a phase change temperature range of 41–48 °C was employed. The results showed that the extended-surface PCM configuration associated with PV-3 provides a more effective passive cooling solution compared to the flat container design. Under natural convection, this thermal advantage of PV-3 became more pronounced, with a maximum temperature reduction of 15 °C at 1000 W/m2 after 170 min of operation, compared to PV-2. Consequently, PV-3 achieved the highest electrical performance, delivering peak efficiency enhancements of 12.05% and 7.38% relative to PV-1 and PV-2, respectively, and average efficiency gains of 7.06% and 5.35% over the entire test period. Under forced convection, however, performance differences among the configurations were minimal because forced convection dominated the heat removal process, reducing the influence of the PCM.