Enhancing passive cooling of solar photovoltaic panels using self-encapsulated phase change materials

The photovoltaic (PV) panels typically lose about 80 % of solar energy as heat, which causes PV cell temperature to rise. This increased temperature degrades their energy conversion efficiency and shortens their lifespan. Phase change materials (PCMs) can be integrated into the back of PV panels to cool them as a promising passive cooling solution. In particular, self-encapsulated phase change materials (SEPCMs) offer advantages like high latent heat, ease of handling, thermal stability, and leak-proof characteristics. However, current studies on SEPCMs for cooling PV panels have yielded suboptimal results, as their thermal properties and thicknesses often do not align with meteorological conditions. To address this challenge, this study investigates how varying the thermal properties and thicknesses of SEPCMs, along with different meteorological conditions, affects the cooling efficiency of PV panels and the phase change behaviour of SEPCMs. The findings indicate that a phase change temperature 5 to 15 °C above ambient temperature, coupled with high thermal conductivity and latent heat, achieves optimal cooling performance. If these properties cannot be satisfied simultaneously, high latent heat may be compromised due to its limited impact on cooling efficiency, while thickness can compensate for latent heat loss. The case study in Hong Kong demonstrates that SEPCM effectively reduces temperature rise in PV cells and mitigates sharp temperature fluctuations, resulting in an increased daily energy output. This study provides valuable guidance for the design and selection of SEPCMs with optimal thermal properties for effective PV cooling in various climates.