Passive Cooling for Photovoltaic Modules

Abstract

The thermal performance of photovoltaic (PV) panels is a critical factor influencing their electrical efficiency, particularly in hot climates where elevated temperatures can significantly degrade power output. This thesis presents a comprehensive numerical investigation into a novel passive cooling system that integrates phase change materials (PCMs) and finned heat sinks to mitigate temperature-induced performance losses in PV panels. The research begins by validating STAR-CCM+, the CFD code employed in this study, over a several sets of simpler cases for which experimental data are available, which between them include all the important physical phenomena present in the proposed PV panel cooling strategy. These are natural convection in differentially heated square cavities, natural convection over open vertical finned domains and melting of PCM materials in a rectangular cavities. Using validated three-dimensional, transient computational fluid dynamics (CFD) models in STAR-CCM+, the behaviour of air and PCM under various thermal loads is captured, with emphasis on flow patterns, temperature distribution, and liquid fraction evolution. Subsequently, a series of twelve PCM–fin cooling configurations are simulated under realistic environmental conditions for a full-scale PV panel, including daily variations in solar irradiance and ambient temperature. Each design is assessed in terms of peak temperature reduction, PCM melting/solidification cycles, electrical power enhancement, daily energy yield, weight increase, and material cost. The results reveal that the optimised design can reduce PV surface temperature by up to 22.3 °C and enhance daily energy output by approximately 10.4%, thereby improving both thermal stability and system longevity. The study also considers the practical drawbacks of the proposed system, including increased structural weight of the heat sink, their material cost, and potential issues related to PCM thermal expansion, like container deformation and PCM leak. Despite these challenges, the proposed approach offers a promising and technically feasible pathway to improving PV performance, particularly for installations in high-temperature regions.