Integration of photovoltaic modules with phase change materials: Experimental testing, model validation and optimization

Phase Change Materials (PCMs) enhance Photovoltaic (PV) system efficiency by stabilizing operating temperatures, reducing heat-induced performance losses, and extending system lifespan. This study evaluates the thermal and electrical behavior of PCM-enhanced PV systems, validates a predictive model, and identifies optimal PCM configurations to maximize energy output. Experimental tests were performed over 47 days at the SolarTechLAB, Politecnico di Milano, Italy, on a standard PV module and three enhanced PV modules integrated with PCM. Three distinct PCMs, all composed of inorganic mineral-based compounds such as salt hydrates, were selected with melting temperatures of 18 °C, 29 °C, and 48 °C, respectively. Measurements included PV rear surface temperatures, heat fluxes, and power outputs. Thermal and electrical performance indicators, including electrical efficiency and final yield, were analyzed alongside detailed thermal analyses of phase change phenomena using charge and discharge indices. A new metric, the global energy gain ratio, is proposed to quantify the increase in electrical energy produced per unit of thermal energy stored by the PCM layer in a given period. The PV-PCM48 module increased energy output by 6.84% and reduced thermal stress with a maximum rear temperature drop of 26 °C, while the PV-PCM29 module improved output by 3.14%. The PV-PCM18 module showed a slight decrease of 0.65%. A lumped parameter model accurately predicted electrical performance and thermal dynamics. Parametric analysis revealed a 10 mm PCM48 layer and a 15 mm PCM29 layer as optimal, yielding, respectively, a further 0.7% and 0.5% increase in energy output compared to the corresponding experimental PV-PCM setups. A melting temperature of 45 °C led to a further increase in the energy output of 0.5% compared to the PV-PCM48 configuration. These findings demonstrate that the experimental PV-PCM configurations tested are close to their optimal conditions.