An Experimental-Based Method to Assess the Effectiveness of PCM Integrated in Photovoltaic/Thermal (PV/T) Systems

Hybrid photovoltaic/thermal (PV/T) modules integrated with phase change materials (PCMs) are an already studied solution to increase the overall efficiency of PV panels. PCMs allow to store, as latent heat, a large share of the incident solar energy not converted into electricity. Different solutions were proposed in literature, focusing on different aspects (efficiency, phase-change process, climate conditions) and comparisons are complex. This paper proposes a methodology for thermal characterization, through a Dynamic Heat Flow Meter (DHFM), of PV/T-PCM modules. The aim is to provide a standard methodology to evaluate and compare the different solutions proposed under the same conditions. The methodology involves two tests, namely the equivalent thermal conductivity test and the sinusoidal thermal response under steady-state and dynamic conditions, respectively. The latter is also proposed as quantitative approach for the selection of the optimal melting temperature of the PCM, based on the working time in the melting temperature range. Results show that the equivalent thermal conductivity ( λ eq ) is not affected by the heat flux direction with solid PCM ( λ eq : around 0.33 W/(m·K)), while for liquid phase, different values for downward ( λ eq : 0.28 W/(m·K)) and upward ( λ eq : 0.33 W/(m·K)) heat flux were obtained. The second test returns that the exploitation of latent heat is higher with a mean temperature of the upper plate equal to 40°C (36.4%) than to 35°C (20.4%).