Optimization of thermal and electrical efficiencies of a photovoltaic module using combined PCMs with a thermo-conductive filler

Abstract The purpose of this study is an optimization of thermal and electrical efficiencies of a photovoltaic module using combined phase change materials (PCMs) with a thermo-conductive filler. Composites of beeswax and coconut oil (BWCO) and its mixture with paraffin (PBWCO) are introduced as novel PCMs and used to thermal regulation in a photovoltaic (PV) module. Terephthalic acid powder (TPA) is added to PBWCO to upgrade its thermal conductivity. The electrical and thermal efficiencies (ηe and ηth), as dependent variables, are investigated by the response surface methodology (RSM) to obtain the optimal condition of the PV/TPA-PBWCO system. The selected independent factors of the cooling system are beeswax weight fraction in BWCO (X1 = 0–100%wt), BWCO weight fraction in PBWCO (X2 = 0–50%wt), TPA weight fraction in PBWCO (X3 = 0–12%wt) and weight of PCM (X4 = 2.1–4.1 kg). Results show that for uncooled mode, ηe and ηth are 8.16% and 58.61%, respectively. The results illustrate the usage of BWCO put out higher electrical and thermal efficiencies than their pure ones. BWCOs with X1 > 45%wt and X1   37.5%wt reduces the effect of the PCM, which is due to the increase of the melting point, although it has slightly increased the latent heat and thermal conductivity, the effect of melting point is more dominant. The addition of TPA to PBWCO remarkably enhances the cooling system performance. The predicted electrical and thermal efficiencies at the optimal point are 14.88% and 90.76%, respectively, at X3 = 8.48%wt and X4 = 3.253 kg.