Synergistic integration of graphene-CNT-doped stearic acid PCM and graphene–metal oxide hybrid nanofluids for enhanced photovoltaic thermal–electrical performance

To enhance the durability of the solar PV systems, it is necessary to use novel materials and methods for cooling and disposal of unwanted heat. In this perspective, phase change materials (PCMs) with hybrid nanofluids are one of the best choices for efficient thermal management. This experiment proposes a novel PV cooling system that uses graphene and CNT nanoparticles (1:1) and (6 w/w%) added stearic acid as a PCM with hybrid nanofluids to maximize heat dissipation and system overall efficiency. The novelty lies in the synergistic combination of graphene-CNT-doped PCM (melting point 59 °C) with graphene-metal oxide hybrid nanofluids. Three hybrid nanofluids were prepared: G-TiO₂, G-Al₂O₃, and G-SiO₂, at a volume concentration of 0.5%, and different flow rates of 2, 4, 6, and 8 LPM were tested. The results proved that the 6 LPM flow rate, with the G-Al₂O₃ nanofluid, gave the best thermal and electrical results. In that, the enhanced absolute electrical efficiency was 4.5%, thermal efficiency by 8.3%, and the Nusselt number was 295 in comparison with the base fluid (DI water). Although the pressure drop and friction factor increased by 0.3 N/m² and 0.08, respectively, with G-SiO₂, it is still controllable with normal pumping. The proposed solar PV cooling system is highly applicable in building-integrated systems, hot climates, and hybrid renewable micro-grid systems.