Unveiling the thermodynamic performance of nano-enhanced bio-PCM for improved efficiency in solar cooling systems

Nano-enhanced bio-based phase change materials have emerged as promising thermal management materials for solar cooling applications because of their ability to improve heat transfer and thermal energy storage performance. This study presents a systematic review and quantitative synthesis of 50 peer-reviewed studies published between 2019 and 2025, focusing on thermodynamic mechanisms, thermophysical characterization, and cooling applications in photovoltaic and photovoltaic/thermal systems. The results demonstrate that nanoparticle incorporation significantly enhances thermal conductivity by approximately 15–400%, particularly with carbon-based nanofillers such as graphene and multi-walled carbon nanotubes, whereas latent heat retention generally decreases by 5–15% due to nanoparticle volume displacement and molecular interactions. The synthesized datasets indicate that an optimal nanoparticle loading of 2–4 weight percent provides a balanced enhancement of thermal conductivity and latent heat storage capacity. The correlation analysis reveals a minimal linear relationship between dispersion quality and latent heat retention, with a coefficient of r = 0.0935. This indicates that dispersion quality alone does not adequately account for the variations in latent heat retention observed across the reviewed studies. Instead, it suggests that factors such as nanoparticle morphology and interfacial compatibility are likely to have a more significant impact on thermodynamic behavior. The synthesis further shows that photovoltaic operating temperature can be reduced by up to 11°C under peak solar irradiance, resulting in an approximately 7.2% improvement in electrical efficiency. Exergy evaluation indicates that the latent phase contributes the highest useful exergy, approximately 42%, while demonstrating lower thermal irreversibility. Despite substantial material-level improvements, the aggregated system-level performance remains constrained by thermal resistance, methodological inconsistencies, and integration challenges in practical PV and PV/T configurations.