State-of-the-art review on nano enhanced PCMs for solar energy storage applications

Solar thermal energy storage has emerged as a critical component in improving the efficiency and reliability of renewable energy systems. This review examines the role of nano-enhanced phase change materials (NePCMs) in solar thermal energy storage systems, with emphasis on their thermophysical enhancement mechanisms, preparation methods, and performance in applications. The study critically evaluates how nanoparticle incorporation improves thermal conductivity, heat transfer behavior, and thermal stability of conventional phase change materials. In addition, key preparation methods and their influence on material performance and scalability are discussed. The review further analyzes the application of NePCMs in solar thermal systems, including solar cookers, solar dryers, and solar-thermal-assisted power systems, alongside associated engineering challenges. Reported studies indicate that incorporating nanoparticles can enhance thermal conductivity by approximately 5% to 100%, depending on nanoparticle type, dispersion quality, and loading concentration. Overall, NePCMs demonstrate significant potential to improve the efficiency and reliability of solar thermal energy storage, though further research is needed to address costs, stability, and large-scale implementation.