Comparative evaluation of sodium nitrate, potassium nitrate, and solar salt as phase change materials for latent thermal energy storage in solar electricity generation in North-Eastern Nigeria

The intermittency of solar energy remains a major constraint to reliable electricity generation, particularly in high-irradiance regions with limited grid infrastructure. Latent thermal energy storage (LTES) systems based on phase change materials (PCMs) offer high energy storage density and near-isothermal operation, making them well suited for solar thermal power applications. This study presents a region-specific, simulation-based comparative evaluation of Sodium Nitrate (NaNO₃), Potassium Nitrate (KNO₃), and Solar Salt as PCMs for latent thermal energy storage under the climatic conditions of North-Eastern Nigeria. A dynamic LTES model was developed in MATLAB/Simulink to analyze thermal behavior during charging and discharging cycles, stored thermal energy, discharge characteristics, and thermal efficiency. The simulation results indicate that Solar Salt achieves the highest total stored thermal energy of approximately 1300 kWh per cycle, followed by NaNO₃ (~780 kWh) and KNO₃ (~520 kWh). Solar Salt also demonstrates superior discharge stability and thermal efficiency in the range of 80–85%, compared with 78–82% for NaNO₃ and 77–81% for KNO₃. Although Solar Salt involves a higher initial material cost, its enhanced thermal performance and sustained power output support its suitability for performance-driven solar electricity generation in high-irradiance regions. The findings provide quantitative guidance for PCM selection in latent thermal energy storage systems under high-irradiance Sub-Saharan African conditions.