Do phase change materials (PCMs) contribute to the enhanced performance and functionality of solar stills? A comprehensive analysis

Abstract

This present review article examined the yield improvement of the phase change materials (PCMs), nanophase change material (nPCM) in the solar still. Relevant literature published between 2003 and 2025 was collected from major scientific databases, encompassing experimental, numerical, and hybrid investigations. It has been observed that PCM significantly improve the overall yield of the solar still. However, in some cases it marginally improves the day yield while it significantly improves the nocturnal yield. Based on the literature paraffin wax is readily used with solar still. It might be due to several important factor including their availability, favourable operating temperatures (40–60 °C), chemical stability, and strong compatibility with container materials. Moreover, it has been observed that copper oxide (CuO) and aluminum oxide (Al₂O₃) are most frequently employed with the PCM to improve its thermophysical properties. The choice may be fairly based on their low cost, favourable thermophysical properties, and wide availability. Finding suggests a bit modification in the solar still involving paraffin wax PCM, copper oxide (CuO) nanoparticles, and an electric heater can improve the yield up to 196%. It has been noted that addition of Glauber’s salt (PCM) with 10% CuO nanoparticles based solar still yielded 11 L/m²/day, showing the system’s suitability for small-scale domestic applications. In the most favourable cases, the integration of nanoparticles into PCM has achieved yield improvements exceeding 300% in active solar still configurations. Moreover, the review critically discusses leakage and degradation of the PCMs thermophysical properties and explores a wide range of practical solution to prevent it. It has been observed that the polystyrene shell (PS) can strongly holds the shape of the PCM and reduces the significant effect of external forces. Thus, improving the PCMs mechanical as well as thermophysical properties. Lastly, it concludes by highlighting key challenges and suggesting future research paths for developing effective PCM/nPCM based solar stills.