Comparative Experimental Efficiency of Solar Water Heating Systems With Enhanced Thermal Performance: A Review

ABSTRACT Harnessing solar energy, solar water heating systems (SWH) offer a reliable and eco‐friendly way to meet hot water requirements, reducing reliance on fossil fuels and mitigating climate change. This review comprehensively assesses experimental efforts to enhance the thermal performance of SWH systems. It examines innovations in collector configurations, selective optical coatings, and advanced working fluids, such as nanofluids. The analysis evaluates key metrics, such as thermal and exergy efficiencies, by comparing experimental results with theoretical models, emphasising the importance of empirical data in addressing operational challenges. Comparative evaluations indicate that specific enhancements have improved thermal efficiency by over 60% compared to conventional designs. Nevertheless, issues related to cost, material durability, and scalability persist. The study highlights research gaps, including the need for sustainable phase change materials (PCMs), extended studies on nanofluid stability, and AI‐driven optimisation of system performance. These findings underscore the crucial role of experimental research in bridging the gap between theoretical models and practical applications, thereby supporting the broader adoption of SWH systems to promote global energy sustainability and decarbonization objectives.