Phase change materials for solar-powered devices

Solar energy has found widespread applications in diverse sectors, including cooking, electricity generation, space heating, water heating, and industrial processes. Despite its abundance and sustainability, the major limitation associated with solar energy utilisation is its intermittent nature, which restricts continuous energy availability due to diurnal and seasonal variations. This intermittence necessitates the incorporation of efficient energy storage systems to ensure reliability and improved performance of solar-powered technologies. Consequently, research on energy storage systems has become a focal area of interest among contemporary researchers. Energy storage can be achieved in various forms, among which thermal energy storage (TES) is particularly attractive due to its simplicity, cost-effectiveness, and compatibility with solar systems. TES retains excess heat for utilization later, thereby enhancing system efficiency and energy utilisation. The choice of TES material and operating temperature depends strongly on the specific application. The performance of a TES system is highly influenced by the type of storage medium and the temperature at which it operates. In this regard, phase change materials (PCMs) have attracted significant interest in recent years. They possess a high latent heat of fusion, undergo phase change at nearly constant temperature, and can absorb or release large amounts of heat within a limited temperature interval. A wide range of solar-powered technologies for instance solar cookers, solar water heaters, solar air heaters, and solar thermal power plants are now incorporating PCMs to overcome the mismatch between energy supply and demand. The use of PCMs in these systems stabilizes temperature profiles, extends the duration of operation, enhances overall efficiency, and enables better exploitation of solar energy, especially during periods of low or no sunshine This review comprehensively summarises the recent advancements and diverse applications of PCMs in solar-powered devices, highlighting their role in improving thermal performance, storage efficiency, and overall system reliability.