ABSTRACT
Solar water heating systems (SWHSs) are generally used in the residential, commercial, and industrial sectors in the whole world community. In such type of systems, thermal energy storage is playing a critical role to maintain the temperature of stored water. As solar radiation is available only in day time, however, several users would like to use the hot water during off sunshine hours. Therefore, storage concept is needed to sustain the hot water temperature during late evening hours. To resolve such type of issue, phase change materials (PCMs) can be a good option. PCM can store the energy in the form of latent heat of fusion during the charging mode and stored heat can be released later to heat water as per the requirement. It has been seen that for a good thermal performance of solar water heater a PCM with the high latent heat of fusion and with large surface area for heat transfer is required. This chapter summarizes the role of the PCM in SWHSs.
