it can be seen that melting of RT20 PCM is much faster than RT28HC. The RT20 has a melting onsettemperature of 21.2 _C. It means it will start to melt earlier than RT28HC which has the melting temperature 28 _C. Again the energy density of RT20 is much smaller than RT28HC. So for a given temperature, RT20 will change its phase much faster to stabilize the system. Another important observation is; for higher energy density PCM i.e. RT25 and RT28HC, the full PCM domain will not be melted as indicated in Fig. 5. This is because heat energy due to the given solar irradiance (750 W/m2 for present study) is consumed by the melted PCM as sensible heat before reaching the solid portion of the PCM. As a result there is no contribution of latent heat energy at that time. This is an indication of proper size selection of the PCM chamber. From Fig. 5 it can be seen that for an operational time of 480 min, RT20 is fully melted where as RT25 and RT28HC are melted 80% and 65% respectively. The phenomenon of melting can also be described by the individual cell temperature inside the PCM. In the present study PCM domain is divided into 10 cells where cell 1 is near to the PV module. From