The solidification dynamics of cylindrical encapsulated PCM have been analyzed under convective boundary conditions that relate to thermal energy storage systems. A three dimensional, transient CFD model has been solved for examinations. Besides the widely used conduction model of solidification, in this study, the effect of natural convection within the liquid layer has been considered in the numerical model. The effects of parameters such as the initial superheating temperature, the encapsulation size, and the heat transfer coefficient at the outer surface of the capsule have been examined in terms of solidification dynamics and extracted energy during the phase change process. It was found that while the diameter of encapsulation significantly affects the solidification and the energy extraction times, the effect of encapsulation height on the solidification and the energy extraction times are not notable.