Latent heat thermal energy storage units employ phase change materials to store and release heat at a nearly constant temperature, ensure high heat transfer efficiency, as well as high charge and discharge capacity. Phase change materials (PCMs), allow a more compact, efficient, and therefore economical system to operate. Thermal Energy Storage (TES) systems are of growing importance within the energy awareness, because of TES can reduce the levelized cost of electricity of solar cooling systems. This paper proposes a comprehensive methodology where simulations were performed to demonstrate the phase change process of paraffin wax and to improve the effect of PCM modules on the heat transfer process. PCM modules were tested in the laboratory, then their impact on thermal energy storage were determinate. The rise of COP of solar absorption cooling system was calculated.