This work aims to study the phase change heat transfer of a Latent Heat Energy Storage System (LHESS) which consists of a sealed cylindrical capsule filled with a phase change material (PCM) placed at the focus of a concentrating solar collector. A numerical model was created using enthalpy porosity formulation and was validated by comparing the results to a similar study. This model was then applied to the current problem to study the phase change transfer of paraffin wax in a parabolic trough. A constant heat flux boundary condition was applied to different sections of the circumference of the absorber tube which varied along the circumference to account for the different values of flux at different parts of the tube. Values of the melt fraction and temperature were recorded at regular intervals of time to analyze the melting process of the PCM during the charging process of the LHESS.