During the last twenty years, the comfort and cooling requirements of office buildings and occupants have evolved significantly in Reunion Island, particularly during the summer period. This intensive use of air conditioning has resulted in a significant increase in electricity consumption such as traditional cooling technologies (mechanical vapor compression systems). In this context, solar cooling systems are one of the more interesting alternatives to conventional air conditioning systems. Thus in 2008, the PIMENT laboratory in Reunion Island proposed to set up an experimental platform called "RAFSOL", on the University Institute of Technology of Saint-Pierre, to study the absorption solar cooling technology for a University building. Experimental and numerical investigations of RAFSOL allowed to identify several research topics to improve global performances of the installation. One of them concerns the incorporation of a new thermal storage into the solar cooling system. Indeed, the addition of thermal storage (hot and/or cold) give the following advantages: (i) sufficient cooling power to cover the entire building’s needs, (ii) intelligent use the weekend energy potential, (iii) prevents overheating of the solar loop because of lower cooling needs. This thermal storage would also improve the system performance since it brings the temperatures of the hot and cold sources closer to their nominal values and thus optimizes the running time of the absorption chiller. In this work we decided to study only the incorporation of a hot thermal storage composed of a phase change material, and to investigate the influence of this storage on the solar cooling system performances. Three different phase change temperatures are investigated according to the state of art of this echnology: 79, 84 and 90°C. Simulation results are then analyzed and discussed to identify the optimal configuration of the thermal storage. In this first approach, the results show that the most interesting melting temperature, to improve most of performance indicators is 79°C.