Experiments and simulations were carried out to assess a passive device for cooling photovoltaic cells under concentrated sunlight. The cooling device was made of a Graphite- Phase Change Material (PCM) composite inserted in an aluminum enclosure. The PCM considered in this work was selected among several commercially available materials. Experimental plots of material temperature versus time were recorded for various incident solar powers and compared to 3D-thermal simulation predictions. Theoretical cell temperature profiles obtained using the PCM-based device were compared to those obtained without PCM, that is, using bulk (PCM-free) aluminum heat sink. The interest of using PCM cooling systems in CPV applications was finally discussed.