An integration of passive and active cooling systems for thermal regulation of concentrated photovoltaic (CPV) solar system has been developed and modeled. A heat storage battery of phase change material (PCM) is combined with a closed loop water cooling system in the developed design. A two dimensional model has been developed for the simulation of the CPV layers with the integrated cooling system. Results have been investigated to evaluate the thermal and electrical performances of the system components and the entire system. Further investigations have been conducted to study the effects of different arrangements of the PCM plates in the water tank on the system performances. Enhancing the system performance by using nanofluid as heat transfer fluid (HTF) was also evaluated. Results showed that the proposed system achieves 60% reduction in the CPV average temperature compared to the conventional direct PCM-PV and water-cooling individual systems. At 10 concentration ratio (CR) and 0.01 m/s HTF velocity, the cell temperature does not exceed 78 °C. Moreover, the PCM maximum temperature is kept below the degradation temperature limit. The effect of the PCM plates’ arrangements in the water tank on the system performance is negligible. Using nanofluid as HTF enhancer increases the CPV efficiency by 2.7% and reduces the PV maximum temperature and the PCM melting time by 4 °C and 12%, respectively.