Temperature is one of the most important factors of solar photovoltaic panel (PV) efficiency. Increasing the temperature causes serious damage to the solar panel. In this research, the effect of the new model of the porous fin as rows of connected spheres on surface temperature was investigated. For achieving this target, the rigid fins and this model of porous fin were compared. Thermal radiation was also examined to increase accuracy in the calculations. After validation and grid study, two models of heat sink with distinct vertical layers and two horizontal layers of connected spheres have been investigated to cool down the PV panel. After that, the new concept of porous heat sink was optimized based on sensitivity analysis (SA) and Differential Evolution (DE) optimization algorithm. A combination of numerical modeling and D.E optimization can improve the final efficiency and increase heat transfer. In this study, by considering the porosity range between (0-70%), we try to find the optimal value of porosity. The results show that by using the special form of porosity on the back layer of the P.V panel, the heat transfer can be increased up to 15%. It's also indicated that the optimization process can improve the Nu and reduce calculation cost. This optimization algorithm is 34 times much faster than another optimization process in CFD method.