In this work we studied the grating shape and their dimension effects on the optical, the electrical properties and therefore on the efficiency of thin film solar cell. This study was introduced using 3d numerical simulation results obtained from Multiphysics simulator. The semiconductor transport model is applied for solving the electrical properties, whereas the optical effect was applied to the PV by using electromagnetic module. The PV efficiency was improved by 1.73 % in case of using half circle grating compared to solar cell without grating. After study the effect of different types we extract the equivalent circuit of each thin film solar with one type of presented grating types.