This paper presents an 3D TCAD model of crystalline Silicon (c-Si) solar cells. Physical parameters used in the model are discussed. Simulation results are compared to experimental current-voltage curves and solar cell figures of merit namely open-circuit voltage, short-circuit current density, fill factor, and conversion efficiency, allowing us to determine an optimum design for these devices. Particularly, the model is applied to conventional p-type c-Si solar cells with rear contacts based on Laser-Firing technique and to Doped by Laser (DopLa) crystalline Silicon solar cells.