We use Silvaco software (atlas tcad) simulation to investigate the effect of dielectric layer deposed on rear surface of solar cells passivated emitter and rear totally diffused (PERT). For an improved performance for this solar cell, several physical factors must be considered, such as the light trapping behavior, and the resulting passivation performance and rear surface recombination currents were investigated. Particular consideration will be given to the back surface reflector (BSR) impact on reflection surface, interface passivation, and on the I–V characteristics. Numerical simulations show that using a layer of two dielectrics (SiNx/SiO2) with optical indices and thickness optimized in combination with contacts located (optimized metallization fraction f) at the rear surface allow for energy conversion efficiencies of 21.26% compared to a single layer of dielectric SiN 21.01%.