The electrical characteristics of the a-Se/c-Si heterojunction Solar Cell have been studied, where current-voltage characterization under dark conditions shows that forward bias current varieties approximately exponentially with voltage bias. This conforms to tunneling-recombination model, and reverse bias shows little stop and soft breakdown voltage. The current-voltage characterization under illumination found that the efficiency η increase with increasing the thickness and annealing temperatures from 0.806 to 1.62 and from 0.806 to 2.61, while increasing with increasing annealing temperatures because of structure changes of the films and improve interface layer between a-Se and c-Si. At deposition SiO2 it was found from the current-voltage characterization under illumination that the values η increase from 0.806 to 2.22.