This work is devoted to studying the effect of the doping degree of the rear isotype layer in the silicon bifacial solar cell (SC) using the “Sentaurus TCAD” modeling software package. The “Sentaurus TCAD” system allows to create a model of SCs with different structures and illumination conditions. The tools of the software system allow to change the physical parameters of the base and isotype layer of the SC. The traditional design of a monofacial sensitive SC with the structure n+-p-p+ and p+-n-n+ was investigated for comparative analysis. For the traditional design of a monofacial sensitive SC, the best results are achieved with a doping concentration of the rear isotype p+ (n+) layer of 1019 cm−3 for both structure types n+-p-p+ and p+-n-n+. Results showed that at the same time, the efficiency of SC with the n+-p-p+ structure is 5% higher than the efficiency of SC with the p+-n-n+ structure. When the bifacial sensitive SC was illuminated from the back side, the highest value of the short-circuit current was achieved at a doping concentration 1019 cm−3 for the p+ layer in the n+-p-p+ structure and 1019 cm−3 for the n+ layer in the p+-n-n+ structure. At the same time, the efficiency of SC with the n+-p-p+ structure is 17% higher than the efficiency of SC with the p+-n-n+ structure. When bifacial sensitive SC was illuminated from the front side, the highest efficiency value was achieved at a doping concentration of 1018 cm−3 and 1019 cm−3 for heavily doped p+- and n+- layers of both n+-p-p+ and p+-n-n+ structures. The assessment showed that in the case of simultaneous illumination of the front and back surfaces of bifacial sensitive SC, the short-circuit photocurrent density is increased by 1.57 times. Thus, the output power increases by 1.56 times.