Large-scale bifacial photovoltaic modules have the advantages of high unit yield and production. Because the module weight increases with the module size, the power conversion efficiency can decrease owing to defects such as encapsulant delamination and cell cracking caused by the increased deflection of the module. However, research on the design optimization of large-scale bifacial photovoltaic module frames is lacking. Therefore, in this study, we analyzed the deflection of large-scale bifacial photovoltaic modules using finite element analysis (FEA). Furthermore, we propose an optimal design for a solar module frame that minimizes both module deflection and frame weight using the response surface methodology (RSM). We established 32 experimental setups utilizing the design of experiments with five frame shape factors placed at two levels each. The results of structural analysis showed that the maximum deflection occurred at the center of the module. The results obtained using RSM for minimizing deflection and weight yielded optimal factors as follows: a, b, c, d, e were found to be 1.9 mm, 14.0 mm, 1.5 mm, 1.7 mm, and 2.5 mm, respectively. A comparison of the deflection and weight between the existing and optimal conditions obtained from structural analysis revealed an increase in weight of approximately 4.5% compared to the existing conditions. Simultaneously, a deflection reduction of approximately 15.8% was observed.