Investigating the effect of device dimension on the silicon solar cell, by using the PC1D numerical simulation environment, we report strong correlation of efficiency of the silicon solar cell with its size. The results showcase finer efficiency at the lower n-type thickness and higher p-type thickness. The internal quantum efficiency (IQE) and external quantum efficiency (EQE) too exhibit variation with the device size. As a whole, based on the statistical analysis, especially regression, variance, and best subsets selection, the paper depicts that the p-type thickness, ISC and VOC are the preeminent parameters to model the silicon solar cell.