We propose in this work, a method of simulation based on the resolution of the equations of continuities for homostructures of silicon-based solar, and used a method of calculation the photocurrent delivered by the silicon solar cell applying the equations of continuities and the currents by analogy to the phenomena of loads transport according to the model of an homojunction n-a-Si:H/p-a-Si:H. We used Matlab software to simulate and optimize the layers thicknesses to achieve the maximum photocurrent generated under AM1.5 solar spectrum. The optimization of donor layer thickness shows clearly that the best results are obtained with the finest structures.  We worked out a numerical model based on the resolution of the equations of continuities who gave the results in good agreement with literature and which allowed, moreover a better control of the performances of the cells based on silicon, for their improvement.