Computer simulation for the silicon solar cells is established using Matlab/Simulink. The output characteristics and maximum power point tracking (MPPT) curve are calculated. A new criterion based on the traditional perturbation and observation (P&O) method is given, with which a control module of solar cells is designed. Simulation results indicate that this module can adapt to the rapid changes in temperature and light, track the maximum power point much better than the traditional methods in speed and stabilities.