This paper deals with the peak cut system composed of PV power generation and storage battery. Recently, the demand for electric power becomes much greater especially in summer. Therefore, cutting and shifting the peak power consumption attracts ever-increasing attention. The introduction of the peak cut system results in the extensive reduction of power charge. In this paper, we investigate the effective design method of both PV and storage battery capacities in the system by means of computational simulation. Some numerical results are also presented to demonstrate the validity of the proposed method.