The economic efficiency of photovoltaic (PV) and battery systems for residential power distribution is evaluated quantitatively for the first time under a rate system using electricity prices that change at hourly intervals (i.e., real-time pricing, RTP). The evaluation model assumes that the option price of a feed-in tariff (FIT) decreases continuously. The proposed operational method focuses on utilizing both a low-price grid and home-generated power cooperatively. The economic effect of implementing this system is clarified by a computational simulation.