In the past, we have proposed some battery operations in a photovoltaic (PV) system using the PV output and load power forecasts. In the proposed method, we utilized multi-objective optimization for a residential area model that includes a large number of PV systems with storage batteries. To practically demonstrate that the proposed operation effectively improves the economic and environmental efficiencies, it is indispensable to evaluate the forecast error effects on operation design of PV system with storage battery. In this paper, we propose a method for evaluating the robustness of battery operation taking account of the statistical characteristics of forecast errors. Some numerical examples, which show the validity of the proposed method, are also presented.