Photovoltaic (PV) systems have rapidly proliferated in Japan. One resulting problem is that PV output not consumed by residences is fed to distribution lines, significantly increasing voltage in the distribution system. Power conditioning systems must therefore suppress PV output to maintain appropriate voltage levels. This paper proposes a control method for diverting reverse power flow into storage batteries, avoiding the need for suppression. Another problem is that batteries are expensive, making it necessary to reduce total battery capacity. This paper therefore identifies residences where storage batteries should be introduced by calculating a suitability evaluation coefficient. This allows allocation of a priority sequence for introducing batteries into highly ranked residences. The authors furthermore begin investigation of battery control methods for effective suppression of battery output.