Control of supplying power to a storage device is performed based on carbon emission strength or a power rate.A battery center 13 that constitutes a storage device 11 performs radio communication with a gateway 4 and is controlled by the gateway 4. The gateway 4 collects a measured value of power consumed by electric appliances in a home and obtains the carbon emission strength in real time. A solar panel 9 is provided and a battery of the storage device 11 is charged with an output of the solar panel. The battery is also charged with direct current power obtained from power from outside. The power is stored in the storage device 11 based on the carbon emission strength by charging control.