摘要 |
<p>A storage battery is charged with power supplied from at least one of a commercial power system and an independent power source, and supplies the charged power to a plurality of electric devices or the commercial power system. A control unit switches the operation state of the storage battery to either charging or discharging, and switches connection destinations of the storage battery. When the commercial power system is not in a power outage state, the control unit supplies power from the storage battery to the electric devices or the commercial power system only if the remaining level of the storage battery exceeds a reference value.</p> |