System comprising: a switching device; and a power supply control apparatus comprising: an inverter configured to convert electric power of a distributed power supply and supply the converted electric power to the switching device; a controller configured to detect a power outage in a power grid and to control an output voltage of the inverter to rise to a first voltage when the controller detects the power outage in the power grid and to maintain the output voltage at or below the first voltage when the output voltage reaches the first voltage; wherein the switching device is configured to switch supply for powering at least one load from i. a first electric power to be supplied by the power grid to ii. a second electric power to be supplied by the inverter characterized in that: the switching device is configured to switch from i to ii if the output voltage of the inverter reaches the first voltage; the controller is configured to control the output voltage to rise to a predetermined voltage exceeding the first voltage after having maintained the voltage at or below the first voltage. a switching device; and a power supply control apparatus comprising: an inverter configured to convert electric power of a distributed power supply and supply the converted electric power to the switching device; a controller configured to detect a power outage in a power grid and to control an output voltage of the inverter to rise to a first voltage when the controller detects the power outage in the power grid and to maintain the output voltage at or below the first voltage when the output voltage reaches the first voltage; wherein the switching device is configured to switch supply for powering at least one load from i. a first electric power to be supplied by the power grid to ii. a second electric power to be supplied by the inverter characterized in that: the switching device is configured to switch from i to ii if the output voltage of the inverter reaches the first voltage; the controller is configured to control the output voltage to rise to a predetermined voltage exceeding the first voltage after having maintained the voltage at or below the first voltage. an inverter configured to convert electric power of a distributed power supply and supply the converted electric power to the switching device; a controller configured to detect a power outage in a power grid and to control an output voltage of the inverter to rise to a first voltage when the controller detects the power outage in the power grid and to maintain the output voltage at or below the first voltage when the output voltage reaches the first voltage; wherein the switching device is configured to switch supply for powering at least one load from i. a first electric power to be supplied by the power grid to ii. a second electric power to be supplied by the inverter characterized in that: i. a first electric power to be supplied by the power grid to ii. a second electric power to be supplied by the inverter characterized in that: the switching device is configured to switch from i to ii if the output voltage of the inverter reaches the first voltage; the controller is configured to control the output voltage to rise to a predetermined voltage exceeding the first voltage after having maintained the voltage at or below the first voltage.