In recent years, as a distributed power-generator that generates power in a consumer, a photovoltaic cell (PV) and a gas power-generator are widely used (See PTL 1, for example). The gas power-generator includes a household fuel cell using city gas or propane gas.
Also, an increasing number of cases are assumed where a storage battery is introduced, in the consumer, for charging power from a power system during night time when the power rate is low and for supplying (discharging) the power to a load during daytime.