An apparatus for controlling the operation of power conditioners (10) for supplying the generated power to an external power system such as a commercial power system, in which power conditioners (10) are interconnected to an external power system, the power conditioners (10) are interconnected through information exchange means, at least one of the power conditioners (10) monitors the reverse power flow, and the power conditioners (10) exchange the monitor information with information of the other power conditioners (10), thereby equalizing the outputs of all the power conditioners (10). A generator (42) has armature windings (60), and an inverter circuit (13) of the power conditioner (10) provided for each of the armature windings (60) is controlled by cable or radio.