Provided are a solar panel (1), a first DC/DC conversion circuit (13), a DC/AC conversion circuit (21) connected via a DC bus (25), a second DC/DC conversion circuit (17) for controlling bus voltage in the case of power outage, a first control section (14) having two kinds of control modes and controlling the first DC/DC conversion circuit (13), a second control section (18) for controlling the second DC/DC conversion circuit (17), and a third control section (22) for controlling the DC/AC conversion circuit (21). The second control section (18) controls bus voltage in the case of power outage, and the first control section (14) switches the control mode based on information of the second control section (18).