SYSTEM INTERCONNECTION DEVICE FOR DECENTRALIZED POWER SUPPLY

A system interconnection device (10) for a decentralized power supply includes a power generation device (11), an alternating-current system power supply (20), a plurality of electric wires (21, 22), an inverter (13), a reactor (14a, 14b), a connection electric wire (23), a condenser (14c), a plurality of normally-open type first and second switches (15a, 15b), a loop circuit (A) and a control unit (16) controlling the switch (15a, 15b) to be open and closed. The control unit (16) includes a welding determination portion (16) determining that a contact point of the first switch (15a, 15b) is welded in a case where a current flows in the loop circuit (A) when the control unit (16) commands the first switch (15a, 15b) of the switches (15a, 15b) provided at the loop circuit (A) to be open, the first switch (15a, 15b) serving as a subject of determination being determined whether the contact point is welded, and commands the second switch (15a, 15b) to be closed, and when the control unit (16) applies a voltage to the loop circuit (A).