Solar power generation system with shut-off devices

A solar power generation system, comprising:

• a string including a plurality of solar cell module groups connected in series with each other, the solar cell module groups each including one or more solar cell modules connected in series;
• an inverter connected to the string and configured to convert DC power output from the string to AC power;
• a first shut-off device connected to a first electric path connecting some of the plurality of solar cell module groups;
• and
• a second shut-off device connected to a second electric path connecting others of the plurality of solar cell module groups different from the plurality of solar cell module groups connected by the first electric path,
• wherein
• each of the plurality of solar cell module groups in the string each has an open circuit voltage equal to or less than a predetermined open circuit voltage,
• the first shut-off device cuts off the connections between said some of the plurality of solar cell module groups connected to the first electric circuit in response to a first control signal from the inverter,
• the second shut-off device cuts off the connections between said others of the solar cell module groups connected to the second electric circuit in response to a second control signal output from the first shut-off device by a communication system different from power line communication and sent to the second shut-off device by a communication line connected between the first shut-off device and the second shut-off device,
• the plurality of solar cell module groups in the string includes a first group, and
• the first shut-off device includes
• a first open-close unit connected to an anode-side terminal of the first group;
• a first semiconductor switching device connected in series between the anode-side terminal of the first group and the first open-close unit;
• and
• a first power supply unit configured to generate power to drive the first open-close unit, the first power supply unit having an anode-side terminal connected between the anode-side terminal of the first group and the first semiconductor switching device, and a cathode-side terminal connected to a cathode-side terminal of the first group,
• the first semiconductor switching device being configured to enter an OFF state in a case where an amount of power generated by the first group falls below a predetermined threshold.