A solar power generation system includes a string, an inverter, and first and second shut-off devices. The string includes a plurality of solar cell module groups. The first shut-off device cuts off the connections between the plurality of solar cell module groups of a first electric path in response to a first control signal. The second shut-off device cuts off the connections between the plurality of solar cell module groups in a second electric path in response to a second control signal output by a different communication system. The first shut-off device includes a first open-close unit, a first semiconductor switching device connected in series to the first open-close unit and a power supply unit configured to generate power to drive the first open-close unit. The first semiconductor switching device enters an OFF state if the amount of generated power is smaller than a predetermined threshold value.