To provide a power supply system for suppressing generation of excessive reverse-flow power by supplying a greening apparatus of a customer with surplus power when power generated by a power generator of the customer causes the reverse-flow power.

A customer 1 has a power supply system 10 including a power meter 2, a rooftop greening apparatus 3, and a power generator 4. The power generator 4 is equivalent to a private power generation facility and includes a solar panel 42, a power conditioner 7, a changeover section 6, and a distribution board 5. When reverse-flow power is detected, the changeover section 6 is operated to form a power supply path so that power from the solar panel 42 is supplied to the rooftop greening apparatus 3.