Unit 8 at the Bruce nuclear generating station in Tiverton is producing electricity for the province again.
Bruce Power reports Unit 8 was returned to service on Sunday after being shutdown for nearly two weeks.
The Independent Electricity Market Operator had requested the shutdown because it had too much power and not enough demand.
It was the second time in two months that Bruce Power was asked to shut down a reactor due to a surplus of electricity.
Units 3 through 8 at the Bruce A and B stations remain online.