The Engie diesel generator in Port Lincoln has been permitted for use as a backup generator to meet energy shortfalls.
The generator is one of two Engie generators that were mothballed last year, ahead of their permanent closure in 2028.
In December, Energy Minister Tom Koutsantonis sought to change the rules that would give the Australian Energy Market Commission the power to bring decommissioned generators back.
The State Government has welcomed the decision, saying it will provide a temporary backup supply in the event of a future gas shortage.
The move comes amid the completion of the long-awaited New South Wales inter connector.