The world’s largest lithium-ion battery has officially been turned on in South Australia promising to usher in a revolution in how electricity is produced and stored.

Tesla boss Elon Musk has made good on his promise to build the 100-megawatt facility on deadline or provide it free after blackouts last year that critics of the state’s Labor government blamed on pro-renewable policies.

The battery had begun dispatching some power into the state’s electricity network on Thursday afternoon as temperatures rose above 30C.

The state’s premier, Jay Weatherill, flicked the switch at Jamestown on Friday, saying it was history in the making. “I want to express my gratitude to the workers who have constructed this battery, they have every right to be proud of what they have constructed,” he said in a statement.

The project grew out of a Twitter bet between Australian software billionaire Mike Cannon-Brookes and Telsa and SpaceX CEO Elon Musk. In response to Cannon-Brookes’ incredulity about the speed that Tesla was claiming it could install grid-tied batteries, Musk promised to deliver a system to South Australia, a state that’s suffered debilitating blackouts in recent summers, “in 100 days or its free.”

Lithium-ion Battery