Tesla boss Elon Musk has lived up to his promise to complete the world’s largest lithium-ion battery within 100 days or hand it over to the South Australian state government for free. The 100MW/129MWh installation has now been turned on and is providing some power to the state’s electricity network. It was due to be switched on tomorrow, but extreme weather conditions expected to hit the state over the next few days brought the launch forward.

Musk had promised to have the battery up and running within 100 days of signing the contracts; if not, he wouldn’t charge anything for the system. The launch arrived just 63 days after pen was put to paper.

The battery stores energy generated by the neighboring Hornsdale Wind Farm, owned by French company Neoen. It can power 30,000 homes in the event of blackouts, which have plagued the state following a storm last year, but it will mostly be used to supply extra energy during periods of peak demand.

“The completion of the world’s largest lithium-ion battery in record time shows that a sustainable, effective energy solution is possible,” said Tesla. “We are proud to be part of South Australia’s renewable energy future, and hope this project provides a model for future deployments around the world.

While opponents of the battery have called it a "Hollywood solution,” the state’s premier, Jay Weatherill, said: “While others are just talking, we are delivering our energy plan, making South Australia more self-sufficient, and providing back up power and more affordable energy for South Australians this summer.”

“The world’s largest lithium-ion battery will be an important part of our energy mix, and it sends the clearest message that South Australia will be a leader in renewable energy with battery storage.”

The battery comes as part of Weatherill’s $550 million (US $416 million) plan to reduce the state’s reliance on the national power grid. Precisely how much it cost has not been revealed.