That's no small feat considering the battery is the size of a football field and is capable of powering 30,000 homes. Tesla's battery farm is tied into Neoeon's Hornsdale wind farm, which is several hours north of Adelaide.
"Neoen is pleased to be able to reinforce its Australian footprint through the achievement of the Hornsdale Wind Farm & Battery and is extremely proud to contribute further to the development of renewable energy in Australia".
Neoen deputy CEO Romain Desrousseaux said: "We would like to acknowledge the efficiency, support and vision of the South Australian Government to bring the state to the forefront of global energy storage technology".
The move fufills a promise by the firm's founder Elon Musk to build it in 100 days or give it away for free.
The 100MW battery was switched on by South Australia's premier, Jay Weatherill on Friday, December 1 who said that it was "history in the making".
"The completion of the world's largest lithium-ion battery in record time shows that a sustainable, effective energy solution is possible", Tesla said in a statement.
Supporters, however, say it will help stabilise the grid in a state that now gets more than 40 percent of its electricity from wind energy, but needs help when the wind dies down.
South Australia, which relies heavily on solar and wind-generated energy, has been scrambling to find a way to bolster its fragile power grid since the entire state suffered a blackout during a storm a year ago.
"Neoen and Tesla approached the State Government with their bold plan to deliver this project, and they have met all of their commitments, ensuring South Australia has back up power this summer", he added.
Some have called the battery a "Hollywood solution", which likely stems from the flashy nature of the battery's creation in a country that does still rely partly on fossil fuels. "It can address those stability issues very quickly without needing to resort to using large power plants", said Praveen Kathpal, vice president of AES, a losing bidder to build the battery.