Elon Musk will keep his promise to deliver a large-scale Powerpack system to the government of South Australia in 100 days, or make it free, after Tesla won a bid “to provide a 100 MW/129 MWh Powerpack system to be paired with global renewable energy provider Neoen’s Hornsdale Wind Farm near Jamestown” in the Australian state.

Tesla announced Thursday on Twitter it had won the bid for what will be “the world’s largest lithium-ion battery storage project,” and Musk followed suit by lauding Australia for its renewable energy focus.

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In a statement Thursday on its website, Tesla said: “Tesla Powerpack will charge using renewable energy from the Hornsdale Wind Farm and then deliver electricity during peak hours to help maintain the reliable operation of South Australia's electrical infrastructure. The Tesla Powerpack system will further transform the state’s movement towards renewable energy and see an advancement of a resilient and modern grid.”

The capacity being installed by Tesla is the entire storage component of the project, and the company says it will be complete by December. The system will meet power requirements for over 30,000 homes, a number roughly the same as the homes that lost power during a state-wide blackout in September, according to the statement.

South Australia Premier Jay Weatherill issued a statement Friday local time (Thursday in the United States) about the timeline for Tesla to finish building the system.

“Confirming the commitment from Tesla CEO Elon Musk to deliver the battery within 100 days or it is free, it has been agreed between Tesla and the South Australian Government that the starting date for the 100 days will be once the grid interconnection agreement has been signed,” he said in the statement.

The battery will be operational round-the-clock and will provide emergency backup power whenever there is a shortfall in energy requirements in the state. The grid-scale energy project will also help manage peak load during the summer, an important factor given the blackouts that occurred during the Australian summer in the beginning of 2017. 

“The deal will also bring other investments by both Neoen and Tesla into South Australia’s economy, with details to be announced in the future,” Weatherill’s statement added.

Read: Elon Musk Says Tesla Powerwall Doesn’t Make Economic Sense In The US

It is not clear what that investment could be, or how much Tesla stands to gain from this Powerpack deal. However, the Tesla statement spoke about what the company is already doing in Australia’s power sector, and how the Powerwall could also be used in South Australia.

“Tesla’s Powerwall is now being installed for residential customers across Australia and ramping up quickly. The same technology that can help stabilize the South Australian grid can also be used by homeowners to collect energy during the day so it is stored and made available day and night, providing uninterrupted power even if the grid goes down,” the statement said.