Tesla has agreed to build the world’s largest lithium-ion battery storage project in South Australia, billionaire founder Elon Musk said on Friday. The electric car company, which also makes the Tesla Powerpack storage battery, outbid 91 other companies to win a contract to install a 100 megawatt facility. It will partner with French renewable energy firm Neoen, and get energy from their Hornsdale Wind Farm near Jamestown, South Australia. The facility will be able to power 30,000 homes, according to CNBC.

Tesla’s Powerpack will charge using the energy produced from the wind farm and then deliver electricity during peak hours.

Musk announced the partnership at a press conference in Australia, followed by a tweet, in which he said the energy storage facility will be three times bigger than any on the market at the moment.

“You can essentially charge up the battery packs when you have excess power when the cost of production is very low … And then discharge it when the cost of power production is high, and this effectively lowers the average cost to the end customer,” Musk said at the press conference on Friday. “It’s a fundamental efficiency improvement for the grid.”

Musk also said that if the project is not completed in 100 days, it will be free, honoring a pledge he made a few months ago. Lyndon Rive, Musk’s cousin and co-founder of Solar City which recently merged with Tesla, said in March that the company could install a 100 to 300 megawatt energy storage project. Rive said at the time that this could be achieved within 100 days.