Tesla Inc (NASDAQ:TSLA) will build the world’s largest lithium-ion battery storage system in Australia under a “historic” deal announced on Friday.

Elon Musk said that Tesla will install a 100-megawatt facility within 100 days or it will be free.

The deal was signed by Tesla, French renewable energy firm Neoen, and South Australia to build the energy system that will protect the state from an energy crisis, BBC News reported, citing Premier Jay Weatherill.

Tesla will get energy from Neoen’s Hornsdale wind farm near Jamestown to build the battery storage system that will be able to power 30,000 homes. The battery is expected to be ready this year.

“There is certainly some risk because this will be largest battery installation in the world by a significant margin,” Musk said in Adelaide on Friday, noting that “the next biggest battery in the world is 30 megawatts”.

According to the government, the Tesla-built battery will be capable of providing additional power during emergencies.

“It will completely transform the way in which renewable energy is stored, and also stabilize the South Australian network as well as putting downward pressure on prices,” Weatherill said.

Tesla Inc (NASDAQ:TSLA) outbid 91 companies to win a contract for the installation of a 100-megawatt system, CNBC reported.

“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.

“We actually insisted in the contract that we be held to the hundred days or it’s free. That’s what we said publicly, that’s what we are going to do,” Musk said.

On Friday, shares of Tesla Inc (NASDAQ:TSLA) were down 5.58% in the pre-market session. The stock of the company is up more than 44% so far this year.