Tesla CEO Elon Musk made a bet that he'd build the world's largest lithium-ion battery in Australia in 100 days.

If his company failed, Musk would personally pay for the project, but the battery is now ready for its first test ahead of full operation—and on schedule.

The massive 129-megawatt-hour battery will plug into South Australia's electricity grid so it can store renewable energy and supply it when needed.

DON'T MISS: Tesla offers South Australia battery storage within 100 days

South Australia already generates 40 percent of its energy from wind power, and its government announced a $150 million fund to support more renewable energy projects earlier this year.

The electric-car maker was selected over 90 bids to complement the Hornsdale Wind Farm, built by French renewable energy company Neoen, Mashable reported on Wednesday.

The battery will store energy for when it's needed during peak demand periods, and has the capability to power up to 30,000 homes.

Tesla South Australia lithium-ion battery storage

Tesla South Australia lithium-ion battery storage

Perhaps not so coincidentally, the 30,000 figure is the same number of homes that lost power in a major blackout this past September.

Musk famously took to Twitter when asked if he could guarantee the installation of 100 Mwh in 100 days.

"Tesla will get the system installed and working 100 days from contract signature or it is free," Musk tweeted back to the challenge, and added, "That serious enough for you?"

READ THIS: Tesla Semi, new Roadster distract from Model 3 production problems

Now, Australian regulators will ensure the system is fully optimized for the grid and that it meets all South Australian standards before it goes online December 1.

"While others are just talking, we are delivering our energy plan, making South Australia more self-sufficient, and providing backup power and more affordable energy for South Australians this summer," said Premier Jay Weatherill of the Tesla project.

Tesla has also begun installing solar panels and battery storage system at Puerto Rican hospitals in the aftermath of Hurricane Maria, to help with power needs as the island rebuilds after the devastating storm destroyed much of its electric-power infrastructure.

2017 Tesla Model 3 in Tesla assembly plant parking lot, Fremont, CA, November 2017

2017 Tesla Model 3 in Tesla assembly plant parking lot, Fremont, CA, November 2017

The Silicon Valley automaker has been busy with the battery project at the same time it is working to move past "production hell" with its lower-priced Model 3 electric car.

Musk said in July the company would be building 5,000 cars a week by the end of December, but since July, the company has built only a few hundred Model 3s.

CHECK OUT: Tesla Semi: 500-mile range, lower running costs than diesel... and it's fast

In typical Musk fashion, things didn't stop; Musk recently revealed the Tesla semi truck and a brand Roadster sports car.

Musk claimed the semi will enter production in 2019 and pre-orders are already open. The Roadster, meanwhile, is promised to arrive in 2020.


Follow GreenCarReports on Facebook and Twitter