Tesla builds world’s biggest lithium ion battery; Musk on track to win wager

Tesla has completed construction of the world's largest lithium ion battery in Australia, putting it on track to meet a 100-day deadline for switching the battery packs on, the South Australian government said today Thursday.

Elon Musk

Chief executive Elon Musk will thus get paid for building the 129 megawatt hour battery – he had promised to give it to the state for free if he did not meet the deadline.

Tesla won a bid in July to build the battery for South Australia, the country's most wind power-dependent state, with a vow from Musk to install it within 100 days of signing a grid connection agreement or give it for free.

When the grid connection deal was signed on 29 September, Tesla was already half way through installing the battery packs.The Tesla Powerpacks have now been fully installed at a wind farm in Hornsdale, 230km north of the capital, Adelaide.

The wind farm is run by France's Neoen. Testing is set to begin to provide grid security services in South Australia.

''While others are just talking, we are delivering our energy plan, making South Australia more self-sufficient, and providing back up power and more affordable energy for South Australians this summer,'' state Premier Jay Weatherill said in a statement.

When fully charged, the Tesla Powerpack is expected to hold enough power for 8,000 homes for 24 hours, or more than 30,000 houses for an hour during a blackout.

The state has yet to say how much it would pay for the battery, which is part of a A$510 million ($390 million) plan that includes diesel-fired generators to help keep the lights on following a string of blackouts over the past 18 months.

Australia's energy market operator has warned that power supply will be tight this summer, particularly in South Australia and neighbouring Victoria, where one of the market's biggest coal-fired power plants was shut in March.

A 250MW gas-fired generator, expected to cost $360 million, is also due to come online this summer to provide extra power.

The battery is the result of a Twitter bet between the Tesla founder and Atlassian Corp's Mike Cannon-Brookes last March that Musk would supply the battery within 100 days or it was free. The clock began ticking when Musk visited Adelaide in September to sign off on the deal.

Musk had said that if he failed to meet the deadline, it would have cost him ''probably $50 million or more''.

The Tesla plant will be called upon during periods of ''load shedding'' - when excess demand would otherwise result in blackouts.

Weatherill said the battery was now completed and the testing will ensure it is optimised and meets energy market regulatory requirements.

''It sends the clearest message that South Australia will be a leader renewable energy with battery storage,'' he said.

''An enormous amount of work has gone in to delivering this project in such a short time, and I look forward to visiting Jamestown next week to personally thank those who have worked on this project.''