The world’s largest lithium-ion battery officially began supplying power to South Australia’s power grids on Friday. The 100-megawatt battery was built by Tesla in just 63 days – much before the company founder Elon Musk’s self-imposed deadline of 100 days ends.

Musk had promised to not charge the government if his team did not meet the deadline.

South Australia has faced troubles with electricity supply for several months, including one occasion last year when the entire state lost power. But the new source of renewable energy in Jamestown will provide “clean and affordable wind energy...24 hours a day, 7 days a week...whether the wind is blowing or not”, said a government release.

The battery was launched by South Australian Premier Jay Weatherill and the deputy chief executive of French company Neoen, Romain Desrousseaux. Neoen runs the wind farm to which the Tesla Powerpacks battery is attached.

“This is history in the making,” Weatherill said.

Musk describes the battery as three times more powerful than the next biggest battery, BBC reported. When fully charged, it can power up to 30,000 homes for an hour.

The battery was “fully installed” last week, and was awaiting regulatory approvals.

Tesla had won the bid to build the battery in July, and it was already halfway through when the countdown actually began with the signing of a grid connection agreement on September 29.

South Australia is the country’s most wind power-dependent state, and had announced a $550-million energy plan to improve its electricity services. Power supply from conventional energy sources are expected to be tight this year, the country’s energy market operator has warned.