The first stage of the Waratah Super Battery at Munmorah has been energised and registered with the National Electricity Market.
The milestones pave the way for commissioning works necessary for the project to begin operation next year.
The 850 megawatt (1680 megawatts-hours) battery project is critical for NSW's energy security, as the state's coal-fired power stations close.
It is designed to enhance grid reliability in the state by acting as a shock-absorber in the event of sudden power surges from events such as lightning strikes.
The broader project includes upgrades to the state's existing transmission network, and the development of an overarching control system.
"This is a huge step forward for the Waratah Super Battery project and our state's transition to secure, reliable grid powered by renewables and storage," director power systems at EnergyCo Lulu Shao said.
"Registering on the National Electricity Market is no easy feat, especially for the largest single dispatchable unit on the market and one of the largest grid-scale batteries in the world."
"This milestone is a testament to the hard work and collaboration of Akaysha and Transgrid and their delivery partners."
"We look forward to seeing further progress as the Waratah Super Battery undergoes more testing in the lead up to its big debut next year."
