Final testing is underway on South Australia's big battery after work to increase its capacity by 50 per cent to 150 megawatts.
Energy Minister Dan van Holst Pellekaan said the project was entering its critical testing phase by activating the battery's full capacity.
"The increase in storage power and capacity means a faster response to disturbances such as network faults, so that within milliseconds the Hornsdale Power Reserve can help stabilise the grid," the minister said.
Independent modelling suggested the reserve had already delivered more than $150 million in customer savings within its first two years of operation.
"Upon successful completion of testing in the next few months, we expect these savings will continue to grow," Mr van Holst Pellekaan said.
The Hornsdale Power Reserve - already the world's biggest battery - was built by Tesla and is owned by Neoen Australia.
Neoen Australia Managing Director Louis de Sambucy said the testing phase ensured the completed expansion met the highest performance standards.
"The expansion will make Hornsdale Power Reserve 50 per cent bigger and will deliver ground-breaking innovations to increase grid security and further unlock renewable energy performance in South Australia," he said.
The state government is providing $15 million across five years for the project, while the federal government is investing $50 million and the Australian Renewable Energy Agency (ARENA) a further $8 million.