Key Takeaways
- Battery discharge rates have surged over the last two years, especially in 2025.
- As of August, there is a total of 7,201 MW and 13,741 MWh of battery capacity on the main grids.
- In South Australia, big batteries have accounted for up to 30% of the evening peak supply.
There has been a lot written, particularly on this website, about the growth in big battery storage on Australia’s main grid in recent times – it appears to be the only part of the green energy transition that is going to plan.
This graph below – courtesy of Perth-based futurist and solar-battery hybrid developer Ray Wills – shows a new angle to the growth, capturing the increase in collective battery discharge over the last two years.
In calendar 2023 not a lot changed, but growth started to happen again in 2024, and in 2025 it has already surged more than two fold in just eight months.
Graph: Ray Wills
According to Wills’ data there is 7,201 MW and 13,741 MWh of battery capacity on the main grids as at the end of August, and the discharge rates are rapidly increasing, averaging around 7 GWh a day in the last 2 weeks of August, and the surge expected to continue into springtime.
This data does not include household batteries, now being installed at the rate of more than 400 MWh a month – three times the size of the original Hornsdale battery.
Big battery discharge is already accounting for nearly 20 per cent of the supply in the evening peak in Western Australia’s isolated grid, and that will jump significantly when the 500 MW, 2,000 MWh Synergy battery at Collie is commissioning later this year, and another four big batteries under construction are also completed.
In the country’s main grid, big batteries have accounted for up to 30 per cent of the evening peak on occasions in South Australia, and regularly contribute more than 5 per cent of supply across the whole national electricity market.
