Grid-Scale Battery

Scale and context

The home battery market in Australia - measured in GWh of total installed capacity - remains smaller than the grid-scale market, which has grown rapidly since Neoen’s Hornsdale Power Reserve (150 MW / 193.5 MWh) was commissioned in South Australia in 2017.

Grid-scale batteries (formally called Battery Energy Storage Systems, or BESS) connect at the transmission level (66 kV and above) or distribution level and operate as fully registered market participants in the NEM. They bid into the FCAS and energy markets just like a gas peaker plant, but can respond in milliseconds rather than minutes.

What they do

Frequency regulation (FCAS): The primary revenue driver for many early Australian grid batteries. Fast-responding batteries can detect a frequency deviation and inject or absorb power within 100–150 milliseconds, stabilising frequency while slower generators respond. Hornsdale’s FCAS earnings in its first year exceeded initial projections significantly.

Energy arbitrage: Charge during low-price periods (overnight, midday solar surplus) and discharge during high-price periods (evening peak, hot days). The economics of arbitrage depend on the spread between cheap and expensive periods - a spread that’s grown as renewable penetration has increased midday oversupply.

Firming renewables: A wind or solar farm with co-located storage can shift generation from when the wind blows or sun shines to when the grid needs it. This “firming” is increasingly required as coal plants exit and reliability obligations shift to renewable + storage combinations.

The scale of development in Australia

As of 2024–2025, several multi-hundred MW battery projects are operating or under construction in Australia, including:

• Waratah Super Battery (NSW): 850 MW / 1,680 MWh
• Victorian Big Battery (VIC): 300 MW / 450 MWh
• Torrens Island Battery (SA): 250 MW / 250 MWh

These are distinct from the aggregated VPP capacity of residential batteries, though AEMO’s long-term planning treats both as part of the storage resource mix needed for a high-renewable grid.