FCAS revenue surges for South Australian batteries during July-August 2025
September 25, 2025
July-August 2025 was a great time to be a battery in South Australia!
Revenue from Frequency Control Ancillary Services (FCAS) for South Australian batteries surged due to frequent price spikes in the Lower 1 Second market. Prices in the Lower 1 Second market often sit near $0/MWh. However, daily average prices in SA exceeded $300/MWh on 12 days over the two months. These price spikes were driven by network outages, which triggered the need for FCAS to be procured locally.
Australia’s National Electricity Market (NEM) has 11 market revenue streams that utility-scale batteries can tap into. This includes:
– One market for wholesale energy that batteries can arbitrage by charging when power prices are cheap, and discharging when prices are high;
– Two markets (raise and lower) for regulation FCAS, which correct minor frequency deviations; and
– Eight markets (1-second, 6-second, 60-second, and 5-min, each with raise and lower markets) for contingency FCAS, which correct major frequency deviations.
Very Fast (1-second) FCAS markets in Jul-Aug accounted for more than half of the total market revenue earned by Neoen’s Hornsdale Power Reserve for the entire eight month period from Jan-Aug 2025.
Similarly, AGL’s Torrens Island BESS earned >40% of its year-to-date market revenue from the 1-second markets during Jul-Aug.
FCAS markets have become increasingly saturated in recent years as more batteries have entered the NEM and put downward pressure on prices. However, the events during Jul-Aug shows that high volatility (and hence high revenues) are still possible in these markets.
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