​Transmission constraints have been a problem for New South Wales in 2025. They have prevented low-priced renewable generation in the South West from reaching demand centres, creating the conditions for increased volatility. And they’ve made it difficult for batteries in constrained regions to dispatch into these price spikes, costing these systems money.
Smart optimisers have been able to find ways to maximise output during price spikes, even whilst constrained. However, last week, multiple different batteries were caught out charging during price spikes - showing constraints can still cause problems.
New South Wales saw back-to-back extreme price spikes on 20 and 21 November, each hitting $14k/MWh for a single interval (13:25 on the 20th, 09:10 on the 21st). Five different batteries charged across the two spikes, costing operators between $600/MW and $1,100/MW per MW, equivalent to around 20% of their November revenue so far.
Despite involving different assets on different days, the two events shared a common root cause: network constraints that triggered locational price adjustments, while demand steeply ramped up between dispatch intervals.
This article looks at the conditions that caused the price spikes, the cost to batteries from the two events, and how locational pricing and bid dynamics caused batteries to charge whilst prices hit $14k/MWh.
Similar conditions were experienced again during a price spike on 25 November to $20,000/MWh, with Capital charging during the spike.
Charging during price spikes cost batteries 20% of November’s revenues
November 2025 has been a relatively low volatility month for batteries in the NEM, including New South Wales. The short price spikes offered an opportunity to boost revenues on paper, but in practice cost all systems located outside of Sydney.
