SA1 experienced sustained negative pricing at −$1.05/MWh during the 18:50 settlement interval on 8 September 2026, with negative prices persisting across 2 intervals. The event occurred during an evening period characterised by high wind generation (1558 MW) and minimal load-shedding capacity from battery and solar assets.
The negative pricing was driven by a binding constraint (F_T+LREG_0050) with elevated marginal values (ranging from 6.76 to 7.01), indicating a physical or operational limit that forced economic dispatch away from marginal cost equilibrium. With wind generation substantially exceeding minimum load requirements and dispatchable gas capacity already committed, the constraint created a structural surplus that depressed spot prices into negative territory, requiring financial incentives to curtail or shift demand.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.