SA1 experienced sustained negative pricing over a 3-interval window on 20 September 2026, with the Regional Reference Price reaching −$2.94/MWh at 14:50 and remaining negative at approximately −$1.10/MWh across most of the period. The region's generation mix was dominated by wind generation (1264.55 MW) with minimal demand from conventional sources, creating a structural oversupply condition.
The negative pricing was driven by a binding constraint (F_T+LREG_0050) with elevated marginal values ranging from $27.14 to $42.13/MWh, which restricted the ability to export or otherwise manage excess supply. With wind generation substantially exceeding local demand and a constraint limiting relief options, the market pricing mechanism pushed prices negative to incentivise demand response and discourage further generation, a characteristic outcome when supply management options are constrained.
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.