SA1 experienced sustained negative pricing at −$2.18/MWh across two consecutive intervals (11:50 and 11:55 on 12 September 2026), representing a minor negative price event. Prices recovered to positive levels immediately before and after this period, with the region's generation mix dominated by wind (913 MW) and battery resources (321 MW combined).
The negative pricing was driven by a binding constraint (F_T+RREG_0050) with marginal values of $4–5/MWh, indicating the constraint was preventing further dispatch of lower-cost generation and forcing the market to value exports or load curtailment negatively. The high wind generation (913 MW) combined with low solar output (0 MW) and elevated battery supply (321 MW) created an excess generation condition that the binding constraint could not fully resolve, resulting in downward pressure on prices that fell below zero as demand in the region could not absorb available supply.
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.