South Australia (SA1) experienced sustained negative pricing at −$1.02/MWh across two consecutive 5-minute intervals (15:50 and 15:55 on 9 August 2026), representing a minor pricing anomaly. This occurred against a backdrop of high wind generation (1,750.66 MW) and moderate gas-fired output, with prices reverting to positive levels (55–64 $/MWh) in surrounding intervals.
The negative pricing was driven by binding constraints with modest marginal values (ranging from $4.48 to $5.47/MWh), with the constraint F_TASCAP_RREG_0220 active across three intervals and F_T+RREG_0050 binding in two intervals. The high wind output relative to regional demand, combined with these binding constraint limitations on dispatch flexibility, created downward pressure on prices sufficient to push into negative territory; the low marginal values of the constraints suggest they provided limited relief to this supply–demand imbalance.
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.