SA1 experienced sustained negative pricing at approximately −$7/MWh across three consecutive intervals (04:15–04:25 on 15 September 2026), with prices fluctuating between −$7.25 and −$6.39/MWh over the broader 35-minute window. The event occurred during pre-dawn hours with high renewable generation, particularly 388 MW of wind output, offsetting modest solar and gas-fired generation.
Negative pricing in SA1 reflects an oversupply condition during low demand hours, exacerbated by substantial wind generation that could not be economically curtailed. The binding constraint F_T+LREG_0050 carried significant marginal values (ranging from 18–104 $/MWh), indicating it was actively limiting dispatch flexibility; this constraint's presence prevented generators from adjusting output to rebalance the market, forcing the marginal unit into a loss-making position and driving prices negative.
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.