SA1 experienced sustained negative pricing across three intervals on 21 September 2026, with prices reaching −$14.38/MWh during the 04:50 settlement period. The region's generation mix was dominated by solar (268–275 MW) and wind (110 MW) output during early morning hours, combined with significant gas-fired generation (202 MW CCGT), creating an oversupply situation.
The negative pricing reflects an excess of generation relative to demand during the pre-dawn period when solar was unexpectedly high and local consumption remained low. A binding constraint (F_T+LREG_0050) with marginal values of $36–46/MWh constrained dispatch flexibility, preventing the market from freely curtailing or exporting excess supply, thereby forcing the price into negative territory to incentivise demand or reduce generation.
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.