QLD1 experienced sustained negative pricing over a 3-interval period on 15 September 2026, with the minimum price reaching -$10.32/MWh at 04:10. The event occurred during early morning hours when solar generation remained elevated at approximately 1,750–1,766 MW alongside substantial black coal output of 2,744 MW, creating an oversupply condition.
The negative pricing reflects a structural oversupply of generation relative to demand during the early morning solar peak. The binding constraint F_T+LREG_0050 held consistently across all intervals with declining marginal values (ranging from $104.03 to $9.86/MWh), indicating that constraint-driven curtailment requirements were progressively reducing but remained in effect. The combination of inflexible coal baseload, high solar generation, and minimal flexible load or battery storage capacity (0 MW) forced the market into negative pricing to incentivise demand response and enable dispatch of otherwise uneconomic units.
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.