QLD1 experienced a moderate price spike with the region settlement price reaching $420/MWh in three intervals (19:30, 19:40, and 19:50) on 23 September 2026, with prices oscillating between $264–$420/MWh over the 30-minute period. The spike occurred during evening peak demand with a generation mix heavily weighted towards black coal (4314 MW) and gas OCGT (797 MW), supplemented by wind (831 MW) and battery storage (134 MW).
The binding constraint F_TASCAP_RREG_0220 was active across all five intervals with marginal values ranging from $4.95–$7.49/MWh, indicating this constraint was limiting dispatch capability and contributing to price elevation. The constraint's modest marginal contribution to the $420 price suggests other factors—likely demand-supply balance tightness during evening peak or availability limitations on generation plant—were the primary drivers of the spike, with the binding constraint exacerbating rather than solely determining the outcome.
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.