QLD1 experienced sustained negative pricing at approximately -$3/MWh across three consecutive 5-minute intervals on 16 September 2026 at 02:45–03:10 UTC, with a floor price of -$4.09/MWh. The region was operating with high solar generation (approximately 4,952 MW combined) and moderate coal output (2,676 MW), creating a structural oversupply during the pre-dawn period.
The negative pricing reflects excess renewable generation that could not be immediately cleared or stored, pushing marginal dispatch cost below zero. The binding constraint F_T+RREG_0050 held a marginal value of $3.80–$4.79/MWh during this period, indicating that this constraint was the active limit on dispatch flexibility; the gap between the constraint's marginal value and the negative price suggests that generation scheduling or ramping constraints prevented further reduction of excess supply, forcing the market price negative to encourage load-shedding or curtailment.
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.