QLD1 experienced sustained negative pricing of approximately $-2/MWh across two consecutive 5-minute settlement intervals (23:10–23:15 on 21 May 2026), representing a minor market event. Prices had declined from $5.71/MWh earlier in the evening, dropping through $2.10/MWh before turning negative, indicating a supply-demand imbalance.
The negative pricing was driven by excess renewable generation (approximately 5,311 MW of combined solar and wind output) combined with inflexible coal baseload (3,454 MW) unable to ramp down quickly enough during the evening transition period. The binding constraint F_MAIN+RREG_0220 with marginal values of $7.49–$11.67/MWh indicates network congestion or minimum load constraints preventing efficient dispatch, forcing generators to accept negative prices rather than curtail output, a typical occurrence during high solar penetration periods with transmission limitations.
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.