QLD1 experienced sustained negative pricing across three consecutive intervals on 23 August 2026 from 02:50 to 03:20, with the minimum price reaching −$8.51/MWh. The event occurred during early morning hours with high solar generation (approximately 1,728–1,897 MW) combined with substantial coal-fired output (3,259 MW), creating an oversupply condition in the region.
The negative pricing was driven by a supply-demand imbalance during the shoulder pre-dawn period when solar generation remained elevated whilst daytime demand had not yet increased. The binding constraint F_T+RREG_0050 with marginal values around $4.22–$4.23/MWh indicates that operational limitations were active during this period, preventing efficient load-following and forcing generation to be backed down, which compressed prices into negative territory as dispatchable units were constrained in their ability to reduce output.
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.