QLD1 experienced sustained negative pricing of approximately −$2/MWh across two consecutive intervals (21:55 and 22:15–22:20 on 3 September 2026), with prices reaching −$3/MWh at peak. The region had high solar generation (4,497 MW combined) and substantial black coal output (3,576 MW), creating excess supply conditions.
The negative pricing resulted from oversupply in QLD1, where combined renewable and thermal generation exceeded demand despite modest gas and battery output. The binding constraint F_T+RREG_0050 exhibited high marginal values (ranging from 22.74 to 114.96 $/MWh) across the period, indicating this constraint was actively restricting generator dispatch and preventing normal market clearing. With supply unable to be fully backed down due to this constraint limitation, generators faced negative prices to incentivise reduced 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.