QLD1 experienced sustained negative pricing at −$2.65/MWh and −$1.99/MWh across two consecutive intervals (01:15–01:20 on 3 June 2026), representing minor negative pricing with near-zero prices in adjacent periods. This indicates a temporary supply–demand imbalance requiring financial compensation to reduce generation or increase consumption.
The sustained negative pricing was primarily driven by elevated daytime solar generation (combined 5,083 MW across QLD1) coupled with relatively high black coal output (2,861 MW) creating excess supply during low-demand periods (just after midnight). Binding network constraints—particularly the F_S+TBTU_L1 constraint with a marginal value of $95—indicate transmission bottlenecks that prevented efficient distribution of generation across the NEM, forcing the market to impose negative prices to curtail inflexible generation sources, particularly coal units with slow ramp-down capabilities and solar output that could not be rapidly reduced.
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.