VIC1 experienced two intervals of negative pricing on 17 September 2026, with prices reaching -$5.03/MWh at 03:50 and -$1.24/MWh at 04:05. The region's generation mix was dominated by brown coal (3,259.63 MW) and solar (992.02 MW), with combined wind output of 373.38 MW, creating an oversupply condition during the early morning period.
The negative pricing appears driven by excessive renewable and coal-fired generation relative to demand during the early morning dispatch window, with insufficient flexible load or dispatchable capacity to absorb supply. The binding constraint F_T+LREG_0050, which showed marginal values between 30.8–47.4 across successive intervals, indicates a tightening or active constraint limiting withdrawal or ramp capability; this operational restriction likely prevented efficient dispatch of excess generation, forcing prices negative to incentivise consumption or constrain supply.
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.