VIC1 experienced sustained negative pricing of −$20/MWh across three consecutive intervals (22:25–22:30) on 18 September 2026, following a period of increasingly negative prices from 21:55. The event occurred during a period of high renewable generation (2,271 MW wind, 1,055 MW solar) combined with brown coal baseload (1,728 MW), creating excess supply.
The negative pricing reflects the classic over-supply condition where high wind and solar generation coupled with inflexible brown coal output exceeded demand, necessitating financial incentives to reduce generation or increase consumption. The binding constraints with substantial marginal values—particularly F_T+RREG_0050 at $282.59/MWh—indicate that constraint-driven dispatch limitations prevented efficient redistribution of excess VIC generation to other regions, forcing prices negative as the system sought to manage surplus supply within the constrained region.
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.