VIC1 experienced brief negative pricing in two consecutive intervals (00:20 and 00:25 on 7 September 2026), with prices reaching −$0.55/MWh. The event occurred during an overnight period characterised by high renewable energy supply (wind generation of approximately 4,854 MW and solar output of 1,093 MW) combined with significant brown coal generation (2,335 MW).
The negative pricing reflects an oversupply condition typical of high-renewable, low-demand periods where marginal generation costs fall below zero. The binding constraint F_T+LREG_0050 with marginal values around $21.38–$21.95/MWh suggests a significant physical limitation was actively constraining the dispatch solution, preventing conventional generators from turning down or off. This constraint binding, combined with the inflexible output of brown coal (2,335 MW) and the high renewable contribution, created downward pressure on prices as dispatchable supply could not reduce quickly enough to balance the excess generation.
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.