VIC1 experienced sustained negative pricing at −$6/MWh for one interval on 23 September 2026 at 23:40 UTC, following a period of very low positive prices. The pricing event occurred during an evening period with high renewable generation (approximately 5,538 MW of wind and solar) and substantial brown coal output (2,593 MW).
The negative pricing reflects an oversupply condition in VIC1 where inflexible generation (coal) combined with high renewable output exceeded demand, creating downward price pressure. The binding constraint F_TASCAP_RREG_0220 with a marginal value of $4.97 indicates a transmission or reserve regulation constraint was active, which likely restricted the ability to export excess VIC1 generation or import demand support, trapping surplus supply locally and driving prices negative.
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.