VIC1 experienced sustained negative pricing of −$5/MWh across 8 consecutive 5-minute intervals between 15:20 and 15:55 on 4 September 2026, with the lowest price reaching −$5.09/MWh. The event occurred during a period of high wind generation (approximately 7,167 MW combined) and significant brown coal output (2,797 MW), indicating excess supply in the region.
The negative pricing was driven by a binding constraint (F_TASCAP_RREG_0220) with marginal values ranging from $5.49 to $6.80/MWh, which restricted the ability to export surplus generation out of VIC1. With substantial wind generation unable to be economically accommodated within regional demand and constrained export capacity, generators were forced to bid lower prices to remain dispatched, resulting in the sustained negative pricing outcome.
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.