VIC1 experienced sustained negative pricing at $-5/MWh across three consecutive intervals (21:10–21:20) on 4 September 2026, with prices remaining negative through to 21:45. The region's generation mix was dominated by wind (6,796 MW combined) and brown coal (2,713 MW), alongside 224 MW of battery discharge, creating an oversupply condition during a period of relatively low demand.
The negative pricing reflects a supply-demand imbalance driven by high wind generation coinciding with low demand during the evening period. Multiple binding constraints with positive marginal values (F_TASCAP_RREG_0220 at $4.97/MWh and F_T+RREG_0050 at $4.44/MWh) indicate that network or reserve requirement constraints were active, forcing continued dispatch of inflexible generation (brown coal) despite weak demand, which pushed the marginal price into negative territory as generators bid to remain online.
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.