VIC1 experienced sustained negative pricing reaching -$2.99/MWh across 2 intervals on 20 September 2026 at 23:15–23:20, with prices oscillating between near-zero and slightly positive values in the surrounding periods. The event occurred during a period of high renewable generation, with wind contributing approximately 3,188 MW and solar 898 MW across the region.
The negative pricing was driven by an excess of low-marginal-cost renewable generation (wind and solar totalling over 4,000 MW) relative to instantaneous demand, creating downward pressure on the spot price. Multiple binding constraints with marginal values between $3.44/MWh and $4.69/MWh (F_T+LREG_0050 and F_TASCAP_RREG_0220) indicate that network or regulation capacity limits prevented the market from freely dispatching renewable output, forcing marginal generators to operate at negative prices to remain dispatched and satisfy dispatch targets.
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.