VIC1 experienced two intervals of negative pricing at $-8/MWh on 22 September 2026 at 23:45 and 23:55, following a period of price volatility between $0–$34/MWh. The negative prices occurred during a period of high solar generation (1,485.51 MW) and substantial brown coal output (3,424.28 MW), indicating an oversupply condition in the region.
The negative pricing was driven by a binding constraint (F_TASCAP_RREG_0220) with a marginal value of $7.79–$4.68 across the affected intervals, indicating that network or reserve regulation limitations forced dispatch of lower-value generation. The combination of high solar generation reaching its peak in late afternoon and inflexible brown coal baseload generation created a supply excess that could not be readily exported or curtailed, pushing prices negative as the market sought to balance supply and demand.
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.