VIC1 experienced sustained negative pricing between 03:50 and 04:25 on 18 September 2026, with prices ranging from −$10.10 to −$16.54/MWh across 8 consecutive intervals. The negative pricing occurred during a period of high renewable generation, with wind and solar combined contributing approximately 3,735 MW against total system demand.
The negative pricing appears driven by a combination of high renewable energy inflexibility and an active binding constraint with substantial marginal values (ranging from $99.09 to $107.17/MWh on constraint F_T+LREG_0050). During low-demand overnight hours with elevated wind and solar output, dispatchable generation (brown coal at 1,911 MW) remained online, creating oversupply conditions that forced prices negative. The binding constraint's high marginal value indicates a physical or operational limitation was actively suppressing dispatch, preventing adjustment of the generation stack to better match the renewable supply profile.
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.