VIC1 experienced sustained negative pricing at −$5.03/MWh during the 00:40 settlement interval on 22 September 2026, with negative prices occurring across 2 intervals. High renewable generation (584.94 MW wind, 723.6 MW additional wind, and 779.25 MW solar) combined with substantial brown coal output (2,650.59 MW) created surplus supply conditions.
The negative pricing was driven by oversupply conditions during a period of elevated renewable generation concurrent with inflexible baseload coal generation. Binding constraints on transmission capacity—evidenced by multiple constraint equations carrying marginal values ranging from $3.91 to $6.80/MWh—restricted the ability to export excess generation from VIC1, forcing the marginal price into negative territory to incentivise demand response and reduce output.
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.