VIC1 experienced two consecutive intervals of negative pricing at -$0.05/MWh on 18 June 2026 between 11:40 and 11:45, following a sharp price decline from $5.08/MWh. The negative pricing occurred during a period of high wind generation (approximately 3,773 MW average) and elevated battery charging, with prices recovering to -$0.05/MWh in subsequent intervals.
The sustained negative pricing was driven by oversupply conditions in VIC1, evidenced by high instantaneous wind output coupled with battery charging drawing 202 MW from the grid. Multiple binding constraints with modest marginal values (ranging from $2.75 to $4.99/MWh) indicate system congestion constraints were active but not sufficiently binding to prevent negative prices, suggesting that dispatch requirements to manage these constraints forced the market into a supply-surplus condition where marginal generation became uneconomic.
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.