South Australia (SA1) experienced sustained negative pricing at –$3/MWh across six consecutive 5-minute intervals from 00:40 to 01:05 on 12 June 2026. The region generated substantial renewable output (approximately 1,839 MW combined wind and solar) during a period of low demand, creating oversupply conditions.
The negative pricing resulted from high renewable generation (wind at 1,416.74 MW and solar at 422.69 MW combined) during low-demand night-time hours, creating a structural surplus that required market prices to go negative to incentivise demand or curtail marginal generation. Multiple binding constraints with positive marginal values (ranging from $4.35 to $5.6/MWh) indicate network or system security limits were active, preventing efficient export or generation adjustment and forcing the region to absorb excess supply domestically at negative rates.
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.