South Australia achieved 95.4% renewable penetration on 19 September 2026, with wind generation dominating at 815 MW and battery storage contributing 84 MW. Negative wholesale prices from −$34.50 to −$58.03/MWh prevailed across the period, indicating surplus renewable generation that exceeded demand.
The sustained negative pricing reflects oversupply conditions typical of high wind output periods in SA. Binding constraints with marginal values of $4.80–$15.99/MWh suggest physical network limitations or regulation requirements were active; these constraints likely prevented further export or load-shedding mechanisms that would have otherwise cleared the excess generation, forcing prices into negative territory to incentivise consumption or curtailment.
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.