South Australia (SA1) experienced sustained negative pricing on 22 September 2026, with prices reaching a minimum of −$4.49/MWh during the 00:40 interval. The price declined progressively over a 20-minute window, with two intervals recording negative pricing as generation exceeded local demand.
The negative pricing was driven by high instantaneous renewable energy generation, particularly solar (373.53 MW and 352.99 MW) and wind (436.38 MW) output during low-demand overnight hours. Multiple binding constraints with positive marginal values indicate that interconnector or network limitations prevented efficient export of surplus generation to neighbouring regions, forcing marginal generators and loads to accept negative prices to rebalance supply.
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.