SA1 experienced sustained negative pricing during the early morning of 4 September 2026, with prices falling to −$0.52/MWh across two intervals between 23:45 on 3 September and 00:05 on 4 September. The event occurred during a period of high renewable generation, particularly wind output of approximately 1414 MW, combined with low overnight demand.
The negative pricing resulted from an oversupply condition where renewable generation, especially wind, significantly exceeded demand in SA1. A binding constraint with marginal values ranging from $4.66 to $6.99/MWh was active throughout the period, indicating that constraint-induced restrictions on dispatch pathways forced generators to pay for the privilege of injecting energy. The combination of high wind output, moderate solar generation (95 MW in the early interval), and low overnight consumption created downward price pressure that breached zero, requiring generators to accept negative returns to maintain grid stability.
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.