South Australia experienced two consecutive settlement intervals (23:15 and 23:20 on 26 July 2026) with negative pricing at −$1/MWh, representing a minor negative price event. The price reversal occurred after a period of positive pricing ranging from $28–$37/MWh, suggesting a sudden shift in supply–demand balance.
The negative pricing coincided with high renewable generation output, particularly wind at 1504 MW across the generation mix, combined with significant gas-fired generation (OCGT and CCGT totalling approximately 964 MW). A binding constraint with marginal values around $4.62–$4.64/MWh was active during the event, indicating that dispatch was constrained by a specific network or operational limit. The combination of excess renewable supply during a period of binding constraint pressure likely forced the market price negative as generators were required to maintain output despite reduced demand or export limitations.
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.