South Australia (SA1) experienced two intervals of negative pricing at −$6/MWh on 10 September 2026 at 23:25 and 23:50, with prices recovering to near-zero or positive levels in surrounding intervals. The region's generation mix was dominated by renewable sources (solar at ~350–375 MW and wind at 508 MW) with supporting gas-fired capacity, creating an oversupply condition typical of evening shoulder periods.
The negative pricing reflects excess renewable generation relative to demand during low-consumption evening hours, a common driver of negative prices in high-wind and high-solar regions. Binding constraints with marginal values of $4.16–$4.99 (primarily F_TASCAP_RREG_0220 and F_T+RREG_0050) indicate that network or regional regulation constraints were active and limiting dispatch flexibility, preventing generators from economically managing the surplus and forcing prices negative to incentivise demand 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.