South Australia (SA1) experienced sustained negative pricing during the early morning period of 23 August 2026, with two intervals recording prices around −$3/MWh. The negative pricing occurred against a background of high renewable generation, particularly solar (278–230 MW) and wind (169 MW) output, combined with moderate gas generation.
The negative pricing appears driven by an excess of low-marginal-cost renewable generation relative to local demand during the low-demand pre-dawn period, compounded by binding constraints on Tasmania-linked capacity (F_TASCAP_RREG_0220 and F_TASCAP_LREG_0210) that limited the ability to export excess supply to neighbouring regions. The high marginal values on these binding constraints (ranging from 4.61 to 10.44 $/MWh) indicate tight capacity on those interconnection pathways, forcing the local market to absorb surplus renewable output, pushing prices negative to incentivise load.
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.