South Australia (SA1) experienced two intervals of negative pricing on 17 August 2026 at 23:25 and 23:55, with the lowest price reaching -$1/MWh. The negative prices occurred in an environment of high wind generation (1125 MW) combined with substantial solar output (176 MW aggregate), creating a local generation surplus.
The negative pricing appears driven by elevated renewable generation that exceeded regional demand, particularly from wind resources. Multiple binding constraints with significant marginal values (F_T+LREG_0050 at $12.72/MWh, F_TASCAP_RREG_0220 at $4.95–$6.76/MWh, and F_T+RREG_0050 at $5.25/MWh) indicate dispatch restrictions were active, likely limiting the region's ability to export excess generation or dispatch inflexible generation downward, thereby pushing prices negative to incentivise consumption or constraint relaxation.
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.