South Australia (SA1) experienced sustained negative pricing reaching -$4.78/MWh across 2 intervals during the 18:40–18:45 settlement period on 13 July 2026. Prices had been slightly negative in the preceding intervals (-$1.07 to -$1.10/MWh) before deepening sharply. The generation mix was dominated by wind output at 1,490.75 MW with minimal demand absorption from batteries, contributing to surplus supply conditions.
The negative pricing was driven by a binding constraint (F_T+RREG_0050) with marginal values ranging from $3.91 to $4.92/MWh, indicating a tight operational limit that forced the market into surplus conditions. High wind generation (1,490.75 MW) combined with low flexible demand absorption—evidenced by minimal battery charging (0.08–0.03 MW) and zero solar generation—created excess supply that the system was unable to dispatch economically, pushing prices below zero to incentivise consumption.
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.