NSW1 experienced sustained negative pricing at −$7.91/MWh across two consecutive intervals (04:05–04:10 on 13 August 2026), following a sharp price drop from +$42.80/MWh. The negative pricing occurred during a period of high renewable generation (2,238.79 MW solar, 784.05 MW wind) combined with baseload coal output (3,506.06 MW), creating a supply surplus.
The negative pricing was driven by a rapid supply–demand imbalance in which high solar and wind generation combined with inflexible baseload coal output exceeded demand, pushing the system toward forced spill of renewable energy. The binding constraint NSA_Q_GSTONE34_250 remained active throughout the period with marginal values ranging from $9.07 to $77.89/MWh, indicating that a physical or network limitation prevented economic re-dispatch and forced the market to accept negative prices to incentivise demand response and curtail supply.
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.