NSW1 experienced sustained negative pricing at −$7.23/MWh during the 04:40 interval on 19 August 2026, with negative prices occurring across 2 consecutive intervals in early morning trading. The event followed a sharp price decline from $23.99/MWh at 04:10 to negative territory by 04:35, indicating a rapid shift in market conditions over approximately 25 minutes.
The negative pricing was driven by a substantial oversupply of renewable generation, with solar and wind combined contributing over 3,000 MW against relatively modest dispatchable generation (3,190 MW black coal, 12 MW gas). Binding constraints with marginal values up to $25/MWh, particularly the constraint F_S++HYSE_R60, indicate that transmission limits were restricting the ability to export surplus renewable energy out of NSW1, forcing down-regulation and creating the conditions for negative pricing to clear the market.
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.