NSW1 experienced sustained negative pricing over three consecutive intervals during the early morning period of 20 September 2026, with prices ranging from −$10.50/MWh to −$8.36/MWh. The event occurred during a period of high renewable generation, with solar and wind combined providing approximately 4,043 MW of the total generation mix.
The negative pricing reflects an oversupply condition driven by high solar and wind generation during low-demand overnight and early-morning periods, which necessitated continued operation of inflexible thermal capacity (black coal at 1,869 MW). Binding constraints with significant marginal values—particularly the constraint with a $49.97/MWh shadow price—indicate physical or operational limitations preventing efficient export or storage of excess generation, forcing the market price down to encourage demand response and curtailment.
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.