QLD1 experienced sustained negative pricing at −$1.31/MWh across two intervals (21:45 and 22:00–22:05 on 16 September 2026), with prices reaching a minimum of −$1.31/MWh. The event occurred during an evening period with high solar generation (approximately 4,144 MW combined) and substantial coal-fired output (3,399 MW), creating an oversupply condition.
The negative pricing was driven by excess generation relative to demand, evidenced by the simultaneous contribution of high solar output and baseload coal generation during the evening period. Binding constraints with marginal values up to $28.25/MWh suggest that transmission or regulation constraints were actively limiting system flexibility, preventing efficient dispatch of available generation and forcing marginal units into negative pricing to manage the surplus supply condition.
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.