NSW1 experienced sustained negative pricing reaching −$6.22/MWh over 2 intervals on 12 September 2026 at 20:50–20:55, representing a minor severity event. Prices had declined progressively from +$64.95/MWh earlier in the evening, dropping through zero before reaching the minimum negative price.
The negative pricing occurred in a generation environment with high renewable output (wind 324 MW, solar 95 MW, battery 244 MW) and substantial baseload coal generation (4392 MW), creating structural oversupply. A binding constraint with marginal values between $14.24–$16.35/MWh was active during the pricing trough, indicating that transmission or network congestion forced the system to accept negative-priced generation to maintain constraint compliance, pushing spot prices negative.
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.