SA1 experienced sustained negative pricing at −$0.05/MWh across two consecutive intervals (11:40 and 11:45) on 18 June 2026, following a sharp price decline from $4.96/MWh in the preceding interval. This minor negative pricing event occurred within a generation mix dominated by wind output (1,943 MW) and supported by gas-fired and battery generation.
The negative pricing reflects excess renewable generation relative to load and available transmission capacity, with wind providing substantial supply at low marginal cost. Multiple binding constraints with marginal values between $2.75 and $4.99/MWh constrained the system's ability to export surplus generation or adjust output, forcing spot prices to zero and then negative to incentivise demand response or curtailment. The binding constraints indicate transmission or network limitations were active in managing the high wind output during this period.
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.