SA1 experienced sustained negative pricing reaching −$2.72/MWh over a 2-interval window on 20 September 2026, following a period of volatile and near-zero pricing. The region's generation mix was dominated by wind (850 MW) and solar (624 MW combined), creating a significant energy surplus with limited demand absorption.
The negative pricing was driven by oversupply of renewable generation (wind and solar totalling ~1,474 MW) during a period of soft demand, with minimum load constraints preventing further downward price adjustment. Multiple binding constraints with non-zero marginal values, particularly the repeated activation of F_TASCAP_RREG_0220 at $3.44/MWh and F_T+LREG_0050 at $4.69/MWh, indicate that dispatch flexibility was constrained, preventing conventional generation from being fully backed down and forcing the market to price demand-side participation into negative territory to manage the surplus.
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.