SA1 experienced two consecutive intervals of negative pricing at −$0.04/MWh on 18 August 2026 at 13:00 and 13:05, following a sharp price decline from $7.44/MWh in the preceding interval. The region's generation mix was dominated by wind (1915 MW) with modest support from gas and battery resources, whilst solar and most thermal plant were offline.
The negative pricing resulted from structural oversupply: high wind generation (1915 MW) significantly exceeded regional demand, forcing generators to accept negative prices rather than curtail output. A binding constraint (F_T+LREG_0050) with declining marginal values through the period ($26.92 to $13.85/MWh) indicates a transmission or network limitation was actively constraining dispatch options, preventing efficient export of surplus generation and compressing local prices into negative territory as the marginal generator was forced to pay for dispatch.
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.