SA1 experienced sustained negative pricing at −$15.28/MWh in a single interval (12:40) on 12 June 2026, with broader negative pricing across the settlement period ranging from −$3 to −$15/MWh over two intervals. The region was generating substantial wind output (1313.55 MW) alongside battery discharge (152.30 MW combined) against minimal gas generation, creating a structural oversupply condition during the midday valley.
The severe negative price spike was driven by binding constraints with measurable marginal values, particularly F_T+RREG_0050 which repeatedly constrained dispatch at values between $2.98 and $4.98/MWh. The underlying cause was excess renewable generation (predominantly wind) combined with battery discharge operations during a low-demand period, forcing the market into a must-run scenario where constraint-binding prevented efficient load absorption, driving prices deeply negative as generators were compelled 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.