SA1 experienced sustained negative pricing during the 17:45–18:15 interval on 11 July 2026, with two intervals settling at approximately −$1/MWh and prices ranging from −$4.60/MWh to +$3.68/MWh. Wind generation dominated the SA1 region at 1823 MW, with minimal solar, gas, and battery contributions during an evening period.
Negative pricing was driven by high wind generation coinciding with low demand during the late afternoon-evening transition, creating excess supply that could not be readily exported or reduced. Binding constraints with marginal values between $3.07/MWh and $5.00/MWh, specifically constraint F_TASCAP_RREG_0220, indicate active congestion or operational limitations that prevented adequate dispatch flexibility or interregional transfers to clear the surplus generation, forcing the regional price into negative territory to incentivise demand response or constrain generation.
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.