SA1 experienced sustained negative pricing reaching −$18.58/MWh across 2 consecutive intervals (22:30 and 22:35 on 22 September 2026), following a sharp price collapse from $80.08/MWh in the prior interval. The region was operating with substantial renewable generation (wind at 882 MW and solar at 172–294 MW combined) alongside thermal capacity, creating an oversupply condition.
The negative pricing was driven by binding constraints with significant marginal values, particularly F_T_NIL_MINP_R6 (ranging from 8.27 to 11.60 $/MWh) and F_T+RREG_0050 (9.22 to 11.45 $/MWh), indicating that physical or operational limits forced the dispatch stack to accept negative prices to balance supply with restricted export capacity or other network limitations. High renewable output relative to demand, combined with these binding constraint pressures, left dispatchable generators unable to reduce output economically, necessitating downward price adjustment to clear the market.
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.