South Australia (SA1) experienced sustained negative pricing, reaching a minimum of –$10.14/MWh across three intervals during the early morning period of 5 September 2026. Prices progressively declined from –$6.21/MWh to –$10.14/MWh between 05:45 and 06:10, indicating growing downward pressure on the regional spot price.
High renewable generation, particularly wind output at 1034.43 MW combined with solar generation totalling 130.19 MW, created substantial excess supply during the low-demand early morning period. This excess generation, coupled with binding constraints on both lower and upper regulation services (F_T+LREG_0050 and F_T+RREG_0050) carrying material marginal values between 3.57 and 9.03, suggests that dispatch flexibility was constrained and the market required additional downward adjustment, pushing prices into negative territory as generators were required to run or curtail output to maintain system security.
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.