South Australia (SA1) experienced sustained negative pricing at $-1/MWh across two consecutive 5-minute intervals (04:05–04:10 on 1 June 2026), following a period of moderately low but positive pricing. This minor severity event occurred during early morning hours when solar generation was ramping up alongside substantial wind output.
The negative pricing was driven by an oversupply of renewable generation, particularly wind (1,386.52 MW) and solar (222.9–266.26 MW), combined with insufficient demand and limited flexibility to curtail synchronous generation. The binding constraint F_MAIN+RREG_0220 (regulating raise constraint on the main interconnector) remained active with declining marginal values (7.99–10.99 $/MWh), indicating transmission limitations prevented efficient export of excess renewable energy out of SA, forcing the market to pay generators to reduce output or absorb surplus supply domestically.
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.