South Australia (SA1) experienced sustained negative pricing of approximately -$2/MWh across two consecutive intervals (05:40-05:45 and 05:55-06:00) on 3 June 2026 during early morning hours. The negative pricing occurred despite the region being classified as a minor severity event, indicating temporary oversupply conditions were quickly resolved.
The negative pricing was driven by excessive renewable generation, particularly wind (1,677 MW) and solar (255.6 MW combined) flooding the SA1 market during low-demand early morning periods. Binding transmission constraints—notably the Tasmanian interconnect constraints (F_S+TBTU_L1 with $95 marginal value and F_TASCAP_RREG constraints)—prevented efficient evacuation of excess generation to neighbouring regions, forcing generators to accept negative returns rather than curtail output, particularly wind assets with negligible marginal costs.
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.