South Australia (SA1) experienced very high renewable energy penetration of 96.0% during the early morning period of 2 June 2026, driven predominantly by wind generation (1,693 MW) and solar output (504 MW combined). Negative spot prices ranging from -$1 to -$4/MWh occurred across consecutive five-minute settlements, indicating excess supply relative to demand and the need to constrain renewable generation.
The exceptionally high renewable penetration was driven by strong wind generation during off-peak hours combined with early morning solar contribution, overwhelming demand in the low-demand period. Binding constraints on the main transmission network (F_MAIN++RREG_0220) with marginal values of $6.80-$7.79/MWh indicate network congestion or stability requirements forced the dispatch of lower-value renewable energy, resulting in negative pricing as renewables were required to be curtailed or dispatched at loss-making rates to maintain system security and manage surplus 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.