South Australia 1 (SA1) experienced a high renewable penetration event at 87.3% during the early morning period of 31 May 2026, with wind and solar generation collectively providing approximately 880 MW of the region's output. This high renewable penetration coincided with sustained negative spot prices ranging from -$1.88/MWh to -$0.10/MWh across five consecutive settlement intervals, indicating oversupply conditions.
The negative pricing was driven by excess renewable generation (particularly wind at 312.5 MW and solar at 567.8 MW combined) during a low-demand overnight/early morning period, where the system was forced to accept additional output without sufficient load to absorb it. The binding transmission constraints (primarily on regional boundary flows) with marginal values between $5.44–$6.81/MWh further restricted the ability to export excess generation interstate, forcing the region to manage oversupply through negative pricing to incentivise load shifting and discourage additional synchronous generation dispatch.
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.