Capacity Auction

The 2025 Capacity Auction is the competitive procurement mechanism administered by the IESO (Independent Electricity System Operator) that secures capacity needed to meet Ontario's resource adequacy requirements on a short-term basis. The auction enables participation from existing and non-committed demand response, generation, energy storage, and import resources that compete to make their capacity available in the energy market.

Capacity suppliers who secure an obligation in one or both of two six-month obligation periods (summer 2026 and winter 2026/27) can receive payment based on the auction clearing price for making their capacity available during a window of hours on each business day. The auction was held from November 26-27, 2025, and results are available through IESO public reporting systems.

Participants must comply with Market Rules and Market Manuals as outlined in the IESO's Renewed Market Rules and Manuals Library and Capacity Auction Rules Library. Capacity testing is required, with data submission templates and timelines provided for the testing period of June 1-5, 2026. Demand response contributors must submit management and measurement data according to published timelines for both 2025 and 2026 submission cycles.

Participants interested in the auction are encouraged to review all associated documentation, enroll in eLearning modules, and consult the Guide to Capacity Auction Activities via Online IESO. The IESO provides pre-auction and post-auction reports, capacity test FAQs, and force majeure notification forms. For questions regarding participation, contact customer.relations@ieso.ca.