Capacity Auction

The annual Capacity Auction is one of the competitive procurement mechanisms included in the IESO’s Resource Adequacy Framework. The Capacity Auction serves as the short term balancing mechanism in the framework, securing the capacity needed to meet Ontario’s short-term resource adequacy needs.  The Capacity Auction enables participation from a diverse range of resources that compete to be available for two six-month obligation periods (summer and winter).

As enhancements are introduced over time, the Capacity Auction is expected to attract a broader mix of resources, enabling the IESO to further increase competition, and incent greater resource reliability and market performance.

2022 Capacity Auction

The 2022 Capacity Auction was held from Wednesday, November 30 to Thursday, December 1, 2022 for the summer 2023 and winter 2023/2024 obligation periods. Please subscribe to the IESO bulletin for future updates.

Please contact if you have any questions regarding the Capacity Auction.

See archive section below for past Capacity Auction results and supporting materials.

Past Capacity Auctions

  • Capacity Auction Timelines for December 2021
  • Capacity Auction Workbook
  • Auction Reports: Pre-Auction Report, and Post-Auction Report are available via the IESO Public Reports site    
  • Demand Response Contributor Management and Measurement Data Submission Timelines for December 2021 Capacity Auction 
  • Capacity Auction Zone Table 
  • Capacity Auction Rules Library (past Capacity Auction Rules and Manuals) 
  • December 2021 Capacity Auction Results 


    What resources can participate in the Capacity Auction?

    There are four classes of resources that can participate:

    • Demand Response (DR) resources, including physical hourly demand response (HDR), virtual HDR – residential, virtual HDR – commercial and industrial (C&I) and dispatchable loads (DLs)
    • Generation Resources
    • System-backed Capacity Import Resources, and;
    • Storage Resources

    What do I need to do to participate in the Capacity Auction?

    Interested organizations must become authorized as a Capacity Auction Participant (CAP). This process must be completed at least 40 business days before the start of the offer submission window of an auction. The CAP authorization process is a one-time process, meaning a CAP will be then able to participate in all subsequent auctions. Following authorization, a CAP will then complete the capacity enrolment process and submit auction deposit in order to participate in the Capacity Auction. A capacity enrolment request can be modified up until the last day to submit a request, at which point, modification is locked in Online IESO.

    What happens before the Capacity Auction?

    The Pre-Auction period begins approximately two months prior to the start of the offer submission window for the Capacity Auction, when the IESO publishes the Pre-Auction Report.

    The Pre-Auction Report includes the following information for each commitment period:

    • Key Milestone Dates, including submission of capacity enrolment information, payment of auction deposit, and date of auction
    • Auction Parameters, including Target Capacity, Maximum and Minimum Clearing Prices, Capacity Limits, and;
    • Zonal/ Import/ Interface Constraints.

    What happens during the Capacity Auction?

    Following the auction submission period, the IESO processes all capacity auction offers, determines clearing prices and quantities. The results are published five business days after the auction submission period in the Post-Auction Report which includes the following information for each obligation period:

    • Capacity Auction clearing price;
    • Amount of MW cleared for each electrical zone;
    • List of successful CAPs and their capacity obligations; and
    • Enrolled auction capacity, by participant

    What happens after the Capacity Auction?

    Following the auction, a successful participant will be required to become authorized as a Capacity Market Participant. The authorization allows a participant that clears the auction to receive availability payments, subject to non-performance charges, and to satisfy their Capacity Obligation(s). Payments are based on the total cleared capacity and the applicable auction clearing price.

    Demand Response Auction

    For information relating to the former Demand Response Auction, including Pre-Auction Reports, Post-Auction Reports and other related documents visit the Demand Response Auction webpage.