IESO Secures Resources via 2025 Capacity Auction
December 4, 2025
Ontario’s electricity grid is prepared for the next 18 months as the IESO announced today that 1,833 megawatts (MW) of supply for summer 2026 and 1,125 MW for winter 2026-2027 were acquired through its 2025 Capacity Auction.
With electricity demand increasing, coupled with pressure on supply due to nuclear refurbishments – namely, the Pickering “B” units – this annual auction is critical in helping support reliability in Ontario’s system as grid conditions change from season to season. Capacity Auction resources help provide assurance that additional resources are available if needed during extreme conditions.
The Capacity Auction leverages market forces and competition to help meet Ontario’s reliability needs in a transparent manner, while providing revenue opportunities for large businesses. This year’s auction results reflect a combination of short-term supply dynamics and an increase in the auction’s target capacity. Following the outcome of this year’s auction, the total cost of the capacity secured is expected to represent approximately 1 per cent of total system costs.
For clearing prices and other details, please see the post-auction report, which will require the use of the Microsoft Edge web browser.