2026 Capacity Auction — What It Means to Your Bottom Line

Both grid operators serving Illinois hold annual capacity auctions that set a major cost driver on electric bills — and 2026 brought two very different outcomes depending on which territory you're in. 

Ameren Illinois territory (MISO): The 2026/27 Planning Resource Auction, effective June 1, 2026, cleared Ameren's summer capacity price at $424.30 per MW-day — down from last year's record of $666.50, but still roughly 14 times higher than the $30 per MW-day cleared just two years ago. Prices eased mainly because more capacity was offered into the auction, not because underlying demand pressure let up: peak demand actually grew year-over-year, driven in large part by data center development across Illinois.

ComEd territory (PJM): PJM's 2026/27 Base Residual Auction cleared at $329.17 per MW-day across its footprint — the FERC-approved price cap, and a 22% increase over the prior year's $269.92. Unlike MISO, this result rose rather than fell, driven by the same underlying force: rapid data-center-fueled demand growth continuing to outpace new generation supply.

WHAT THIS MEANS FOR YOUR BOTTOM LINE

• Capacity costs are a pass-through charge in both territories, not something a supplier contract controls — they show up on your bill regardless of who supplies your energy, and they typically reset annually with each territory's auction results.

• Whether prices went up (ComEd/PJM) or came down from a record high (Ameren/MISO), capacity charges remain historically elevated in both territories, and industry watchers expect that to continue for at least the next few years as data center and industrial load growth keeps outpacing new supply.

• Persistently high capacity costs make it more valuable to actively manage your peak demand in either territory, since your capacity charges are driven by your highest usage hours, not your total usage.

• A fixed-price supply contract won't automatically shield you from capacity cost changes — capacity is typically billed separately as a pass-through. Some contract structures do allow capacity, transmission, and other charges to be locked in as part of the deal, but that's generally not advisable, since it usually means paying a fixed price regardless of what your actual usage ends up being.

WHAT WE RECOMMEND

• Review your account's Peak Load Contribution (PLC) — the days and hours that set your capacity costs — and look for ways to shift usage away from those windows.

• Talk with us about demand management opportunities that could reduce your peak demand and, in turn, your capacity charges going forward, whether you're in Ameren or ComEd territory.

• If your contract is coming up for renewal, don't wait until the last minute — market conditions shift, and locking in early can matter.