On September 1, 2026, the Illinois Commerce Commission (ICC) approved 600 MW of Indexed Storage Credit (ISC) contracts at an average strike price of $442/MW-day. With an ISC, a storage project bids a strike price, then is paid, or pays back, the gap between that strike price and a market reference price.

It was Illinois’ first ISC procurement toward its target of 3 GW of storage by 2030. The Illinois Power Agency (IPA) had sought 1,038 MW this round, leaving a 438 MW shortfall.

Although Illinois spans both PJM and MISO, the shortfall sits entirely in PJM. PJM's ComEd zone had a 588 MW target and contracted only one 80 MW project. MISO's Ameren footprint had a 450 MW target and contracted four projects totaling 520 MW. The IPA has not published how many bids it received in either zone.

Illinois is one of two states to award ISC contracts this September. NYSERDA awarded 950 MW in New York from a pool of 46 bids totaling 6.3 GW. Both programs are contracts for difference between a strike price and a reference price. However, the programs differ in who can bid, how winners are chosen, and how much risk projects carry.

Key takeaways

• The entire shortfall from Illinois' first ISC solicitation sits on the PJM side of the state. PJM's ComEd zone contracted 80 MW against a 588 MW target, while MISO's Ameren footprint contracted 520 MW against a 450 MW target.
• At the $442/MW-day average strike price, Ameren projects would have paid the utility back every day from June to August 2025, because of MISO's high summer capacity price. Over the 12 months to May 2026, the contract would still have paid projects a net $27,400/MW.
• Illinois selected winners on price alone and approved them six days after bidding closed. NYSERDA scored non-price factors alongside strike prices and took about eight months to select winners.
• Projects selected by Illinois carry more risk than those in New York. Paybacks are uncapped, and a forced outage reduces what a project is paid but not what it owes.

What is the Indexed Storage Credit?

The ISC works like a contract for difference. Each project bids a strike price. The contract pays the gap between that strike price and a reference price, which estimates what a model battery could earn in the energy and capacity markets. If the reference price exceeds the strike price, the project pays back the gap.

The reference price has two parts. The energy component is based on zonal day-ahead top-bottom (TB) spreads, adjusted for an assumed round-trip efficiency. The capacity component is a capacity price multiplied by a capacity accreditation factor.

In Illinois, ISC eligibility is reserved for four-hour stand-alone batteries, so the energy component always uses the host load zone’s TB4 spread (the gap between each day's four highest- and four lowest-priced hours) at a fixed 85% round-trip efficiency.

The capacity price is the RTO's auction price: MISO's seasonal Planning Resource Auction (PRA) price in the Ameren zone, and PJM's Base Residual Auction (BRA) price in ComEd. The accreditation is the project's own rating, as approved by its RTO and updated every May.

The ISC is calculated daily against one reference price per utility, with Ameren Illinois and ComEd as the counterparties.

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ComEd contracted just 14% of its target

The ICC approved five stand-alone, four-hour projects:

• Gatehouse: 185 MW, Washington County (Ameren), Invenergy
• KCE IL 1: 100 MW, Clay County (Ameren), Key Capture Energy
• KCE IL 2: 100 MW, Fayette County (Ameren), Key Capture Energy