Illinois commercial electricity costs are rising, and the increases are structural rather than seasonal. The main driver is not fuel. It is capacity: the charges utilities pay through the PJM and MISO markets to guarantee enough power is available at peak demand. Those charges spiked at the 2025 PJM capacity auction, started flowing into ComEd and Ameren bills in June 2025, and are filed to step up again in June 2026. For a manufacturer on a demand-metered rate, this is the part of the bill that has grown fastest, and it is the part on-site generation can actually move.
ComEd's summer 2025 default supply price reached 10.03 cents per kWh, and ComEd's April 2026 filing to the Illinois Commerce Commission proposes a summer 2026 supply charge about 12 percent higher again. The Citizens Utility Board has warned that total ComEd bills could rise another 20 to 25 percent starting June 2026 as new PJM capacity prices take effect.
- 1 Illinois commercial power costs are climbing for structural reasons (PJM and MISO capacity markets plus fast-growing data center load in northern Illinois), not a one-time seasonal bump.
- 2 ComEd's capacity-driven charges rose in June 2025 and are filed to rise again about 12 percent in summer 2026. Ameren's all-in residential rates are up roughly 94 percent since 2021, with summer supply swinging into the low-teens of cents per kWh.
- 3 CRGA, signed January 2026, is the state's response (3 GW of storage by 2030, virtual power plants, time-of-use pricing). Most of that relief lands medium-term. Near-term exposure through at least mid-2027 remains.
- 4 The one cost lever a manufacturer controls directly is behind-the-meter generation. On-site solar and storage cut the demand and capacity portions of the bill, and the federal safe-harbor window of July 4, 2026 is the cheapest moment to lock in the economics, without committing to build.
What Is Actually Driving Illinois Commercial Power Costs Up
A commercial electric bill has two big pieces: the energy you consume (measured in kilowatt-hours) and the capacity and demand charges tied to how much power you draw at peak. The piece climbing fastest in Illinois is the second one. Capacity is the cost of keeping enough generation on standby to meet the highest demand moments of the year. PJM Interconnection sets that price for northern Illinois through an annual auction, and MISO does the same for the downstate Ameren footprint. When the auction clears high, every utility in the region pays more, and that cost lands in commercial bills.
Three forces are pushing Illinois capacity and supply costs higher at the same time:
- PJM capacity prices jumped roughly elevenfold for the ComEd zone. At the 2025 capacity auction, clearing prices for the ComEd locational area moved from $28.92 to $329.17 per megawatt-day. That increase flows directly into the supply and capacity components of ComEd-area commercial bills.
- Data center load is growing fast in northern Illinois. New data center demand on the ComEd grid raises peak load and the amount of capacity the region has to procure. More peak demand chasing the same grid pushes capacity prices, and therefore rates, higher.
- Capacity charges hit hardest in summer. Seasonal capacity and demand charges concentrate in the summer months, which is why both ComEd and Ameren commercial rates step up between June and September rather than staying flat across the year.
ComEd Territory: What Changed in 2025 and What Is Filed for 2026
ComEd's default supply price (the Price to Compare) reached 10.03 cents per kWh for summer 2025, from June through September, before easing to about 9.69 cents for the non-summer months. The June 2025 increase was driven by supply and capacity costs rather than delivery, and it traced directly back to the record PJM capacity auction and rising regional demand. For a typical customer that meant a 10 to 15 percent jump in the total bill.
The pressure has not let up heading into 2026. The Illinois Commerce Commission approved a $243 million ComEd delivery rate increase effective January 2026. Then, in an April 2026 filing to the ICC, ComEd proposed a summer 2026 supply charge about 12 percent higher than the current one, a direct reflection of the higher PJM capacity prices entering the 2026 to 2027 delivery year. The Citizens Utility Board has warned that the combined effect could add another 20 to 25 percent to ComEd bills starting June 2026.
Large commercial and industrial facilities usually buy their supply competitively rather than on ComEd's default Price to Compare, so they are not capped by the residential supply rate. But the same PJM capacity prices are embedded in competitive supply offers and in the capacity tags assigned to demand-metered accounts. A bigger plant does not avoid the capacity increase. It often feels it more directly through its demand charges.
Ameren Territory: The Downstate Picture
Downstate, Ameren Illinois customers face a parallel squeeze driven by the MISO capacity market. Ameren's standard supply rate sits around 8.77 cents per kWh for the first block of usage, but the all-in residential rate has risen to roughly 15.5 cents, up about 94 percent since 2021. In the summer, all-in rates climb toward 20 cents per kWh, and the supply portion historically swings from the high-single-digits into the low-teens of cents per kWh as seasonal capacity charges take effect.
For a downstate manufacturer, the pattern is the same as in ComEd territory even though the market operator differs: the fastest-growing part of the bill is capacity, it concentrates in summer, and it is largely outside the facility's control unless the facility changes how much grid power it draws at peak.
On a demand-metered commercial account in Illinois, demand and capacity charges often make up 30 to 60 percent of the total electric bill. They are billed on peak kilowatts and capacity tags, not just on energy consumed. This is the portion rising fastest, and it is the portion that on-site solar paired with battery storage is specifically built to reduce.
CRGA Is Real Relief, but Most of It Lands Later
Illinois has responded to the capacity-cost problem. The Clean and Reliable Grid Affordability Act (CRGA) was signed into law on January 8, 2026 and takes effect June 1, 2026. It directs the state to procure 3 gigawatts of grid-scale battery storage by 2030, requires ComEd and Ameren to stand up virtual power plant and demand-response programs, introduces time-of-use pricing, and creates a statewide integrated resource planning process. The Illinois Power Agency estimates the package could deliver more than $13 billion in consumer savings over 20 years.
That is genuine, and it improves the long-run backdrop for behind-the-meter generation. But the timeline matters. The storage targets run to 2030, the renewable build-out to 2035, and the savings projection is a 20-year figure. In the near term, through at least mid-2027, ComEd and Ameren customers remain exposed to the elevated PJM and MISO capacity prices already baked into the 2025 to 2026 and 2026 to 2027 rate structures. CRGA is a reason to expect relief eventually. It is not a reason to wait, because the costs are rising now and the relief is mostly later.
The One Cost Lever a Manufacturer Actually Controls
A manufacturer cannot control the PJM auction, the growth of data center load, or the pace of CRGA implementation. What a facility can control is how much grid power it buys, and when. That is where on-site generation changes the math. Solar shaves the energy you pull from the grid and trims the midday peak. Battery storage paired with that solar discharges during the highest-demand windows, which is what reduces the demand and capacity charges that are climbing fastest. It is a direct hedge against the exact line items driving Illinois bills up.
Timing is the other half of it. The federal solar Investment Tax Credit safe-harbor deadline is July 4, 2026. Safe-harboring preserves the 30 percent federal credit, plus the 10 percent Energy Community bonus where the facility address qualifies, on a three-year build window. It requires committing about 5 percent of total project cost, and it does not commit the manufacturer to building. So the prudent sequence is to lock the economics now, while grid costs climb and the credit is at its current vintage, and then take up to three years to decide how and whether to build.
Safe harbor is option-preservation, not a project commitment. Roughly 5 percent of project cost preserves the 30 percent federal credit for up to three years. With grid costs rising through 2027 and CRGA relief landing mostly later, locking in the on-site hedge at today's incentive vintage is the low-regret move. If the assessment shows the project does not pencil, the engagement ends there.
See What Rising Costs Mean for Your Facility
Twelve months of utility bills and a facility address. GEC will model your current demand and capacity exposure, show what on-site solar and storage would offset, and verify the federal and Illinois incentives that apply at your address. No commitment to move forward.
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Get Ahead of the 2026 Cost Increases
ComEd and Ameren costs are climbing now, and CRGA relief is mostly later. GEC will model what on-site solar and storage would offset at your facility and verify which incentives apply before the July 4 safe-harbor window closes. Start with 12 months of utility bills.
