ComEd vs Ameren Illinois: Which Utility Territory Has Lower Energy Costs in 2025

ComEd vs Ameren Illinois 2025: A Side-by-Side Breakdown of Electricity Rates and Delivery Costs

Before diving into supplier strategies, let's understand the landscape. Both ComEd and Ameren Illinois are regulated by the Illinois Commerce Commission (ICC), which approves their delivery rates and service standards. On the supply side, both territories are fully deregulated — meaning customers in either territory can choose their own electricity supplier.

Service Territory Overview

ComEd (Commonwealth Edison) serves approximately 4 million customers across 11,400 square miles of northern Illinois. Its coverage includes the Chicago metro area, the collar counties, and northern rural communities. ComEd is a subsidiary of Exelon Corporation and operates one of the most complex urban electrical grids in the country.

Ameren Illinois serves approximately 1.2 million electric customers (and 816,000 natural gas customers) across central and southern Illinois — a territory of roughly 43,700 square miles encompassing Springfield, Peoria, Decatur, Champaign-Urbana, and the Metro East region. Ameren Illinois is a subsidiary of Ameren Corporation.

2025 Rate Comparison: Supply Rates (Price to Compare)

As of Q1 2025, the approximate Price to Compare (supply rate only) for each utility's residential customers:

Note: Supply rates change quarterly. Always verify current PTCs directly with each utility before making supplier decisions.

Delivery Charges: The Non-Negotiable Portion

Delivery charges are where the structural differences between the two utilities emerge most clearly. ComEd's urban density means higher infrastructure investment per customer — but that same density also means more ARES competition for supply. Ameren's rural expanses involve longer distribution lines and different cost structures.

Delivery charges are non-negotiable regardless of which supplier you choose. Your savings leverage exists entirely on the supply side. For a 750 kWh/month household, delivery charges alone account for $45–$55 per month — roughly 35–45% of the typical total bill.

Why Your Utility Territory Determines How Much You Pay — And What Illinois Businesses Can Do About It

Your utility territory shapes your bill in three fundamental ways: the delivery rate structure, the capacity market you participate in (ComEd is in PJM; Ameren is split between PJM and MISO), and the density of ARES competition in your area.

The PJM vs. MISO Difference

ComEd operates entirely within the PJM Interconnection — the grid operator covering the mid-Atlantic, Midwest, and parts of the South. Most of Ameren Illinois also operates in PJM, though some southern portions touch the MISO (Midcontinent Independent System Operator) footprint.

This matters because PJM's capacity market (the mechanism that ensures enough power plants are available to meet peak demand) has seen elevated capacity prices in recent years, directly impacting supplier rates in ComEd territory. Businesses in ComEd territory may therefore see slightly higher capacity-related costs embedded in their supply rates compared to Ameren territory. For a deep explanation, see our guide on Capacity Charges and Illinois Winter Energy Bills.

ARES Competition Density

ComEd's large urban service territory attracts the most ARES competition in the state — more suppliers competing for your business means better pricing. The Chicago metro area in particular has dozens of active suppliers offering residential and commercial rates. Ameren's more rural territory sees somewhat less competition, though major ARES still actively serve it.

What Businesses Can Do Regardless of Territory

The most powerful action any Illinois business can take — ComEd or Ameren — is to stop accepting default utility supply and start participating in the competitive market. Specifically:

• Audit your current rate: Compare your current supply rate against the utility's published PTC. Are you already with an ARES? Is your contract still competitive?
• Request competitive bids: Have a broker solicit quotes from 8–12 ARES simultaneously. The spread between highest and lowest bids is often 15–20%.
• Look at demand response: Both ComEd and Ameren offer demand response programs that pay businesses to reduce consumption during peak events — a revenue stream that many small businesses overlook entirely.
• Optimize your rate class: Confirm you're on the most advantageous rate schedule for your usage profile. Misclassified commercial accounts sometimes pay significantly more than necessary.

How Illinois Commercial Customers Can Switch Suppliers to Beat High ComEd and Ameren Rates in 2025

Switching commercial electricity suppliers in Illinois is a straightforward process — but it requires preparation and timing to maximize value.

Step 1: Pull Your Interval Data

Commercial accounts have access to 15-minute or hourly interval data via the utility's smart meter system. This data reveals when you actually use power — critical for suppliers to accurately price your account, especially if you have production schedules, HVAC loads, or equipment cycling that creates usage spikes. Request this data from your utility's business portal or via your broker.

Step 2: Define Your Procurement Strategy

Are you a business that values budget certainty above all? A fixed-rate, all-in contract is your best fit. Do you have flexibility in when you run equipment? An index-based or block-and-index structure might capture more savings. A hybrid approach — fixing a base load at a fixed price while leaving incremental usage floating — often delivers the best risk-adjusted outcome for medium and large commercial accounts.

Step 3: Issue a Competitive RFP

Your broker should issue a formal Request for Proposal (RFP) to 8–15 ARES active in your territory, specifying your contract length, product type (fixed, index, or hybrid), and any green energy requirements. Suppliers respond with binding quotes, and you can compare them side by side.

Step 4: Execute the Contract and Monitor

Once you've selected your supplier, the paperwork goes through your utility's electronic data interchange system. The switch typically takes effect within one to two billing cycles with zero disruption to your service. After signing, your broker should monitor your bills quarterly for billing errors and alert you when market conditions suggest a strategic renewal or blend-and-extend opportunity.

Real Savings Strategies: How to Lower Your Energy Bill Regardless of Whether You're in ComEd or Ameren Territory

Beyond supplier selection, both ComEd and Ameren customers have access to a set of proven, often underutilized savings strategies that work independently of which competitive supplier you choose.

Utility Rebate Programs

Both ComEd and Ameren run robust energy efficiency rebate programs funded by the Illinois Energy Efficiency Portfolio Standard (EEPS). These programs offer cash rebates for LED lighting upgrades, HVAC equipment replacement, motor controls, compressed air optimization, and building envelope improvements. A typical small business can recover $2,000–$8,000 in rebates through a properly documented efficiency project. Visit the Energy Efficiency for All Illinois resource for program details.

Time-of-Use Rates

ComEd's Hourly Pricing program (RTOP) passes wholesale market prices directly to customers willing to shift usage to off-peak hours. Businesses with flexible loads — pumps, chillers, compressors, EV chargers — can save 15–25% annually by enrolling. For details, see our guide on Time-of-Use Rates in Illinois.

Demand Response Participation

PJM's demand response programs, available to ComEd customers and many Ameren customers, pay businesses to curtail electricity use during grid stress events. Annual payments of $50–$200 per kW of curtailable capacity are common — a meaningful revenue stream for manufacturers, large office buildings, and retail centers.

LED and Controls Upgrades

One of the highest-ROI efficiency investments for Illinois businesses remains commercial LED lighting. With utility rebates often covering 30–60% of project costs and average payback periods under two years, lighting retrofits deliver immediate bill reductions that compound annually — regardless of your supplier or utility territory.

Frequently Asked Questions: ComEd vs Ameren Illinois 2025

Is ComEd or Ameren cheaper in 2025?

In 2025, ComEd's residential Price to Compare is generally slightly lower than Ameren's on a per-kWh basis, but Ameren's monthly customer charge is slightly lower. The best approach is to compare competitive ARES offers in your specific territory rather than relying on utility default rates.

Can I switch electricity suppliers in the Ameren territory?

Yes. Both ComEd and Ameren Illinois territories are fully deregulated for supply. Residential and commercial customers in both territories can choose from dozens of ICC-licensed Alternative Retail Electric Suppliers.

What areas does ComEd serve in Illinois?

ComEd serves northern Illinois, including Chicago and the surrounding suburbs (Cook, DuPage, Kane, Lake, and McHenry counties) as well as northern rural communities — approximately 4 million customers.

What areas does Ameren Illinois serve?

Ameren Illinois serves central and southern Illinois including Springfield, Peoria, Champaign-Urbana, Decatur, Galesburg, and the Metro East region near St. Louis — approximately 1.2 million electric customers.

Why are electricity bills higher in ComEd territory?

ComEd's urban service territory includes Chicago's dense and aging grid infrastructure, driving higher delivery charges per customer. However, the highly competitive ARES market in ComEd territory creates significant supply-side savings opportunities that can offset delivery cost differences.

How do I compare electricity suppliers in Illinois?

Work with an independent energy broker who can solicit quotes from multiple ARES in your utility territory simultaneously. Always compare all-in rates — including energy, capacity, and transmission components — against your current utility Price to Compare.