Key takeaways
- ComEd offers multiple rate classes for commercial and industrial customers, and being on the wrong one is common.
- Rate class assignment is based on peak demand, not usage, and often does not reflect a facility’s current operations.
- A tariff review is one of the fastest ways for an Illinois facility to cut its electric bill without operational changes.
ComEd’s rate structure is complex, layered, and rarely explained in language that facility managers can act on. Most Illinois commercial and industrial customers are on the same rate they were assigned when the account was opened, sometimes twenty years ago, without anyone reviewing whether that rate still fits.
The result: a lot of Illinois facilities are on rates that overcharge them for their current operating profile. Here is how the structure actually works and where the money leaks.
The Basic Structure of a ComEd Commercial Bill
A typical ComEd bill for a commercial or industrial customer has four main components: a delivery charge for using the utility’s wires and infrastructure, a supply charge for the energy itself, capacity charges passed through from PJM, and various riders and adjustments.
Each of these components is calculated differently depending on your rate class. Delivery charges include both consumption (per kWh) and demand (per kW) components. Supply is per kWh. Capacity is per kW per day. Riders apply various uplifts. The interaction between these components is what makes one rate class dramatically better or worse than another for a given operating profile.
The Main Rate Classes for C&I Customers
Rate 6 covers small commercial customers below a certain demand threshold. It is straightforward but not designed for facilities with meaningful peak demand.
Rate 6L is the general commercial and light industrial rate for facilities with demand between roughly 100 kW and 400 kW. Most mid-sized facilities land here by default.
Rate 7 is the medium and large industrial rate, applying to facilities above roughly 400 kW of demand. The structure differs meaningfully from 6L, with higher fixed charges but lower per-unit rates.
Rate 8 covers extra-large industrial customers, typically over 3 MW of demand. Highly specialized structure with different demand billing mechanics.
The rate that fits a 200 kW facility is punishing for a 500 kW facility. And vice versa.
Where Facilities Get Trapped
Growth without reassessment. A facility opened on Rate 6L at 250 kW, expanded operations, and now runs at 500 kW. It is likely paying materially more on 6L than it would on Rate 7. The trap: assuming ComEd will move you automatically.
Scaledown without reassessment. A facility that once ran at 700 kW downsized to 350 kW. Still on Rate 7, it is now paying higher fixed charges than a similarly sized facility on Rate 6L. The trap: forgetting to request a rate change after downsizing.
Seasonal operations. A facility with sharp peak-season demand and low off-season demand can be on the wrong rate depending on which season dominates its billing average. The trap: being billed on annual assumptions that do not fit seasonal patterns.
Riders and Adjustments That Compound the Problem
Beyond the base rate class, ComEd bills carry several riders that adjust the base rate. These include the Purchased Electricity Adjustment (PEA), the Environmental Cost Recovery Adjustment (ECRA), Distributed Generation rebates, and various customer-specific adjustments.
Individually, these adjustments look small. Cumulatively, they can shift a bill by 5 to 15%. And their impact varies by rate class. A rate class that looks slightly better on base rates can end up materially worse once all riders are factored in. The only way to know is to model the full bill under alternative rate classes using a representative twelve months of interval data.
How to Know If You Are on the Wrong Rate
If your average monthly demand has changed by more than 20% up or down since your account was opened, your rate class is probably suboptimal. If your ratio of demand charges to consumption charges is materially different from similar facilities in your industry, it is worth investigating. If you have never modeled your bill under alternative rate classes, you likely have money on the table.
Rate class reviews routinely surface five- and six-figure annual savings with zero operational change.
ComEd territory analysis
How DataWrangler Handles Rate Class Analysis
DataWrangler pulls twelve months of interval data for each facility and models the bill under every applicable rate class, riders and adjustments included. If a better rate exists, we handle the change request with ComEd and monitor the first three billing cycles to confirm the savings landed. That is part of how DataWrangler cuts 10 to 25% off commercial and industrial electric bills in Illinois.
Check Your Rate Class
Your rate class is printed on every ComEd bill. Compare your current demand and consumption profile to the class you are on. If it does not fit, a change is worth pursuing.
Upload your bill for a free rate class analysis or see how DataWrangler works with Illinois facilities.