How to Read a ComEd Commercial Electric Bill
By Illinois Commercial Energy editorial team
Reviewed by JakenEnergy commercial energy team
How to Read a ComEd Commercial Electric Bill
A commercial electric bill can look like a wall of numbers, but it is really a few distinct stories stacked together: what it costs to deliver power to you, what the energy itself cost, how much you used and how hard you pulled, and a set of regulated adjustments. This article walks through those sections so you can find each number and understand what drives it. ComEd serves northern Illinois and operates in the PJM market, which shapes several of the charges you will see.
The two halves: delivery and supply
The most important distinction on any ComEd commercial bill is between delivery and supply. Delivery is the cost of moving electricity to your building across ComEd's poles, wires, and transformers, and of the metering and service that go with it. ComEd is your delivery utility, and delivery charges are ComEd's regardless of who sells you the energy. The delivery utility always owns the wires, the meter, and responsibility for outages.
Supply is the cost of the energy itself. That energy comes either from ComEd's default service or from a competitive supplier, an ARES, that you chose. Switching to a competitive supplier changes only the supply portion of your bill; it does not change your delivery charges or who to call during an outage. Because this delivery-versus-supply split is the foundation for everything else, we cover it in depth in a dedicated guide on reading delivery versus supply on the ComEd bill, and this article focuses on the surrounding line items rather than duplicating that explanation.
Usage: kilowatt-hours
Somewhere in the delivery or account-summary section, the bill states your energy usage in kilowatt-hours (kWh) for the billing period, typically with the meter readings that produced it. Kilowatt-hours measure the total quantity of energy you consumed. This is the number most people think of as their usage, and it drives the energy component of supply.
The summary usage on the bill is not the same as interval data. The bill gives you a monthly total; interval data gives you the hour-by-hour shape behind it. If you want to analyze peaks or plan around capacity, you request that detail separately, as described in our guide on requesting and using interval data — note the summary figure and the detailed history serve different purposes.
Demand: kilowatts
Many commercial rate classes bill a demand determinant in addition to energy. Demand, measured in kilowatts (kW), reflects the highest rate at which your facility drew power during the period, not the total it consumed. Two buildings can use the same kilowatt-hours in a month yet have very different demand if one draws steadily and the other spikes.
On the bill, look for a line expressed in kW, separate from the kWh energy line. This is the determinant behind demand charges, and because it is set by your peak, it can be influenced by how you schedule equipment. Our overview of commercial demand charges explains how these determinants are measured and why the shape of your load, not just the total, drives this part of the bill.
Capacity and the PJM connection
Capacity is a distinct cost bucket, separate from the energy you consume and the transmission that carries it. In PJM, capacity charges are driven by a customer's peak-load contribution, sometimes called a capacity tag, which is typically set from your usage during prior-year system coincident-peak hours. It is the region's way of paying to have enough resources available to meet peak demand reliably.
How capacity appears on your bill depends on your supply arrangement. A competitive supplier may fold capacity into a single all-in supply rate or may itemize it as its own line. Either way, the underlying driver is your peak-load contribution. To keep the three supply-side cost buckets straight, see our explainer on capacity, energy, and transmission as three buckets, which shows how each is measured and billed differently.
Riders and adjustments
Below the main charges you will usually find a set of riders and adjustment lines. These are additional charge or credit components approved through the Illinois regulatory process, and they exist so that specific costs stay itemized rather than buried in a single rate. They can include purchased-electricity adjustments, charges tied to state-approved energy programs, taxes, and other pass-through items.
The exact riders, their names, and their amounts can change over time as tariffs are updated. Rather than memorizing them, treat this section as a checklist: each line should be identifiable, and if one appears that you do not recognize, it is reasonable to ask ComEd or your advisor what tariff it comes from. The value of the itemized format is transparency, so use it.
Taxes and local charges
Illinois commercial bills also carry applicable taxes and, in some jurisdictions, local charges. These are typically calculated on defined portions of the bill and appear as their own lines. They are not something you negotiate with a supplier, but they are part of understanding your total cost, so it is worth knowing which lines are tax and which are energy or delivery.
Putting the sections together
Reading the bill top to bottom, a useful mental model is to sort every line into one of a few groups: delivery (ComEd's charge to bring power to you), supply (energy, and often capacity, from ComEd default service or your competitive supplier), usage and demand determinants (the kWh and kW that quantities are billed on), and regulated riders, taxes, and adjustments. Once each line has a home in one of those groups, the bill stops being a wall of numbers and becomes a map of your cost.
Where to go next
If you want to act on what you find, two directions follow naturally. To compare suppliers or understand a renewal, focus on the supply half and the usage and demand that drive it. To manage cost, focus on demand and capacity, which respond to how and when you operate. For a broader orientation to buying power in the state, our commercial electricity overview ties these threads together, and the ComEd-specific detail lives on our ComEd utility page.
Sources
This article is educational and does not promise any specific savings, rate, or outcome for any business.
Frequently Asked Questions
QWhat is the difference between delivery and supply on a ComEd bill?
Delivery covers moving electricity to your building over ComEd's wires and is charged by ComEd, your regulated delivery utility. Supply is the cost of the energy itself, which comes either from ComEd's default service or from a competitive supplier you chose. Delivery stays with ComEd regardless of who supplies your energy; only the supply side changes if you switch suppliers.
QWhere do I find my demand charge on the bill?
On many commercial rate classes, the bill lists a demand determinant measured in kilowatts, separate from the kilowatt-hours of energy used. This reflects the highest rate at which your facility drew power during the billing period. Look for a line labeled with kW or demand, which is distinct from the kWh energy quantity.
QWhat are riders and adjustments on my bill?
Riders and adjustment lines are additional charge or credit components approved through the regulatory process. They can cover things like purchased-electricity adjustments, efficiency program costs, or other pass-through items. They appear as separate lines so the cost components stay transparent, and their presence and labels can change over time.
QDoes my capacity cost show up as its own line?
It depends on who supplies you and how they present charges. Capacity is one of the cost buckets inside the supply portion of your bill, driven by your peak-load contribution in PJM. A competitive supplier may bundle it into a single supply rate or itemize it, so review your contract to see how capacity is passed through.
QHow do I get my usage data from ComEd?
As the account holder you can access your usage through ComEd's online account tools, and you can request interval data or authorize a broker or supplier to receive it. The bill itself shows summary usage, but the detailed interval history that supports peak and capacity analysis is requested separately from the utility.