There is a charge on your bill that was decided last summer, by what your building happened to be drawing during about ten hours you were not told about at the time, and it prices your electricity for the twelve months that follow. It may be its own line. It may be folded invisibly into your supply rate. Either way it is there, and almost nobody who is quoting you a price will bring it up.
What a capacity charge is paying for
Energy pays for the electricity you actually consume. Capacity pays for the promise that enough generation exists to serve everyone on the worst day of the year, whether or not that generation ever runs.
The grid operator for northern Illinois, PJM, buys that promise years ahead and allocates its cost to customers in proportion to how much each one contributed to the system's peak. Your share is set from what your meter recorded during the highest system hours of the prior summer, both the highest hours on the PJM system as a whole and the highest hours on the ComEd system. Those hours are identified after the fact. You cannot know at three o'clock on a July afternoon whether the hour you are in will turn out to be one of them.
That is the part worth sitting with. This is not a charge based on your annual usage. It is a charge based on a handful of hours, chosen retroactively, that then applies to the whole year.
Where it is on your bill, and what to do if it is not
On some accounts it appears plainly, as a capacity or capacity obligation line on the supply side. On others it does not appear at all, because it is bundled into a single all-in supply rate and you are paying it without seeing it.
If you cannot find it, the question to put to whoever supplies your energy is direct: is capacity bundled into my rate or billed separately, and what is my current capacity obligation in kilowatts? That obligation figure is the input to everything below, and you are entitled to it.
An offer that quotes a low energy rate while passing capacity through separately is not comparable to one that includes it. This is one of the specific places a supply comparison quietly goes wrong.
Is it worth fighting
Two conditions have to hold, and both are answerable from what is in front of you.
It has to be large enough to matter. If it is a separate line, read it off twelve bills and compare it to the totals. If it is bundled, you need the obligation in kilowatts and the rate applied to it before you can size it. A charge you cannot size is a charge you cannot make a decision about, and the correct response to that is to ask for the number, not to guess at it.
You have to be able to move load on short notice. The whole strategy for reducing a capacity obligation is curtailment: cutting your draw during the specific hours that turn out to be system peaks. Those hours are forecastable but not certain, so in practice it means being willing and able to shed meaningful load on a handful of hot afternoons, on a day's notice, and being wrong sometimes.
A building that can shift a process, precool, or idle a line for three hours has a real lever. A building whose load is a continuous process that cannot be interrupted does not, and no amount of monitoring changes that. It is better to establish which one you are before buying anything that promises to help.
What we can and cannot compute here
We will say this plainly, because it is the kind of thing a vendor would not. Reconstructing your capacity obligation exactly requires a full prior summer of your own interval data and the settled peak hours for that summer, and it is a distinct calculation from the demand charge on the delivery side. Our engine records that calculation as not yet built, and reports its absence rather than substituting a softer number for it.
What you can establish today, without us and without any software, is whether the charge is separately billed, how large it is, and whether your operation has any flexibility to act on it. Those three answers decide whether the exact figure is worth chasing at all.
What is a capacity charge on an electricity bill?
It is the cost of the grid operator securing enough generation to meet peak demand, allocated to you in proportion to your contribution to the system peak. It pays for availability rather than for energy you consumed.
How is my capacity obligation calculated in ComEd territory?
From what your meter recorded during the highest system hours of the prior summer, on both the PJM system and the ComEd system. Those hours are identified after the fact and the resulting obligation applies for the following twelve-month period.
Is a capacity charge the same as a demand charge?
No. A demand charge is billed by the utility on your own single highest interval in the billing month and sits on the delivery side. A capacity charge comes from the wholesale market, is based on your usage during system-wide peak hours in a prior summer, and sits on the supply side.
Can I reduce my capacity charge?
Only by reducing your draw during the specific hours that turn out to be system peaks, which are forecastable but not certain. That requires the ability to shed real load on short notice on a handful of summer afternoons. If your load cannot be interrupted, there is no lever here regardless of how large the charge is.