The energy price gets all the attention on ComEd Hourly Pricing, but the bill carries a second moving part that the flat rate hides: a monthly Capacity Charge set by what your home was drawing during five specific hours of the previous summer. It is not new. It has been on Hourly Pricing bills for years, its published rate rose in June 2025, and it rose again by about 21 percent in June 2026. This page gives you the mechanism, the filed rates, the actual five hours for the last two summers, and the reason it matters for the worth-it question.
What the capacity charge is
Every supplier in PJM's market has to pay for enough generating capacity to cover its customers' share of the grid's peak. On the flat rate, ComEd folds that cost into the Price to Compare and you never see it. On Hourly Pricing, the energy price is passed through raw, so the capacity cost has to be billed separately. It shows up as a line called Capacity Charge, and it works like a residential version of the commercial demand charge: it is set by your draw at a few moments, not by your total energy.
The formula on the bill is your Capacity Obligation, in kilowatts, multiplied by the published Monthly Capacity Charge, in dollars per kW per month. The obligation is your Peak Load Contribution: your average draw during the five hours of the prior summer when the whole PJM system peaked, adjusted by published scaling factors. It is fixed for a PJM planning year, June through the following May, so the summer you just had sets the charge you pay for the next twelve months.
The five hours that set it
PJM publishes the five coincident peak hours after each summer. These are the ones on file:
- Summer 2024, setting the charge for June 2025 through May 2026: June 21, July 15, July 16, August 1 and August 28, every one of them the hour beginning 4 PM Central.
- Summer 2025, setting the charge for June 2026 through May 2027: June 23, June 24 and June 25, then July 28 and July 29. Four of the five were the hour beginning 4 PM Central; June 25 was the hour beginning 1 PM.
Ten hours across two summers, all on weekday afternoons in late June through August. That is the entire window that decides a year of capacity charges. A home that ran its air conditioning hard through those specific afternoons carries a high obligation for the following year; a home that happened to be empty carries a low one. Nothing you do overnight, in winter, or on any other summer afternoon touches it.
The filed rate, and why it rose
The Monthly Capacity Charge is published by the Illinois Commerce Commission as Informational Sheet No. 4, a supplement to Rate BESH. The periods on file:
| billing months | published rate, $ per kW-month |
|---|---|
| June to August 2025 | 8.33100 |
| September to December 2025 | 8.31935 |
| January to May 2026 | 8.32925 |
| June 2026 to May 2027 | 10.11236 |
The June 2026 step is an increase of about 21 percent. The published rate is built from PJM's capacity price for each planning year, so it moves when that price moves. Flat-rate customers pay for the same capacity inside the Price to Compare, which also reset upward in June 2026; Hourly Pricing customers see it as its own line.
So each kilowatt of obligation now costs $10.11 a month, or about $121 a year, up from $8.33 a month. A home whose obligation is 2 kW pays roughly twice that; a home at 4 kW pays roughly four times. Those multiples are the arithmetic of the published rate, not a forecast of any bill, and they leave out the published scaling factors that adjust the obligation itself.
What it does to the worth-it math
This is the piece most comparisons get wrong in both directions. Put the raw hourly price next to the Price to Compare and Hourly Pricing looks like a large saving, because the flat rate carries capacity and the raw price does not. Add the capacity charge back and the gap narrows, sometimes a lot, sometimes not much, depending on one thing: what your home drew in those five hours.
That is why no calculator can settle the question from a monthly total. Two homes using identical kilowatt hours over a year can have very different five-hour draws, and the difference is a year of capacity charges. The honest reconstruction prices every hour of your own usage on both rates and adds the capacity charge your own summer would have set, which is what is ComEd Hourly Pricing worth it describes and what we do from your ComEd usage data once you connect it. Summer afternoons carry the energy risk and the capacity risk at once, which is why they decide the whole year.
Is the ComEd capacity charge new in June 2026?
No. It has been a line on Hourly Pricing bills for years. What changed in June 2026 is the rate, up about 21 percent to $10.11236 per kW-month, and the summer that sets the obligation, which is now summer 2025.
How is my capacity obligation calculated?
From your usage during the five PJM system peak hours of the previous summer, averaged and adjusted by published scaling factors. ComEd's own Usage Data Tool shows your Capacity Peak Load Contribution if you are on Hourly Pricing.
Can I lower my capacity charge?
Only by drawing less during next summer's five peak hours, and you do not know which hours those will be until PJM publishes them after the summer. They have all fallen on hot weekday afternoons, most at 4 PM Central. Reducing air conditioning in that window on the hottest days is the only lever, and it is a guess about which days will count.
Does the flat rate have a capacity charge?
Yes, but you never see it. It is inside the Price to Compare. Hourly Pricing shows the same cost as a separate line, which is why comparing the raw hourly price to the flat rate overstates the saving.