PJM capacity charges: how to lower a site's peak load contribution
Milvian AI teamFacilities and infrastructure intelligence
A PJM customer's capacity charge follows its load in the grid's five highest summer peak hours. That average, scaled by the utility, fixes the charge for the following twelve months. With the 2026/2027 price at $329.17 per MW-day, cutting load in those five hours is worth more than it has been in years.
Why capacity costs jumped
PJM's auction for the 2026/2027 delivery year cleared at $329.17 per MW-day across its whole footprint, the cap approved by FERC, up from $269.92 for 2025/2026. PJM said its forecast peak rose by more than 5,400 MW in a year, mostly from data centers, electrification and economic growth.
PJM estimated the result could raise some customers' bills by 1.5 to 5 percent, depending on how states and suppliers pass it through. In northern Illinois, ComEd estimated customers could pay about 12 percent more on average from June 2026 through May 2027.
How the charge is built
| Step | What happens | What a building controls |
|---|---|---|
| The summer window | PJM records its five highest system peak hours, each on a separate day, between 1 June and 30 September. | Load on the hot weekday afternoons most likely to become peaks. |
| Your peak load contribution | Your average demand across those five hours, scaled by zonal and system factors. | Interval data shows your actual demand in each of the five hours. |
| The following year | That obligation is billed in monthly installments across the next delivery year. | Missing a single peak hour keeps a full year of cost in place. |
| The price | $329.17 per MW-day for 2026/2027, about $120,000 a year for each MW of contribution before utility scaling. | Every 100 kW shed in the peak hours avoids roughly a tenth of that. |
Why buildings miss the peaks
Nobody knows which five hours count until the season ends. Utilities and suppliers send alerts on likely peak days, but an alert at noon is useless if the plant has no agreed response and the chiller staging was set in May.
The response that works is a sequence decided in advance: precool spaces in the morning, hold a higher zone setpoint through the alert window, stage chillers so a second machine does not start, and pause flexible loads such as EV charging, pumping to storage tanks or process batches. Aqueduct holds that sequence per site and runs it where control is enabled, with owner approval, through BACnet or Modbus field devices, with every command logged so the event can be audited later.
A playbook for summer 2027
- Get demand by feederA main meter shows the total. Feeder meters on HVAC, lighting and plug loads show what can actually be shed.
- Rank sheddable loadsList each load by kW, how long it can pause and the comfort or process cost of pausing it.
- Agree the sequence before JuneFacilities, tenants and operations sign off the steps and limits once, not on the afternoon of an alert.
- Act on every likely peakFive hours count, but which five is unknown, so respond to each alert across the season.
- Verify the reductionCompare event hour demand with the weather-adjusted expected demand for that hour, so the kW shed is a measured number.
Where this is going
PJM's 2026/2027 auction cleared only 139 MW above the region's reliability requirement, a margin PJM itself said shows a tightening balance between supply and demand. Capacity will stay a large share of commercial bills while data center load keeps growing.
Sites that meter feeders and agree a curtailment sequence this winter will be ready for the first alert of the 2027 season.
Sources
| Source | Link |
|---|---|
| American Public Power Association, PJM auction procures 134,311 MW of generation resources | publicpower.org |
| Citizens Utility Board, why is the ComEd price spiking (June 2026) | citizensutilityboard.org |
| Vistra, 5 coincident peak service | commercial.vistracorp.com |
| Constellation, PJM's five coincident peaks: what you should know | blogs.constellation.com |
