PJM Capacity Prices and ComEd Business Bills

PJM capacity prices matter to ComEd-area businesses, but an auction clearing price is not a retail bill rate. The bill effect depends on the relevant delivery year, the account's capacity obligation, utility and supplier rules, losses, reserves, and the contract's capacity treatment.

PJM's capacity market page is the primary location for auction reports and results. PJM announced that its 2027/2028 Base Residual Auction cleared at the then FERC-approved cap of $333.44 per MW-day UCAP and procured 134,479 MW through the auction. PJM also stated that the total cleared capacity was short of the reliability standard. Those figures describe a wholesale reliability market result, not a customer's cents-per-kWh charge.

What the capacity market buys

Energy markets pay for electricity produced. Capacity markets compensate qualifying resources for an obligation to be available during the delivery year, subject to market rules. PJM's Reliability Pricing Model uses auctions to procure resource adequacy for forecast peak demand plus reserves.

The auction is denominated in dollars per MW-day. Retail electricity bills commonly use kWh, so the auction number cannot be pasted into a bill without converting the account obligation and applying the relevant retail treatment.

The account side: Peak Load Contribution

A ComEd account's Peak Load Contribution, or PLC, is an account-specific input commonly used in capacity cost allocation. It is not the same as the highest demand visible on a monthly bill. PLC reflects PJM/utility peak and scaling rules for the applicable period.

A simplified capacity model is:

annual capacity estimate = account capacity obligation in MW × applicable $/MW-day × days × contract/utility adjustments

The actual retail calculation can include scaling, loss, reserve, zonal, reconciliation, or supplier-specific elements. Ask the supplier for the exact formula and PLC value it will use.

Delivery years prevent timing mistakes

Capacity prices apply to defined delivery years. A calendar-year contract can span two capacity delivery years and therefore two capacity inputs. A quote received today can also cover a future delivery period with a different auction result.

For every offer, record:

contract start and end dates;
capacity delivery year(s) crossed;
PLC source and effective year;
whether capacity is included, fixed as an adder, or passed through;
reset and reconciliation language;
the supplier's loss and reserve treatment.

Four common retail structures

Capacity included in a fixed price. Confirm the definition and exclusions; “fixed” can still contain change-in-law clauses.
Capacity passed through. The invoice changes with the stated formula and account obligation.
Capacity fixed as a separate adder. The commodity and capacity are quoted separately but both may be fixed for a period.
Hybrid or reset structure. Capacity is fixed for one delivery year and repriced for another.

The correct offer comparison values all four on the same account, PLC, and delivery-year assumptions.

Operational peak management is not an instant bill discount

Reducing load during system peak-risk periods can influence future obligations under applicable rules, but the result is retrospective and uncertain. Businesses should not buy a “PLC reduction” service based solely on a claimed event calendar.

Evaluate:

which peaks and weather conditions drive the methodology;
how alerts are generated;
the facility's safe, controllable load;
production, comfort, and restart costs;
measurement and baseline method;
when any lower obligation could affect bills;
whether the supplier contract passes the benefit through.

Do not apply PJM conclusions to Ameren Illinois

Ameren Illinois is in MISO, not PJM. MISO uses its own resource-adequacy auction and tariff framework. Use the MISO annual Planning Resource Auction materials for Ameren-market context. A PJM $/MW-day figure and ComEd PLC explanation are not an Ameren cost estimate.

Procurement checklist after a major auction result

Identify affected contract delivery years.
Obtain current PLC or account capacity inputs from an authorized source.
Request supplier capacity formulas in writing.
Reprice pass-through and included structures on one model.
Run a PLC and price sensitivity table.
Check that the executed contract matches the proposal.
Avoid representing the wholesale clearing price as a guaranteed bill increase.

From a $/MW-day headline to an account effect

The gap between an auction headline and a business's bill is where most misunderstanding happens. A clearing price is expressed in dollars per MW-day and describes what qualifying resources are paid to be available across a delivery year. A retail bill is expressed in kWh and reflects one account's obligation, the utility's and supplier's rules, losses, reserves, and the contract's capacity treatment. To move from one to the other you need the account's capacity obligation — its Peak Load Contribution — and the exact formula the supplier will apply. Without both, an auction number is context, not a quote. The correct discipline is to ask the supplier, in writing, for the PLC value and the capacity formula it will use, and then to reprice every offer on that same PLC and delivery-year basis.

Peak Load Contribution is worth understanding on its own because it is where a facility's own behavior enters future cost. The PLC reflects how the account performed during the peak periods that set the tag under PJM and utility rules; it is not the largest demand number printed on a single monthly bill. Because the tag carries forward into a future delivery year, load reduction during peak-risk periods can influence a later obligation — but the effect is retrospective and uncertain, and it only helps the bill if the supplier contract actually passes the benefit through. Treat a vendor's "PLC reduction" event calendar as a hypothesis to verify, not a guaranteed discount.

Common mistakes reading capacity into bills

Pasting a $/MW-day clearing price directly into a cents-per-kWh comparison without converting the account obligation.
Ignoring that a calendar-year contract can straddle two capacity delivery years, and therefore two capacity inputs.
Applying a ComEd/PJM PLC explanation to an Ameren account. Ameren Illinois is in MISO, which runs its own resource-adequacy auction and tariff.
Assuming "fixed price" means capacity is fixed. A fixed commodity price can still pass capacity through or contain change-in-law language.

Frequently asked questions

Does a higher PJM capacity auction price automatically raise my bill? Not by itself. The bill effect depends on your account's PLC, the delivery years your contract crosses, and whether capacity is included, fixed as an adder, or passed through. A wholesale clearing price is not a retail rate.

What is Peak Load Contribution and where do I get mine? It is an account-specific capacity input reflecting your peak behavior under PJM/utility rules. Obtain the current value from an authorized source — your utility account or, with authorization, your supplier — rather than estimating it from a monthly demand figure.

I'm an Ameren business — does any of this apply? The PJM figures do not. Ameren Illinois sits in MISO, so use the MISO Planning Resource Auction materials for market context and confirm capacity treatment with your supplier.

Can reducing load during peaks lower my capacity cost? Possibly, in a future delivery year, if the methodology and your contract both allow the benefit to flow through. The result is uncertain and retrospective, so weigh production, comfort, and restart costs before buying a curtailment service on a claimed event calendar.

Sources

PJM — Reliability Pricing Model (capacity market) page
MISO — annual Planning Resource Auction results review
Related guides: compare offers apples to apples, demand and interval data, and the commercial demand charges overview.

Source check date: July 19, 2026. PJM posts subsequent auctions, incremental results, and scaling data; use the results applicable to the contract period.