What is PJM 5CP
Five hours a summer set your capacity bill for a full year. PJM finds the five highest daily peaks of the season, reads your load during those hours, and that number — your Peak Load Contribution — is what capacity charges multiply against from the following June.
How the five are chosen
From June 1 through September 30, PJM tracks the highest hourly load of each business day across the whole RTO. The five biggest of those daily peaks are the coincident peaks. Weekends and NERC holidays are excluded by rule, two peaks can land in the same week, and a mild June day that led the standings can fall out in August. Nothing is final until the season ends.
PJM publishes the official five in mid-October, using unrestricted peaks — observed load plus an estimate of the demand response that curtailed away. Your meter's average draw across those five hours becomes your PLC for the delivery year starting the next June 1.
Why the hours are worth so much
Capacity prices cleared at their cap for the third straight year. The 2027/28 Base Residual Auction — the delivery year summer 2026 peaks bill against — cleared at $333.44 per MW-day across the RTO. Over a 365-day year that is roughly $121,700 per megawatt of PLC, before zonal scaling factors. A facility that curtails one megawatt through the five CP hours keeps that money.
Source: PJM 2027/2028 Base Residual Auction report (pjm.com). Your bill applies zone-specific scaling to the RTO price; the calculator uses the RTO clearing price and your rate wins if you enter one.
The catch
You only find out which five hours counted in October, months after they happened. Curtailing every hot afternoon costs production; curtailing none wears the full tag. The whole game is knowing which afternoons are the real candidates, before they happen, with enough lead to act.
That is what the live PJM dashboard answers each business morning by 10 AM ET, and the track record shows how those calls have graded: 18 of the 20 CPs across 2022–2025, flagging 36 days where the blanket approach needs 86.
What a megawatt is worth
PLC reduction × rate × 365. Default rate is the 2027/28 RTO clearing price; zonal scaling and your supplier's pass-through terms adjust the exact figure. Missing even one of the five hours forfeits that hour's share.
5CP is capacity. NSPL is transmission.
A second tag, Network Service Peak Load, is set by your load at your transmission zone's own annual peak and drives network transmission charges the same way. The zone peak usually lands on or near a 5CP day, so curtailing the right afternoons often trims both tags at once.
Informational only; curtailment decisions and their outcomes are yours. WattMarkets is not a licensed advisor and makes no guarantee of accuracy.