As we head into a new coincident peak (CP) season across North America, it is a great time to revisit what CP programs are, how they work across major ISOs, and how Enverus performed during last summer’s season.
What Is a Coincident Peak?
A coincident peak is the system‑wide moment when total grid demand reaches its highest level, and a customer’s load during that same interval is used to allocate capacity cost (generation adequacy) and/or transmission costs (grid infrastructure). The fundamental principle behind CP programs is cost causation: customers who contribute the most load when the grid is under the greatest stress pay a higher share of fixed system costs (transmission and capacity). As a result, CP programs are designed to:
- Incentivize customers to reduce load during critical hours, and
- Allocate transmission and capacity costs based on each customer’s contribution to peak system demand.
How Coincident Peaks Are Calculated by ISO
While the underlying principle is the same, each ISO administers its CP program differently.
ERCOT (4CP) – Transmission-focused
- Metric: Four Coincident Peaks (4CP).
- Period: June–September.
- Calculation: ERCOT identifies one system-wide summer peak per month. A customer’s contribution across the four peak events is averaged and used to determine transmission-related charges in the following calendar year.
PJM (5CP / PLC) – Capacity-focused
- Metric: Five Coincident Peaks (5CP).
- Period: June–September.
- Calculation: PJM identifies the five highest system-demand periods during the summer. A customer’s average load during these events determines their Peak Load Contribution (PLC), which directly drives capacity costs in the subsequent PJM capacity year (June–May).
NYISO (1CP / ICAP tag)
- Metric: One Coincident Peak.
- Period: July–August.
- Calculation: NYISO determines a single summer coincident peak. A customer’s load during that peak establishes their ICAP value for the following capacity year (May–April).
ISO New England (ISO‑NE) – 1CP with Transmission Variants (through 2025)
- Metric: One Coincident Peak.
- Period: Typically summer, with no restriction on month, weekday, or weekend.
- Calculation: The single annual system peak sets a customer’s contribution for capacity obligations in the following June–May year.
Note: As of early 2026, ISO New England (ISO-NE) is moving away from the “one day-per-year” annual peak model and transitioning to a Prompt/Seasonal Capacity Market under the Capacity Auction Reforms (CAR). Under the new reforms (effective for the current 2026 cycle and beyond), ISO-NE is shifting to seasonal cost allocation. Instead of one annual peak, capacity costs will be allocated based on your contribution to both Summer and Winter seasonal peaks.
Enverus CP Call Performance – 2025 Season
In addition to providing 15-day-ahead load forecasts across these ISOs, Enverus also issues Coincident Peak calls to alert customers when a CP is likely to occur.
Table 1 summarizes the 2025 CP intervals, the number of Enverus calls issued, and whether the peak was successfully predicted.
| Market | Program | 2025 Peak Intervals | Number of calls by Enverus | Accurately predicted? |
| PJM | 5CP | June 23rd, HE18 June 24th, HE18 June 25th, HE15 July 28th, HE18 July 28th, HE18 | 8 | Yes Yes Yes Yes Yes |
| ERCOT | 4CP | June 19th, 17:00 July 30th, 17:00 August 18th, 17:00 September 4th, 17:30 | 10 7 7 6 | Yes Yes Yes Yes |
| ISO-NE | 1CP | June 24th, HE19 | 3 | Yes |
| NYISO | 1CP | July 29th, HE19 | 6 | Yes |
Enverus successfully predicted all coincident peaks across PJM, ERCOT, ISO‑NE, and NYISO with at least one day of advance notice, and with a relatively small number of calls. Beyond CP calls, Enverus’ day-ahead load forecasting models also outperformed ISO forecasts throughout the season:
| Market | CP Period | Enverus MAPE | ISO MAPE |
| PJM | June-July | 1.81% | 2.24% |
| ERCOT | June-September | 1.88% | 2.30% |
| ERCOT | June-September | 2.97% | 3.84% |
| NYISO | July | 2.32% | 2.72% |
These results underscore the precision, reliability, and adaptability of Enverus’ forecasting tools and analyst-driven insights. By accurately identifying coincident peak risk with minimal calls, and consistently outperforming ISO load forecasts, Enverus empowers customers to proactively manage CP exposure and stay ahead in increasingly dynamic power markets.