ERCOT’s 2026 Four Coincident Peaks are the four 15-minute intervals of highest grid demand — one in each month, June through September — that set your 2027 transmission charges. The season closed September 30, 2026; ERCOT confirms the four settlement intervals only after the season, so the 2026 peaks here are preliminary — BOT’s read of ERCOT’s real-time system load, at hourly resolution — until ERCOT publishes its official 15-minute intervals in late November.
Every summer, four fifteen-minute windows decide what a large Texas electricity customer pays to move power for the following year. The 2026 season just closed. This post explains the mechanism, carries the four 2026 peaks — preliminary now, final once ERCOT publishes them — and lays out what a building can still do before June 2027. The preliminary peaks are the highest-load hour in each month that BOT identified from ERCOT’s real-time system load (hourly resolution); ERCOT’s own Four Coincident Peak file, published in late November, is the final source of record — it pins the exact 15-minute interval — and nothing here is taken from a third-party blog.
The 2026 intervals
ERCOT determines the four coincident peaks — the single highest 15-minute system demand interval in each of June, July, August, and September — from settlement data after the season ends, and publishes the official Four Coincident Peak file in late November. As of October 1, 2026 those official settlement values are not yet published; the table below carries BOT’s preliminary peaks — the highest-load hour in each month from ERCOT’s real-time system load (hourly resolution) — which will be reconciled to ERCOT’s official 15-minute intervals when the file posts.
| Month | Date | Hour-ending (CT) | ERCOT system load, hourly resolution (BOT ErcotLoad app) |
|---|---|---|---|
| June 2026 | Jun 18, 2026 | HE17 | 82,772 MW |
| July 2026 | Jul 22, 2026 | HE18 | 91,134 MW |
| August 2026 | Aug 24, 2026 | HE18 | 90,817 MW |
| September 2026 | Sep 12, 2026 | HE17 | 86,489 MW |
Preliminary. Each row is the highest-load hour in that month, identified by BOT from ERCOT’s real-time system load (hourly resolution; BOT ErcotLoad app). Hour-ending, Central Time — HE18 is the hour ending 6:00 PM CT. These will be reconciled to ERCOT’s official Four Coincident Peak file — the final source of record, which pins the exact 15-minute interval — when it publishes in late November 2026. Nothing here is taken from a third-party blog.
How the four peaks become a 2027 charge
For a transmission-level or large commercial customer, next year’s transmission cost-of-service is allocated by its demand during these four intervals: the customer’s average contribution to the four grid peaks sets its share of transmission charges for the following calendar year. The mechanism is defined by ERCOT and the Public Utility Commission of Texas; the exact formula and eligibility live in ERCOT’s official materials. The practical consequence is blunt — four afternoons in one summer price twelve months of transmission the next year, which is why operators track the season so closely. The full mechanics are in our ERCOT 4CP explainer.
Did our buildings reduce during the peaks?
BOT tracks ERCOT peak season for its own four-building West Houston portfolio and publishes its 4CP calls — forecasts, response actions, and results. Through the 2026 season we pre-cooled ahead of the forecast peak windows and coasted through them to hold demand down during the likely intervals. We are not publishing a 2026 reduction figure here until the intervals are final and the avoided demand can be stated against ERCOT’s confirmed peaks — a measured number against the wrong intervals is just a guess. The verified figures will follow this post’s update, consistent with how we handle measurement and verification.
What to do before June 2027
- Know whether 4CP even applies to you. It drives transmission allocation for larger, transmission-level loads; confirm your tariff and eligibility with your provider.
- Instrument the building. You cannot shave a peak you cannot see in time — interval metering and a forecast are the price of entry.
- Build the curtailment playbook now. Pre-cooling and setpoint strategy are decided in spring, not on a 103°F afternoon. Our demand-response guide and summer cooling-cost guide cover the moves.
- Lease where it is already done. In an owner-operated building that tracks 4CP, the discipline is in the operating budget you inherit.
4CP, handled by the building
Four Class A West Houston buildings, continuously monitored, peak season tracked and published — the operating discipline your rate benefits from.
See the buildings How 4CP works