What ERCOT Corrected On July 27
ERCOT said errors in forecast-input processing, input alignment, and model optimization caused its 2026 Ancillary Service Plan to use less net-load uncertainty than the PUCT-approved methodology required. When ERCOT reran the model with the approved parameters, the combined ECRS and Non-Spin requirement averaged about 3,700 MW more per hour than the quantities posted to date.
That figure is a corrected planning requirement, not 3,700 MW of load shed or a measured operating shortfall. ERCOT said it had experienced no reliability issue from the lower quantities. Real-time Non-Spin purchases, available resource headroom, and growing battery capacity helped reduce the operational gap.
ERCOT will not revise its posted August 2026 quantities. It may buy more Ancillary Services closer to real time or use Reliability Unit Commitment when risk assessments warrant it, and it plans to use the corrected model when developing the proposed 2027 methodology.
What The September 2 Meter-Data Error Changes
ERCOT's September 8 Market Notice M-A090826-01 describes a separate Market Management System problem on Operating Day September 2. A scheduled database load did not update part of the network model correctly, leaving out multiple meters until ERCOT corrected the model at 13:22. ERCOT says affected Real-Time Resource Meter Prices were therefore calculated incorrectly from 00:00 through 13:22—a 13-hour-22-minute window by KilowattLogic calculation.
ERCOT also says it cannot accurately recreate the missing Electrical Bus shift factors needed to recalculate the affected SCED prices. Under Nodal Protocols Section 6.3(4), those September 2 prices therefore cannot be corrected. The notice does not enumerate every affected meter or publish an aggregate dollar impact.
Market participants with index, imbalance, generation, or settlement exposure should identify affected meter mappings, reconcile the relevant September 2 statements, preserve dispute deadlines, and trace any contract pass-through before assigning an account-level impact. The notice does not establish that every ERCOT real-time LMP was wrong, that retail bills were broadly affected, or that a customer is automatically owed a credit.
How The June Through September Operating Signals Fit
ERCOT's June 2026 public notices show a cluster of operating messages during the first week of summer operations. The most relevant commercial signal is repeated evening deployment of Non-Spin, a reserve product ERCOT can call when the system needs additional offline capability brought into the operating stack.
The June 6 notice posted 997.5 MW of Non-Spin beginning at 20:14 CT, with all Non-Spin recalled at 22:15. ERCOT also posted a June 6 sudden generation-loss event of 706 MW, with frequency declining to 59.950 Hz while load was 52,082 MW. Those are operating facts, not a retail-rate forecast or a claim that firm load was shed.
Late-August notices extend that evidence. On August 29, ERCOT posted an initial 667.7 MW deployment plus three additional postings totaling 177.2 MW; on August 30, it posted an initial 362.8 MW plus four additional postings totaling 172.0 MW. All Non-Spin was recalled by 21:35 and 21:40, respectively, and ERCOT's daily notices reported no sudden generation loss above 450 MW for either operating day.
The September 2 sequence was larger. ERCOT posted an initial 888.4 MW deployment at 20:13, followed by postings of 3.0, 10.0, 43.5, and 264.0 MW. KilowattLogic sums those time-stamped notices to 1,208.9 MW. All Non-Spin was recalled at 22:00, and ERCOT's next daily notice said no sudden generation loss greater than 450 MW occurred September 2. Read this operating sequence beside EIA's sustained ERCOT load record, without recasting either source as a price or emergency finding.
ERCOT's next distinct contingency notice covers September 5. It reports a sudden generation loss at 02:11 totaling 654 MW, with frequency declining to 59.959 Hz while system load was 60,125 MW. KilowattLogic calculates the lost generation at 1.09% of contemporaneous load and the frequency change at 0.041 Hz below 60. Those calculations help scale the event; they do not prove customer load shed, a market emergency, or a delivered-rate effect.
| Date | ERCOT Notice Signal | Buyer Read |
|---|---|---|
| June 4 | 929.6 MW of Non-Spin deployed at 20:53 and recalled at 22:30. | Evening reserve actions were showing up before the hottest part of summer. |
| June 5 | 572.8 MW of Non-Spin deployed at 20:31 and recalled at 22:10; ERCOT also posted two sudden generation-loss events for that operating day. | Index-exposed loads should treat isolated operating notices as settlement-risk inputs, not just reliability trivia. |
| June 6 | 997.5 MW of Non-Spin deployed at 20:14 and all Non-Spin recalled at 22:15; ERCOT later posted a 706 MW sudden generation-loss event at 08:23. | The useful signal is reserve readiness during shoulder-evening hours, not a claim that Texas was short of firm load. |
| July 27 | ERCOT disclosed model-input and optimization errors; corrected ECRS plus Non-Spin requirements average about 3,700 MW more per hour. | Treat the correction as methodology and settlement-risk context. ERCOT reported no reliability issue and kept August posted quantities unchanged. |
| August 29 | ERCOT posted an initial 667.7 MW Non-Spin deployment at 20:30, then three explicitly additional notices totaling 177.2 MW; all Non-Spin was recalled at 21:35. | The evening sequence confirms that real-time reserve actions remained part of the unchanged August operating plan, without an emergency notice. |
| August 30 | ERCOT posted an initial 362.8 MW Non-Spin deployment at 20:12, then four explicitly additional notices totaling 172.0 MW; all Non-Spin was recalled at 21:40. | A second consecutive evening sequence strengthens the readiness signal, but does not establish a retail-price or customer-bill outcome. |
| September 2 | ERCOT posted an initial 888.4 MW Non-Spin deployment at 20:13, followed by 3.0, 10.0, 43.5, and 264.0 MW postings; all Non-Spin was recalled at 22:00. | KilowattLogic totals the sequence at 1,208.9 MW. ERCOT posted no sudden generation loss above 450 MW for the operating day. |
| September 2 SCED | ERCOT says missing meters caused affected Real-Time Resource Meter Prices to be calculated incorrectly from 00:00 through 13:22; the needed shift factors cannot be recreated, so those prices cannot be corrected. | Review affected settlement statements and meter mappings. Do not infer that every ERCOT real-time LMP or retail bill was wrong. |
| September 5 | ERCOT reported a sudden generation loss at 02:11 totaling 654 MW. Frequency declined to 59.959 Hz while system load was 60,125 MW. | KilowattLogic calculates the trip at 1.09% of contemporaneous load. It is a reserve-readiness data point, not a load-shed or retail-rate finding. |
Why The Existing Owner Was Updated
This page already owned the ERCOT methodology-error, Non-Spin, generation-loss, and buyer-settlement intent. The July reserve-model disclosure, September 2 SCED meter-data error, and August 29 through September 5 operating evidence belong to that same decision path, so updating the existing owner is more useful than publishing a second article with overlapping explanations.
The timing matters. ERCOT's summer operations outlook says its forecasted peak is 92,211 MW under expectations for hotter weather and significant load growth, with an estimated 1,725 MW of expected large-load growth from May through September 2026. ERCOT also said it may add 26 new congestion management plans for summer 2026, a preliminary 42% increase, due to increasing demand in several Texas weather zones.
What Not To Infer
- Do not treat Non-Spin deployment as proof of a grid emergency unless ERCOT issues that emergency notice.
- Do not treat one generation-loss posting as proof that customer load was shed or that a scarcity-pricing event occurred.
- Do not treat the affected SCED meter-price notice as proof that every real-time LMP or retail customer bill was wrong.
- Do not treat the 3,700 MW corrected model difference as load shed, an outage total, or an immediate reliability deficit.
- Do not assume August posted quantities or customer charges changed; ERCOT explicitly kept the August plan in place.
- Do not convert ERCOT operating notices into guaranteed retail-price increases.
- Do not assume the June or August patterns predict every summer evening; use them as readiness signals alongside weather, load, reserve, and price data.
Commercial Buyer Actions
- Activate 4CP monitoring now: ERCOT summer peak intervals can shape next-year transmission charges. Do not wait for an emergency alert to test curtailment procedures.
- Review ancillary-service pass-throughs: Buyers on real-time or pass-through structures should know how ECRS, Non-Spin, RUC, and closer-to-real-time procurement flow into settlement language.
- Reconcile September 2 settlements: Market participants should identify affected meter mappings and preserve applicable statement-review or dispute deadlines before assigning a dollar impact.
- Pre-stage flexible load: Sites with refrigeration, pumping, manufacturing batch processes, batteries, or backup generation should define who can curtail, how fast, and under what commercial threshold.
- Separate reliability from procurement: ERCOT's summer market outlook says forward prices for summer 2026 were trending lower than the same time last year, so reserve activity should be read beside price curves, not in place of them.
Where This Fits In The ERCOT Cluster
Use this operating update as the live signal, then move into the ERCOT Summer 2026 pricing outlook for forward-market context, the ERCOT 4CP strategy guide for delivery-charge exposure, and the ERCOT large-load queue analysis for long-term planning pressure.
Sources: ERCOT Market Notice M-C072726-01, Discrepancy from 2026 Ancillary Services Methodology; ERCOT Market Notice M-A090826-01, Impacts to SCED due to Incorrect Meter Data; ERCOT June, August, and September 2026 public notices; ERCOT Summer 2026 resources; ERCOT 2026 Summer Weather and Operations Outlook; ERCOT 2026 Summer Markets Outlook. Reviewed September 9, 2026.