The short version. On Saturday, Oct 31, 2026, three 138 kV transmission lines hit their limits at different times of day. West Hub real-time prices averaged about $36 per MWh above North Hub. The day-ahead market had expected about $9. ERCOT's prices show one line was limiting power flowing out of the Leon Switch area toward Putnam. That was an export limit, not an import shortage. No official has explained the day yet. Below: what the data shows, who it touched, whether more local solar or batteries would help, and what it means for shoppers. Our readings are labeled.
What happened on Oct 31
When a transmission line reaches its limit, prices differ from place to place. That is congestion. ERCOT's public constraint data (report NP6-86-CD) shows three binding 138 kV lines:
- Scurry Chevron–Knapp (Oncor, Scurry County) was binding about 23.9 hours.
- Leon Switch–Putnam was binding from 1:20 AM to 9:55 AM. ERCOT lists it as running from Leon Switch to Putnam. It sat at the report's $3,500 maximum shadow price from 5:25 AM to 9:10 AM. The day-ahead files we checked show the line only under a different contingency, at $26 per MWh or less.
- Temple Switch–Temple Southeast (Oncor, Bell County, in Central Texas) was binding from about 10:50 AM to 6:20 PM.
Together they make up about 89% of the day's total "shadow price × hours" score, which ranks how hard and how long a line was constrained. It is not dollars. Our estimate: real-time congestion rent was about $11.4 million, which shows scale, not a cost to any one party. West priced above North in every hour, by roughly $17 to $64 per MWh.
Which way the power flowed on Leon Switch–Putnam
ERCOT's bus-level prices (report NP6-787-CD) show the direction. From 6 to 9 AM, the Leon Switch 138 kV bus averaged about −$500 per MWh, while Putnam bus 4B averaged about +$1,800. A constrained line pushes prices down at its sending end and up at its receiving end. So power was being pushed from Leon toward Putnam.
Our reading: this was an export bottleneck out of the Leon and Eastland generation area, not an import shortage. Negative prices at Leon suggest supply there was held back. ERCOT's file puts the line's limit near 86 MW and shows it up to 4.8 MW over in 30 five-minute intervals. Leon Switch settles in the West load zone, but that zone price is an average, not Leon's own.
A household or small business in West Texas or DFW
Wholesale prices are not a bill. On a fixed-rate residential plan, your energy price per kWh stays the same for the contract term (wholesale prices vs. home bills).
Two of the three lines are Oncor lines. Oncor delivers power in Dallas–Fort Worth. In West Texas the delivery utility is Oncor or AEP Texas North, depending on the city (city guide).
ERCOT, the grid operator
ERCOT's notices from Oct 28 to 31 did not state a cause, and its transmission outage reports sit behind a login. After three earlier West price events, ERCOT's first public explanation came 31 to 42 days later, in its Monthly Operational Overview. The October overview is expected around Nov 16 to 19 (our inference).
Oncor and AEP Texas, the line owners
Oncor owns the Scurry and Temple lines. For Leon Switch–Putnam, an AEP Texas filing lists a "Putnam – Leon (ONCOR)" 138 kV line, about 20.8 miles, in Callahan and Eastland counties, rebuilt and energized in March 2023 (PUCT Control 56006, item 156). Our reading: AEP Texas North has the Putnam end, Oncor has the Leon end, and Leon Switch is in Eastland County. No document we found says so outright.
For Scurry, ERCOT recommended a $78.0 million Oncor project for a December 2028 in-service date (PUCT Project 55999, item 253). For Temple, ERCOT's Board reviewed a $272.6 million Oncor project, also expected in service December 2028 (Board item 10.2). We found no planned project for Leon Switch–Putnam.
Our reading: until the 2028 projects are done, the Scurry and Temple constraints can return when conditions resemble Oct 31.
PUCT and the market monitor
The Public Utility Commission of Texas (PUCT) sets state policy. ERCOT's independent market monitor, Potomac Economics, wrote in 2025:
"The West Zone is the largest contributor to intrazonal congestion costs because it is export constrained in the panhandle because of the abundance of renewables in the area and import constrained in the Permian Basin."
— Potomac Economics, 2025 State of the Market Report
We found nothing from the PUCT or the monitor about Oct 31.
Wind and solar generators
Wind came in about 2 GW below the day-ahead forecast on average, mostly in the West region. Against forecasts made about 65 minutes ahead, it was close (about 109 MW short).
Solar was near zero for most of the Leon–Putnam window. Across Texas, it produced under 1 MW until 7 AM and 36 MW from 7 to 8 AM. Of the line's 104 binding five-minute intervals, 80 came before 8 AM.
Our reading: low wind does not explain this line. A line that limits exports points to more supply behind it than it could carry out. We could not see what was generating at Leon.
Would more local solar or batteries help?
Our reading: batteries on the Putnam side could have helped overnight. New solar there would have helped only late in the event. New solar on the Leon side would have made it worse. Nothing in the queue would have been running on Oct 31.
- Side matters. Supply on the Putnam side cuts the flow. Supply on the Leon side adds to it. A battery charging on the Leon side would also help.
- Timing favors batteries. The line was binding about 8.6 hours, mostly before sunrise. A four-hour battery could cover about half.
- Connection point matters. Most queued projects connect at 345 kV, where our estimated effect on this line is near zero. We estimated effects from how prices at each substation moved with this line's shadow price, not from ERCOT's network model.
- Scale is unknown. We cannot say how many MW would have cleared the price.
ERCOT's October 2026 interconnection queue lists these proposed projects. All are early stage, with no interconnection agreement, and their dates can slip:
- Could help (our reading): Star Grass, 150 MW of solar with storage in Eastland County, connecting near Putnam, proposed for September 2029. Guitar BESS, a 205 MW battery in Callahan County, proposed for December 2027.
- Would work against relief on the Leon side: Damia, 306 MW of solar and 153 MW of storage in Eastland County, proposed for July 2028.
Of the helpful-side projects we checked, only Hamby Solar (206 MW, Jones County) has a signed agreement. Its effect on this line looks small.
Will the 765 kV lines fix this?
No published document says so. The 765 kV lines are Permian import paths due around 2029 to 2031, and Scurry County is on none of their county lists. The documented fixes for Scurry and Temple are Oncor's local rebuilds. For Leon–Putnam, unknown.
What it means if you shop for electricity
On a fixed-rate residential plan, your energy price per kWh holds for the contract term, so a day like Oct 31 does not change it. A fixed rate does not promise a lower bill, and your price can change when the term ends.
Shopping is simple. Compare fixed-rate plans for your ZIP code at powerhopper.energy. Hop to a better rate.
What we do not know
- The actual MW flow on Leon Switch–Putnam. ERCOT's flow data is not public.
- Why the contingency coded DLNCSWE5 bound, and why the day-ahead market missed it.
- What was generating at Leon.
- Leon Switch's county and who owns each end of the line. We read both from the AEP filing.
- How many MW of relief it would have taken to clear the price.
- Whether the December 2028 dates still hold.
Sources
- ERCOT public data: SCED shadow prices and binding constraints (NP6-86-CD), LMPs by electrical bus (NP6-787-CD), LMPs by resource node, zone and hub (NP6-788-CD), DAM shadow prices (NP4-191-CD), settlement points list (NP4-160-SG), wind forecasts (NP4-732-CD, NP4-742-CD) and solar production data, retrieved Nov 2, 2026.
- ERCOT, Generation Interconnection Status Report, October 2026 (product page: PG7-200-ER).
- AEP Texas (North Division), Construction Progress Report, PUCT Control 56006 item 156.
- ERCOT, Monthly Operational Overview, June 2023, plus the March 2024, February 2025 and December 2025 overviews used for timing.
- ERCOT Notice of Acceptance with Oncor Dermott Area 138-kV Line Upgrades, PUCT Project 55999, item 253.
- ERCOT Board, Item 10.2, Oncor Temple Area RPG Project.
- Potomac Economics, 2025 State of the Market Report for the ERCOT Electricity Markets.
- PUCT, Permian Basin Reliability Plan.
- ERCOT, Permian Basin Reliability Plan Study, July 2024 (mirror).
- Power Hopper, ERCOT hub and load-zone prices dataset (v2.0), DOI 10.5281/zenodo.23888997, CC BY 4.0. Estimates in this brief are Power Hopper's own.
- Power Hopper, Texas wholesale electricity prices and city guides.
Power Hopper is not affiliated with or endorsed by ERCOT, the PUCT, Oncor, AEP Texas or Potomac Economics. This brief was prepared with AI assistance. Reviewed by Brent Ward on November 2, 2026. Power Hopper is a PUCT-registered Texas electricity broker and earns a commission when a customer enrolls through us. That never decides what we cover or how.
BJW Ventures LLC d/b/a Power Hopper, PUCT Registered Electricity Broker BR260201