Flagtail BESS
203.8 MW storage in Grimes, TX · In queue since April 2021 · Proposed COD July 2026
203.8 MW
Capacity
1
Components
Battery
5y 1m
In Queue
Facility Study
IA Status
COD target: 2026
Total Duration
5y 3m
Interconnection request submitted to ISO/RTO
ERCOT uses a serial "connect and manage" approach — fastest among major ISOs.
Typical: 18–30 months (fastest major ISO)
Interconnection agreement not yet executed
Typical: 30–60 days (negotiation)
Proposed COD: 2026-07-01
The Flagtail BESS project is a proposed 203.8 MW battery storage project located in Grimes County, Texas. Developed by Flagtail LLC, the project entered the ERCOT interconnection queue as entry ERCOT-22INR0515 on April 5, 2021. The proposed commercial operation date is July 1, 2026, and the project's interconnection status is currently in the Facility Study phase.
The project consists entirely of battery storage, with a total capacity of 203.8 MW. The point of interconnection is Tap 138kV 5 Sandy Switch - 7 Sandy. The project is listed as active in the ERCOT interconnection queue.
Generated from interconnection queue and public data sources
State
TX
County
Grimes
Grid Region
ERCOT (Texas)
Market
ISO/RTO Member
Developer
Flagtail LLC
Utility
—
Entity
ERCOT
Service Type
—
Point of Interconnection
Tap 138kV 5 Sandy Switch - 7 Sandy
Data Source
LBNL
- ISO / RTO
- ERCOT
- Trading Hub
- HB_NORTH
- Hub Confidence
- LOW
This project's market context is estimated from its Point of Interconnection. Hub and node assignments are approximate and based on geographic inference from the POI substation name.
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