A 110 MWac solar project in Hill County, Texas, has reached substantial completion and received approval to connect to the state’s power grid, marking the final stage of construction for Mitsui’s first utility-scale solar project in the United States.
The Three W Solar project, located near Hillsboro on approximately 875 acres, has completed construction and the required Electric Reliability Council of Texas (ERCOT) approvals, according to Black & Veatch, which served as the engineering, procurement and construction contractor. The facility has a nameplate capacity of 150 MWdc, or 110 MWac, and is designed to generate enough electricity to serve as many as 45,000 homes.
The ERCOT approval allows the facility to connect to the Texas grid and clears the way for final turnover to Mitsui’s operations and maintenance organization. Black & Veatch said construction activities included installation of the solar racking piles, a generator step-up transformer and the project’s collector substation infrastructure, followed by commissioning.
Project changed hands before construction
Mitsui did not originally develop Three W Solar. OCI Solar Power developed the site for roughly two years before selling the 110 MWac project to Mitsui in April 2023.
When OCI announced the sale, it said the project had reached the construction-ready stage, with work expected to begin in 2024 and operations targeted for 2025. The project covers 875 acres near Hillsboro, south of Dallas.
Mitsui then advanced the project as part of its expansion into U.S. renewable generation. In 2024, the company said the Hill County solar plant formed part of its broader effort to build an integrated power business in Texas.
Mitsui plans to sell the project’s electricity in the wholesale market and to industrial customers through its U.S. energy-marketing subsidiary.
Construction progressed into 2026
Independent project tracking shows Three W Solar remained under construction in early 2026, with Mitsui identified as the project’s owner. The facility is located in Hill County and has a reported 110 MWac capacity.
The project’s final construction phase focused on completing generation equipment and electrical infrastructure before the ERCOT approval required for grid connection.
The project also has a documented ERCOT interconnection, reflecting the infrastructure needed to bring its output onto the Texas transmission system.
Three W Solar’s completion comes as solar generation continues to expand across the ERCOT market. The facility is smaller than several of the large solar plants recently brought online in Texas, but its completion adds another utility-scale generating resource to the state’s rapidly expanding electricity system.
For Mitsui, the project also represents a shift from development and investment into operating renewable generation. The company now has the project positioned for turnover to its operations and maintenance organization following the completion of construction and grid-connection requirements.
Black & Veatch said its work on Three W Solar began in 2024 and included the project’s engineering, procurement and construction scope, as well as the associated collector substation. The contractor has now completed its delivery role as Mitsui moves the facility toward operation.
U.S. Solar Expansion Gains Momentum
Three W Solar adds another utility-scale renewable project to a U.S. solar market where developers continue to advance large projects toward operation. In Utah, the Utah Solar 1 Energy project recently reached financial close, clearing the way for full construction of its planned 300 MWac solar facility in Millard County.
The two projects also rely on long-term power supply agreements. EDF power solutions North America is developing Utah Solar 1 under a 30-year agreement with the Southern California Public Power Authority, which will supply the project’s electricity to Los Angeles Department of Water and Power customers. The project is expected to begin delivering power in 2027.
Factsheet: Project: Three W Solar
- Location: Hill County, near Hillsboro, Texas
- Site: Approximately 875 acres
- Capacity: 150 MWdc / 110 MWac
- Owner: Mitsui & Co.
- Original developer: OCI Solar Power
- EPC contractor: Black & Veatch
- Grid: ERCOT
- Latest milestone: Substantial completion and ERCOT approval for grid connection
- Construction period: Began advancing toward construction in 2024
- Operations: Final turnover to Mitsui’s operations and maintenance organization
Leave a Reply