The White Tank battery energy storage project in Maricopa County, Arizona, is moving toward construction after GridStor closed a $220 million financing package for the 100-megawatt facility.
The financing announced September 21 combines a tax-equity bridge, construction financing and term debt. ING Capital, KeyBanc Capital Markets and Zions Capital Markets provided the financing for the project, which is scheduled to begin commercial operations in the first half of 2027.
White Tank will provide 100 MW of power and store 400 megawatt-hours (MWh) of electricity. Arizona Public Service (APS) will control when the system charges and discharges under a 20-year tolling agreement.
The project is planned on a nine-acre site immediately east of APS’ Colter substation near Avondale. The site sits within a larger property of more than 50 acres and will contain battery enclosures, substations and related electrical infrastructure. GridStor says the project was deliberately located next to existing electric infrastructure to support the surrounding area.
Construction set to begin in October
The financing arrives just ahead of the project’s planned construction start.
Canadian Solar’s e-STORAGE signed a battery supply and long-term service agreement for White Tank in March 2025 and said construction was scheduled to begin in October 2026. The company will supply its SolBank 3.0 battery technology and about 120 battery enclosures for the facility.
The project therefore has moved through development, utility contracting and equipment procurement before reaching the latest financing milestone.
Strata Clean Energy originally developed White Tank before GridStor acquired the project in September 2025. Strata had secured the 20-year APS tolling agreement in November 2024 after White Tank was selected through an APS procurement seeking 700 MW of clean-energy resources.
GridStor took over the project with the planned commercial operation date still set for the first half of 2027. Strata is continuing to provide consulting support through the transition to commercial operations.
Project designed around existing grid infrastructure
White Tank’s location is closely tied to its electrical connection.
Maricopa County planning documents identify the project as a battery energy storage system on nine acres near the northeast corner of Indian School Road and El Mirage Road. The project site is immediately east of the APS substation that provides its planned point of interconnection.
The county approved a zoning change for the project, while GridStor says it is working with Maricopa County and Rural Metro Fire on facility design, construction planning and emergency-response preparation.
Construction traffic will use West Indian School Road, with traffic controls planned during the construction period. GridStor estimates the project could create about 50 full-time construction jobs.
The physical facility will operate differently from a conventional power plant. White Tank will not generate electricity. Instead, it will store electricity and return it to the grid when APS requires additional capacity.
At its full 100-MW output, the four-hour system can discharge 400 MWh before it needs to recharge.
Arizona demand raises need for storage
The project is advancing as APS deals with record electricity demand across its service territory.
APS reached a new peak demand of 9,164 MW on August 2, exceeding the previous record of 9,053 MW set on July 24. GridStor said the White Tank project will help APS manage rising demand and maintain reliability as Arizona’s population and industrial activity grow.
The timing also reflects the growing role of battery storage in Arizona’s power system. Solar generation can provide substantial electricity during the middle of the day, while demand can remain elevated into the evening after solar output begins to fall.
A four-hour battery can shift stored electricity into that higher-demand period without requiring a new conventional generation plant at the project site.
$220M financing brings project closer to construction
The latest financing is significant because it provides capital for the project’s remaining development and construction work rather than simply marking an earlier development agreement.
GridStor now expects White Tank to move into construction in October, with commercial operations targeted for the first half of 2027.
The company acquired the project from Strata as part of its expansion in utility-scale battery storage. GridStor says its later-stage development and construction pipeline now exceeds 3 GW across the western and central United States.
For White Tank, the immediate focus is construction of the battery system and associated electrical infrastructure, followed by testing and commissioning before the facility enters APS’ system.
The project will add 100 MW of dispatchable battery capacity to an Arizona grid that is experiencing increasingly high peak demand, while its four-hour duration will allow APS to shift up to 400 MWh of stored electricity into periods when the system needs it most.
The need for dependable power is also becoming a major consideration for large data center campuses. In Fort Wayne, Indiana, Google is seeking approval for 228 additional backup generators at its data center, adding another layer of power resilience as the facility expands.
White Tank project factsheet
- Project: White Tank Reliability Project
- Location: Maricopa County, near Avondale, Arizona
- Sector: Battery energy storage
- Developer and operator: GridStor
- Original developer: Strata Clean Energy
- Power capacity: 100 MW
- Energy capacity: 400 MWh AC
- Battery system: Canadian Solar’s e-STORAGE SolBank 3.0
- Battery enclosures: Approximately 120
- Project site: Approximately 9 acres
- Property: More than 50 acres
- Point of interconnection: APS Colter substation
- Utility: Arizona Public Service
- Operating agreement: 20-year tolling agreement
- Financing: $220 million
- Financing structure: Tax-equity bridge, construction financing and term debt
- Financing partners: ING Capital, KeyBanc Capital Markets and Zions Capital Markets
- Planned construction start: October 2026
- Expected commercial operation: First half of 2027
- Estimated construction jobs: About 50
- Total project cost: Not disclosed
- September 21, 2026 milestone: $220 million financing close
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