Developer and operator GridStor, backed by Goldman Sachs, has announced it has secured financing for its White Tank BESS in Arizona, with $220 million agreed across a range of financial instruments.
The 100 MW / 400 MWh White Tank facility will be operated under a 20-year tolling agreement with the local utility, Arizona Public Service (APS), and is located in Maricopa County, where most of Phoenix is located. EcoStor said it is expected to be placed in service “in the first half of 2027.”
Arizona’s state utilities continue to break all-time records for power demand, with APS notching a peak electricity demand on August 2 that was 5% higher than the previous record set in 2025, driven by population growth, manufacturing, especially in chip fabs, and data center expansion. The White Tank battery storage project will reinforce APS’ system reliability.
In terms of financing, the company said its three banking partners on the deal, ING Capital, KeyBank N.A., and Zions Capital Markets, structured a $220 million tax equity bridge, construction, and term debt financing agreement. The financial close of the project marks GridStor’s fourth financing move within the past twelve months as it builds out or acquires more than 3 GW of BESS.
What they said:
“We are proud to work with three distinguished financial partners to complete the financing of the White Tank Reliability Project,” said Chris Taylor, CEO, GridStor. “Trusted partnerships like these are critical for advancing large-scale power supply and infrastructure to meet surging demand for new power capacity. We thank ING, KeyBanc Capital Markets, and Zions for placing their trust in us.”
“We are pleased to complete the financing of the White Tank battery energy storage project with GridStor,” said Filipe Barreto, Director, ING. “This transaction reflects ING’s confidence in the sector and our commitment to financing energy infrastructure that enhances grid reliability and supports the transition to a lower-carbon energy future. We look forward to building on this success with GridStor.”
“Battery storage has become an essential part of how utilities address growing load, reliability requirements and changing grid conditions,” said Greg Berman, Managing Director, Utilities, Power & Renewable Energy, KeyBanc Capital Markets. “We’re proud to have arranged this financing for GridStor’s White Tank project and support the development of infrastructure that can be deployed quickly and at scale to help address the nation’s evolving energy needs.”
“We are pleased to provide this strategic financing to support the continued growth of Arizona’s energy capacity,” said Robert Park, Head of Power and Project Finance, Zions. “This transaction underscores our Power and Project Finance team’s expertise in structuring tailored financial solutions in the power sector, and we are proud to have supported GridStor in this project transaction.”
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