A battery storage facility rising in Hidalgo County, Texas has secured a $58 million tax equity investment. The deal between tax equity investor Foss & Company and battery developer GridStor supports the Gunnar Reliability Project, a battery storage system that's expected to come online later this year.
A Capital Stack Years in the Making
According to IndexBox, Foss & Company finalized a partnership flip structure to help fund the utility-scale battery system, which GridStor is constructing in Hidalgo County. The tax equity transaction utilizes Section 48 Investment Tax Credits, expanded under the 2022 Inflation Reduction Act, which provide a 6% base credit that can increase to 30% when projects meet prevailing-wage and apprenticeship standards, according to Eide Bailly. That equity piece follows a $120 million debt package GridStor closed in March, funded by lending partners NORD/LB and Siemens Financial Services, per GridStor's own announcement of the financing agreement.
Once operational, the Hidalgo County facility is expected to supply power equivalent to serving 95,000 average Texas households during peak demand hours.
Second Deal Between Foss and GridStor
GridStor's 220-megawatt Hidden Lakes Reliability Project in Galveston County was completed in late 2025. Bryen Alperin, partner and managing director at Foss & Company, said the Hidalgo County deal highlights the firm's confidence in utility-scale battery storage, per IndexBox's reporting, and that grid operators increasingly depend on storage to balance supply and demand. Foss & Company plans to expand its pipeline with GridStor in the coming years, the outlet reports.
Spencer Mash, SVP of finance and head of capital markets at GridStor, expressed satisfaction with completing the financing alongside Foss, saying the transaction reflects the maturation of the battery storage sector and growing confidence among financing partners. The deal adds another utility-scale battery storage asset to Foss & Company's renewable energy tax equity portfolio. Founded in 1983, Foss & Company has allocated more than $11 billion in tax equity for corporate clients and invests across historic rehabilitation, renewable energy, and advanced energy production.
GridStor's South Texas Expansion
GridStor, founded in 2022 and headquartered in Portland, Oregon, is capitalized by a fund managed by Goldman Sachs Asset Management, according to KeyBanc Capital Markets. The company builds and operates battery projects it says are intended to enhance the reliability of America's power system, developing, acquiring, building, and operating utility-scale standalone storage primarily across North America.
GridStor's growth hasn't been without friction elsewhere. Hoodline previously reported on suburban opposition in Liberty, Missouri, where residents are fighting a proposed 200-megawatt GridStor facility near the Tapp Farms subdivision. GridStor's 220-megawatt Hidden Lakes project in Texas was completed in late 2025.
