Finance
New wave of funding powers US battery tech and projects
XL Batteries has secured backing to commercialize flow battery systems which use an organic electrolyte, rather than vanadium, and two utility-scale developers have landed extensive credit lines.
By
Max Hall
Sep 19, 2025
Finance
Flow batteries
Grid-scale
Industry
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Flatiron's 200 MW/800 MWh Taft battery will be constructed at Uxbridge, Massachusetts. | Image: Imagery ©2025 Airbus, CNES / Airbus, Maxar Technologies, Map data ©2025/Google Maps.
The announcement of $7.5 million of funding for a Massachusetts company to scale its organic flow battery technology capped a 24-hour period this week which saw almost $900 million of European, US, and South African loans committed to US energy storage.
Marlborough-based XL Batteries on Wednesday said the $7.5 million secured from New York-based venture capital backer Merrin Investors will enable it to commercially scale its long-duration energy storage flow batteries.
With XL having recently constructed a pilot scale facility at Texan bulk liquid and gas storage business Stolthaven Terminals, and signing a strategic partnership for data center deployment with Prometheus Hyperscale, the company acknowledged the priorities of President Donald Trump’s US administration by saying its batteries reduce “reliance on foreign supply chains.”
XL Co-founder and Chief Executive Tom Sisto said, “This investment from Merrin Investors underscores that XL Batteries is built to thrive in today’s environment. Over the past several months, XL has hit several key milestones that prove our technology is effective. Now, with Merrin’s support, we are bringing the next generation of safe, cost-effective, long-duration batteries to market at a pace to meet growing demand.”
That investment came a day after Boston-based Nexamp, Inc. and Colorado-headquartered Flatiron Energy revealed new borrowing.
Flatiron has secured $540 million finance from a consortium of lenders for its planned 200 MW/800 MWh Taft battery energy storage system in Uxbridge, Massachusetts. The project, due online in “late 2026,” will support the Independent System Operator New England grid in the east of the commonwealth. The battery will be named after Lydia Chapin Taft, America’s first woman voter, who cast her groundbreaking ballot in Uxbridge in 1756.
The providers of construction and bridge loans to Flatiron, as well as letter-of-credit facilities, included North Carolina-based First Citizens Bank, German federal state-backed lender Norddeutsche Landesbank Girozentrale, French bank Societe Generale, Spanish group Santander, and Anglo-South African business Investec.
“We are pleased to support Flatiron Energy in delivering a project that enhances grid reliability and benefits communities across eastern Massachusetts,” said Mike Lorusso, group head of energy finance at First Citizens Bank.
Other, unnamed investors provided term loans and preferred equity and tax credit transfer commitments as part of the $540 million package.
Commercial and industrial solar developer Nexamp has landed a $350 million commitment from Australian lender Macquarie Asset Management to branch out into utility-scale solar and energy storage projects.
“Given rising electricity demand and the need for reliable, low-cost, and homegrown power, we are seeing significant need for utility-scale solar and battery [energy] storage projects,” said Matthew Sweeney, managing director at Macquarie Asset Management. He added, “By enabling Nexamp to advance its 6 GW utility-scale pipeline, this transaction positions the company to capitalize on the growing market demand and deliver sustainable, clean energy solutions at scale.
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