South Korean company SK On has entered the US battery energy storage system (BESS) market with lithium iron phosphate (LFP) batteries, securing a BESS supply contract with Flatiron Energy Development.
The agreement sees SK On supplying up to 7.2GWh of BESS for energy storage developer Flatiron’s projects in New England and elsewhere through 2030.
SK On will initiate the supply of containerised BESS units, equipped with 1GWh of LFP batteries, for a project in Massachusetts, with shipments starting in the second half of 2026.
The company will start mass-producing LFP batteries for BESS by utilising part of its electric vehicle (EV) battery manufacturing lines at SK Battery America (SKBA), its wholly-owned subsidiary in Commerce, Georgia.
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SK On plans to develop LFP battery manufacturing by upgrading existing production lines, supporting its localisation initiatives.
At that time, the company also noted its plans to expand its US battery plants. SK On was operating two battery plants in the US and intends to build four more with its partners.
It states that its BESS will have a modular design for flexible and scalable solutions, complemented by advanced safety features like heat propagation prevention and electrochemical impedance spectroscopy (EIS)-based diagnostics to ensure reliable operation.
In a recent webinar hosted by Energy-Storage.news with Clean Energy Associates, Daniel Finn-Foley and Christian Roselund from CEA’s Market Intelligence Team mentioned that new rules put in place following the passing of the US budget reconciliation bill, HR1, are likely to make Korean battery manufacturers the leading suppliers in the US BESS market.
This is because new foreign entity of concern (FECO) restrictions cut off energy storage project developers and equipment manufacturers from receiving tax credit incentives if more than a certain proportion of material assistance, including materials, components, investment and services, comes from Chinese companies.
With battery cells currently comprising the biggest share of energy storage system costs, the prospects for using Chinese-made battery cells, as most projects currently do, are limited. At the same time, US-China tariffs present further uncertainties for the procurement of cells from the world’s biggest lithium-ion battery-producing country.
Founded in 2021, Flatiron specialises in developing utility-scale BESS projects. It oversees the full value chain, from design through construction to long-term operations across North America.
