US sees first Gigawatt-scale Energy Storage System (ESS) agreement sealed by SK On

South Korean battery-maker SK On has secured its first large-scale energy storage system (ESS) order in the United States, marking a full-fledged entry into the North American market. The energy storage system order was signed with Flatiron, a renewable energy developer headquartered in Colorado.

The deal, worth a gigawatt-hour of container-type ESS units equipped with lithium iron phosphate (LFP) batteries, will see SK On provide products for a project in Massachusetts. Deliveries are scheduled to begin in the second half of 2026.

The ESS battery products from SK On feature a high-voltage module-based design, allowing flexible capacity expansion. This technology secures additional safety through a mechanism that blocks heat diffusion to adjacent modules and a diagnostic system based on electrochemical impedance spectroscopy.

Choi Dae-jin, head of ESS business at SK On, stated that the agreement expands both battery chemistry and business portfolio. "We are excited to partner with Flatiron on this project and to continue our efforts in the US market," he said.

Jonathan Poor, Chief Operating Officer (COO) and co-founder of Flatiron, expressed his excitement about the partnership. "We are thrilled to continue our partnership with SK On on multiple upcoming projects," he said.

SK On plans to convert part of SK Battery America's Georgia plant into an ESS-dedicated production line for LFP batteries starting in the second half of 2026. This move aims to establish a local supply system to meet customer demand.

The contract grants SK On the right of first offer on Flatiron's additional ESS projects totaling 6.2 GWh by 2030. However, the agreement does not mention any specific additional GWh capacity for ESS projects by 2030 or any new large-scale project outside of the one in Massachusetts.

The potential expansion of the supply to 7.2 GWh through further negotiations is possible. SK On is using LFP cells to enhance price competitiveness and stability in the US market.

The partnership between SK On and Flatiron is significant as it expands the battery chemistry and business portfolio of both companies. SK On is planning to continue strengthening its position in the North American ESS market based on local production and advanced technology.

This first large-scale project in the US is a significant step for SK On as it seeks to expand its global footprint. The company is committed to providing innovative and safe energy storage solutions to meet the growing demand for renewable energy storage.