Iron-Sodium Grid-Scale Batteries Pass Factory Acceptance Test: Field Deployment is Next in 2026 Followed by U.S. Manufacturing: Longer Duration Storage is a Main Goal

     Company Inlyte Energy announced that it successfully completed a factory acceptance test at its facility near Derby, U.K., validating its grid-scale iron-sodium batteries. The testing was observed by representatives of the Southern Company, which plans to install the batteries at a test site in Wilsonville, Alabama, in early 2026.

     Iron-sodium batteries are a viable alternative to lithium-ion batteries. They are among several non-lithium battery chemistries being explored to solve some of the shortcomings of lithium-ion batteries. Both sodium and iron are abundant and inexpensive, which gives these batteries an advantage. They can provide a chemical source with very little volatility, compared to lithium, nickel, and cobalt, and they do not have the safety risks inherent in flammable liquid electrolytes. The biggest advantage of iron-sodium batteries over lithium-ion batteries is duration. Iron-sodium batteries can provide multi-hour or multi-day storage compared to lithium’s one to four hours, and occasionally to six hours. Iron-sodium batteries have a solid electrolyte and operate at elevated temperatures.

     Inlyte’s validation of the technology during the factory acceptance test revealed that the batteries are ready for deployment. According to Battery Technology, the round-trip efficiency is comparable to lithium-ion and much better than the average for other long-duration storage methods.

“According to the company, the integrated systems (cells, inverter, and controls) achieved 83% round-trip efficiency, including auxiliaries, competitive with high-performance lithium-ion and notably above the 40–70% typical for other LDES approaches. Inlyte claims that the tested system represents the world's largest sodium metal chloride battery cells and modules ever constructed, capable of storing over 300 kilowatt-hours of energy each.”

     Iron-sodium batteries will likely be used mostly for longer duration storage and thus be more complementary to shorter duration lithium-ion batteries, which will continue to be heavily utilized at grid-scale. There is a clear need for more long-duration energy storage (LDES) on power grids to provide reliability and to better integrate intermittent renewables, decreasing curtailment losses. Decarbonization scenarios will require more LDES to meet trajectories. The batteries are also expected to have significantly longer lifespans than lithium batteries.  

     Earlier this year, the company entered an agreement (an MOU) with HORIEN Salt Battery Solutions (formerly FZSoNick), the world's most established manufacturer of sodium metal chloride (SMC) batteries, to aid in developing a factory in the U.S. This collaboration will speed up bringing the batteries to market, which is expected to happen in 2027. Inlyte Factory 1, scheduled to come online by 2027, will be the first.

"HORIEN has led the way in demonstrating the safety, reliability, and performance of SMC battery technology, and now, with Inlyte, we see a pathway to accelerate adoption of the technology into the global energy storage market," said Giovanni Zola, CEO of HORIEN.

     Currently, Inlyte is finalizing site selection for the manufacturing facility in the U.S. Once the site is developed, batteries are expected to be commercially available, beginning in 2027.

  

  

References:

 

Grid-scale iron-sodium battery energy storage system reaches field-ready milestone in US. Bojan Stojkovski. Interesting Engineering. December 13, 2025. Grid-scale iron-sodium battery energy storage system reaches field-ready milestone in US

Inlyte Energy Completes Factory Acceptance Test of First Full-Scale Iron-Sodium Battery Storage System. Inlyte Energy. Press Release. December 11,2025. Inlyte Energy Completes Factory Acceptance Test of First Full-Scale Iron-Sodium Battery Storage System

Iron-sodium EV battery challenges Tesla Megapack, offers 7,000 cycles 20-year-life: Testing results, spanning over a year, project a battery life of at least 7,000 cycles or 20 years. Bojan Stojkovski. Interesting Engineering. March 30, 2025. Iron-sodium EV battery challenges Tesla Megapack, offers long-term use

Could Iron–Sodium Batteries Replace Lithium Ion? Iron–sodium batteries gain momentum for long duration storage; Inlyte Energy milestone shows potential to enhance grid reliability and resilience. Battery Technology. December 12, 2025. Could Iron–Sodium Batteries Replace Lithium Ion?

Inlyte Energy and HORIEN Announce Strategic Partnership to Scale Iron-Sodium Battery Manufacturing in the United States. Inlyte Energy. Press Release. March 27, 2025. Inlyte Energy and HORIEN Announce Strategic Partnership to Scale Iron-Sodium Battery Manufacturing in the United States

Inlyte Energy. Website. Inlyte Energy – Reliable grid batteries made from naturally abundant and inexpensive raw materials.