US-based startup BEESt has launched a new redox flow battery technology that reportedly achieves 20 times higher energy density than conventional vandium redox flow energy storage systems.
“Our battery is well-suited for solar and other renewable projects because it provides extended-duration storage without degradation, enabling round-the-clock reliability,” the company’s CEO, Joley Michaelson, told pv magazine. “That makes it effective for both hybrid renewable systems and standalone stationary storage. Its compact footprint also makes it easier to deploy alongside solar where space is limited.”
“Our initial focus will be the commercial and industrial market, especially government, critical infrastructure, and industrial users who require absolute energy reliability and safety. We will follow with a residential launch in early 2028,” he added.
The system’s key innovations include an electrolyte made with zinc–polyiodide (ZnI₂), developed by the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL), and a “patent-pending” cell stack based on unspecified “earth-abundant” alloy materials sourced in the United States.
The residential system is planned to have a power rating of 20 kW, a storage capacity of 25 kWh, and a average use of 5 h. The device for commercial and industrial use has a power rating of 40 kW, a storage capacity of 100 kWh, and a average use of 6.5 h.
As for the largest system, conceived for industrial and utility-scale project, is expected to have a power rating of 200 kW to 2.4 MW, a storage capacity of 400 kWh to 1,600 kWh, and an average “multi-day” use.
All systems feature an energy density of 320 Wh/L, a roundtrip efficiency of up to 80%, and a 100% depth of discharge (DoD). Power and energy components are physically separated to enable modular designs and easy expansion.
The system is backed by a 30-year warranty, with the electrolyte being guaranteed for 20 years.
“Our zinc–polyiodide redox flow battery is built as infrastructure. It delivers a 20–30 year lifespan with stable capacity and scalability, which lowers the levelized cost of storage (LCOS) and adds enterprise value by reducing energy costs for subsequent owners,” said Michaelson. “DOE’s Long Duration Storage Shot sets a target of $0.05 per kWh LCOS by 2030. Analysis shows zinc–polyiodide systems are on track to meet or approach this threshold, reinforcing their role as infrastructure-grade assets.”
The batteries will be manufactured in the United States through contract partners, with multiple production sites planned nationwide. BEESt said the design uses widely available components to simplify manufacturing and scale efficiently, while the compact form factor reduces siting challenges and installation costs.
“Redox flow storage is much easier to site than lithium,” noted Chief Science Officer, Kevin Meagher. “Our zinc–polyiodide chemistry delivers more than ten times the energy density of conventional flow systems, which means smaller tanks and a compact footprint. It’s non-toxic, non-flammable, and doesn’t require the costly environmental controls that other storage technologies depend on.”
“Our focus is mission-critical infrastructure—data centers, cold storage, healthcare, and government operations—where downtime is not an option,” Michaelson concluded. “These facilities need storage that lasts well beyond lithium’s four-hour limit. With a U.S.-made, OBBBA-compliant platform and an any-duration design ranging from 5 hours to multi-day, we’re delivering reliability that qualifies for incentives, lowers lifetime cost, and makes projects bankable at scale.”
