Moonwatt has introduced a sodium‑ion‑based battery system designed specifically for hybrid solar projects, offering it as a lower‑cost, safer alternative to conventional lithium‑ion storage.
The company’s modular “string battery” units use passive cooling within a silent, hermetically sealed enclosure and connect directly to solar arrays via a shared hybrid inverter.
The technology is engineered to simplify hybrid plant design by reducing balance‑of‑plant requirements, cutting O&M costs and improving efficiency through full DC‑coupling. Moonwatt says the architecture scales from kilowatt‑level systems to multi‑gigawatt deployments and can be installed beneath solar panels without foundations.
The Dutch Business Agency (RVO) has awarded Moonwatt a €1.15 million DEI+ grant in recognition of the system’s innovation and its potential to support large‑scale solar‑plus‑storage adoption. The company will deploy its first project in 2026 at Cleantech Park Arnhem, Netherlands, in partnership with IPKW and Veolia.
Moonwatt’s design is built around four pillars: sodium‑ion NFPP chemistry for improved thermal stability, safety and resistance to degradation; a passive cooling system with no moving parts and robust protection against dust, water and air ingress; a distributed “string battery” layout for flexible siting; and a DC‑coupled configuration that removes the need for an additional MV transformer to cut balance‑of‑plant costs and boost efficiency by avoiding unnecessary AC/DC conversions.
CTO Guillaume Mancini said: “At the inception of Moonwatt, sodium-ion technology gave us the freedom to design a fundamentally different product: passively cooled, distributed, safer, and more efficient. We are excited to deploy this innovation which we believe will transform the battery energy storage sector status-quo, just as solar string inverters replaced solar central inverters in many applications. We view this new approach as a way to keep on reducing the cost of firm solar power.”
Image: Moonwatt’s battery energy storage solution underneath PV panels on a solar plant. Credit: Moonwatt
