Moonwatt to deploy new class of sodium-ion battery energy storage system specifically developed for hybrid solar plants
Illustration: Moonwatt’s battery energy storage solution underneath PV panels on a solar plant
Moonwatt’s modular “string batteries” leverage sodium-ion cells housed in a passive-cooled, hermetically sealed and silent battery enclosure. The batteries are DC-coupled to solar panels via a shared hybrid inverter.
Engineered from the ground up, Moonwatt’s proprietary solution tackles the challenges of solar plant hybridization: reducing costs, simplifying O&M, improving performance, and scaling seamlessly from kilowatts to gigawatts.
Moonwatt will deploy its first project in 2026 at Cleantech Park Arnhem in the Netherlands, in partnership with IPKW and Veolia.
Recognizing the innovation and practical benefits of Moonwatt’s technology for advancing solar hybridization, the Dutch Business Agency (RVO) has awarded the company a €1.15M DEI+ grant to accelerate its development.
Amsterdam, Netherlands — January 28th 2026 — Solar deployments are booming, but stand-alone solar increasingly struggles with grid congestion and price cannibalization. The next generation of solar plants must natively integrate storage to deliver flexibility and resilience.
Moonwatt has conceived and engineered a Battery Energy Storage System (BESS) from the ground up, purpose-built for seamless solar hybridization. This proprietary solution is built to reduce costs, simplify operations, improve performance, and scale seamlessly from kilowatts to gigawatts. The system combines battery enclosures with hybrid string inverters, enabling efficient DC-coupled solar-plus-storage integration.
Moonwatt will deploy its flagship project in the Netherlands in 2026 at Cleantech Park Arnhem, in partnership with IPKW and Veolia.
Moonwatt has also has secured a €1.15 million DEI+ grant from the Dutch Business Agency, as a recognition of Moonwatt’s development work and of its technology’s innovativeness.
Illustration: Cleantech Park Arnhem located in the Netherlands
Moonwatt’s Edge
Driven by the conviction that solar-plus-storage plants will form the backbone of tomorrow’s power grids, Moonwatt has been dedicated since its inception in 2024 to developing, prototyping, and testing an innovative battery energy storage system purpose-built for solar hybridization. This differentiated product design is built on 4 pillars:
1 • Sodium-Ion Chemistry (NFPP)
Moonwatt’s BESS solution is based on sodium-ion NFPP chemistry, leveraging abundant raw materials such as sodium. Compared to lithium-ion, sodium-ion NFPP offers superior thermal stability and safety, reducing the risk of thermal runaway. It also demonstrates excellent degradation performance and strong resistance to cycling under both low and high ambient temperatures, ensuring long-term reliability and efficiency.
2 • Advanced Passive Cooling
Moonwatt has engineered an innovative ultra efficient thermal management system that requires no moving parts. This design ensures silent operation, minimal maintenance, and best-in-class IP protection against dust, water and air ingress. By removing complex HVAC systems, Moonwatt dramatically lowers O&M costs while improving reliability in harsh outdoor environments. The enhanced nature of the cooling system means that the system can run at very low or at very high temperatures for prolonged periods of time with minimal degradation.
3 • Distributed “String Battery” Architecture
Moonwatt’s modular architecture minimizes land use and can be installed anywhere, for instance directly beneath solar panels. The product’s lightweight design allows for quick deployment using a standard forklift and eliminates the need for foundations. This approach mirrors the scalability of solar string inverters, enabling projects to expand from kilowatts to gigawatts with ease; perfect for both solar plants new-builds and retrofits.
4 • DC-Coupled Design
Moonwatt integrates solar and storage through a single hybrid inverter, creating a fully DC-coupled architecture that removes the need for additional MV transformer. This reduces electrical balance-of-plant costs, increases efficiency by avoiding unnecessary AC/DC conversions, and enables charging from clipped solar energy; maximizing asset utilization and boosting revenues.
Overall, Moonwatt’s solution addresses the most pressing pain points of energy storage deployments: CAPEX and OPEX costs reduction, better roundtrip efficiency, improved fire safety, and reduced noise. The result: greater flexibility, lower costs, and accelerated solar adoption.
“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.”
Contact
Email: contact@moonwatt.com
Website: www.moonwatt.com
About Moonwatt:
Founded in 2024 and headquartered in Amsterdam, Moonwatt is developing the next generation of highly competitive Energy Storage Systems utilizing advanced sodium-ion battery technology. The company’s development work encompasses both the hardware and software components of its storage technology. Moonwatt’s products are uniquely dedicated to coupling with solar power plants. The company’s mission is to make affordable solar power dispatchable anytime, anywhere. Since its inception, Moonwatt has attracted a talented team of experts from the battery energy storage sector. Visit www.moonwatt.com to learn more.