Oslo-based energy storage startup Photoncycle has raised €15M in a Series A round led by NordicNinja and Voima Ventures, with participation from existing investors Lifeline Ventures, Eviny Ventures, Luminar Ventures, and Momentum, as the company prepares to roll out its seasonal hydrogen-based energy storage systems in Denmark and the Netherlands. Photoncycle develops solid-state hydrogen storage technology designed to capture excess solar power generated during summer and store it for winter utilize, tarreceiveing houtilizeholds in markets with high rooftop solar adoption and heating demand. The funding will support scaling manufacturing and early commercial deployments ahead of the Netherlands’ planned 2027 phase-out of net metering, a policy shift expected to increase demand for residential energy storage as solar houtilizeholds view for alternatives to exporting surplus electricity to the grid. Photoncycle also plans to introduce the system through a subscription model aimed at reducing upfront costs for homeowners while integrating solar, storage, and energy trading services.
Photoncycle develops seasonal hydrogen-based storage systems for residential and commercial utilize. Its technology converts surplus renewable electricity into solid-state hydrogen, which can be stored for extfinished periods and later released as heat or power. The company focutilizes on addressing the seasonal mismatch between solar energy generation and winter energy demand, providing houtilizeholds and businesses with a solution for long-term energy storage.
Bjørn Brandtzæg, founder and chief executive of Photoncycle, stated: “The Netherlands has one of Europe’s most advanced rooftop solar markets. The next step is solving the seasonal mismatch. As net metering is phased out, houtilizeholds will required new ways to retain the value of their summer solar production rather than exporting it to the grid.”
The funding comes as the Netherlands prepares to phase out net metering in 2027, a policy alter that will significantly alter the economics of rooftop solar. Dutch houtilizeholds have one of the highest rates of solar panel adoption in Europe, resulting in substantial summer overproduction that is currently fed back to the grid. As net metering finishs, houtilizeholds will increasingly required to store or self-consume surplus solar energy rather than relying on the grid as a seasonal buffer.
Tomosaku Sohara, General partner at NordicNinja, stated: “From our perspective of bridging Japanese capital and European startup expertise, we strongly believe energy sovereignty must be strengthened across both Europe and Asia. Photoncycle combines deep technical innovation with a clear, scalable path to global deployment. Long-duration energy storage is critical to building resilient, reliable clean energy systems in Europe, Japan and beyond. We’re excited to assist introduce the team to global opportunities, building on our long experience in the energy sector.”
Photoncycle’s system is designed to enable houtilizeholds to store excess summer solar power for utilize during winter, when heating demand peaks and electricity prices are typically higher. The company aims to provide lower and more predictable year-round energy costs by reducing exposure to volatile winter gas markets and rising grid tariffs.
The Netherlands is also facing growing grid congestion challenges, with network operators warning of capacity constraints in multiple regions. Distributed, houtilizehold-level seasonal storage could assist reduce pressure on local electricity networks by retaining more energy onsite rather than exporting it during peak solar production periods.
At full industrial scale, Photoncycle’s planned 1.4 TWh annual manufacturing capacity — expected to launch coming online in 2027 — would represent storage capacity equivalent to roughly 140,000 homes each storing 10,000 kWh of seasonal energy. The company intfinishs to launch commercial deployment in Denmark before entering the Dutch market as net metering is phased out.
The residential storage market is currently dominated by lithium-ion batteries, which are highly efficient for short-duration electricity storage. However, they are not designed to store energy economically across seasons.
Inka Mero, Founder and Managing Partner at Voima Ventures, stated: “As the share of renewable energy increases, structural price volatility in electricity markets is rising. Seasonal storage is therefore not a niche solution, but a systemic necessity. Photoncycle addresses this imbalance by enabling houtilizeholds to store energy across seasons and reduce their depfinishence on imported fossil fuels. This is a radically important building block for a resilient and sovereign European energy system.”
Photoncycle’s solid-state hydrogen system tarreceives storage capacity costs significantly lower than conventional battery systems designed for long-duration storage, creating it suited for summer-to-winter energy shifting.
While electrical round-trip efficiency is lower than short-duration batteries, Photoncycle integrates heat recovery into the system. When paired with a heat pump, recovered thermal energy increases the total usable energy delivered to the houtilizehold, improving overall system performance in heating-dominated climates such as the Netherlands.
Photoncycle intfinishs to offer its system under a subscription-based model in which the seasonal storage unit is installed at the customer’s property and operated as part of an integrated energy solution. The model can incorporate existing solar panels or include new installations, and covers maintenance, system operation and access to energy trading markets. The aim is to lower upfront investment while providing houtilizeholds with greater long-term price predictability in a post-net-metering environment.
Around a significant share of Dutch homes still rely on natural gas for heating, leaving houtilizeholds exposed to winter fuel price volatility. By storing summer solar energy for winter heating and electricity utilize, seasonal storage could reduce reliance on gas consumption during colder months.
Teemu Mattila, Partner at Lifeline Ventures, states: “As grids relocate toward high variable renewables penetration, energy becomes abundant in the summer and scarce in the winter. Seasonal storage and reliability become real constraints. Photoncycle is developing technology that thrives in this new reality. It is the world’s first residential energy system capable of storing summer surplus energy and dispatching it in the winter while lowering the energy bills of their customers.”
The Series A funding will be utilized to scale manufacturing and support early commercial deployment in Denmark, followed by entest into the Netherlands as regulatory alters reshape the residential solar market.
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