What if you were able to store the summer energy for heating during winter? Well, now you can. We are proud to announce our latest investment that makes this possible: Photoncycle.
Photoncycle is a Norwegian energy storage scaleup that tackle one of Europe’s most persistent renewable energy challenges: enabling households to store surplus summer solar power for winter heating and electricity. 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.
To further accelerathe the growth, Photoncycle have raised €15M led by Voima Ventures and NordicNinja, with participation from existing investors Lifeline Ventures, Eviny Ventures, Luminar Ventures, and Momentum. The funds will support commercial rollout in Denmark and the Netherlands and finance the first phase of an industrialisation plan that includes a proposed 1.4 terawatt-hour annual manufacturing facility.
The investment comes as Europe continues to grapple with the structural vulnerabilities exposed by the 2022 energy crisis. The EU imported €396bn of fossil fuels in 2025, around €880 per citizen, underscoring the bloc’s continued dependence on external supply even as renewable generation expands. Winter exposure remains particularly acute: space heating accounts for 62.5 per cent of household energy use, while natural gas remains a significant component of residential consumption, leaving households sensitive to seasonal price swings in global gas markets.
At full industrial scale, Photoncycle’s proposed 1.4 TWh manufacturing facility would represent storage capacity equivalent to roughly 140,000 homes each storing 10,000 kWh of seasonal energy. Photoncycle’s distributed, household-level seasonal storage is designed to reduce the volume of imported gas required to meet winter heating and electricity demand, and consequently reduce Europe’s reliance on importing fossil fuels in the winter.
Designed for seasonal storage
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.
Photoncycle’s solid-state hydrogen system targets storage capacity costs significantly lower than conventional battery systems designed for long-duration storage, making 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 household, improving overall system performance in heating-dominated climates such as the Netherlands.
Subscription model to lower and more predictable energy bills
Photoncycle intends to offer the system under a subscription model that includes rooftop solar panels, 10,000 kWh of seasonal energy storage, and full servicing. Photoncycle’s system increases household energy independence and improves cost predictability for heating and electricity. By reducing reliance on grid electricity during high-price periods and lowering exposure to grid tariffs, the system is designed to reduce total energy costs by 30 percent on average.
Photoncycle has already seen strong interest from households seeking alternatives to gas-based heating. In Denmark, where Photoncycle has a rapidly growing list of pre-orders, energy prices are among the highest in Europe and 300,000 homes still depend on gas-based heating systems that are set to be phased out by 2035.
Bjørn Brandtzæg, founder and chief executive of Photoncycle, said the company was focused on moving seasonal energy resilience closer to consumers. “Europe is beginning to solve short-duration storage,” he said. “The remaining gap is seasonal. If households can store cheap solar powered summer energy for winter use, they reduce exposure to imported fuel and price volatility as well as to increasing grid costs for consumers.”
Inka Mero, Founder and Managing Partner at Voima Ventures, said: “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 households to store energy across seasons and reduce their dependence on imported fossil fuels. This is a radically important building block for a resilient and sovereign European energy system.”
The Series A funding will now be used to scale manufacturing and early commercial deployment in Denmark initially, followed by Europe’s other large markets including the Netherlands. Beyond Europe, there are opportunities to scale Photoncycle’s breakthrough technology in Asia, including Japan, and in the US.
