Dutch homeowners are staring down a significant change in 2027. The Netherlands is phasing out its net metering policy, which means rooftop solar households will no longer get full credit for the excess electricity they push back to the grid. That surplus power, mostly generated during long summer days, has nowhere to go unless there’s a way to store it for months. That’s the exact problem Photoncycle is building for, and on March 4, 2026 the Norwegian startup announced it raised €15M in Series A funding to bring its seasonal energy storage system to the Dutch and Danish markets.
The round was led by NordicNinja and Voima Ventures, with existing backers Lifeline Ventures, Eviny Ventures, Luminar Ventures, and Momentum also participating.
The Storage Gap Nobody Solved:
Lithium-ion batteries are the default answer when people think about home energy storage. They work well for shifting solar power from afternoon to evening. But storing energy from June to December is a completely different challenge, and standard batteries aren’t designed for that.
Photoncycle’s system uses solid-state hydrogen to do exactly that. Surplus solar electricity gets converted and stored as solid-state hydrogen underground. When winter arrives and heating demand peaks, that stored energy gets released as clean heat and electricity. The company integrates heat recovery into the system, so when paired with a heat pump, households get more total usable energy out of it, which matters in a heating-heavy climate like the Netherlands.
Why the Netherlands Makes Sense:
The Dutch market has one of the highest rooftop solar adoption rates in Europe. Homes generate significant surplus electricity every summer, and under the current net metering setup, they’ve been able to offset winter electricity costs by exporting that summer power. Once net metering ends in 2027, that financial buffer disappears.
On top of that, Dutch grid operators have flagged congestion issues in multiple regions. Distributed seasonal storage at the household level means less energy gets pushed to the grid during peak summer production, which directly helps reduce strain on local networks.
Manufacturing Scale Already Planned:
Photoncycle has already mapped out its production roadmap. The company is targeting 1.4 TWh of annual manufacturing capacity, with the first phase coming online in 2027. For reference, 1.4 TWh is enough storage capacity for roughly 140,000 homes, each storing 10,000 kWh of seasonal energy.
Commercial deployment starts in Denmark first, then moves into the Netherlands as the net metering phase-out takes effect. The sequencing is deliberate, giving the company time to refine operations before entering its primary target market.
A Subscription Model for Upfront Costs:
Buying and installing a seasonal energy storage system outright isn’t realistic for most homeowners. Photoncycle addresses this with a subscription model where the unit is installed at the property and operated as part of an integrated energy solution. The subscription covers the hardware, maintenance, system operation, and access to energy trading markets.
Households can bring their existing solar panels into the system or get new panels as part of the package. The goal is predictable, lower year-round energy costs rather than a large upfront investment, which is a sensible structure given that a significant portion of Dutch homes still rely on natural gas for winter heating and remain exposed to seasonal fuel price swings.
The Investor Rationale:
NordicNinja General Partner Tomosaku Sohara noted that energy sovereignty is a priority across both Europe and Asia, and that long-duration storage is critical infrastructure for resilient clean energy systems. NordicNinja is the largest Japan-backed venture capital fund in Europe, with a portfolio that includes Bolt and Einride, so their involvement signals confidence in Photoncycle’s path to global deployment beyond just the Dutch market.
Voima Ventures, which recently closed a €107M Fund III focused on DeepTech and sustainable energy startups from Nordic and Baltic research institutions, co-led the round alongside NordicNinja.
Seasonal Storage as Infrastructure:
Seasonal energy storage is a category that’s been talked about for years but has had very few commercially viable products at the residential scale. Photoncycle is targeting that gap with a system designed from the ground up for summer-to-winter shifting, not repurposed from short-duration battery technology.
The 2027 timeline is concrete. Net metering ends, manufacturing capacity comes online, and Dutch solar households will be looking for exactly what Photoncycle is building. The €15M Series A gives the company the runway to move from early deployment in Denmark into the larger Dutch market with a product and pricing structure designed for real households.
For founders and operators tracking the residential energy space, this is a useful case study in building around a known, date-certain regulatory shift rather than waiting for market conditions to evolve organically.
