Photoncycle

Photoncycle is an Oslo-based energy technology company developing a residential system for seasonal storage of solar energy. Its product combines rooftop solar panels, an above-ground processing unit containing a reversible fuel cell and a lithium-ion battery for short-duration storage, and an underground storage unit with a stated capacity of up to 10,000 kWh. Surplus summer electricity is used to produce hydrogen from water; the company's patented process then stores that hydrogen in a solid state, which it describes as roughly 20 times denser than lithium-ion storage and around 700 times the capacity of a standard home battery. In winter, the stored hydrogen is converted back into heat, hot water and electricity for the household.

The system is positioned as a replacement for water-based heating systems such as gas, oil and district heating, or water-based underfloor heating, with the company stating that installation requires no interior retrofitting and can be completed in a day by authorised installers. Systems are monitored as a digital twin, with maintenance included. Alongside self-consumption, Photoncycle manages trading of surplus generation, storing energy when solar output is high or grid prices are negative and selling when prices peak.

The technology is being developed in a hydrogen laboratory in Oslo and has been piloted with Norway's largest house builder. The company targets large-scale manufacturing from 2027, with a planned industrial facility of 1.4 TWh annual storage capacity, described as sufficient for approximately 140,000 homes.

Founding story

Founder Bjørn Brandtzæg worked previously on large-scale energy infrastructure projects, founding two companies in the energy infrastructure space and raising more than $1.3 billion in investment. That experience led him to conclude that distributed production and storage would be more resilient than centralised projects. In 2020 he was a visiting fellow at MIT, where Photoncycle was incubated and where he worked with researchers on future energy solutions, concluding that solar's intermittency required a seasonal storage solution. He then assembled a team of engineers and chemists to develop solid-state hydrogen storage.

Business model

Photoncycle sells its energy system as a subscription rather than an upfront capital purchase. Customers pay a refundable deposit of €1,000 when ordering, then a fixed monthly fee starting at €300 depending on the choice of solar panels, which covers hardware, installation and maintenance. The storage unit is installed at the customer's property and operated as part of an integrated energy service, and customers receive 50% of the profits from trading their surplus energy, which the company says can amount to up to €150 per month.

Recurring monthly subscription fees from households, bundling solar generation, seasonal storage, installation, servicing and energy trading, with trading profits shared with the customer.

Traction

The system is in pilot with Norway's largest house builder, with customers signing up via a waitlist ahead of pre-orders. Manufacturing at full industrial scale is planned at 1.4 TWh annual capacity, expected to begin coming online in 2027, which the company equates to roughly 140,000 homes. Photoncycle has been covered by TechCrunch, Dagens Næringsliv and Sifted.

Latest developments

In March 2026 Photoncycle announced a €15 million (~$17 million) Series A led by NordicNinja and Voima Ventures, with participation from existing investors Lifeline Ventures, Eviny Ventures, Luminar Ventures and Momentum. Proceeds are earmarked for manufacturing scale-up, early commercial deployment in Denmark and subsequent entry into the Netherlands, and the first phase of an industrial facility with 1.4 TWh annual storage capacity. The company links Dutch demand to the phase-out of net metering there in 2027.