Photoncycle secures major funding for seasonal home energy storage
Oslo-based climate tech startup Photoncycle has raised €15 million to advance a novel home energy storage system that allows households to store surplus summer solar power for use in winter. The fresh capital will support product development, pilot deployments and the first steps toward commercial rollout in key European markets.
Tackling the seasonal gap in residential solar
While rooftop solar installations are spreading rapidly across Europe, most systems struggle with a fundamental mismatch: peak production occurs in sunny summer months, while peak demand for electricity and heating arrives in winter. Traditional battery storage typically covers only hours or a few days of supply, leaving homeowners reliant on the grid during colder, darker periods.
Photoncycle aims to close this gap by offering a form of long-duration energy storage designed specifically for single-family homes. The company’s technology converts excess solar energy generated in summer into a storable medium that can be efficiently reconverted into heat and electricity during winter, significantly increasing household energy self-sufficiency.
How Photoncycle’s system works
The solution integrates with rooftop solar panels and a compact on-site storage unit. Rather than simply charging conventional batteries, the system uses advanced power electronics and thermal management to capture, transform and retain energy over several months. In winter, the stored energy is released to power home heating systems and electrical loads, reducing reliance on fossil-based grids and volatile energy markets.
By targeting both electricity and heat, Photoncycle addresses two of the most carbon-intensive segments of household consumption. The company positions its product as a critical enabler of decarbonisation in regions with strong solar potential but pronounced seasonal variation, such as Northern and Central Europe.
Scaling up for European energy transition
The €15 million funding round will be used to refine the technology, expand the engineering team and launch large-scale field trials with partner utilities and early-adopter homeowners. The startup plans to prioritise markets where high penetration of rooftop solar and rising energy prices make seasonal storage particularly attractive.
As European policymakers push for higher shares of renewable energy and greater grid resilience, solutions like Photoncycle’s seasonal storage could become a key component of the residential energy landscape, enabling households to turn summer sunshine into reliable winter comfort.