Norwegian energy storage startup Photoncycle has raised €15 million in Series A funding to commercialise its seasonal energy storage technology across Europe. The funding was led by NordicNinja and Voima Ventures, with participation from Lifeline Ventures, Eviny Ventures, Luminar Ventures and Momentum. The company aims to scale a system that can store surplus renewable energy generated in summer for use during winter months. Unlike traditional lithium-ion batteries, the system targets long-duration storage, combining solar generation, an energy processing unit and underground hydrogen storage, aims to lower the upfront cost barrier for households and stabilise energy costs year-round. The system will initially be launched in Denmark and the Netherlands, with high solar adoption and policy incentives supporting decentralised energy systems.