In a detached house in Europe, generation of electricity from PV on the roof is typically 4-15 times higher in the summer than in the winter while demand for energy to meet electricity and heating requirements is 2-3 higher in the winter. A growing number of houses with PVs on the roof makes it increasingly challenging for distribution grids to accommodate surplus electricity in the summer. Growing demand for electricity in the winter as heating is decarbonised and cars are converted to electric charge also puts a strain on the grid infrastructure.

Photoncycle develops technology that can place surplus electricity from rooftop PV and the grid into long term storage located next to the house, using an electrolizer. Green hydrogen produced from water and electricity is stored as a solid in Photoncycle’s developed storage system. The energy is released upon demand to meet electricity and heating requirements in the house and at the grid level.

The Photoncycle energy storage solution has a gravimetric energy density of approximately 3.5 kWh/kg vs 0.3 kWh/kg for a lithium-ion battery. High gravimetric and volumetric energy density combined with low energy storage cost, opens the way for affordable seasonal storage at a household level. A storage system of 3 m3 can store up to 10,000 kWh of energy, sufficient to store the whole surplus electricity production in the summer season in most households.

The technology will enable households to utilise the full potential of their roofs for energy production, utilising all of the generation from their solar PV in-house. Long term storage will allow households to take advantage of seasonal fluctuations in energy prices, importing electricity from the grid in periods when prices are low and exporting electricity to the grid when prices are high.

Based on a feasibility study undertaken by SINTEF, a leading European science research institute, a team of engineers and scientists at Photoncycle developed and validated individual components for our system in 2022. These were integrated and scaled into a functioning prototype of our core technology at the Photoncycle lab in 2023. A full-scale pilot will be developed in 2024 and a first product will be launched in the residential household market in 2025.  

A system patent was filed to the European Patent Office (EPO) in June 2021. In October 2022, EPO confirmed that the technology Photoncycle develops is novel and inventive, the two criteria for obtaining a patent. The patent application will go to national phase in early 2024.