The map is colour-coded to show how much light rooftops receive across the island throughout the year, with dark red areas showing higher potential to generate electricity through solar panels and dark blue showing lower potential.
It does not account for shadowing from trees or neighbouring properties, though a more detailed, paid-for version is available from Digimap for those designing or installing renewable energy systems. Both versions cover rooftop solar generation only, not ground-based systems.
The tool was developed after renewable energy provider Little Green raised the idea with the Committee for the Environment & Infrastructure, to give islanders an independent check on what their roof could deliver.
‘Orientation is one of the biggest factors in how much a solar system actually produces,’ said Little Green commercial director Simon de la Rue. ‘This map gives them an independent, objective check, so any quote can be held to it.’
Digimap used the States’ Digital Surface Model and building data to work out the slope and aspect of every roof on the island.
The map supports Guernsey’s Electricity Strategy, agreed by the States in 2023, which set out plans to boost interconnection alongside locally-generated renewable energy such as solar power. Guernsey had more than 4MW of solar PV installed by the end of 2025, and is aiming for 10MW by 2028.
‘As we get about 30-35% more sunshine than the UK average, this free tool makes us well placed to understand how we can better take advantage of the energy we can harness from the sun,’ said E&I president Deputy Adrian Gabriel.
‘While we’d always encourage islanders to contact trusted professionals before embarking on installing solar panels, this is a really helpful tool to get an initial idea on whether the potential for solar is there for householders.’
The free map can be accessed at Rooftop Solar Panel Suitability.
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