Excerpt from bbc.com
All new housing and commercial buildings in Guernsey must now feature solar panels or another form of renewable energy technology, the island's planning authority has confirmed. Previously such installations were only encouraged; under the updated planning policy roof-mounted solar panels, or appropriate alternatives such as non-roof solar arrays or air source heat pumps, are mandatory.
The move stems from the 2023 Electricity Strategy, which directed the Committee for the Environment & Infrastructure to explore ways to increase on-island generation. Deputy Neil Inder, president of the Development and Planning Authority, framed the change as both an environmental and an energy-security measure, and noted it is far cheaper to fit the technology at build time than to retrofit it later.