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- The mandate from Wales will come into effect 4 March 2027
- Solar Energy UK has welcomed the news
- The mandate does not explicitly state solar panels, but a system for renewable energy generation
Wales will become the first part of the UK to require new build homes to have solar panels fitted as standard following an amendment to Part L of the Building Regulations and will come into effect from 4 March 2027.
The amendment makes the technology a “functional requirement” for homes and non-domestic buildings where construction has not yet occurred.
In a year’s time it will extend to works covered by building control approval, such as installing a new roof or renovations for a material change of use.
Chris Hewett, chief executive, Solar Energy UK, described this as “tremendous news” for Wales.
“Solar Energy UK has long lobbied for solar power to be all but mandatory on new homes and buildings, which will soon see far lower bills than would otherwise have been the case,” Hewett said.
He added that the Building Regulations 2026 do not refer to solar power, instead claiming “a system for renewable electricity generation” should be installed on-site, which means that solar panels will be deployed in almost every case.
Hewett said the rules would be the same as England’s upcoming Future Homes Standard and Future Buildings Standard, which are expected to be finalised this year after years of delay.
These will “all but mandate” solar panels on new homes and buildings, adding that more than 40% of new homes in England are already built with them.
Scotland has yet to mandate solar installations on new buildings, and Northern Ireland is expected to do so soon.
Research from The Microgeneration Certification Scheme (MCS) Foundation found that mandating solar panels, as well as heat pumps of connections to low-carbon heat networks would save a household living in a typical new build more than £1,000 a year. There would also be benefits for grid flexibility, lower carbon emissions, and the domestic renewables industry.
Hewett warns that the rules should avoid encouraging the installation of ‘token’ systems of only a couple of panels, as this can happen under existing energy efficiency requirements.
“If a system capable of generating at least 720kW per year cannot be installed, the requirement will not apply, and the amount is about a fifth of what would be expected from a typical residential installation of 3.5kW,” he said.
“Similarly, building in areas with electrical connection limitations would not be penalised. The rules assume that homes would be unable to supply more than 16 amps per phase, or 3.6kW, to the grid. Beyond that level, permission from the regional distribution network operator is required via a G99 application.”
The MCS has also welcomed the news, citing it as an “extremely positive step forward”, and sets a path that the UK and other governments can and should follow.
An MCS spokesperson said they “looked forward” to the UK government laying down the legislation for the Future Homes Standard in England, which should follow suit.
Hewett concluded that the law encourages developers to go install “more than the bare minimum” needed for compliance, and doing so will count towards meeting energy efficiency requirements and achieving a higher energy performance certificate rating.
“Therefore, reducing running costs and making buildings more attractive to potential buyers or users,” Hewett said.
“It also avoids the perverse incentive under the current approach that allows the energy performance of a building’s fabric to be reduced if solar panels are added.”
