Wales Leads UK Move to Mandate Solar Panels on New Buildings From 2027

In a landmark move, the Welsh government has officially taken the lead in the UK’s green energy race. Wales is set to effectively mandate solar panels on all new domestic and commercial buildings when updated building regulations come into effect in early 2027. Similar requirements are expected to be introduced in England sometime in 2027 as part of efforts to meet net-zero targets and reduce household energy bills. Wales has set the bar high, and the renewables industry is hoping that the UK government will match their timeline after years of delay. 

The Welsh government has announced that solar panels will become a “functional requirement” for all new buildings. Unsurprisingly, Welsh castles and other historic buildings will be exempt. 

From 4 March 2027, an amendment to Part L of the building regulations in Wales will mean that if construction has not yet started, solar is no longer an “optional extra” and instead a standard feature. 

Chris Hewett, chief executive of the trade association Solar Energy UK, said:

“This is tremendous news for Wales, and I applaud the Welsh Government for their wise decision.” 

Although the updated building regulations for Wales do not explicitly set out a solar PV mandate, they do introduce a requirement for “a system for renewable electricity generation” to be installed on site. Solar Energy UK expects that this will most likely lead to rooftop solar being deployed “in virtually every circumstance” as the most practical and affordable way to comply with the new regulations. 

There’s always a risk when technology becomes mandatory that developers will be tempted to install the lowest cost systems just to please building control. However, Solar Energy UK went on to say that forthcoming clarifications should avoid encouraging the installation of token systems of only a couple of panels and link building incentives with the availability of electrical connection in a specified area. Revised guidance setting out the finer details of the new system will be issued in the spring or summer this year following a consultation last autumn. 

New building regulations for Wales include an exemption that will help prevent uneconomical and impractical systems from being installed purely for compliance reasons. The rules state that if it is not possible to install a system capable of generating at least 720 kWh per year on a proposed building, then the requirement will not apply. This amount is about a fifth of what would be expected from a typical residential solar installation of 3.5 kilowatts.

Similarly, buildings in areas with electrical connection limitations will not be penalised. It is assumed that homes would be unable to supply more than 16 amps per phase, or 3.68 kW, to the grid. If this limit is exceeded, permission is required via a G99 application. 

Despite these rules, the government very much encourages developers to install more than the bare minimum needed for compliance. It is in developers’ interest to meet energy efficiency requirements and achieve a higher energy performance certificate (EPC) rating to reduce the building’s running costs and to be more attractive to potential buyers or users. 

From March 2028, the new mandate will be extended to include buildings undergoing major renovations and works covered by building control, such as installing a new roof or renovations for a material change of use. 

Wales’s solar mandate is much like what is expected from England’s Future Homes Standard and Future Buildings Standard. The UK government has already committed to mandate solar panels for new homes and buildings in England through the regulations, although they have not set a date yet.

Currently, over 40% of new homes that are built in England are estimated to come with solar panels.

Solar Energy UK has long advocated for mandatory solar installations on new buildings, arguing that incorporating solar during construction significantly reduces installation costs and leads to much lower long-term energy bills. The visual integration is also seamless. For far too long, developers have built homes that require expensive retrofitting just a few years later. 

For homeowners, installing solar panels during construction is significantly cheaper than retrofitting them later, making new-build requirements one of the most cost-effective ways to expand solar capacity. 

The MCS Foundation, which oversees the Microgeneration Certification Scheme (MCS), setting quality standards for small-scale technologies like heat pumps and solar panels, has welcomed the Welsh government’s announcement that all new homes in Wales will be fitted with solar panels as well as low-carbon heating such as heat pumps from Spring 2027. 

Research conducted by the MCS Foundation found that mandating solar panels as well as heat pumps or connections to low-carbon heat networks could potentially save a household living in a typical new build over £1,000 a year. As well as financial savings, there would be benefits for grid flexibility, lower carbon emissions, and the domestic renewables industry. 

Overall, industry leaders support the mandate, seeing it as a way to significantly reduce carbon emissions and, according to some estimates, such as from Smart Energy Homes, could lower energy costs by up to 64% for homeowners. There are some house builders, according to Inside Housing, who view the new requirements as challenging, noting potential practical difficulties in meeting the strict requirements by 2027 and cost concerns for certain sites. 

There are other concerns as reported by the BBC, regarding the skills gap and the need for greater government assistance for training and workforce development. Although there can be real long-term savings, higher initial construction costs could be a hindrance for developers, leading to calls for better support mechanisms. 

Wales’s move to mandate solar on new buildings marks a major step in the UK’s shift towards cleaner, more resilient energy. While challenges remain around costs and skills, the policy sets a clear direction for future building standards. As England prepares to follow, solar is quickly becoming a standard feature rather than an optional extra.