Solar Panels and Building Regulations: Do You Need Approval?

Planning permission and building regulations are entirely separate systems. Most rooftop solar PV on a domestic dwelling is permitted development under Schedule 2, Class 6 of the GPDO 2015 - meaning no planning application is needed. But permitted development status tells you nothing about building regulations compliance.

Building regulations set the safety and performance standards for how the installation is carried out. Even if you never need to apply for planning permission, you must still meet the relevant Parts of the Building Regulations 2010.

Part P of the Building Regulations covers electrical safety in dwellings and is the most important regulation for solar PV installations. The connection of a solar PV system to the household consumer unit is notifiable electrical work under Part P because it creates a new circuit from the consumer unit.

There are two ways to comply:

• Competent person scheme (most common route): If your installer is registered with an MCS-approved competent person scheme - such as NICEIC, NAPIT, or ELECSA - they can self-certify the electrical work. You receive an installation certificate and notification is made to building control on your behalf. No separate building control involvement is needed.
• Building control notification: If your installer is not registered under a competent person scheme, you must notify your local building control body before work starts. An inspector will check the electrical installation and issue a completion certificate on sign-off.

Always ask your installer for their MCS certificate number and competent person scheme registration before work begins.

Part A of the Building Regulations covers structural safety. Solar panels add weight to your roof structure - typically 10-15 kg/m2 for standard panels plus mounting rails. For most modern houses with tiled roofs and adequate rafters, this is within the structural capacity of the roof without further work.

However, a structural check may be needed if:

• Your property was built before 1950 and has undersized rafters
• Your roof is covered in heavy natural slate
• You are installing an unusually large array
• Your roof structure has any existing signs of movement or repair

A reputable installer will carry out a visual structural assessment as part of their survey. If there is any doubt, they should commission a structural engineer to confirm the roof is adequate. This protects both you and the installer.

Retrofitting or installing a battery storage system (such as a Tesla Powerwall, GivEnergy, or similar) alongside solar panels involves additional notifiable electrical work under Part P. The battery inverter, wiring, and connection to the consumer unit all require Part P compliance, again via either the competent person route or building control notification.

Most MCS-registered solar and battery installers are also registered under the relevant competent person scheme for battery installations, so the self-certification route is still available.

Battery storage also raises Part B (fire safety) awareness points: lithium-ion batteries carry a thermal runaway risk. While there is currently no specific Approved Document requirement for domestic battery storage location, best practice guidance from manufacturers and the Energy Storage Network recommends:

• Installing batteries in a well-ventilated space, ideally a garage or outbuilding rather than a living area
• Keeping batteries away from sleeping areas where possible
• Ensuring smoke detection covers the battery location

Part L of the Building Regulations covers energy efficiency and conservation of fuel and power. Solar PV panels improve your property's SAP calculation and EPC rating - more solar generation means a higher rating. This is relevant if you are carrying out wider works that trigger a formal Part L assessment or if you are required to improve your EPC to a minimum standard (for example, for a rental property).

If you are having solar panels installed as part of a broader renovation or extension project, ensure the overall Part L compliance report accounts for the solar contribution correctly.

You must notify your local building control body before starting work in the following situations:

• Your installer is not registered under a competent person scheme for Part P electrical work
• The installation requires significant structural alterations to the roof
• The work forms part of a larger project (such as a loft conversion) that already has a building control application open

Building control fees for a solar panel inspection are typically modest - contact your local authority building control (LABC) or an approved inspector for a quote. Doing nothing is never the right answer: missing building regulations sign-off can cause problems when you sell your property.

Keep the following documents in a safe place after your solar installation is complete:

• MCS installation certificate (proves compliant installation under the competent person scheme)
• Part P electrical installation certificate or building control completion certificate
• DNO (distribution network operator) notification confirmation if your system exports to the grid
• Smart Export Guarantee (SEG) agreement if applicable
• Manufacturer datasheets and installation manuals for panels, inverter, and battery

These documents will be requested by solicitors during a property sale. Missing MCS and Part P certificates are a common cause of delays in conveyancing.

Solar panels on a detached domestic outbuilding (garage, garden office, or similar) follow the same rules. The electrical connection back to the house is notifiable work under Part P if it creates a new circuit. The outbuilding itself may be exempt from building regulations under Schedule 2 of the Building Regulations 2010 depending on its size and use - but the electrical installation is a separate matter and is always subject to Part P.

If the outbuilding is within 1 metre of a boundary, Part B (fire spread) considerations apply to the building itself, though this is unrelated to the solar installation.