Building regulations for commercial rooftop solar PV
Updated 10 November 2026 · SEO Dons Editorial
When does a rooftop array count as building work?
In England and Wales the Building Regulations 2010 apply to building work, and that includes a material alteration of a building. Regulation 3 makes an alteration material if the work, or any part of it, would at any stage leave the building failing a relevant requirement it met before. The relevant requirements include Part A, structure, and paragraph B4, external fire spread.
A rooftop array engages both. Requirement A1 is that the building carries its combined dead, imposed and wind loads safely to the ground, and B4(2) is that the roof adequately resists fire spreading across its surface and on to other buildings. Rails, panels and any ballast add load and change how wind acts on the roof, and they change what sits on the roof surface. The Welsh Government's guidance for non-domestic solar panels says building regulations will normally apply, that the roof's ability to carry the load will need to be checked and proven, and that some strengthening may be needed.
The regulations also name the system itself. Schedule 3 lists installing, in a building, a system that produces electricity by microgeneration or from renewable sources among the work a registered installer can self-certify, while the self-certification category for replacing roof coverings excludes solar panels.
Which approval route applies in England?
| Route | Who checks the work | What the owner receives |
|---|---|---|
| Full plans application | The local authority or a private registered building control approver; the Building Safety Regulator for a higher-risk building | A completion certificate once the work complies |
| Competent person scheme | An installer registered for that type of work self-certifies it | A certificate of compliance, with the local authority told of the work |
A building notice is not an option for most commercial projects. Regulation 12(3) requires a full plans application for building work on a building to which the Regulatory Reform (Fire Safety) Order 2005 applies, and GOV.UK says the non-domestic premises covered by that Order include all workplaces and commercial premises.
Self-certification only works where the job consists only of the work the registration covers. If the roof structure has to be strengthened, or other building work happens at the same time, that work needs its own approval. GOV.UK's list of competent person schemes has a separate entry for microgeneration and renewable technologies; ask which scheme the installer is registered with and check the register.
Two other cases arise on some commercial sites. A higher-risk building, at least 7 storeys or 18 metres high with at least 2 residential units, or a hospital or care home of that height, needs building control approval from the Building Safety Regulator, unless the work is exempt, done under a competent person scheme or an emergency repair. Where an array went up without approval, a local authority can consider a regularisation application for work carried out after 11 November 1985.
The business commissioning the work is also the client under the regulations' dutyholder rules, which sit alongside CDM 2015. Regulation 11A requires the client to make suitable arrangements for planning, managing and monitoring the project, including enough time and resources, so that the work complies. If a project will involve more than one contractor, the client must make written appointments of a principal designer and a principal contractor for building regulations purposes, or certify in writing that its CDM appointees hold those roles.
What do structure and fire mean on a commercial roof?
For structure, the building control submission is where the roof checks are formally relied on. The survey and appraisal stages that produce them are covered in the guide to commercial PV installations and the feasibility study guide; what matters here is that the calculations and drawings go to building control, or sit within the scheme installer's certification, before the work is treated as compliant.
For fire, B4(2) is a functional requirement and Approved Document B is the guidance on meeting it in England. That guidance is under review. The Building Safety Regulator and the Ministry of Housing, Communities and Local Government consulted from 25 March to 1 July 2026 on changes that include new provisions for roofs with photovoltaic panels: better fire performance for products beneath and around the installation, conditional exemptions for flat roofs where other fire safety measures are in place, and limits on panels near roof openings. GOV.UK says the feedback is being analysed, so these are proposals, not guidance yet. Insurers add their own code; the RC62 fire safety guide covers it.
Once the array is in use, the fire risk assessment has to catch up with it. GOV.UK says the responsible person for non-domestic premises must carry out a fire risk assessment and review it regularly.
Does the electrical work need building regulations approval?
Not under Part P on a purely commercial building. Schedule 1 limits Part P, electrical safety, to installations in or attached to a dwelling, in the common parts of a building serving dwellings, or supplied from a dwelling's source. A mixed-use building with flats can bring parts of an installation within it.
The electrical work is still regulated. Regulation 4 of the Electricity at Work Regulations 1989 requires every system to be constructed so as to prevent danger, so far as is reasonably practicable, and the installer's electrical installation certificate and test results are the evidence a building owner holds. Connecting the array to the distribution network is a separate process with the network operator.
How do Wales, Scotland and Northern Ireland differ?
| Nation | Rules | Who approves | Points to note |
|---|---|---|---|
| Wales | Building Regulations 2010 as they apply in Wales | Local authority building control or a registered building control approver | The same full plans rule for buildings under the Fire Safety Order; a new building control regime from 1 July 2026 |
| Scotland | Building (Scotland) Regulations 2004 | The local authority as verifier: a building warrant before work, a completion certificate after | Work that needs no warrant must still meet the standards |
| Northern Ireland | Building Regulations (Northern Ireland) 2012 | District council building control | Technical Booklets D (structure) and E (fire safety) give the guidance |
Wales. Wales has its own version of regulation 12, with the same full plans requirement for buildings under the Fire Safety Order. New regulations from 1 July 2026 added dutyholder duties for any controlled building work and replaced the deposit of plans with applications for building control approval.
Scotland. A building warrant is required for all building work to which the regulations apply, unless Schedule 3 lists it. The exemption for work on a non-residential building the public cannot enter excludes structural work and alterations to roofs, so an array that alters the roof or its structure needs a warrant. The 32 local authorities are the only appointed verifiers. When the work is finished the relevant person, usually the owner, tenant or developer who ordered it, submits a completion certificate, and the owner must always be named on it. Verifiers seek proof that the electrical installation is properly done, and detailed evidence may be required unless an approved certifier of construction covers it.
Northern Ireland. The Department of Finance says anyone who intends to alter a building or install services must first seek approval from the district council, through plans or, for certain domestic applications only, a building notice. Councils enforce the regulations and inspect the work.
Which documents should the owner keep?
- England and Wales: the building control completion certificate, or the competent person scheme certificate, with the approved plans and structural calculations.
- Scotland: the building warrant, the approved plans and the accepted completion certificate, with any certificates from approved certifiers.
- Northern Ireland: the district council's approval of the plans and any notices it issues.
- Everywhere: the electrical installation certificate and test results, the fire evidence submitted for the roof build-up, and the updated fire risk assessment.
The rest of the handover file, from as-built drawings to warranties, is listed in the installation guide's handover pack. Planning permission is a separate consent with its own rules, covered in the planning permission guide for commercial rooftop solar. Whoever quotes for the work should state which building regulations route it proposes and who will submit the application; you can send an enquiry through the site's form.
Sources
- legislation.gov.uk: Building Regulations 2010, regulations 3, 11A, 11D and 12 (England and Wales versions), Schedules 1 and 3; Electricity at Work Regulations 1989, regulation 4; all checked 10 November 2026.
- GOV.UK: Building regulations approval (overview, how to apply); Competent person scheme: current schemes (last updated 17 September 2026); Fire safety in the workplace: who's responsible; all checked 10 November 2026.
- Building Safety Regulator and MHCLG: Review of Approved Document B: Fire safety guidance, consultation (25 March to 1 July 2026, last updated 15 April 2026), checked 10 November 2026.
- Welsh Government: Building regulations: solar panels (non-domestic); Transitional arrangements for the new building control regime starting on 1 July 2026 (18 June 2026); both checked 10 November 2026.
- Scottish Government: Building standards procedural handbook, third edition, version 1.9 (25 March 2026), sections 2, 3, 5 and 12, checked 10 November 2026.
- Department of Finance (Northern Ireland): Building Regulations in Northern Ireland; Building Regulations Technical Booklets; both checked 10 November 2026.
Common questions
Can a small array on an office go in under a building notice?
Not in England or Wales if the Regulatory Reform (Fire Safety) Order 2005 applies to the building, which covers workplaces and commercial premises. Regulation 12(3) requires a full plans application there. The other route is an installer registered with a competent person scheme for that work self-certifying it.
Does an MCS certificate show building regulations compliance?
Not on its own. Compliance is shown by a completion certificate from building control or a certificate from a competent person scheme authorised for that type of work, and GOV.UK lists the authorised schemes. Ask the installer which of the two its quote includes.
What if an existing array was installed without approval?
In England a local authority can consider a regularisation application for unapproved work carried out after 11 November 1985, and it may ask for alterations first. In Scotland a completion certificate must still be submitted for work done without a warrant, with details equivalent to a warrant application and a higher fee.
Who is liable if the installation breaks the regulations?
GOV.UK says the person doing the work could be prosecuted and fined, and the building control body could make you pay to fix faulty work. In Scotland responsibility for compliance stays with the relevant person even when an agent signs the completion certificate.