RC62 and Fire Safety for Rooftop Solar PV on Commercial Buildings

Updated 20 October 2026 · SEO Dons Editorial

What is RC62, and who wrote it?

RC62: Recommendations for fire safety with PV panel installations is a joint code of practice focused on commercial rooftop systems. Version 2 was published in 2023, developed by RISCAuthority and the Microgeneration Certification Scheme (MCS) with the support of Solar Energy UK, and published by the Fire Protection Association (FPA). MCS lists it with an issue date of 23 February 2023. It replaces the original RC62, first published in 2016, and the rewrite was jointly funded by the FPA and MCS.

Its scope is deliberate. The code applies to every stage of a project, from planning and procurement through design, installation, operation and maintenance, and covers rooftop installations on commercial and multi-residential buildings up to larger utility-scale projects. It is not intended for single dwellings or for roof-integrated panels that form part of the building envelope.

The wording matters when you read it. RC62 uses "must" for a compulsory procedure, "shall" for a mandatory requirement unless compliance is impractical, in which case a written risk assessment is required, and "should" for a procedure that is recommended best practice.

Why do insurers ask for RC62?

Because insurers helped write it. RISCAuthority's membership is a group of UK insurers, and RC62 describes itself as a practical guide for insurers and their clients on procuring, owning, operating and maintaining safe and efficient PV systems. It adds that it does not represent a pan-insurer perspective, and individual insurers will have their own requirements. RC62 is the baseline; the building's own insurer has the final word.

The risk it addresses is rare but costly. RC62 states that the incidence of fires involving PV systems is very low, but that a system not correctly designed, installed or maintained could, like any electrical service, add to the overall risk of fire. It also explains why a PV fire can be expensive: firefighters' concerns about electrical safety could prompt defensive tactics that stop a fire spreading to nearby properties rather than extinguishing it at source, which could result in significant property losses.

Much of the evidence comes from a three-year BRE study published by the government. Its final report found that DC isolators presented the greatest fire risk in its incident database, with approximately 30% of recorded incidents caused by malfunctions in that component, and recorded seven incidents of water entering DC isolators, all with upward-facing cable glands. RC62 summarises the BRE work as identifying DC connectors, inverters and DC isolators as accounting for 84% of PV system related fires.

What does RC62 say about the roof itself?

RC62 starts with the roof build-up. New rooftop installations, including panels and fixing systems, shall not lower the fire performance or classification of the roof, and if installation on a combustible or partly combustible roof is unavoidable, a fire-resistant covering should be applied. Its hazard section goes further, recommending installation on non-combustible roofs meeting Class A1/A2 s1, d0 to BS EN 13501-1, because fires involving combustible roofs spread quickly without the benefit of protection installed inside the building.

Structure is treated as a fire issue too. Arrays, particularly ballasted ones, can significantly increase roof loading and with it the potential for collapse during a fire, so RC62 calls for a structural survey by a competent person before installation. It also flags the chimney effect beneath panels, which can accelerate fire spread, especially on pitched roofs, with heat radiated back onto the roof from the underside of the panels.

The roof recommendations are the most debated part of the code. The National Federation of Roofing Contractors and partner bodies, including Solar Energy UK, have published a position paper arguing for a more nuanced, risk-based interpretation for flat roofing systems, grounded in whole-system performance and real-world test data rather than rigid material classifications. NFRC reported that RISCAuthority had launched a consultation with a view to updating RC62, so anyone specifying a system should confirm which edition their insurer is applying.

How should arrays be laid out around fire walls and access routes?

RC62 is specific about compartmentation. Arrays should not traverse fire barriers or fire walls, and cabling should be sealed or contained to stop fire spreading across them. Where combustible components such as cables cannot avoid crossing a compartment wall, they should run in fire-resistant cable ducts and shafts.

The separation distances are the figures designers most often work to:

2.5 m minimum between PV modules on each side of a compartment or fire wall, as the default.
1.2 m minimum on each side where the potential for fire to spread across the boundary is considered low, meaning all roof elements are non-combustible and the panels have a low propensity for fire spread, with no or minimal burning droplets.
The 1.2 m figure also applies where buildings adjoin town-centre shops and offices and 2.5 m would make PV unfeasible.

Firefighter access is the other layout issue. RC62 asks for safe, clear access routes for servicing, maintenance, cleaning and firefighting, and warns that high-density panel coverage may stop firefighters venting and tackling a fire inside the building, so it should be avoided.

What does RC62 recommend for DC cabling and isolation?

The DC side gets close attention because it cannot simply be switched off. RC62 points out that in daylight, unless modules are shielded from light, potentially harmful voltages are present even when the system is not operating. Its main recommendations are:

Classify the voltage. A design counts as low voltage only within set limits, including no more than 900 V DC between conductors and earth. Where a design cannot be classified as low voltage, additional measures are required, such as isolating DC strings at the modules through a remote switch reachable at ground level, or using module-level electronics that drop to extra-low voltage when the AC supply is disconnected. Those electronics are compared in our guide to string, central and optimiser inverters.
Keep internal DC runs short and protected. Internal DC cable routes should be as short as possible, with mechanical protection such as covered cable tray where cables that may still be live pass through occupied areas.
Reduce separate isolators. Eliminate DC isolators wherever possible, since many inverters now integrate them.
Do not mix connectors. Connectors from different manufacturers should not be mixed, and panel connections should use the connectors the panel manufacturer recommends.
Detect fire where the electronics are. Automatic fire detection should cover every indoor area that houses inverters, isolators and distribution boards.

What inspection and maintenance does RC62 expect?

RC62 treats maintenance as part of the fire strategy. Installations shall be serviced to the installer's instructions and to BS EN IEC 62446-2, and the code points to Solar Energy UK's best practice manual, which recommends inspection of commercial systems at least annually by a competent person. It states that insurers expect a regular cleaning programme for every commercial installation, recommends routine insulation resistance and string series resistance testing to catch connector problems early, accepts thermal-imaging drones where safe roof access is not possible, and asks for inspection after storms. Our guide to commercial solar PV maintenance shows how a maintenance programme puts those points into practice.

How should a business use RC62 when buying a system?

Start with the legal duty. RC62 says that for every relevant PV project to which the Regulatory Reform (Fire Safety) Order 2005 applies, an appropriate fire risk assessment shall be carried out and recorded by a competent person. Then use the code as a procurement checklist. It recommends that the system provider or installation contractor, as a minimum:

holds MCS certification for PV systems and BS EN ISO 9001:2015
is a registered member of a Safety Schemes in Procurement (SSIP) organisation, such as Acclaim or CHAS
holds appropriate certification and competence for DC, low-voltage AC and, where relevant, high-voltage work
holds appropriate insurance, including professional indemnity that covers the scope of the project

Three practical steps follow. Share the proposed design with your insurer before it is fixed, since individual insurers may add their own requirements. Ask each bidder to show on the drawings how the layout meets the fire-wall separations and access routes. And make the handover file, test results and maintenance plan contract deliverables. Our commercial PV installations guide shows where these checks fall in a project programme, and you can request quotes through the site's enquiry form.

Sources

RC62, version 2 (2023), RISCAuthority, MCS and Fire Protection Association, checked 20 October 2026
RC62 library entry, MCS, checked 20 October 2026
Fire and Solar PV Systems: Investigations and Evidence, BRE for BEIS, GOV.UK, checked 20 October 2026
Fire incidents involving solar panels, GOV.UK, checked 20 October 2026
RC62 position paper news release, NFRC, 15 July 2025, checked 20 October 2026

Common questions

Is RC62 a legal requirement?

No. RC62 is a code of practice. The legal duty it points to is the fire risk assessment required where the Regulatory Reform (Fire Safety) Order 2005 applies, and individual insurers can set their own requirements on top of the code.

Does RC62 apply to an existing rooftop system?

Yes. Its scope covers retrofits, new installations and extensions to existing systems. For older systems it highlights the risk from incompatible or poorly made DC connectors and isolators, and calls insulation resistance and series resistance testing a relatively low-cost exercise.

Does RC62 cover battery storage?

No. RC62 does not cover battery energy storage systems and refers readers to a separate RISCAuthority guide, RE1, for commercial lithium-ion battery installations.

Does RC62 apply to ground-mounted solar or PV cladding?

Only in part. Commercial ground-mounted systems are not covered in detail, though RC62 says the risk control principles are similar. PV cladding, facade and roof-integrated systems are outside its scope.