GUIDE · FOR UK SOLAR INSTALLERS · 14 MIN READ

RC62 Solar Fire Safety: What Insurers Expect of Installers

RC62 version 2 published (first edition 2016)

2023

RC62 version 2 published (first edition 2016)

Gap from modules to each side of a fire wall

2.5m

Gap from modules to each side of a fire wall

Roof fire class RC62 recommends for PV

A1/A2

Roof fire class RC62 recommends for PV

PV fires from DC connectors, inverters and isolators (BRE, 2017)

84%

PV fires from DC connectors, inverters and isolators (BRE, 2017)

On a commercial job the building's insurer is a stakeholder, whether or not anyone has told you. If the insurer won't accept the system, the customer can't go ahead, and that usually surfaces late, after the proposal is signed. This guide sets out what RC62 asks for, section by section, so you can design to it from the first site visit.

Last updated 21 October 2026. Summarised from RC62 version 2 (2023), read in full; section numbers are given so you can check each point. Individual insurers have their own requirements, so always ask the customer's insurer what they need. This isn't fire safety advice for a particular building.

What RC62 is, and what it isn't

RC62, Recommendations for fire safety with PV panel installations, is a Joint Code of Practice developed through RISCAuthority, a group of UK insurers, and the Microgeneration Certification Scheme (MCS), with the support of Solar Energy UK. It is published by the Fire Protection Association (FPA) and is free. Version 2 came out in 2023; the original was published in 2016.

Its focus is larger commercial and industrial rooftop systems. It covers rooftop installations on commercial and multi-residential buildings up to utility scale. It does not cover single dwellings, roof-integrated systems where the panels form part of the building envelope, PV cladding or façades, or battery storage, for which it points to RISCAuthority's separate guide RE1.

The wording matters. In RC62, "must" is compulsory; "shall" is mandatory unless compliance is impractical, in which case a written risk assessment is needed; and "should" is recommended best practice. RC62 also says it is not a pan-insurer view: individual insurers have their own requirements. It names the documents to read alongside it, including MIS 3002, the IET Code of Practice for Grid-connected Solar PV Systems, and BS EN 62446-1 and BS EN IEC 62446-2 for testing, documentation and maintenance. Our MIS 3002 guide covers the first.

How big is the fire risk?

RC62 says plainly that the incidence of fires involving PV systems is very low. Its concern is that a system which is not correctly designed, installed or maintained could add to a building's fire risk, as any electrical service could, and that numbers rise as more systems go in.

It cites a 2017 study by the Building Research Establishment (BRE), carried out for the government, which found that DC connectors, inverters and DC isolators accounted for 84% of PV system related fires. Installation issues were the largest single cause, and product failure the second. That is why so much of RC62 is about the DC side and the quality of the install, not the panels themselves.

Roof construction and combustibility

• Non-combustible roofs. PV installations should go on non-combustible roofs meeting Class A1/A2-s1, d0 to BS EN 13501-1. RC62 warns that fires on combustible roofs spread quickly, without the benefit of any protection inside the building (5.4.2).
• Don't lower the rating. New rooftop PV, including the panels and fixing system, shall not lower the fire performance or classification of the roof. If installing on a combustible or partly combustible roof can't be avoided, a fire-resistant covering should be applied (5.1.3).
• Choose modules for fire spread. Panels should have a low propensity for fire spread and little or no tendency to produce burning droplets. With no UK fire test standard yet, RC62 says to judge this from the materials' fire classification and the test data available (5.1.5).
• The chimney effect. Fire can spread faster under panels, especially on pitched roofs, with heat radiated back onto the roof (5.4.3).
• Explosive atmospheres. Where an explosive atmosphere may form, such as grain stores at harvest, ignition sources shall be addressed in a DSEAR assessment (5.1.9).

On older buildings the roof question often comes with an asbestos one. See solar panels on an asbestos roof for the register, the survey and fragile roofs.

Fire walls, separation and access

This is the part that changes a layout, so check it before you fill the roof on the design:

• Arrays should not cross fire barriers or fire walls, and cabling should be sealed or contained so fire can't spread across them (5.5.10).
• Components with combustible elements, such as cables, should not pass over a compartment or fire wall. If that can't be avoided, they should run in fire-resistant cable ducts and shafts (5.5.11).
• There should be a minimum of 2.5m between the modules and each side of a compartment or fire wall (5.5.11).
• Where the risk of fire spreading across is low, meaning all roof elements are non-combustible and the panels have a low propensity for fire spread, a minimum of 1.2m on each side is recommended. The 1.2m minimum also applies to buildings adjoining town-centre shops and offices, where 2.5m would make PV unfeasible and fire spreading across several buildings is improbable (5.5.12).
• Leave safe, clear access routes for servicing, maintenance, cleaning and firefighting (5.4.4), and avoid covering the roof so densely that firefighters can't vent and tackle a fire inside (5.4.5).

Structure and ballast

RC62 links weight to fire: a heavier roof is more likely to collapse in a fire. It says a structural survey should be carried out by a competent person before installation to assess the roof's load-bearing capacity (5.4.6). Ballasted systems can make water pool as the roof flexes, so a thorough structural review is needed to avoid collapse, especially in heavy rain (5.4.7). It notes that systems are designed for wind speeds of 54 m/s (120 mph), that higher speeds have been recorded at exposed, high locations in the UK, and that roofs should be inspected after any extreme weather (5.4.10).

DC voltage, isolation and the fire service switch

RC62 asks you to work out whether the design is "low voltage": not more than 1000V AC or 1500V DC between conductors, or 600V AC or 900V DC between a conductor and earth. That can depend on the inverter, so ask the manufacturer how the DC side is referenced to earth. If the design can't be classed as low voltage, additional fire protection shall be built in, such as isolating the strings at the modules from a remote switch at ground level, or module-level power electronics that drop to extra-low voltage when the AC supply is disconnected (5.5.6).

Other design points on the DC side:

• Decide whether DC disconnection and an interface with the building's fire systems are mandatory under BS 7671, and, subject to the risk assessment, whether the inverter's arc fault protection is acceptable or a stand-alone arc fault interrupter is needed (5.1.6, 5.1.7).
• Arc suppression, module-level power electronics and DC disconnection should be considered against what the fire risk assessment calls for (5.5.8).
• Eliminate separate DC isolators wherever possible; many inverters now have them built in (5.5.18).

The fire service switch. Where BS 7671 requires one, or the client or insurer does, a switch should be fitted in a prominent position firefighters can reach to isolate the DC side remotely. As a minimum it should make the DC wiring inside the building voltage-free. It should sit away from the arrays, is in addition to the normal AC and DC isolators, and should be tested during routine maintenance with the results recorded. RC62 says it isn't needed on single-phase residential properties unless specifically required (5.14.6).

For the fire and rescue service, RC62 also asks for a clearly visible "PV on the roof" sign of at least 100mm × 100mm at the consumer units or the supplier's cut-out (5.14.4), and information at the site entrance or reception showing where the panels and isolation switches are (5.14.3).

Cable routing and protection

• Plan DC cable routes inside the building with firefighters in mind, both where the modules are and on the internal and external routes (5.5.13).
• Keep the internal DC run as short as possible. Where cables pass through occupied areas, give them mechanical protection, such as covered cable tray, because they may still be live in a fire (5.5.14).
• Run DC cables on supported cable management with drainage, tied against wind movement but not so tightly they're stressed (5.7.7). Don't let them lie in water, including inside mounting rails or on flat roofs where water pools (5.7.10).
• Check routes for sharp edges (5.8.4), shade DC cable exposed to UV (5.8.6), and in farm buildings or anywhere rodents are a problem, use sealed trunking or armoured PV cable (5.7.9).
• Inverters lose around 3% of their conversion as heat, so place them with care and keep their ventilation clear (5.5.17, 5.3.12). Automatic fire detection should be installed wherever inverters, isolators and distribution boards sit inside the building (5.3.9).

Connectors and installation

Given the BRE finding, this is where RC62 is most specific. Don't mix DC connectors from different manufacturers: use the connector the panel manufacturer recommends, assembled to its instructions, with the right crimping tool and gland torque. RC62 notes that IEC 62548:2016 and IEC 60364-7-712:2017 don't allow connectors from different makers to be joined, and suggests the operator keeps compatible spares (5.7.4).

• Inspect during the install, not only at the end, so DC cable isn't pinched under modules, a fault that is hard to find later (5.7.5, 5.8.3).
• Keep connectors lying horizontally, off the roof surface and secured, so water can't run in (5.7.6).
• Fit outdoor DC and AC isolators with correctly torqued, bottom-entry glands (5.7.13).
• No hot work near the system unless it can't be avoided, and then under a permit to work (5.3.2). Clear waste away at the end of each working period (5.3.3).
• Every PV project falls under the Construction (Design and Management) Regulations 2015 (5.5.2). Design to the IET PV Code of Practice and MCS requirements (5.5.3), and install to MCS and the IET Code of Practice (5.7.1).

Inspection, commissioning and handover

Inspection follows BS EN 62446-1:2016, and testing and commissioning follow the IET PV Code of Practice and BS EN 62446-1 (5.8.1, 5.9.1). With module-level power electronics, use the manufacturer's test procedures (5.9.2). On bigger jobs, check the supply chain for balance-of-system parts, such as DC cable, connectors and isolators, which subcontractors often source (5.8.2).

At handover, explain the system to the nominated operator and leave full documentation (5.10). RC62 lists what the handover should cover: the purpose of regular visual checks, the damage to look for after a gale or thunderstorm, cleaning and day-to-day maintenance, watching for damaged cable insulation and overheating, and the need for scheduled maintenance (5.3.4), plus where the emergency isolation is (5.3.5). The handover documents may form the CDM health and safety file (5.10.3).

Maintenance after handover

• Installations shall be serviced and maintained to the installer's instructions and BS EN IEC 62446-2:2020 (5.3.13).
• Inspect at least annually (RC62's summary), with Solar Energy UK's best practice manual recommending a competent person inspects commercial systems at least once a year (5.11.1). Inspect again after a storm or extreme weather (5.11.14).
• Insurers expect a regular cleaning programme for all commercial installations, because bird droppings and dirt cause hot spots (5.11.9). Cleaners should know the fire and electrocution risks and work to a risk assessment and method statement (5.11.10).
• Routine insulation resistance testing is recommended, and string series resistance testing can catch connectors starting to heat up (5.11.11). Thermal imaging, by drone where roof access isn't safe, is a cost-effective way to check module health (5.11.12).
• Live online monitoring with error alerts gives early warning of problems (5.11.6).

What the insurer will want to see

RC62 does not set out a single sign-off process, and each insurer has its own requirements. What it does give is a checklist (section 6) with Yes, No, N/A, action required, due date and sign-on-completion columns, following the same sections as above. It is aimed at the building owner and their insurer, so expect it to be used to question your design. The items most likely to come back to you:

• A fire risk assessment for the premises, carried out and recorded by a competent person under the Regulatory Reform (Fire Safety) Order 2005, which RC62 says shall be done for every relevant project (5.1.1).
• Evidence that the insurer and, where needed, the local fire authority were consulted, and who owns the system (5.1.2).
• The roof's fire classification and a structural engineer's report (6.4.2, 6.4.6).
• A layout showing separation from compartment walls and access routes (6.5.11, 6.4.4).
• Your credentials. RC62 recommends the installer holds, as a minimum, MCS certification for PV and BS EN ISO 9001:2015, SSIP membership such as CHAS or Acclaim, the right competence for DC, low voltage AC and, if relevant, high voltage work, and suitable insurance including professional indemnity. ISO 14001 and ISO 45001 are listed as desirable (5.6.4). PV modules should be MCS certified (5.6.9).
• Commissioning records, handover documents and a maintenance arrangement (6.3.13).

If you're not yet MCS certified, our MCS certification guide covers the steps and costs.

Installer checklist

Most RC62 problems are cheap to fix at the survey and expensive to fix after the proposal. At the first visit:

1. 1Ask who insures the building, and talk to them. RC62 says to discuss the project with the current or prospective building insurer (5.1.2). Find out early whether they have their own PV requirements, and who will own the system if it isn't the building owner.
2. 2Check the roof's fire rating. RC62 recommends non-combustible roofs meeting Class A1/A2-s1, d0 to BS EN 13501-1 (5.4.2), and says a new system shall not lower the roof's fire performance (5.1.3). Sandwich panels and insulated build-ups need checking, not assuming.
3. 3Mark the compartment and fire walls on the layout. Keep modules at least 2.5m from each side of a compartment or fire wall, or 1.2m where the risk of fire spreading across is low (5.5.11, 5.5.12). Arrays and combustible cables should not cross them.
4. 4Get the structure checked. RC62 says a competent person should carry out a structural survey before installation, and calls for a thorough structural review on ballasted systems because of water pooling (5.4.6, 5.4.7).
5. 5Plan the DC route and isolation. Keep the internal DC run short, protect it where it passes through occupied areas, and decide early whether a fire service switch is needed (5.5.13, 5.5.14, 5.14.6).
6. 6Leave room to work and to fight a fire. Allow clear access routes for maintenance and firefighting, and avoid covering the roof so densely that firefighters can't vent it (5.4.4, 5.4.5).
7. 7Agree the maintenance before handover. RC62 expects inspection at least once a year and a cleaning programme for commercial systems. Price it into the proposal rather than leaving it to the customer (5.11).

The rest of the site visit is in our commercial solar survey checklist, and the grid side is in the G99 application guide.

RC62 and solar fire safety: FAQ