Are Solar Panels a Fire Hazard?
Solar panels have become a common sight on roofs of every kind, from family homes to the large warehouse and industrial sheds that increasingly carry arrays across their entire roof area. As a source of renewable energy they are a thoroughly good thing, but because a photovoltaic system is, at heart, an electrical installation generating power on your roof, it carries a fire risk like any other electrical system. The risk is genuinely low, and it should not put anyone off solar, yet it is real enough that building owners and responsible persons are right to understand where it comes from and how it is controlled.
What a solar installation actually is
A photovoltaic, or PV, system captures the sun's radiation and converts it into electricity through what is known as the photovoltaic effect, using cells made from a thin layer of semi-conducting material sandwiched between glass and a polymer or glass backing. The panels themselves are only part of the system. The direct current they produce is converted to alternating current by inverters, for use in the building or export to the grid, and many installations now include a battery energy storage system, so that power generated by day can be used after dark. Each of those components, the panels, the connectors, the inverters and the batteries, is a place where a fault could in principle start a fire, which is why the whole system, rather than just the panels, is what deserves attention.
Can solar panels catch fire?
They can, although it is uncommon. The more useful point is that the number of incidents has been rising in step with how many systems are being installed. Reporting in 2023 noted that 66 solar related fires were recorded in the UK in the first seven months of that year, more than the 63 reported across the whole of 2019, a rise that tracks the rapid growth in installations rather than any sudden flaw in the technology. As solar becomes more widespread, simply understanding the common causes is the first step in keeping the risk where it belongs, which is very low.
What causes PV fires
Most solar fires trace back to a small number of recurring causes, and they are worth knowing because each of them is preventable.
The first is installation faults. A PV system installed by someone without the right competence can be left with loose or poor connections that develop into a fire risk over time, which is why the choice of installer matters a great deal. The second is product defects, where poor quality or incompatible components, particularly connectors, raise the risk of failure. The third is planning and design, the clearest example being an array installed on a combustible or partially combustible roof with no fire-resistant covering beneath it, so that a fault in the system can readily involve the building itself.
The fourth group is external influences, which accumulate gradually over the life of the system. Moisture and water ingress into the DC and AC connectors is a known cause of failure, and the gradual accumulation of dirt, bird droppings, leaves and other debris on or beneath the panels can create shading across a cell, producing localised hot spots that, in the worst case, escalate to burning. None of these develops overnight, which is precisely why regular inspection and cleaning are so effective at heading them off.
Battery storage adds another dimensionWhere an installation includes a battery energy storage system, the lithium-ion batteries bring their own considerations, since a battery fault can lead to thermal runaway, a self-sustaining reaction that is difficult to extinguish. A system with battery storage should be assessed with that in mind, including where the batteries are sited in relation to escape routes and the rest of the building.
How the risk is controlled
The measures that keep PV fire risk low are well established. A suitable fire risk assessment that takes the installation into account is the starting point, ideally alongside a conversation with the building owner and the insurer, since insurers increasingly take an interest in rooftop solar. The system should be designed and installed by a certified, competent professional working to the IET Code of Practice for solar PV and to the requirements of the Microgeneration Certification Scheme, which sets and maintains the standards for small-scale renewable technologies and the contractors who fit them.
On the building side, roof materials should be non-combustible wherever possible, with a fire-resistant covering applied where the substrate calls for it, so that a fault in the array cannot easily spread to the structure beneath. A routine of regular cleaning and inspection by a suitably trained person, paying particular attention to bird droppings and the build-up of litter and leaves around and under the panels, addresses the slow external causes before they matter, and appropriate security measures help guard against the theft and vandalism that can damage a system. The full set of recommendations is set out in the RISCAuthority document RC62, the recommendations for fire safety with PV panel installations, which is the reference point we would point a building owner towards.
For commercial and industrial premises in particular, where arrays can cover a very large warehouse or industrial roof, the scale of the installation makes all of this more important rather than less, because a fault on a roof of that size has a great deal of building beneath it. Bringing the PV system within the scope of the building's fire risk assessment, rather than treating it as a separate item that someone else looks after, is the simplest way to make sure it is genuinely accounted for.
As independent assessors covering the North West, North Wales and the West Midlands, we consider rooftop solar as part of the wider fire risk assessment of a building, looking at how the installation sits in relation to the structure and the people who use it, and pointing owners towards the right specialist standards where a deeper technical inspection of the system is warranted.
Solar panels on your building?
We can take your rooftop PV installation into account as part of a fire risk assessment, looking at how it sits alongside the building and its occupants and where further specialist checks may be needed. If you would like to discuss it, please get in touch.
Get in touch Fire Risk AssessmentsThis article is provided for general guidance and does not constitute professional advice for any specific premises, nor a technical inspection of a photovoltaic installation. It refers to the IET Code of Practice for solar PV, the Microgeneration Certification Scheme and RISCAuthority guidance including RC62. Considerable care has been taken to ensure accuracy at the time of writing, but legislation and guidance change over time. Fletcher Risk Management Limited provides Fire Risk Assessments, Fire Door Inspections and Fire Safety Training across the North West, North Wales and the West Midlands.