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The rise of rooftop solar has been a positive trend, but panel fires have increased by 133% since 2022. Peter Apps investigates what could set them alight
Pete Apps is a journalist and author of the Orwell Prize-winning book Show Me The Bodies which covers the build up to the Grenfell Tower
Pete Apps is a journalist and author of the Orwell Prize-winning book Show Me The Bodies which covers the build up to the Grenfell Tower
In June this year, as the UK experienced one of the sunniest summer periods in history, Suffolk County Council turned off the solar panels at about 80 of its schools.
The problem was that, as well as generating free energy, they kept catching fire. A roof fire in a primary school was the third incident of the year. The panels were deactivated to keep the children in school safely.
It is not just Suffolk where there has been rising concerns about the link between solar panels and fire. In August, insurer QBE published data which revealed a sharp rise in incidents. Fire fighters attended 212 incidents in 2025, compared to 91 in 2022 – a 133% rise which far outstripped the 52% rise in solar installations in the same period.
Rooftop solar is a fantastic invention. It is great for the climate, great for energy security and great for individual households struggling with their bills. Its rise has been a positive trend in the built environment over the last decade.
But is there a risk that in our rush to embrace solar, we have forgotten about the care that needs to be taken around fire safety?
“Ultimately, solar PV, if it’s designed, installed, and maintained properly, is inherently as safe as other fixed electrical installations within the home,” says Luke Gonzales, renewable fire safety consultant at the CGM Group. “Solar PV fires are overall low frequency events, but they do carry high consequences.”
“They [solar fires] can end up in total building loss,” he adds. “The damage can come from the fire itself, as well as the water used during fire and rescue service intervention.”
The fires can be fierce and hard to fight. For building integrated systems, a new design where the panels sit within the roof as opposed to on top of it, a fire can get straight into the building.
“If a system on a roof with tiles beneath catches fire, it can generally burn out with no harm done,” says James Hoare, consultant to RISCAuthority of the Fire Protection Association. “I think now with the in-roof systems, if they catch fire, they could set fire to your rafters, to the combustible membrane in the roof, to the battens. It could be a much more serious event.”
The Developer received a tip: A popular solar panel system was not being sold in accordance with its fire testing
As with any electrical system, solar panels need to be installed safely.
“The fire safety risk is not so much with the panel, but with the connection joint behind the panel,” says Nick Williams, technical partnerships manager for Allume UK. This joint needs to be crimped, and if this process is done poorly or inexpertly it can increase the fire risk. But many solar panels are not installed by qualified, experienced electricians.
“They’re often installed by roofing contractors,” adds Hoare. “There’s been a lack of appropriately skilled tradespeople. It’s a new industry and there’s been pressure to install fast. You can find a roofer who has been putting up tiles all his life all of a sudden being told to crimp and connect together a solar array.”
Earlier this year, The Developer received a tip. A popular solar panel system was not being sold in accordance with its fire testing, we were told.
The S4 Mounting System is an increasingly popular choice for builders looking to ‘integrate’ solar panels into the roofs of buildings – a relatively modern way of fitting solar panels where the panels become part of the roof rather than sitting on top. It is a newcomer into a market previously dominated by two big players – GSE and Viridian.
The S4 system was developed by a French company, which entered the UK market in July 2025. Its product is helpful to house builders because it can work with solar panels of different dimensions. This means it can still be useful as the size of the panels change between different brands and designs.
But an important question is fire. The company has a certificate from the British Board of Agrément (BBA) which confirms its panels meet the standard of ‘BRoof(t4)’. This is the required fire performance for a roof system – which proves it can resist the spread of fire.
S4’s certificate confirms that this system requires an aluminium internal plate between modules. This is the system that was fire tested.
But this was what was causing concern. Marketing material, including videos showing how to install the system, did not include the plate. UK suppliers did not appear to be selling this component, despite stocking the rest of the system.
So was this plate, which could be a crucial part of protecting the mounting system from flames if a fire broke out, therefore not being used when the S4 system was installed?
After reviewing the documents, The Developer approached S4, the BBA and the Microgeneration Certification Scheme (MCS) – the UK’s quality mark scheme for small scale renewables.
After carrying out its own investigations, the BBA responded. It told us the system did indeed require the aluminium internal plate to be compliant with the testing on which the certificate was based, and that marketing materials did not always make this clear.
“Following your enquiry, we have today received from the MCS some marketing material issued by a UK company apparently associated with the certificate holder [the certificate was held by S4’s French arm],” the spokesperson said.
“The BBA was previously unaware of the existence of this UK company or the literature in question, which does not align with that agreed by the BBA with the certificate holder. The evidence we have received gives us concern that the product is not being marketed as described in the certificate.
“As a result, we have raised a number of issues with the certificate holder in France and have in the meantime instigated a suspension of the certificate whilst we investigate.”
A spokesperson for MCS also responded to tell us that it was “engaging with both BBA and S4 to understand the status of the investigation and any subsequent action”.
Ylan Sabban, the founder of S4, responded directly. He told us that the system had been tested successfully in configurations involving two and four solar panels, and that its documentation specified that the aluminium intermodule was required.
However, he added that some installers “may have omitted the intermodule on certain S4 installations” – adding that they had developed their skills working on competitor systems “where the junction between modules is treated differently”.
He told us that after the BBA “raised certain questions regarding UK marketing material” the company “responded fully to those questions, and we have immediately made any amendments or clarifications requested of us”.
“We will continue to strengthen our vigilance and our actions with installers to ensure that they fully understand the importance of strictly following the S4 installation manual and all the requirements of the certified system,” he added. Sabban said the company was investing in installer training and support. “The challenge is to change installation habits developed over many years with the systems that have historically dominated the UK market,” he said.
At the time of writing the BBA certificate remained suspended.
Bird poo or fallen leaves need to be cleared to avoid hotspots
Skilled installation is one problem, then there is the question of maintenance. Like any electrical appliance, solar panels need a degree of monitoring – perhaps slightly more so, due to their environment. “The panels are located in a harsh environment, on a roof exposed to all the elements,” explains Hoare.
Any loose or broken connections need to be fixed, and anything blocking the panels, such as bird poo or fallen leaves, needs to be cleared to avoid shading, which can result in hot spots. But this basic maintenance is not necessarily being done.
“When they first started coming out in the early 2000s, they were sold as a plug-in-and-forget technology,” adds Hoare. “Everyone thought they could just stick them on a roof and not make any commitment to looking after them. But many of the fires out there are caused by lack of maintenance.”
“I think a lack of maintenance is the biggest factor,” adds Williams. “I do think a lot of the fire safety issues can be prevented from basically having adequate maintenance surveys on the solar PV stock.”
In the 2010s the government’s ‘Feed-in Tariff’ (which provided building owners with a return for generating solar for the grid) led to a mini-solar boom. But many of those who installed this put little thought, and certainly no budget, into longer term maintenance.
“When financial incentives such as the Feed-in Tariff drove the growth of Solar PV, systems were often sold as maintenance free,” says Gonzales. “ That has made it harder to persuade some building owners to see the value in inspections and maintenance. Some of the issues we’re seeing now involve systems installed 10-15 years ago that haven’t been properly maintained.”
Even in older ‘building applied’ systems – where the panels are fitted to a mounting system that stands a few inches above the roofing tiles – there can still be a major risk.
“We effectively create a little cavity between solar panels and the roof,” says Jeremy Malet, building safety lead at JLM consultancy. “That cavity can trap a lot of heat in the event of a fire from solar panels. That’s an amazing amount of heat that’s going straight back into the roof.”
Newer systems coming onto the market create additional risks. In August, ‘plug-in solar’ became legal for sale in the UK for the first time. These systems can be purchased by private homeowners and quickly installed. They will likely soon be available in the middle aisle of supermarkets and from big DIY stores.
But there are fears the market might start to be flooded with cheap or unsafe options. The London Fire Brigade has issued guidance to buyers which warns that “poor-quality or counterfeit products” could “overheat or fail.” We will see the impact of this in years to come.
Overall, despite these risks, the growth of solar is a good thing. The UK needs to generate more of its own energy. The planet needs us to do so without releasing carbon. Solar still represents, the best, fastest and cheapest way to achieve both those goals.
But one of the fastest ways that this progress could be lost would be for a big fire to cause consumers or insurers to lose faith in the safety of our systems. A poor reputation for safety is hard to escape. Good installation, routine maintenance and safe products are the way to avoid that.
“We should utilise solar as much as we can,” says Malet. “With regards to energy resilience and security makes so much sense.
“I don’t think the fire safety issues should deter us, but we should be doing it while recognising the potential hazards and the risks.”
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