Jon Stretton has seen more than his fair share of fires caused by solar panels. 

But when he was called out to fix faulty panels on a farm in West Berkshire in March, the energy management specialist was horrified by what he saw.

Jon, who is technical director of energy management company OffGrid Pro, says he was asked by the farmer to assess the 500 solar panels on the farm, which are placed on the roof of a cattle shed, because they stopped working for a few days each time it rained.

But while inspecting the panels, Jon discovered that a cheap connector used to link the panels together meant that one of the so-called 'box junctions', which is a protective box installed at the rear of a solar panel, had recently caught on fire.

Thankfully, the fire went out before spreading, Jon says, leaving the box junction blackened and charred. 

He says he doesn't know why the fire went out but warned that hundreds of animals were at huge risk of burning alive in the cattle shed had the fire spread.

He adds: 'Thank God there was not a huge fire – but this was just good fortune as it could easily have spread.

'It was only because the solar panel system was playing up that we had the call.'

Solar panels are behind more than 170 house fires a year – with fire brigades now being called out on average once every two days to tackle solar panel blazes.

Last week, a set of solar panels on a £600,000 new-build home in Wellingborough, Northamptonshire, exploded while a family was inside.

Ring doorbell footage from a home across the street captured the terrifying blaze, showing the roof of the property bursting into flames on Bank Holiday Monday.

The number of solar panel-related fires has soared 60 per cent in two years, official data shows. 

And there are fears the number of fires could soar as Ed Miliband's 'solar roadmap' is pushing households and businesses to install new panels rapidly.

Under the Labour Government's plan, an area more than three times the size of Birmingham will be filled with solar panels in the next five years.

But the number of fires has increased at a faster rate than the number of installations made in recent years, according to insurance company QBE Insurance, which obtained the data from a Freedom of Information request.

It revealed there were 171 fires involving solar panels in 2024, up from 128 in 2023 and 107 in 2022 – a 60 per cent increase in just two years. 

There were an estimated 1.7 million solar panels across Britain in 2024, just 31 per cent up from 1.3 million in 2022, QBE data shows.

Adrian Simmonds, of QBE, says: 'Solar technology is an essential part of the clean energy transition, but the rapid pace of deployment is cause for concern. 

'Our analysis shows fires involving solar panels has risen at twice the rate of new installations over two years to 2024.'

Mr Stretton says many of the fires are caused by poor connections between the panels and the electricity systems (known as MC4s), sub-standard parts attached to the panels and dodgy installations.

He says: 'Sadly, we are seeing an increasing number of residential and commercial solar installation problems. 

'Lives are already being put in danger, but it is only a matter of time before something worse happens.'

Southampton-based Jon says that the risk can be eliminated for as little as £12 and can be as simple as buying an ArcBox, which fits around dangerous connection points.

In the case of the farm, he says: 'Once we got up into the beams to take a closer look, we discovered that a couple of connections seemed like they might have been crimped rather than having the approved MC4 connections. Such a poor connection is extremely dangerous.'

Lee Masson, a forensic investigator for Halliwell Forensics, a company called on by insurance companies to help discover the source of house fires, says: 'There are a wide range of reasons why a fire might have been started by a solar system fitted to a property.

'Among the problems we have come across is mismatched connectors. If these connectors come from different manufacturers [to the panels] with variable tolerances, there is a chance they might eventually overheat and cause a fire.

'Bad weather or birds on the roof can loosen or dislodge connections and cause wires to degrade – with verdigris on copper forming a green oxidation.

'This instability is a potential source for a fire. There have also been instances where electricity inverter or isolation switches have overheated because of loose wiring or because of incompatible or poorly made products that have simply failed over time.'

Experts are now encouraging households to get their own installations checked urgently.

Mr Masson says cheap Chinese copies of original Swiss MC4 connectors may not be made to the same high standard. 

UK fire and rescue services were called out to 38,144 building fires in the year ending December 2024. During this time only 171 callouts involved solar panels.

But Mr Masson says these fires are among the hardest types for firefighters to put out.

He adds: 'The problem you can have with solar panels is they are on the roof, and even if the mains electricity is turned off, the panels may still be generating electricity – which is still held much like a battery.

'Emergency services can be wary of how they might tackle this as water might not be the ideal solution. Being close to a roof space means a solar fire can easily take hold and spread to other homes, too.'

He says regular maintenance could dramatically cut down the risk of a blaze. He points to rental properties that must have an Electrical Installation Condition Report every five years. A professional solar panel check costs roughly £200.

Mr Simmonds says: 'Safe installation and maintenance are essential to reducing fires. We strongly encourage owners to engage certified installers and ensure regular inspections.'

While solar connections have been behind house fires, there is also a concern about the lithium-ion batteries that are often now used in solar installations. 

These batteries allow households to store electricity to be used at night rather than using it as soon as it is generated.

Damage to lithium-ion batteries can cause chemical reactions to the units where there is overheating, for example in high temperatures during summer months. If flammable gases are released by these batteries, it could trigger fires, he warns.

He says: 'Battery storage introduces additional fire risks when units are installed in lofts, airing cupboards or upper floor spaces that are difficult to access in an emergency. 

'They not only increase the likelihood of a house fire but also the potential severity of one.'