The mercury hit 32°C in Suffolk last week, and four schools switched off their solar arrays after a string of fires. One blaze at a primary school in Bury St Edmunds damaged the roof and forced a full evacuation. The incidents, as reported by LBC News, have prompted a wider review of solar safety in the county. For the 1.3 million UK households now generating their own electricity, the question is immediate: could the same happen at home?
What caused the school fires
Fire investigators in Suffolk have not yet published a definitive cause, but the pattern points to DC isolator switches and inverters overheating. These components convert the direct current from panels into alternating current for the grid, and they generate heat. In a heatwave, with roof temperatures hitting 70°C, poorly rated or ageing kit can fail. The Energy Saving Trust notes that most domestic solar fires stem from installation errors, not the panels themselves. Ofgem data shows fewer than 50 domestic solar fires nationally each year, against 1.3 million systems, a failure rate of 0.004%.
What this means for your bill and EPC
A fire is the catastrophic worst case. The more common risk is a system that simply stops working in extreme heat, costing you generation. A typical 4 kW system loses about 0.5% efficiency per degree above 25°C, so on a 35°C day, output drops by 5%. That’s roughly 0.5 kWh lost per day, worth about 15p at current price cap rates. Not a crisis, but it chips away at the payback period. For EPC ratings, a non-functioning solar array is treated as absent, so if your inverter fails and you don’t replace it, you lose the EPC boost that solar typically provides (often two to three bands).
Who qualifies, and who doesn’t
The schools in Suffolk are commercial installations, often with string inverters serving dozens of panels. Domestic systems are smaller, typically 10 to 16 panels, and use microinverters or optimisers that reduce voltage at the panel level. This makes them inherently safer. But the catch is that many UK homes still have older systems installed before 2015, when standards were looser. If your system has a DC isolator switch on the roof, exposed to direct sun, and you haven’t had it serviced in five years, you are in a higher-risk group. MCS-certified installers now use arc-fault circuit interrupters (AFCIs) as standard; older systems often lack them.
What to do by next summer
Book an annual inspection with an MCS-registered electrician, cost typically £100–£150. Ask them to check the inverter temperature rating (most should handle 60°C ambient), the DC isolator seals, and the condition of the roof cable entry. If your inverter is more than 10 years old, consider replacing it with a modern unit that has built-in thermal shutdown. For households on smart export tariffs, a failed inverter means zero income, Octopus Outgoing pays 15p/kWh, so a month offline costs about £20 in lost generation. The next heatwave is not a question of if but when. Act now, and your panels stay safe, and profitable.
Frequently Asked Questions
Only if you notice unusual smells, buzzing, or visible damage from your inverter or isolator switch. For most modern systems with microinverters or optimisers, switching off is unnecessary and will lose you generation income. If in doubt, contact your installer or an MCS-registered electrician.
Most standard home buildings policies cover solar panels as fixtures, provided they were installed by a certified professional. Check your policy wording, some exclude 'gradually developing' faults like corrosion. The Association of British Insurers recommends notifying your insurer of any new solar installation to avoid disputes.
