Do Solar Panels Work in Hail? The 2026 UK Guide

Yes. UK panels survive UK hail comfortably. The international standard they’re tested to (IEC 61215) covers 25mm hailstones at 52mph – which is roughly the upper end of what typical British hailstorms produce. Severe events that exceed it are tens-per-century, not annual.

If a sudden hailstorm has just rattled across your roof and you’re glancing nervously at the inverter app, the data is reassuring. Modern panels use 3.2mm tempered glass and pass mandatory hail testing more demanding than what UK weather typically delivers. Real-world claim rates for hail damage run below 0.1% across tens of thousands of installations. The genuine UK risk is small, geographically concentrated in a band stretching from Lancashire to East Anglia, and concentrated in just a few summer months. Worth understanding what the testing actually covers, where the genuine edge cases sit, and what insurance does and doesn’t pay for.

01 // What happens when hail hits a panel

A solar panel is built around a sheet of tempered glass that’s a lot tougher than ordinary window glass. Modern quality panels use 3.2mm tempered glass on the front face, sometimes a second tempered glass sheet on the back (dual-glass), with the silicon cells laminated between them under polymer encapsulant. When a hailstone hits, the glass spreads the impact force across a wide area before it can concentrate on any single cell, and the encapsulant helps hold everything together if a fracture does occur.

The panel also keeps generating during a hailstorm – the cloud cover knocks output down to roughly 10-30% of clear-sky levels, but the cells respond to the diffuse light coming through the cloud the same way they respond to any other low-light condition. Hail itself doesn’t shut the panel off; only physical damage does, and the threshold for that is high.

Three categories of damage are worth understanding because they fail in different ways:

• Glass fracture – the obvious failure mode. Visible cracks on the front face, usually radial from a clear impact point. Compromises waterproofing as well as output.
• Microcracks in the silicon cells – invisible to the eye but detectable with electroluminescence imaging. Can develop from impacts that don’t break the glass, and tend to spread over time as the panel goes through thermal cycles.
• Cumulative degradation – small impacts that don’t break a panel today can leave stress points that weaken it for the next storm. This is one reason post-hail inspection matters even when nothing looks obviously damaged.

02 // The IEC 61215 hail test, in detail

The IEC 61215 international standard is mandatory for any solar panel sold in Europe, and the hail impact test is one of nineteen tests every panel must pass. The procedure is more demanding than most people assume. A pneumatic launcher fires ice balls at 11 specific points across the panel surface – including corners, edges and the centres of cells where the silicon is most vulnerable. The standard test uses 25mm (one inch) ice balls at 23 metres per second, which is about 52mph. The launch velocity must be maintained within 5%, the impact location within 10mm of target, and the panel must show no visible cracking and lose no more than a small percentage of power output.

The clever part of the test is that the lab ice balls are intentionally denser than real hail. Hail formed under industrial conditions sits at around 0.92 g/cm³; natural hail averages around 0.64 g/cm³. The test ice is therefore about 40% denser than typical natural hail of the same diameter, which means the test impact energy meaningfully exceeds what natural hail delivers in the field. The US Department of Energy’s hail mitigation guidance confirms this and notes that all certified panels pass the test.

The standard also offers higher-tier tests with ice balls up to 75mm and velocities up to 30+ m/s, but these are optional and most manufacturers don’t pursue them unless they’re chasing the US “Hail Alley” market. For UK conditions, the baseline 25mm test is genuinely a relevant bar – it covers what UK hailstorms actually produce in nearly all events. For more on related weather questions, our storms guide covers the wind-load picture in detail.

03 // UK hail reality: what we actually get

The UK is genuinely a low-hail country compared to most of Europe and especially compared to the US. The Tornado and Storm Research Organisation (TORRO) maintains the most comprehensive UK hail database, going back to 1141 AD, and their analysis covers more than 2,500 documented British hailstorms. The numbers are mostly reassuring.

• Damaging hail (TORRO H1+) is reported on 6 to 25 days each year, with an average of 14 days per year across Great Britain. Most days affect only small areas.
• Hail at 20mm+ diameter peaks in June (28% of cases) and July (15%) – the convective storm season. Outside of June-September, large hail is genuinely rare.
• Severe hailstorms (TORRO H5+, hail 50mm+) are concentrated in summer. 41% occur in July, 21% in June, and 93% fall between May and August.
• The most intense British hailstorm on record reached H8 in Hertfordshire on 15 May 1697. Only one H8 event has ever been documented in Britain. Most years see no H5+ events at all.
• The heaviest UK hailstone weighed 190 grams, fallen at Horsham (Sussex) from an H7 storm on 5 September 1958. By comparison, US “Hail Alley” routinely produces hailstones over 400 grams.

The UK’s geographic distribution of hail is also useful to know. Damaging hail is concentrated in a band from Lancashire and Greater Manchester southeastwards through the Thames Valley counties (Berkshire, Bedfordshire, Buckinghamshire, Hertfordshire, Oxfordshire), Greater London, and into East Anglia and the East Midlands. Coastal Scotland, Northern Ireland, the South West and most of Wales see meaningfully less hail damage. TORRO publishes the full Hailstorm Intensity Scale with regional analysis going back to 1650.

Climate change is the obvious follow-up question, and the answer is interesting. A 2025 Met Office study published in Nature Communications found that under a high-emissions scenario severe hail in Europe is likely to become less common overall, though very large hail (5cm+) may become more frequent in southern Europe. For the UK specifically, the study notes hail risk remains low into the future. So this isn’t a growing concern for UK solar in the way that, say, flooding or storm winds are.

04 // When hail does cause damage

The genuinely vulnerable scenarios are worth being clear about. Three things in combination are what produce panel damage in the rare cases where it happens.

Tilt angle is one of the more interesting factors here. Research shows that increasing panel tilt from horizontal to 60° improves survival in severe hail from around 82% to 99%. Most UK rooftop installs sit at 30-45°, which is the sweet spot – steep enough that hail strikes at an oblique angle (transferring less force) but shallow enough for good annual yield. Flat-roof installs at minimal tilt are the most exposed configuration but also the rarest in UK residential.

Microcracks deserve a separate mention because they’re the failure mode most people don’t think about. A panel that survived a hailstorm visually intact may have accumulated microcracks in the silicon cells – sub-millimetre fractures invisible without electroluminescence imaging. These don’t immediately reduce output much, but they tend to spread over time as the panel goes through daily thermal cycles, eventually showing up as degraded performance months or years later. Our microcracks guide covers the diagnostic process.

05 // Real-world claim rates and field data

The most useful data on actual hail damage to solar arrays comes from large-scale field studies, and the picture across them is consistent: hail damage is a small fraction of warranty claims even in regions far hailier than the UK. A 2020 study by the National Renewable Energy Laboratory in the US examined more than 50,000 installations and found that hail accounted for fewer than 0.1% of warranty claims – around 1 in 1,000.

The US figure includes severe hail regions where stones routinely exceed 50mm and which produce most of the world’s commercial hail damage data. UK hail risk is lower than the US national average and probably comparable to the German national average (Germany has a similar climate and similar rooftop solar fleet). For most UK households, the hail risk to a solar array is statistically smaller than the risk of damage to the rest of the roof in the same event.

Worth noting one industry context: a 2024 Trina Solar industry report found that hail damage accounts for 54% of total US solar loss claims with $58.4 million average per claim. Both numbers sound alarming, but they’re driven entirely by utility-scale projects in US hail-prone regions, not residential. UK residential hail risk is in a completely different category. Our storm damage guide covers the broader weather-damage picture.

06 // Insurance and warranty: who pays for what

The question that most needs clear answers, because the most common mistake is trying to claim through the wrong channel. Three relevant cover types and only one of them is the right route for hail.

• Buildings insurance: yes. Standard UK home buildings insurance covers hail damage to solar panels, almost always. Most policies define a hail event by stone size or by damage caused (broken glass, dented metalwork). Make sure panels are listed in your policy schedule and the rebuild value reflects them.
• Manufacturer panel warranty: no. Hail damage is excluded as force majeure or “act of God” under nearly every panel warranty. The warranty covers manufacturing defects and gradual performance degradation, not weather events.
• Installer workmanship warranty: no, unless install quality contributed. Hail through clean tempered glass isn’t a workmanship issue. The exception would be where loose mounting hardware allowed excessive panel flex on impact.

Older policies (pre-2015) sometimes have explicit exclusions for “alternative energy installations”. Most have been updated since, but a five-minute phone call to your insurer to confirm cover is worth doing if you’re not sure. Our solar panel insurance claims guide covers documentation and process in detail.

07 // Practical: what to do, what not to bother with

For most UK homeowners, the right level of preparation is “almost none” – the hardware is already specified for it, the insurance covers the rare event, and most years there’s no damaging hail at all in your area. A short list of things genuinely worth doing.

• Confirm 3.2mm tempered glass on quote sheets. If you’re buying new, this is the current industry standard. Older or budget panels with 2mm glass are best avoided in any hail-prone region.
• Consider dual-glass panels in hail hotspots. If you’re in the East Midlands, Thames Valley, or East Anglia, the marginal cost of glass-glass panels is worth it for the meaningfully better impact resilience.
• Confirm tilt angle is 30-45°. Standard for UK pitched roofs. Flat-roof installs at minimal tilt are the most hail-vulnerable configuration.
• After major hailstorms, photograph and check generation. From the ground, never on the roof. Compare output to the previous fortnight in the inverter app.
• If output drops 10%+ unexplained after a hail event, get it checked. Microcracks are the likely cause and they’re covered by buildings insurance.
• Don’t pay a premium for “hail-resistant” panels in low-risk regions. Standard tier-1 IEC 61215-certified panels handle UK hail comfortably. The premium is a US Hail Alley product.

For owners considering broader weather resilience, our guides on whether solar panels cause roof leaks, lightning, and UK climate panel selection cover the adjacent territory.