Do Snow and Hail Damage Solar Panels? UK Guide

Snow settling on a roof and hail hammering down during a summer storm both look like they should be a problem for something as exposed as a solar panel. In practice, UK solar installations rarely suffer weather damage — not because the weather is gentle, but because the panels and the mounting system underneath them are both tested against exactly this. This guide covers what those tests actually check, what happens to output when snow settles, when ice becomes a genuine hazard rather than a cosmetic one, and what to do (and not do) about it.

Can hail actually crack a solar panel?

Almost never, for a certified panel. Every solar panel sold for UK domestic installation has to pass IEC 61215, the international type-approval standard for crystalline silicon modules, before it can carry the certification that MCS-registered installers require. The hail section of that standard fires 25mm ice balls — roughly the size of a large marble — at the panel surface at around 23 metres per second (roughly 51mph) across eleven separate impact points, including the cell centres, edges and corners. To pass, the panel must show no visible cracking or delamination and no more than a 5% drop in power output afterwards.

That is a genuinely severe test — 25mm hailstones at that speed are large-hail-warning territory, well beyond what most of the UK experiences even in a bad summer storm. A handful of manufacturers additionally test to an extended 35mm ice-ball standard for markets with more extreme hail risk, but that is not required for UK certification. The tempered glass front sheet used on virtually all modern panels is the same category of glass used in vehicle windscreens, which is why hail damage to a properly specified, MCS-certified panel is rare rather than merely uncommon.

What about the weight of snow?

UK mounting systems are load-tested against snow, separately from the panel's own hail rating. MCS 012, the UK standard covering how mounting kits interface with the roof structure, requires the mounting system itself to withstand a downward load of at least 1.0kN/m² (roughly 100kg per square metre), with individual roof hooks or brackets tested to at least 0.25kN each. Snow loading is assessed against BS EN 1991-1-3, the same Eurocode used for the structural design of the roof itself, so a competent installer is sizing the mounting to the same snow-load standard as the building beneath it — not treating the panels as an afterthought.

One detail the current MCS loading guidance calls out specifically: snow can drift and pack against the rear edge of a row of panels, particularly on shallow-pitch roofs or on the lower row of a multi-row array, producing a localised load well above the average ground snow figure for the area. A properly designed system accounts for this in the mounting spec rather than assuming snow load is evenly spread.

Does snow cover actually damage panels, or just cut output?

For the vast majority of UK snowfalls, it is purely an output problem, not a damage problem. A snow-covered panel generates little to nothing while the snow sits on it — the cells need direct light, and even a thin covering blocks most of it. That matters far less to the annual numbers than people assume: December, January and February together typically contribute only around 9–12% of a UK system's annual generation even without any snow at all, because daylight hours and sun angle are already so low. See our full breakdown of how solar panels perform through a UK winter for the month-by-month figures.

Snow typically does not sit for long. Panels are dark, glass-fronted and angled — a south-facing roof pitch of 30–40° sheds snow considerably faster than the flat ground around it, both because gravity does more of the work on a slope and because the dark cell surface absorbs what light does get through and warms enough to loosen the snow's grip on the glass. Flat or low-pitch mounting (common on some flat-roof commercial and outbuilding installs) holds snow for longer, since there is less slope to help it slide, and can lose several days of generation during a prolonged cold snap rather than the day or two typical of a pitched roof.

Ice damming at the panel edge

The genuine hazard is not the panel — it is ice sliding or falling off it. As snow on a panel partially melts and refreezes at the lower edge, it can form a ridge of ice that later releases as a single sheet, sliding off the glass and dropping to the ground (or onto a path, driveway, conservatory roof or parked car below) with no warning. This is the same mechanism as ice damming on a conventional roof, but a smooth glass panel surface can shed a slab more suddenly than tiles or slate. It is worth checking with your installer whether snow guards or a lower-edge rail were fitted or are appropriate for your roof, particularly if the panel's lower edge overhangs a path or driveway.

Should you clear snow off your panels yourself?

No — in almost every case, leave it to melt or clear on its own. The output lost while snow sits is genuinely small in the context of a UK winter, and the risks of trying to remove it yourself are not: climbing onto a snow- or frost-covered roof is a fall hazard even for a competent, equipped professional, and the Health and Safety Executive's roof work guidance treats icy and snow-covered roof surfaces as a serious additional risk factor precisely because they destroy normal footing. Scraping or brushing a panel with a metal tool, a stiff broom or a shovel also risks scratching the anti-reflective coating or cracking the glass — damage the hail test is designed to prevent, self-inflicted instead of weather-inflicted.

If snow genuinely needs clearing — a prolonged, unusually heavy fall, or a flat-mounted system that has lost several days of output — use a long-handled soft roof rake from the ground rather than climbing up, or call a professional. Never attempt it from a ladder against the panel edge, and never in freezing or windy conditions.

Insurance implications

Storm, impact and weather damage to solar panels is normally covered under standard buildings insurance, provided you told your insurer you had them installed. Panels are treated as a permanent fixture of the building, in the same insured-peril category as the roof itself — hail impact, storm damage and the weight of snow (if it did cause structural damage) would typically fall under the same cover as roof damage from a storm. The catch that trips people up is not the weather; it is failing to declare a material change to the property in the first place. See our full guide to solar panels and home insurance for exactly what to tell your insurer and where the gaps commonly appear.

Because a UK-compliant system also has to meet the structural and mounting requirements covered by building regulations, a correctly certified installation gives you a stronger position with an insurer if you ever do need to claim. Our guide to solar panel building regulations covers what your installer should be certifying on your behalf.

For the full picture of how UK winter weather affects your system's output rather than its condition, read our guide to how solar panels perform in a UK winter.