Snow and Wind Loading on Solar Panels

Wind loading

How panels withstand wind

Solar panels are essentially flat plates mounted at an angle — exactly the kind of shape that wind can push, pull, and twist. The mounting system must resist:

• Uplift — wind flowing over the panel creates low pressure above it (like an aircraft wing), trying to pull it off the roof
• Downward pressure — wind hitting the panel face pushes it into the roof
• Lateral forces — wind from the side creates shear loads on the mounting brackets

UK mounting systems are engineered to handle these forces with significant safety margins. The standard design load for solar installations considers wind speeds from the site-specific wind zone map, typically:

• Basic wind speed: 21–30 m/s depending on location (higher in Scotland, coastal areas, and elevated sites)
• Design wind pressure: typically 1,000–2,400 Pa after accounting for height, terrain, and exposure factors

Most quality solar panels are rated to 2,400 Pa front load and 1,200 Pa rear load. The mounting system (rails, hooks, fixings) must match or exceed this.

How panels fail in storms

Panel damage from wind is extremely rare in the UK, but when it happens, the cause is almost always:

1. Poor installation — insufficient roof hooks, missed rafters, or weak fixings
2. Damaged or decayed roof structure — the panel mounting is only as strong as the rafters and tiles it's attached to
3. Flat-roof ballast failure — insufficient weight holding the mounting frames down on flat roofs
4. Extreme events — once-in-a-century storms exceeding design parameters

Well-installed solar panels on a sound roof structure will comfortably survive any storm the UK typically experiences.

Snow loading

Is snow a real concern in the UK?

For most of the UK, no. Snow loading on solar panels is a minor consideration because:

• UK snowfall is typically light — heavy snow is infrequent in England and Wales
• Panels are tilted — snow slides off pitched panels naturally
• Dark surfaces absorb heat — even on cold days, panels absorb some sunlight through snow, warming slightly and promoting melting
• Snow doesn't last long — UK temperatures rarely stay below freezing for extended periods in most regions

Where snow matters

• Scottish Highlands — significant snowfall and extended cold periods
• Elevated sites (above 200m) — more snow, colder temperatures, slower melting
• North-facing roofs — snow lingers longer without direct sun
• Flat panels — snow sits on horizontal panels without sliding off

For these situations, the structural engineering must account for snow loads as per BS EN 1991-1-3 (Eurocode 1: Snow loads). Your installer should check the snow zone map for your location.

Snow load specifications

Solar panels are typically rated for a snow load of 2,400–5,400 Pa (equivalent to roughly 0.2–0.5m of packed snow). UK ground snow loads range from 0.3 kN/m² in lowland southern England to 1.0+ kN/m² in Scottish Highlands.

The mounting system and roof structure must support the combined weight of the panels plus snow. A structural assessment is essential for properties in high-snow areas.

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Should you clear snow off panels?

No. Do not climb on your roof to clear snow from solar panels.

The safety risk of climbing on a snow-covered, slippery roof massively outweighs any benefit from a few hours or days of restored generation. Falls from height are a leading cause of fatal injuries in the UK.

Instead:

• Wait for it to melt — it usually does within a day or two in most of the UK
• Accept the production loss — a few days of zero generation in winter has minimal impact on annual yield (winter generation is already low)
• If snow persists for weeks (exceptional circumstances), use a soft-bristled telescopic brush from ground level to gently push snow off the lower edge of accessible panels

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Mounting system standards

MCS-certified installations must comply with MIS 3002 (the MCS installation standard for solar PV), which requires:

• Roof survey assessing structural capacity, tile condition, and rafter spacing
• Wind load calculation for the specific site using BS EN 1991-1-4
• Snow load calculation where applicable
• Fixing specification — correct hook type, rail size, and fixing intervals for the calculated loads
• Documentation proving the mounting system meets the loads for that specific site

This is one of many reasons MCS certification matters — it ensures your installation has been engineered for your specific roof, location, and conditions. A non-MCS installation may skip these calculations.

Extreme weather events

The UK has experienced increasingly severe storms (Storm Eunice in 2022, Storm Ciaran in 2023). Reports of solar panel damage from these events were extremely rare — a testament to the robustness of properly installed systems.

However, if you do experience storm damage:

1. Do not approach damaged panels — they may still be generating voltage in daylight
2. Switch off the system at the isolator if safely accessible
3. Contact your installer for assessment
4. Contact your insurer to report the damage
5. Photograph the damage for insurance and warranty purposes

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