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Solar Panel Snow Loss Calculator (UK)

Calculate yearly energy lost to snow cover on UK solar PV by tilt, latitude and seasonal snowfall. Free calculator covering MCS-compliant installations.

Solar Panel Snow Loss Calculator

Annual snow loss
0.4%
kWh lost to snow
13 kWh
Revenue lost
£4
Monthly losses
MonthLoss (kWh)Loss (%)
Dec21.9%
Jan52.8%
Feb52.8%
Mar21.9%

How to use this calculator

Enter six values to estimate annual energy lost to snow cover and the December-to-March monthly breakdown:

  1. System size (kW) — total installed nameplate. The UK domestic average is 4.0 kWp.
  2. Peak sun hours per day — UK lowland sites average 2.4–2.8 from PVGIS-Europe. The Solar Energy UK Yield Calculator gives location-specific values.
  3. System efficiency (%) — the derate. PVGIS uses 86% (14% loss) by default; MCS-quoted figures often assume around 78%.
  4. Panel tilt (°) — fixed angle from horizontal. The UK roof average is 30–40 degrees.
  5. Annual snowfall (cm) — total winter season. Met Office HadUK-Grid data gives station-level averages.
  6. Electricity rate (£/kWh) — current domestic unit rate. Ofgem’s price cap from January 2026 sits around 25–28 p/kWh.

How much UK snow loss to expect

Lowland England and Wales see modest snow loss. Even the snowiest December-February months from the 2009/10 and 2017/18 events produced annual PV losses under 2% in Sheffield, York, and Birmingham field data shared with Solar Energy UK. Most installations south of Manchester lose well under 1% per year averaged over a decade.

Scotland is different. Sites in the Cairngorms and Northern Highlands receive over 50 days of snow cover per year at elevations above 300 m. A 4 kW Aviemore array can lose 3–5% annually, concentrated in January and February. Tilt and orientation matter much more than panel brand at these latitudes — a 25-degree south-facing roof loses noticeably more than a 40-degree south-facing roof on the same property.

UK snow loss benchmarks

Energy Saving Trust and Solar Energy UK field data combined with PVGIS-Europe snow modelling give these annual loss ranges for a typical 30-degree roof install:

LocationAnnual snowfallSnow loss
Aberdeen20 cm0.6–1.0%
Belfast8 cm0.2–0.5%
Birmingham12 cm0.4–0.7%
Cardiff5 cm0.1–0.3%
Edinburgh18 cm0.5–0.9%
Glasgow15 cm0.4–0.8%
Inverness35 cm1.5–2.5%
London4 cm0.1–0.2%
Manchester10 cm0.3–0.6%
Newcastle14 cm0.4–0.7%

For ground-mount installs at 40 degrees+, halve these. For low-tilt commercial roofs at 10–15 degrees, roughly double them.

The Marion 2013 NREL snow-loss model adapted for UK conditions

The reference for residential snow-loss modelling is Bill Marion’s 2013 NREL paper on Colorado and Wisconsin field data. The model captures three effects:

  1. Sliding clears snow within hours once panel temperature exceeds 0 °C. UK winters rarely sustain sub-freezing daytime temperatures for more than 3–5 days, so snow rarely persists more than a week.
  2. Diffuse albedo from snow on the ground partially offsets direct losses. UK snow on the ground is short-lived, so this effect is smaller than in Scandinavia.
  3. Tilt is the dominant control. Doubling tilt from 15 to 30 degrees roughly halves snow loss in Marion’s data set.

For UK adaptations, the model uses PVGIS-Europe winter-share assumptions (about 8% of annual production falls in December-February at UK latitudes, versus 18% in Mediterranean climates) and a sliding threshold calibrated for wetter UK snow.

What reduces snow loss in the UK

Pick a tilt of 35–40 degrees

UK roof pitches typically sit at 30–45 degrees, which is in the optimum band for snow shedding. Avoid integrated in-roof systems at low pitches under 25 degrees — they trap snow at the bottom edge and take longer to clear.

Choose frameless glass-glass modules

REC Alpha Pure, SunPower Maxeon 6, and LG NeON H glass-glass panels shed snow within an hour of the sun emerging because there is no aluminium edge to catch a snow lip. The premium over standard framed mono-PERC is around £25–£40 per panel.

Use MCS-certified installers familiar with snow-load areas

MCS contractors working in Scotland routinely allow for 50–75 kg/m² snow loading and use racking certified to BS EN 1991-1-3 with a Sk value of 0.40 kN/m² or higher. Lowland England installers often default to Sk 0.25 kN/m², which is fine for Manchester but inadequate for Aviemore.

Solar Energy UK regional guidance

Solar Energy UK’s 2025 Domestic PV Performance in the UK note recommends that installers in Highland, Cumbria, and the Pennines explicitly include a 1.5–3% snow loss line in MCS yield calculations to set realistic homeowner expectations. The note also flags that PVGIS-Europe v5.2 already includes a Marion-style snow correction by default, so comparing to PVGIS figures usually doesn’t require manual adjustment.

Common mistakes

  • Treating UK snow as a deal-breaker. Outside Highland Scotland, snow loss is a fraction of cloud-cover loss. Choosing a slightly different orientation matters more.
  • Walking on snow-covered panels. Even with frost, panel glass is treacherously slippery. CDM 2015 risk assessments preclude this.
  • Ignoring snow-guard requirements over driveways. Building Regulations Part A and CDM 2015 require risk-assessment of sliding snow onto walkways. Add £50–£100 for a snow-guard rail.
  • Comparing to PVGIS without checking snow is included. PVGIS-Europe v5.2 includes snow loss; older v4 outputs do not. Confirm the version in your MCS calculation.

Sources

Frequently asked questions

How much energy do UK solar panels lose to snow each year?
Most of England and Wales averages 5–25 cm of seasonal snowfall, which translates to annual PV losses of 0.3–1.0%. Scotland sees 30–80 cm at lowland sites and 200+ cm in the Cairngorms — those installations lose 1.5–4%. The MCS Domestic Installation Standard MIS 3002 does not require snow-loss derating because UK losses are small compared to the broader weather model used in the SAP solar performance calculation, but high-tilt installations in northern Scotland should account for it in PVGIS-Europe yield estimates.
Should I clear snow off my UK solar panels?
Almost never. UK snow events rarely exceed 48 hours of complete coverage outside the Scottish Highlands, and the few kWh recovered don't justify the fall risk. Energy Saving Trust and MCS both advise against roof access by homeowners. If you live in an exposed Highland site with weeks of continuous snow cover, a soft-bristle telescoping snow rake reaching from ground level is acceptable — never walk on the panels and never use metal tools, which scratch the anti-reflective coating and void the panel warranty under MCS-published guidance.
What tilt should I use in snowy parts of the UK?
MCS recommends 30–40 degrees as the standard optimum for England, which is steep enough to shed UK snowfall within a day of clearing skies. Scottish Highland installations benefit from 40–45 degrees to clear snow faster and align with the lower winter sun angle (sun barely reaches 12 degrees above the horizon at solstice in Inverness). Frameless modules shed snow noticeably faster than framed panels with an aluminium edge that traps a 2–3 cm snow lip.
Does the MCS performance estimate include snow loss?
Not explicitly. The MCS yield calculation uses SAP irradiance tables that already reflect long-term average weather, including overcast and reduced winter irradiance, but it does not separately model panel-surface snow obstruction. For lowland UK sites this is rarely material — snow loss is well within the ±10% MCS quote tolerance. For Scottish Highland installations above 300 m elevation, add 1.5–3% to the expected loss when comparing actual production to MCS estimates.
Will snow damage solar panels in winter?
No. Panels installed to BS EN 61215 standards are rated for at least 5400 Pa snow load — roughly 1.5 metres of wet snow. The UK has never recorded a domestic PV panel failure from snow load. The bigger risk is snow sliding off the array onto a person or vehicle below, which is why some installers add snow guards on south-facing roof edges over driveways. Check your installer's risk assessment under CDM 2015 for buildings with public footways or driveways below the array.

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