Snow on solar panels stops most of the light reaching the glass, so a covered array produces very little until the snow slides or melts off. The safe answer to “should I clear it” is that you leave it: the Health and Safety Executive’s first duty for work at height is to avoid working at height at all where that is reasonably practicable, and the amount at stake is a few kilowatt-hours a day. A zero day with snow lying on the roof is normal, and a zero day on the clear, bright morning afterwards is not. Your own production history tells you which one you had.
Do solar panels work in snow?
Not while the glass is covered. Once the snow slides or melts off, production picks up again by itself, with no fault to fix. How fast it sheds depends on the angle of the panels, the mounting, the glass surface and whether the panels are framed, according to Sandia National Laboratories. A steeply pitched, framed array in the wind is a different case from a shallow one in still air.
Over a year the cost is small. In US data, Sandia puts snow losses at 1 to 12 percent a year, though a single month can lose as much as 100 percent.
Sandia also notes that snow puts “excessive and uneven stress on modules, cells and systems, the long-term impact of which is unknown”. That is about load, not output, and it is why manufacturers write about snow at all.
How much snow a UK roof actually sees
The Met Office puts the UK average at 13.0 days of lying snow a year (1991–2020), with Scotland highest at 23.0. More snow falls than settles. Many of its ten snowiest stations, from Cairngorm Chairlift at 75.2 days down to Ballater Field Centre at 35.4, are mountain weather stations, not houses.
Days of lying snow are measured on the ground, and a pitched roof facing south in weak winter sun is a different surface from a field. Take the UK’s 13 days as a guide to how often the question comes up, not as a count of days your panels were white.
Should you clear snow off your solar panels?
Take this as two separate questions, because they have different answers.
Going up on the roof. Don’t. The HSE’s first rule for work at height is to avoid it where reasonably practicable. It treats all roofs as fragile until a competent person has confirmed they are not, and records falls from roof edges on domestic jobs as well as commercial ones. Even a job of a few minutes on a roof needs properly secured ladders, roof ladders and people trained to use them.
Those rules are written for people at work, not for a householder on their own house, but they are the standard the trade works to, and a clear answer to whether a Saturday in January is the day to get a ladder out. LG’s installation manual puts it in one line: “Installation during rain, heavy wind or snowy day may result in bodily injury or death.”
How to remove snow from the panels you can actually reach from the ground. If part of an array is within reach (a garage roof, a ground mount, a flat-roof frame), use a soft brush, as Canadian Solar specifies, and do not scrape: dry rubbing can cause micro scratches. Canadian Solar’s manual adds: “Do not stand, step, walk and/or jump on modules under any circumstances. Localized heavy loads may cause severe micro-cracks at cell level, which in turn may compromise module reliability and void Canadian Solar’s warranty.” LG’s manual says the same (“Do not stand on or step on the module”) and rules out aggressive and abrasive cleaners or chemicals.
Snow load: what snow does that is not about output
Manufacturers design against snow load, not snow shading. In heavy-snow areas (above 2400 Pa), Canadian Solar says extra support bars should be considered so that snow does not damage the lowest row of panels, and LG recommends extra support on the lower row against slipping snow.
Sliding snow is itself a load the installer has to design for. That is a fact about your mounting system, decided when it was installed. Whether yours was designed for it is a question for the installer or a competent surveyor; you cannot settle it from the ground. If your installer is no longer trading, the installer-gone-bust guide covers who holds the paperwork. Wind and hail leave the same kind of question behind, and solar panels after a storm goes through what can be checked from the ground and what cannot.
What a snow day actually costs
Winter output is small before snow is involved, which is most of the answer.
The same table explains the other winter question. July for that system is 476.04 kWh and December is 136.59 kWh, so December is about 29% of July on an identical roof. A December reading that looks alarming next to your summer numbers is usually the season doing exactly what the model says it does. If El Niño is in the headlines while you read your own December line, what a seasonal forecast can and cannot say about that month is the same weather-or-fault question asked of the season rather than of one snowy morning.
Solar panels not producing in winter: snow, or a fault?
Your own production history answers it, in about ten minutes and with no equipment.
Two zeros look identical in an app and mean opposite things. A zero on a day when snow was lying on the array is the system behaving correctly. A zero on the clear, cold, bright morning two days later, when the neighbours’ roofs are bare and the sun is on your panels, is a fault that has been sitting there, hidden behind a plausible excuse.
The method is a comparison:
- Get your daily kWh. The manufacturer’s app or portal shows production by day, and some will export or email a monthly report. Daily resolution is what you need; a monthly total hides exactly the days you are asking about.
- Get the weather for those same days. Met Office observations, or any station record for your area, tell you which days had snow lying and which were clear.
- Lay them side by side. Zeros that line up with snow days are the season. A zero, or a fraction of what the days either side of it produced, on a day the weather allowed output is the finding. The full walk-through is in how to check your solar production against the weather.
- Then check whether it recovered. Snow ends. If production comes back as the roof clears, you are done. If the array stays flat while everything around it thaws, take it to the offline / not-producing triage.
There is a variant of this that catches slower problems. Compare this winter’s daily numbers with the same weeks last winter on the same roof. With the same tilt, orientation and shading and roughly comparable light, a gap that persists across weeks of similar weather is not snow, and producing less than expected is where that goes next.
Before the first frost rather than after it, check that the alerts from your system come to you, and not only to an installer’s mailbox. A winter of quiet zeros is the exact situation where nobody notices, and who gets your solar alerts walks through where they are actually pointed.
Questions owners ask
Do solar panels work in snow?
Glass covered in snow lets very little light through, so a covered array produces very little until the snow slides or melts off, and then production picks up again by itself. In US data, Sandia National Laboratories puts snow losses at 1 to 12 percent a year, with single months as high as 100 percent.
Should I clear snow off my solar panels?
Not from the roof. The Health and Safety Executive's first duty for work at height is to avoid it where reasonably practicable, and its roof-work page says all roofs should be treated as fragile until a competent person confirms they are not, with falls from roof edges occurring on domestic projects. LG's installation manual states that installation during rain, heavy wind or a snowy day may result in bodily injury or death. Waiting costs a few kilowatt-hours a day.
How do you remove snow from solar panels without damaging them?
Canadian Solar's installation manual says snow should be removed using a soft brush, that dry dirt must not be scraped or rubbed away because it can cause micro scratches, and that you must not stand, step, walk or jump on modules under any circumstances — localised heavy loads may cause micro-cracks at cell level and void the warranty. That rules out shovels, brooms with hard edges, hot water and climbing on the array.
How much does a day of snow cover cost me?
For the PVGIS worked example on this page — 4 kWp, 35° tilt, due south — December comes to 136.59 kWh across 31 days, about 4.4 kWh a day. A fully covered day costs roughly that: about £1.10 at an assumed 25p/kWh. December for that system is about 29% of July, so a low December reading on its own is the season, not a fault.
My panels produced zero. Is it snow or a fault?
Look at the weather record for those days, then at your own daily kWh history in the manufacturer's app or monthly report. Zero on days with snow lying on the array and zero again on the clear, bright days that followed are two different findings. The second one is a fault to triage.