Cold is good for panels
Solar cells lose a little efficiency as they heat up, which is why every spec sheet lists a temperature coefficient. On a clear 20-degree January morning in Colorado, panels run cooler and convert light a bit more efficiently than on a 95-degree July afternoon. High elevation adds thinner air and often clearer skies.
Cold doesn’t make up for short days, though. For Denver, the PVWatts model from the national renewable-energy lab in Golden estimates that a south-facing array at a typical roof pitch makes roughly two-thirds as much in December as in June: about 104 kWh per installed kW versus about 156. That seasonal swing is built into how we size your system.
How snow comes off
Panel glass is smooth and dark, so a thin layer of snow lets some light through, the panel warms, and the whole sheet lets go and slides. On a typical Front Range storm followed by sun, arrays often clear within a day or two, sometimes within hours. Steeper arrays shed faster. Low-slope and flat-roof arrays hold snow longer.
Clearing snow yourself is rarely worth the risk. Climbing onto a snowy roof is dangerous, and metal shovels or ice scrapers can scratch the glass or damage the frame. If you want to clear an array, do it only from the ground, with a soft-headed rake made for solar panels, or put the array somewhere you can reach it, like a ground mount.
Where the snow lands matters
Panels shed snow in sheets, and a sheet sliding off a two-story roof can be heavy. We avoid putting arrays directly above entry doors, walkways, decks, driveways and gas meters, and we talk about snow guards where the layout can’t avoid those spots. This is a design conversation worth having before the permit is drawn, not after the first storm.
Mountain homes add ice dams and deep drifts. An array can change how snow sits on a roof, so we look at eaves, valleys and where meltwater will refreeze before we finalize the layout.
Snow load, racking and mountain roofs
Every county and city building department sets a design snow load, and in the high country it can be several times the Front Range value. Racking, attachments and sometimes the roof framing itself have to be checked against it, which is why mountain permits often need an engineer’s letter. A quote that doesn’t mention snow load for a home above about 7,000 feet should prompt questions.
Ground mounts are the other answer in deep-snow country. We set the lower edge high enough to clear expected drifts and use a steeper tilt so snow sheds on its own. You can also reach the panels from the ground. On a foothills or mountain lot with room, a ground mount often beats a shaded, snow-loaded roof.
Net metering carries summer into winter
Under Xcel Energy’s net metering, extra solar you send to the grid in spring and summer becomes credit on your account that rolls forward, and it’s what covers the shortfall in December and January. Co-ops and municipal utilities settle credits on their own schedules, and some pay less for exported energy than they charge you. Check your utility’s rules; our net-metering guide covers them.
That’s why we size on your 12-month usage and a full year of modeled production, not a single month. A system that looks “too big” in June is usually right-sized for the year.
Batteries care about cold more than panels do
Lithium batteries protect themselves in the cold. Tesla lists Powerwall 3’s operating range as –4°F to 122°F. Enphase’s IQ Battery 10C datasheet notes that charging power is reduced below 59°F and discharging power below 32°F. Neither will stop working the first cold night, but a battery on an unheated north wall at 8,000 feet behaves differently from one in an attached garage.
Where we can, we put batteries in a garage or another sheltered spot, both for cold performance and to keep snow and sun off the enclosure. Outdoor installs are fine when the equipment is rated for it; we just plan the spot with winter in mind.
FAQ
Questions we hear
How much production do I lose to snow in a Colorado winter?
It depends on your elevation, tilt and how long snow sits. On the Front Range most snow slides off within a day or two of sun, so snow is a small part of the winter dip. Short days and low sun angle cause most of it. We model a full year for your address rather than quote a blanket percentage.
Should I brush snow off my panels?
Usually no. It isn’t worth a fall, and hard tools can scratch the glass. If you want to clear a ground mount or low array, use a soft-headed rake made for panels, from the ground. Otherwise let the sun do it.
Do panels make any power when covered in snow?
A thin, light layer lets some light through; a thick, wet layer stops production until it slides. That’s part of why we favor steeper tilts in snowy areas.
Is solar worth it in mountain towns with heavy snow?
Often, yes. High elevation and clear winter skies help, but snow load, shading from pines and steep terrain add design and permitting work. A ground mount with a steep tilt is frequently the best option on mountain lots with room.
Will snow sliding off my panels damage anything?
It can, if the array sits above a walkway, door, deck or meter. We plan layouts to avoid those spots and add snow guards where needed.
Can my battery sit outside in winter?
The batteries we install are rated for outdoor use, but they reduce charge or discharge power in deep cold to protect themselves. A garage or sheltered wall is usually the better spot in Colorado.