Do solar panels work in a Montana winter?
They work, and a system sized on the whole year is built to carry December. A panel in Whitefish produces about three times as much electricity in July as it does in December, and the design expects exactly that. The actual monthly shape is below, from NREL’s PVWatts production model, so you can see it before anyone asks you to sign anything.
A year on a Whitefish roof
The table shows how many kilowatt hours one kilowatt of installed panels produces each month in Whitefish, facing south at a 30 degree tilt, with typical real-world losses already counted. Multiply by system size and the shape holds.
| Month | kWh per kW installed |
|---|---|
| January | 45 |
| February | 65 |
| March | 106 |
| April | 119 |
| May | 132 |
| June | 125 |
| July | 152 |
| August | 140 |
| September | 117 |
| October | 85 |
| November | 49 |
| December | 44 |
| Full year | 1,179 |
NREL PVWatts v8 model for Whitefish: premium modules, 14% assumed system losses, typical‑year weather data. NREL’s quoted uncertainty on annual estimates like these is roughly ±10%.
Two numbers to sit with. December: 44 kilowatt hours per installed kilowatt. July: 152. The design never looks at December alone, because a grid-tied system is sized against annual usage, and what your roof sends back to the co-op is credited to your account. Winter is in the math from day one. More than a hundred Northstone systems have been through valley winters this way.
What snow actually does
Snow covers panels, and covered panels make nothing. What matters is how long the cover lasts. Panels are smooth, dark glass mounted at an angle, so on most days after a storm the sun warms the surface and the load slides off in sheets, often while the shingles beside the array still hold white. A stretch of back-to-back storms can keep an array buried longer. The table is why that’s survivable: December and January together account for about 8 percent of the year’s production, so a buried week in January costs the year far less than a cloudy week in June would.
We don’t recommend climbing a winter roof to clear panels. The few kilowatt hours December is holding aren’t worth a fall, and the design already counted December at its real value.
Sizing for a place with real winters
We size a system from twelve months of your actual bills and design to cover about 100% of annual usage. Roof geometry gets modeled per house: pitch, direction, shading. Tilt earns its keep here. The table above assumes 30 degrees, and the same Whitefish roof modeled at a 20 degree pitch gives up about 3.6 percent over the year, most of it in the winter months when the sun rides low.
The residential page covers how a design comes together; a free consultation puts your own roof through the model, in writing, free. Whether it pencils out in 2026 is answered in the worth-it guide, along with the incentives that survived into 2026.
Fair questions
Do solar panels produce anything while snow is falling?
Very little during a storm, and nothing while panels are fully covered. The design already accounts for this: December and January are the two smallest months in the production model, and the annual sizing counts them at their real values.
Should I clear snow off my solar panels?
We’d rather you didn’t. Roof work over ice is a bad trade for the few kilowatt hours a December day holds, and the angled glass usually sheds on its own within days of a storm.
How much less do panels produce in a Montana winter?
In Whitefish, the model puts December at about 44 kilowatt hours per installed kilowatt and July at about 152, roughly a three‑to‑one swing. The full monthly table is above.
Does northwest Montana get enough sun for solar to make sense?
Yes. One kilowatt of panels in Whitefish models at about 1,179 kilowatt hours per year, with roughly ±10% model uncertainty, and more than a hundred Northstone systems in this valley run on exactly that sun. What your own roof would make is what the free consultation shows you, in writing.
Source: NREL PVWatts v8, fetched July 2026 for this site. Production figures are model estimates for a typical weather year, and a given year will vary.