Yes. They work all winter. They make less, and the reasons are not the ones people expect.
Panels run on light, not heat. A cold, clear January morning on the bench above Salt Lake or Boise is a good morning for a solar panel, and cold cells actually convert a little more of the light they get than hot cells do in July. If anything, winter air helps.
What cuts winter production is that the sun is up for nine hours instead of fifteen and it sits low in the south, so its light comes in at a slant and spreads over more roof. A December day in northern Utah or southern Idaho produces a fraction of a June day. How big a fraction depends on the roof pitch and direction, so we do not put a percentage on a page. Your monitoring app will show you the curve after the first year. The sizing math we use already accounts for it, because we size to the whole year, not to the best month.
On the Wasatch Front and in the Cache and Treasure valleys, a winter inversion parks a lid of haze over the valley floor for days at a time. Under it, panels produce like it is overcast, because it is. Homes on the benches above the inversion keep producing. There is nothing to do about it except know it is coming and let the annual number carry it.
Snow on a panel stops it cold. Snow on a panel does not stay long. Panels are smooth glass, they sit on a pitch, and the dark surface warms as soon as the sun touches the edge, so on most roofs we install the snow slides off in a sheet within a day or two of the storm, sometimes all at once with a noise you will learn to recognize. A few days of lost production after a big dump is normal and it is already in the annual estimate. What we tell every customer: do not get on the roof to clear it. Not with a rake, not with a broom. A winter roof is how people get hurt, and the panels will clear themselves.
If your array is on the ground, you can brush it off from the yard. That is one of the reasons we like ground mounts on lots with the room.
No. The install season runs all year on our crews, and a system finished in November starts earning in November. The panels are not waiting for warm weather. They are waiting for daylight, and there is daylight every day, even under the inversion.
Written and reviewed by the Intermountain Wind & Solar team. Reviewed September 2026.
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