Do Solar Panels Work in Winter? Real Production Numbers and What to Expect

The short answer: yes, solar panels work in winter — and in cold, clear conditions they often work better than on a hot summer day. The catch is shorter days and lower sun angles, which do reduce your total monthly output. Understanding that distinction is the difference between setting realistic expectations and feeling ripped off by your system.

Here's what the data actually shows, what snow does to your panels, and how to plan for the seasonal dip.

Last updated: 2026-06-20

Cold Temperature Actually Increases Panel Efficiency

This surprises almost every homeowner. Solar panels are semiconductor devices, and like most electronics, they perform more efficiently when they're cool. Most panels are rated at 25°C (77°F). Every degree above that, efficiency drops — typically 0.3% to 0.5% per degree Celsius, depending on the panel's temperature coefficient.

Flip that around: a cold January day at 5°C (41°F) gives your panels a 5–10% efficiency boost over their rated output. A brutal July afternoon at 45°C (113°F) could cut efficiency by 8–12% from that same baseline.

This is why solar production per hour of sunlight is often higher in February than August in places like Massachusetts, Pennsylvania, or Oregon.

The actual winter problem isn't temperature — it's daylight. A city like Chicago gets about 5.5 peak sun hours per day in July. In December, that drops to roughly 2.9. Your panels are working harder per hour, but they have far fewer hours to work with.

Real Production Numbers: What to Expect Month by Month

To make this concrete, here's approximate monthly production for a 10kW system in three different U.S. climates, based on NREL's PVWatts modeling data:

Denver, CO (high altitude, sunny winters):

July: ~1,650 kWh
December: ~950 kWh
Winter drop: ~42%

Atlanta, GA (mild winters, moderate sun):

July: ~1,430 kWh
December: ~890 kWh
Winter drop: ~38%

Seattle, WA (cloudy, short winter days):

July: ~1,190 kWh
December: ~380 kWh
Winter drop: ~68%

Seattle is the outlier — it's not just the short days, it's the persistent cloud cover. For most of the continental U.S., a winter drop of 35–50% from peak summer is a reasonable expectation.

The important thing to understand: your installer should account for this in their proposal. If a solar company shows you annual production numbers without breaking them down by month, ask. You need to know what January looks like, because that determines whether you're drawing from the grid (and how much) in your worst months.

Getting multiple quotes that include monthly production estimates — not just annual totals — is the best way to sanity-check these numbers for your specific roof and location. EnergySage is the most straightforward way to get competing proposals that include that breakdown, all without fielding calls from a dozen different salespeople.

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For lighter use — a few key devices, a small space heater, phone charging — the Jackery Explorer 2000 Plus at around half the price point covers most winter outage scenarios. Both units can be recharged from your solar panels if you have them, or from your car, which matters a lot when a storm knocks out power for four or five days.

The Bottom Line on Winter Solar Performance

Solar panels absolutely produce power in winter. Cold, sunny days in places like Colorado, Utah, or New England can produce some of the highest per-hour output you'll see all year. The trade-off is hours, not efficiency.

For most U.S. homeowners, winter production will be 35–55% lower than summer peak — a known, modelable, plannable reality that any well-designed system accounts for. The homeowners who end up unhappy with their solar in winter are almost always the ones who weren't shown realistic monthly projections before they signed.

Know your December number before you commit. Compare proposals that include it. And if winter power outages are a concern in your area, factor backup storage — whether a whole-home battery or a capable portable unit — into your planning from the start.

Start With Accurate Numbers for Your Home

The most useful next step is seeing what a solar system would actually produce in your specific location, on your specific roof. Getting free quotes from multiple certified installers — with monthly production breakdowns — costs nothing and gives you real data to evaluate.

Get competing solar quotes on EnergySage →

Compare offers side by side, see December production estimates, and get a realistic payback period before you talk to a single salesperson.