Do Solar Panels Work in Winter? Why Winter Is a Smart Time to Go Solar in St. Louis
Do Solar Panels Work in Winter? Why Winter Is a Smart Time to Go Solar in St. Louis
When St. Louis homeowners start thinking about solar, one question usually comes up first: will it still work when it’s cold, cloudy, or snowing?
The short answer is yes. Solar panels keep producing electricity all winter. Output dips because the days are shorter and the sun sits lower in the sky, not because of the cold.
Here’s what winter really means for a solar system in St. Louis, and why it’s a smart time to start a project.
Main points:
- Solar panels run on sunlight, not heat, so they keep working through the winter.
- Cold temperatures help panels operate more efficiently.
- Winter production is lower mainly because of shorter days and a lower sun angle.
- Net metering bill credits and battery storage help balance seasonal changes in output.
- Starting your project in winter puts your system on track for peak spring and summer production.
Do Solar Panels Work in Winter?
Yes, solar panels work in winter. They generate electricity any time daylight reaches them, including on cold, cloudy, and snowy days, though total output is lower than in summer because winter days are shorter and the sun is lower in the sky.
That’s because panels run on light, not heat. As long as light reaches the panels, they keep producing.
For St. Louis homeowners, that means solar panels in winter still offset your electricity use, even when each day’s output is lower than in summer.
How Cold Weather Affects Solar Panel Efficiency
Are solar panels less efficient in winter? The opposite is true.
According to the U.S. Department of Energy, solar cells generally work best at low temperatures. Panels lose a small amount of efficiency as they heat up and gain it back as they cool down, so a cold, clear winter day can deliver some of your system’s most efficient hours of the year.
Every panel has a temperature coefficient, a rating that shows how much output drops for each degree Celsius above a standard test temperature of 77 degrees Fahrenheit. A coefficient closer to zero means the panel handles heat better.
On a hot July afternoon, rooftop panels run hotter than that test temperature, which slightly trims output. In January, they stay cool.
Why Solar Panels Produce Less in Winter
So, do solar panels produce less in winter? Yes, but not because of the cold. Three things drive the seasonal dip:
- Shorter days: Fewer daylight hours mean fewer hours of production.
- A lower sun angle: Winter sunlight hits panels at a more oblique angle and travels through more of the atmosphere, so less energy reaches them.
- More cloud cover: Cloudy days reduce output, though panels still produce power from indirect light.
A well-designed system is sized around a full year of production, not one season.
Estimated Monthly Production for a St. Louis Home
Estimates are for a 7-kilowatt, south-facing roof system with a 25-degree tilt and 14% system losses, the PVWatts default. We modeled them with the PVWatts calculator from the U.S. Department of Energy’s National Laboratory of the Rockies, using typical-year weather data for St. Louis. Your system’s actual production depends on its size, roof direction, shading, and local weather.
What Happens When Snow Covers Your Solar Panels?
Solar panels and snow usually coexist just fine. Panels are tilted, and their dark glass absorbs sunlight and warms up, so melting snow tends to slide right off.
According to the U.S. Department of Energy, most snow melts quickly off solar panels or blows off in the wind. Heavy snow that sticks around can limit production until it clears.
Snow on the ground can even reflect extra light onto uncovered panels.
In St. Louis, heavy snow cover rarely lasts long. The National Weather Service reports that the area averages a little over 18 inches of snow per winter season, and prolonged stretches of extreme cold are rare.
How Net Metering Balances Summer and Winter Production
Net metering credits you for extra electricity your system sends to the grid, helping smooth out the gap between long summer days and short winter ones.
Under Missouri’s net metering law, the power your panels send to the grid offsets the power your home pulls from it during the same billing period. When your system produces more than your home uses in a billing period, your utility company applies a credit for the excess to your next bill.
Those excess credits are valued at no less than your utility’s avoided fuel cost, which is typically lower than the retail rate you pay, and they expire 12 months after they’re issued. That’s why the best results come from sizing your system around your home’s annual electricity use, so sunny-month production and winter usage balance out over the year.
Illinois rules work differently. Since January 2025, new solar customers in Southern Illinois receive Illinois net metering credits that offset the supply portion of their bill, but not delivery charges.
Solar Batteries and Winter Power Outages
Winter storms can knock out power. A standard grid-tied solar system shuts off during an outage, a safety feature that protects utility crews working on the lines.
Adding battery storage changes that. A battery stores extra solar energy and keeps your essential circuits running when the grid goes down, so you can keep the lights on, the refrigerator cold, and the furnace fan running.
Pairing storage with a home solar installation is one of the most reliable ways to prepare for a winter power outage at home.
Why Winter Is a Smart Time to Start Your Solar Project
Starting the process in winter means your system can be ready for spring and summer, when production peaks.
Here’s what happens before your system goes live:
- Consultation and site assessment: Brda Electric evaluates your roof condition, sun exposure, shading, and electrical panel. This is a good time to consider the best roof types for solar if your roof is due for replacement.
- System design and proposal: Brda designs a custom system based on your energy use and roof layout, then walks you through a clear proposal.
- Permitting and utility coordination: Brda secures permits and handles the interconnection paperwork with your utility company.
- Installation: Brda’s licensed, in-house electricians install your panels, wiring, and inverter equipment.
- Inspection and activation: Once the final inspection clears, your system is activated and starts generating power.
Timing matters for incentives, too. Qualifying Missouri and Illinois homeowners may be eligible for tax savings worth 50% or more of their system’s cost. A separate option may offer a cash payment of about 25% of the system’s cost. These options have deadlines, and planning and installation take time. Eligibility and savings vary. Learn more about current solar incentive programs.
Planning ahead in winter also gives you time to compare equipment with the Solar Panel Buyer’s Guide and review flexible financing options.
Get Your St. Louis Home Ready for Solar Season
Solar panels keep working through a St. Louis winter, and winter is the best time to plan. Starting now gives you time to design, permit, and install your system before peak production in spring and summer.
Family-owned since 1989, Brda Electric is a local electrical contractor that designs and installs solar systems for homeowners across St. Louis and Southern Illinois. Our licensed, in-house electricians handle every step, so your system is built to perform in every season. For a deeper look at going solar, explore the complete home solar guide.
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Frequently Asked Questions
Do solar panels work when it’s cloudy or snowing?
Yes. Panels produce power from direct and indirect sunlight, so they work on cloudy days at a reduced level. Light snow has little effect, while heavy snow pauses production until it clears.
How much less do solar panels produce in winter in St. Louis?
Based on the PVWatts estimates above, a typical St. Louis home system produces roughly half as much in December as it does in July. November through January are the lowest-producing months, while late spring and summer are the highest.
Should I remove snow from my solar panels?
Usually, no. Snow tends to slide off tilted panels on its own. Never climb onto your roof, and call a professional if heavy snow or ice is a concern.
Can solar panels power my home during a winter power outage?
Only with battery storage. A grid-tied system without a battery shuts off during an outage for safety. A solar battery stores energy so your essential circuits stay powered when the grid goes down.
Is winter a good time to install solar panels?
Winter is a great time to start. Design, permitting, and utility approvals take time, so starting in winter helps your system be ready for peak spring and summer sunlight.