Do solar panels work in winter?

Key Takeaways

• Solar panels work fine during the winter and can generate energy more efficiently in the cold.

• However, decreased sun hours, overcast skies, and snow buildup can reduce overall output.

• Proper installation and maintenance let you get the most out of your solar panels in the wintertime.

Don’t assume a winter wonderland is a bad climate for solar. Solar panels work well in winter, with cold temperatures actually increasing efficiency by about 20%. That said, shorter daylight hours and snow coverage may reduce overall output. Panels operate well in extreme cold (down to -40°F) and snow typically slides off when installed at proper angles. Read on to learn how to optimize your solar panel performance during winter months.

How solar panels work in winter temperatures

Solar panels work efficiently in winter because of the temperature coefficient effect. This means colder temperatures boost efficiency by about 0.4% to 0.5% per degree Celcius below 25°C (or 77°F). 

For example, at freezing temperatures of 0°C, efficiency increases by 10% to 12.5% compared to 25°C. And if the temperature drops to -20°C, your panels could convert energy 20% to 25% better.

This is all because solar panels work by moving charged electrons between semiconductor materials. Higher temperatures let more electrons recombine without contributing to the current, while low temperatures keep electrons moving forward. 

You can read more about the science behind the phenomenon in this study from the Nanyang Technological University in Singapore.

What about sunlight availability in winter?

While low temperatures can help efficiency, fewer daylight hours and lower sun angles can reduce total output during the winter.

Daylight hours directly impact your solar panel system's performance. In northern regions, peak sun hours can drop by as much as 50%, while the intensity of available sunlight also goes down This double reduction means your system generates less electricity during these months.

Your panels face more challenges as the sun travels a lower path across the winter sky. This lower position creates longer shadows across your array and reduces the direct sunlight hitting your panels at optimal angles.

If you live in higher latitudes, you'll have more intense seasonal variations in solar production compared to those living closer to the equator.

Interestingly, if your property has snow-covered surroundings, you might benefit from albedo reflection, or sunlight bouncing off the snow onto your panels. This can partially offset the seasonal reduction in direct sunlight.

Impact of snow and ice on performance

When winter arrives, your solar panels might face a paradox. They operate more efficiently in cold temperatures, but snow and ice accumulation can reduce their output by blocking precious sunlight from reaching the PV cells.

You’ll still get some output if snow and ice partially cover your solar panels. Modern inverters let individual panels keep working with partial shade. Total snow coverage can stop output, though.

If you've installed your panels at steeper angles (30° or more), the panels can naturally shed snow. This happens because the dark panel surfaces absorb what sunlight they can, creating a thin layer of melting snow that helps the remaining accumulation slide off more easily.

How much snow can a solar system handle?

Solar panels are typically engineered to handle snow loads between 60 and 120 pounds per square foot. That said, you should be mindful that excessive buildup can put stress on the mounting structure. The individual panels might be rated for a certain weight, but how they’re installed on your roof and the type of roof you have also matter.

How to clean snow from solar panels

You might want to consider using a soft rake, roof rake, or leaf blower when the snow isn’t shedding fast enough. These tools allow you to safely clear panels without risking damage to their sensitive surfaces. You can use lukewarm water to clear off ice but avoid hot water.

Frameless panels are better for snowy regions

Frameless solar panels are completely smooth so they shed snow faster. Framed panels have raised edges that can trap snow, on the other hand. This design also reduces structural stress from the weight of accumulated snow. This is something to think about if you live in a snowy region.

Cloudy vs. clear winter days

Wintertime in your region may also bring more clouds. When heavy clouds blanket the sky, your system might produce a fraction of its clear-day capacity. Lighter cloud cover is less problematic.

Overall, cloudy days can reduce output by 23% to 67%. If you add a lower sun angle and fewer sun hours to the equation, your solar panels might not output much power on some days.

Battery storage and grid connection in winter

For safety reasons, your standard grid-tied solar panels will automatically shut down during power outages. You’ll be without power unless you've invested in battery backup systems.

By adding battery storage to your solar setup, you gain crucial resilience during winter's unpredictable weather patterns. Not only can you maintain power during snowstorms and outages, but you can also capture excess energy on bright winter days to use during evening hours when utility rates typically peak or during extended cloudy periods.

That said, solar batteries don’t like the cold. Freezing temperatures can reduce storage capacity, so you'll want to locate your batteries indoors to provide a constant temperature.

Are solar panels worth it for wintry regions?

At the end of the day, solar panels can still be a good investment even if you have a long winter. Cold regions that are higher in elevation still get plenty of sunlight throughout the winter. Solar panels can also be worth it when comparing your electric bill to the cost and payback period of panels on your home. That said, solar isn’t best for everyone, so take time to calculate your expected return on investment.

FAQs about solar panels in winter

Below are a few frequently asked questions about solar panel functionality in winter.

How cold is too cold for solar panels?

Solar panels work efficiently in cold temperatures, even below freezing. Panels are usually rated to function down to -40°F (also -40°C) so most people don’t have to worry about cold temperatures being an issue.

At what temperature do solar panels stop working?

Solar panels usually work between -40°F and 185°F. Efficiency will drop off significantly with temperatures outside this range. Solar panels can work in climates from equatorial to sub-arctic with the right technology and installation.

Do solar panels work if they are covered with snow?

Snow-covered panels work partially. Thin snow allows limited production while heavy snow blocks it completely. The tilt and dark surface help panels get rid of snow on their own, but you might consider soft rakes for persistent buildup.

Will my solar panels work on a cloudy day?

Yes, your solar panels work on cloudy days, but at reduced efficiency. Heavy clouds can cut production by 67%, though cooler temperatures actually improve panel performance.