Do Solar Panels Work When It Snows?

There’s a common misconception that you have to live in a warm, sunny place like California or Arizona to see benefits from solar panels. In reality, photovoltaic (PV) solar panels can produce power even in snowy winter weather, although energy generation may be less consistent during periods of heavier snowfall. Below, we cover everything you need to know in order to maximize solar energy output in cold, snowy conditions. 

Can Solar Panels Still Generate Energy in the Snow?

The U.S. Department of Energy (DOE) has tested PV panels in all kinds of weather to come up with design innovations that optimize energy generation and durability. Documenting solar panel performance across a variety of regions and time periods, researchers at DOE regional test centers have found that PV panels still generate considerable amounts of electricity in places that receive significant snow. In fact, very cold weather and snow’s reflective properties can actually be good for PV performance.

A recent Canadian study came to a similar conclusion. Researchers at the University of Alberta found that snow reduced energy output by only about 3%. The angle at which the panels are mounted had a much larger impact on energy generation than snowfall, they reported, since the angle of the panel affects how much snow accumulates and how much direct sun it receives. The study concluded that the ideal angle for mitigating snow accumulation is about 45 degrees.

How your solar system performs in winter weather is also affected by the quantity and quality of snow. Light snow poses little problem for panels. Depending on the angle of the panels, snow may slide right off before it’s had a chance to accumulate. The wind will blow it away as well, and a bit of sunshine frequently melts it fast. Light also reflects through the snow to reach the panel. In short, panels will be back to optimal production not long after it stops snowing.

Heavier snow could be more problematic. The weight of the snow may place stress on the system’s frames, especially the joints, or mounting points, creating tiny cracks. Over time, this can cause wear and tear that affect panel performance. If a cold snap lasts for several days, or if there are episodes of extremely cold weather only a few days apart so that snow melts and then refreezes, ice may pose a challenge. 

Your state may have resources for analyzing a PV system's energy generation potential given climatic conditions where you live. For example, the University of Minnesota has created an app that will analyze the average amount of energy a solar system generates anywhere in the state, along with a month-by-month breakdown of how much sun the area receives. It also provides an overview of an area's suitability for solar (optimal, good, fair, marginal, poor), the best size of solar system for your needs along with cost, and the average payback time given state, federal, and other available incentives.

The National Renewable Energy Lab’s PV Watts calculator is another simple tool that lets you enter any U.S. zip code to generate an estimate of the average month-by-month value of a residential solar system. 

What About Cleaning?

A benefit of wintery weather for solar panels is that snow has properties that allow it to bond with dirt, helping to clean the panel as snow melts away. That means that solar panels in snowy climates may actually stay cleaner and thus work more efficiently.

While it’s tempting to climb up on the roof after a snowstorm to remove snow from your panels, solar companies generally advise against it. First, saving a few kilowatt hours of energy isn’t worth the risk of slipping off an icy roof or ladder. Second, you might damage the electrical equipment or scratch your panels while sweeping or raking away snow, adversely affecting the system’s performance and possibly jeopardizing its warranty. 

It is usually best simply to let nature do the work for you. Although there's a risk of weather-related wear and tear over time, panels are generally designed to withstand the pressure of heavy snow. In most cases, snow melts off panels within a few hours or a few days, even in places with frequent winter storms and frigid temperatures. You may see reduced energy output during such times, but over the course of a year, solar systems in places that snow a lot perform similarly to places with less or no snow. 

If you have questions about cleaning and maintenance of solar panels, or the effects of snow on PV systems, contact a licensed, certified solar installer. And if you’re trying to evaluate whether going solar makes sense where you live, check out Treehugger’s article “Is Solar Worth It?”, which provides several resources for calculating the costs and benefits.