There are many myths about solar panels, and one of the most pervasive is that they don’t work during winter. Many believe that solar panels shut down once the ice and snow begin to cover rooftops. While it’s true that solar panels are not as efficient during the colder months, they still function perfectly well during winter. In fact, cold weather has nothing to do with a drop in solar efficiency whatsoever, with photovoltaic solar panels working better in colder climates.
This article takes a closer look at this common myth and discusses why solar panels are less efficient during winter.
Will Solar Panels Work in Winter?
While less efficient, solar panel systems function perfectly well during winter. Solar panels work by absorbing photons (light rays) from the sun; this means that they’ll continue to produce electricity, even in subzero temperatures, as long as there is sunlight. Unfortunately, the shorter days of winter, combined with heavy snowfalls, will reduce the sunlight exposure to solar panels. Less sunlight means a lower energy output, and you can expect solar panels to be about 50% less efficient during the winter months compared to the height of summer.
How Do Solar Panels Work?
Solar panels are composed of many small photovoltaic solar cells. These cells possess two semiconductive materials (usually silicon) between a casing, like glass or metal. As light passes through the panel, photons knock electrons free from the conductive material, creating a small electrical current. The electrical current is then captured by the cell and funneled directly into a house to power appliances and systems, into a solar battery for later use, or back into the electrical grid.
How Do Colder Temperatures Affect Solar Panels?
It might be hard to believe, but solar photovoltaic (PV) systems are more efficient in cold temperatures than in warm ones. Specifically, solar panel PV systems have higher efficiency in cold temperatures because they absorb electricity from sunlight. Solar cells work by capturing the energy produced by electrons from when they are at rest to when they become agitated. The difference between the at rest energy and the final energy after exposure to sunlight is the amount of power the solar cells absorb. As a result, the lower the at rest energy of the electrons, the more power the solar cells will absorb when the electrons become agitated.
To make this easier to understand, think of these electrons as batteries that charge and fill with power when they’re hit by sunlight. If the electron battery is 0% at rest and jumps up to 100% when the sun hits it, the solar cells absorb 100% of the energy generated. But, if the electron is 30% at rest and jumps to 100% when the sunlight hits it, the solar panel only absorbs 70%.
In cold temperatures, the electrons have less energy at rest, allowing the solar panels to absorb energy more efficiently when agitated. The most efficient temperature for solar panels to absorb energy is 77°F.
Will Snow and Cloud Cover Affect Solar Panels?
While cold weather may not affect solar panel systems, the other elements that come along with winter can result in lower solar panel performance. When panels are covered in a layer of snow, it will prevent sunlight from reaching the cells. As a result, the heavier snowfalls they experience, the lower the wintertime energy production. Thankfully, solar panels are angled toward the sun and slopped, meaning they’re pretty good at shaking off snow if they become coated. While heavy snowfalls can impact a solar system’s efficiency, they typically don’t have a sizable impact on the overall amount of electricity a home takes in.
Cloud cover and daylight hours are two winter weather conditions that can’t be controlled or mitigated. On cloudy winter days, solar panels will be less effective because there is less direct sunlight to absorb. They can still absorb indirect sunlight, but this is much less efficient. This concept applies to both the winter and cloud cover. For states like New Jersey, New York, and Massachusetts, fewer sunny days mean fewer solar rays to absorb and less electricity for their systems. Thankfully, due to these states’ impressive solar programs, local homeowners can still greatly benefit from solar power.
Do You Have to Clean Snow Off of Solar Panels?
Most solar panel companies don’t recommend cleaning snow off solar panels. Panels are built to withstand the extra weight of heavy snow and winter’s extreme temperatures, so you usually won’t have to worry about saving them. Furthermore, due to the slope and sunlight received by solar panels, you won’t have to worry about snow for very long after a downfall. In the worst cases, you can damage your solar panels by attempting to clean them, leading to costly repairs and a voided warranty. If you want to squeeze out every ounce of renewable energy from the panels, you could clean the surrounding snow from your rooftop. Doing this will allow nearby shingles to absorb more sunlight and help the snow on your panels melt faster through ambient heat.
While solar arrays are less efficient on winter days than on summer days, they still produce plenty of power for a home. You can expect around 50% less solar energy during winter than in summer. While you may experience some additional loss of efficiency from overcast days, rain, and snow, the increased efficiency panels gain from colder weather can easily make up for that. We recommend using net metering programs or investing in solar battery storage to offset winter energy bills.