A common misconception is that solar panels produce very little energy, or no energy at all during the cold, snowy winter months.
However, this just isn’t the case. Solar panels still produce energy during the winter, even if you live in an area that is cold or snowy. Of course, snow will reduce solar energy output, but over the long term, the energy you lose will be very minimal.
Solar panels and solar energy systems are powered by light, not heat, so they will continue to fuel your home as long as light hits them, regardless of the temperature.
It is also important to remember that the majority of annual sunlight comes during the summer, where days are longer and the sun’s energy is more concentrated. This means that a few days of snow covering your solar panels won’t make a big difference in annual energy production.
How do Solar Panels Perform During Snowstorms?
Typically, if solar panels are mounted on the roof, they will be tilted to a certain degree. In addition, they will most likely be installed facing south, west, or southwest.
This is to ensure that the panels are in the best position to get the maximum amount of sunlight possible.
However, this positioning can also be useful in the event of snowfall. Because the solar panels are smooth and tilted, snow won’t stick to them like it would to rough roof shingles. Instead, it will usually slide away quickly and easily on its own.
In addition, even if there happens to be a bit of snow that doesn’t slide off the panels on its own, it will most likely melt away the next time the sun comes out.
Solar panels are designed to attract sunlight, and naturally melt snow off due to the heat they attract from the sun. The panels are also placed on the side of the roof that gets the most direct sunlight, which helps in the process.
Notice how in the image above, snow has slid off the sections of the roof with solar panels, whereas areas with shingles still have snow on them.
What if there’s a BIG snow storm?
If you live in an especially snowy area, there may be occasional instances when the snow piles up on your solar panels after very big blizzards. When the panels are buried in deep snow, light can’t get through to them and they are unable to produce energy.
If you’re concerned about the weight of the snow and/or how long it will take to melt off of the solar panels, it may be necessary to have the snow manually removed from the roof by a professional. (DO NOT try to climb onto your roof yourself to remove snow).
However, most of the times, the combination of the sun’s heat, wind, and the tilt of solar panels will eventually remove (even heavy snow) on its own. Over the long run, the buildup of snow on solar panels won’t make a very big difference in total energy production.
In fact, in a study by the Northern Alberta Institute of Technology, solar panels which had snow removed only experienced 1% to 5% more production than ones left unmaintained, during a 3 year period.
This result shows just how limited the effect of snow is on solar power systems. Even in areas of Canada like Edmonton, Alberta, solar panels have been shown to be a viable cost-effective option.
How do Solar Panels Perform in the Cold?
According to Dr. Greg Reed, Director of the University of Pittsburgh’s Center for Energy and the Energy GRID Institute, “like any electrical device, solar panels actually perform better under cooler temperatures. Cool, sunny locations can create some of the most efficient outputs of solar panels.”
Essentially, although the temperature doesn’t affect the amount of solar energy a solar panel receives, it does affect how much power you will get out of it.
This happens because light is composed of high-energy photons, which are the particles that carry energy. When sunlight hits the solar panels, the electrons at rest in the panels (low energy) are excited by the photons from the sunlight (high energy).
The solar panel electrons then move from a low-energy state to a high-energy state, and the solar cell is designed to extract these electrons in their high-energy state.
Power is produced from the difference in the low and high-energy states. The bigger the difference, the more power produced. This means that more power is produced if electrons start at a lower original temperature.
In other words, solar panels are much more efficient at cooler temperatures than at warmer temperatures. As the panels get hotter, they will produce less power from the same amount of sunlight.
The bottom line?
Cold weather on its own should not negatively affect the production of your solar energy system; if anything, it will increase your system’s power output.
You can learn more about how solar cells and solar panels work in the video below:
Solar Panel Performance when it's Cloudy
Sun exposure is important for solar panels to produce energy effectively. Not surprisingly, a solar power system will generate the most electricity on clear, sunny days.
However, even on cloudy days, the average solar panel can still produce 10 to 25 percent of its rated capacity depending on the density of the clouds.
Solar panels are able to generate some energy even when it’s overcast because ultraviolet rays still reach the earth’s surface in abundance, regardless of the clouds, and the panels can adequately convert a portion of that UV light into electricity.
Ever wonder why you still need to use sunscreen on cloudy days? Well, it’s because UV rays can still penetrate the clouds and reach the Earth’s surface. That same concept applies to solar panels.
Although 10 to 25 percent of rated capacity may not seem like enough energy to power your home or business, it’s important to consider how much sunshine you receive over an entire year rather than on any particular day.
Even areas that experience cloudy winters can still be effective environments for solar energy systems. Lower production on cloudy days is made up for during other, sunnier parts of the year (like in the summer).
How can I check up on my system’s performance during winter?
Most solar energy systems come with a monitoring platform that can be accessed online from anywhere in the world using a computer, tablet, or smartphone.
If you’re not sure whether or not your system includes monitoring, talk to your solar installer and they should be able to provide the appropriate information.
If your system does include monitoring, it’s smart to keep an eye on it year round to ensure that everything is working properly, but it’s especially important to check it in the winter.
That way, if your panels become too covered in snow to produce power, you’ll see it on your monitoring system and be able to quickly schedule a removal. It will also all you to see what percentage of rated capacity your solar panels are producing on cloudy days.