It's late October in Montana and we're already seeing some early season snowfall. Some Montanans are enjoying the early wintry vistas, some are getting excited for ski season, and for owners of rooftop or ground-mounted solar systems they may be wondering: do I need to clear the snow off of my panels?
To Brush or Not to Brush
A thin layer of snow is unlikely to be a problem. In fact, research has shown that as the panels begin to collect sunlight they'll warm up and the snow will typically either burn off of slide off of the panels without any need to brush them. At this point, the snow will actually clean the panels, especially if it melts and slides off naturally. Like rain, this will actually end up boosting production by removing dirt.
It's true that if you're solar panels are covered in thick, deep snow that they will see reductions in energy production. It might be good to consider finding a safe way to clear the snow from your panels to ensure you can harness that free, clean energy shining down. The graph below from an MREA member shows the boost in energy production after clearing thick snow from the panels.
Roof angle is another consideration. Most rooftop solar systems are flush-mounted, meaning they lay flat on the roof. The steeper the roof angle, the more likely the snow is to slide off. More shallow roof angles likely won't benefit from this type of free snow-removal service. For ground-mount systems you may be able to rotate the panels to make them more easy to brush or to a point where the snow will slide off naturally.
You should also consider if the savings are going to be worth it for you. Winter production will be lower in Montana due to our shorter winter days. With net metering, the bill credits that you built up over the summer months can be used to offset your winter energy bills. If this is a purely economic decision for you, look into how much additional production you'll get from clearing the snow off versus letting it melt naturally.
Some Montanans go out and brush the snow off of their panels every time it snows. Some might only brush if they get a good snow dump. Others won't brush at all! Importantly, if you decide to clear the snow off of your rooftop system make sure you're doing it safely. Look into harnesses or any other gear you need while working on a roof, or use a roof rake like MREA Board Member Pat Judge demonstrates below (in this case, the sun did most of the work for him!).
Ultimately, deciding whether to clean off the snow from your panels is a personal question that you need to answer yourself. From research and what we know from our installers here in Montana, snow can affect production but it depends on how much snow there is, among other factors. Of course, if you're having a hard time deciding what to do the best person to ask is your installer! Ask during the installation process, or follow up with them before the winter really gets underway.
- Let it Snow: How Solar Panels Can Thrive in Winter Weather (U.S. Dept. of Energy)
- Solar and the snow (PV Magazine, discussing utility scale solar and snow)
For those who haven't installed solar yet, winter is a great time to begin your planning. It's a good time to get on your installers schedule for the Spring. You can find a local installer in MREA's directory.