You just had your first snowfall of the year, and now you are probably thinking, “What happens to my solar system when it snows?” We’re glad you asked! When the snow begins to fall, we end up with a couple of options. If snowfall is light, it’s fine to go up and give the panels a good swipe. Otherwise, all that’s really needed is to stand back and wait. The solar panels do all the work themselves both quickly and efficiently.
Even from underneath the snow, your panels are soaking up a small amount of UV rays from the sun, and those rays warm the panels as they make electricity. As the panels warm up, they start to melt the ice directly on top of them, and then friction does the rest. Assuming the panels are placed at an angle on the roof, the snow slides off as the bottom layer melts, freeing your panels from their icy blanket.
The color of the panels helps too. Most panels are either black or dark blue, which allows them to soak up heat and stay hotter for longer, making better use of the sparse amount of sunlight shining through the snow. Hotter panels make for a faster melting process, and in most cases, they free themselves in about a day.
If you’re worried about your system’s production during the winter months, don’t sweat it. SunRun plans ahead of time for a seasonal drop in production as the weather gets cloudy and the days get shorter. Besides, if you live in an area that receives a lot of snowfall, the light reflected off the snow might keep your panels generating a little extra.
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Actually, a very big factor in how quickly snow will melt and slide off your panels is roof pitch. A relatively shallow roof pitch such as ours — 19 degrees — means snow will sit a long time, up to three days even in sunny conditions here in Colorado. We lost about 250 kWh of production, one month’s worth of spring/fall electric use for us, last winter due to snow. Multiply that times thousands of similar rooftops in Colorado and other snowy, but also sunny places, and the lost kWh really start to add up — literally into the millions every year. And yet the solar industry doesn’t seem to care much, and tends to tell customers the same sort of thing you tell us here — essentially let the snow sit. There’s got to be a better way, and if we really relied on solar to power us in the U.S., rather than using it as an “extra” on top of coal and natural gas electricity, we’d have found this better way a long time ago.
If you’re a consumer considering solar in a snowy area, I’d suggest thinking of some of the things I wish we’d considered before buying our 5.59 kW system in Colorado — http://solarchargeddriving.com/editors-blog/on-going-solar/607-snow-on-solar-panels-six-design-considerations.html
Christof Demont-Heinrich
Solar Homeowner & Editor of SolarChargedDriving.Com
Flat roofs are not optimal for solar panels, and piling up snow is only one reason. This post is very helpful to homeowners.