The Effect of Snow on Solar Panels

By Matthew Wheeland - August 5, 2010

snow

Can solar panels work in snow?

Yes, we know it’s high summer right now, but because we run group discounts on solar in places like Denver, we get questions about snow and solar panels pretty much year round. Solar panels definitely work in snowy climates–homeowners in snowy Germany, for example, are leading the world in terms of putting solar panels on their roofs.

What happens when snow gets on the panels? They can still work under a light snowfall, but after snow completely blocks out sunshine, they’ll stop generating power. This can happen after more than a couple of inches of snowfall. Because of the way that solar cells are wired together, if one area of a panel is covered with snow, it can shut off the rest of the panel as well.

How can snow be removed from solar panels?

It’s often possible just to wait for the snow to melt, which can happen quickly depending on the weather conditions. Black panels like SunPower’s help the snow melt faster. Because solar panels have a slippery surface and sit at an angle, it can be easy for snow to slide off (please note that this can sometimes happen unexpectedly, so you may need to be careful when walking underneath!).

Sue Okerson, a PURE member in Denver, says that “It does mean we have to shovel the south side of the house more than once, but it’s so worth it. Our last Xcel bill was $6.36…fees and taxes!  We love our system!”

There are several other ways that people try to keep snow off their panels. First, ground-mounted panels can be tilted to a steeper degree in the winter to help snow slide off more easily; the angle can also better capture winter light. In heavy snowfall, some people choose to use a roof rake to sweep the snow off. A German company makes a product similar to windshield wipers to automatically brush snow aside, although this isn’t yet available in the United States.

How can snow help?

Like other electronics, solar panels actually work more efficiently in cold weather, so winter isn’t automatically a bad thing. On a clear day after it’s snowed, your solar panel output can actually be greater than in the summertime because the sun is reflected off the bright white ground. Homeowners in snowy climates have reported that their solar panels can operate at better than 100% of their rated power. When snow comes off panels, it helps clean them, which gives an additional boost to their productivity. Even if there are days when your panels are covered with snow and not pumping out power, it’s also important to remember that your total energy generation is calculated over a year, so day-to-day variations– or lower generation over winter months– can be made up at other times.

Image credit: solardave.com

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