The Effect of Snow on Solar Panels

posted by Adele on August 5th, 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 1BOG 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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11 Responses to “The Effect of Snow on Solar Panels”

  1. Brad says:

    I bought an extendable pole and a shop broom that fit it. It’s probably a bit heavy for most people, but it works great for me. Lift it and set the broom head all the way up at the top of the panels and then walk it backwards and it pulls the snow right off. With heavy snowfall or snow that has partially frozen to the panels it may take a few passes, but the sun here in Denver is so nice and bright that once you get any portion of the panels exposed the sun will melt the rest quickly.

  2. Hayden Dills says:

    This is a fantastic article. I’m always looking for great resources to send to our residents, and your post is without a doubt worth sharing!

  3. Kade says:

    I just got a phone call from a guy wanting to install snow guards who installed solar panels on his business. They heated up and the snow slid off and smashed his windshield of his truck parked beneath.

  4. Rod Pennington says:

    Solar Panel Deicer Sock pays for itself in electricity generation in a single day. http://store.airconditioner-portable.com/ice-dam-melt-sock.html

  5. Dave Dugdale says:

    Adele, I am so glad that you liked my Flickr photo so much that you included it on this page. I enjoy when people use my photos, but as I noted on Flickr below each photo I let people use my photos on the condition that they provide me credit to my solardave.com site. Please add my link when you can.
    Thanks, Dave

  6. Mike says:

    I have panels covering my south roof, it is to awkward to rake, has anyone used a heat tape or snow guard?

  7. Laurie McGovern says:

    What if you need roof repair or replacement down the road after the panels are installed? panels have to be removed to repair/replace roof and then solar remounted? or is the panel then no good to reuse? can panel be removed and remounted ourselves? or must the co do the work? You may email back lmg028@gmail.com

  8. [...] One Block Off the Grid : The Effect of Snow on Solar Panels. [...]

  9. Tom says:

    Has anyone had any experience using Roof de-icing cable? I am sitting here in Ontario, Canada today with not a cloud in the sky and have 2 of 39 panels generating. I don’t like the idea of melting material across my panels, ditto getting on the roof with a rake to push the snow off. Ladders and I don’t get along so I’m not sure I want to climb the ladder to pull the snow off over 20′ of panels and on top of me.

    I know the idea of electric cable to melt the snow to generate electricity does seem somewhat counter however I’m thinking of just plugging in as needed.

    Any experiences?

  10. [...] via The Effect of Snow on Solar Panels. [...]

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