Do Solar Panels Work in the Winter?

Solar Panels In Winter
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A question I often get when I’m about talking about solar in New England is “do solar panels work in the winter”. It’s not an unreasonable question for anyone who is familiar with a typical New England winter.  

After all, it would stand to reason that a solar panel that is covered in snow is going to be unable to generate very much electricity. Add in the shorter days and the fact that the sun is lower in the sky in winter time, and some people wonder if that’s not a recipe for power outages.

While it’s certainly true that a solar array is going to generate less power in the winter than in the summer, solar panels do, in fact, work perfectly well year-round. In this article I’ll explain why the difference in production levels is not as great as most people think and how winter time generation and summer time generation can work together to give you solar energy all year long.

Panels are More Efficient in Winter

Most people are surprised to learn that solar panels actually perform more efficiently in cold weather. This is because electrical conductivity is boosted in cold temperatures. 

This increased efficiency makes up for some, though not all, of the diminished generation caused by shorter days, lower sun and snowfall. 

Another thing to remember is that solar panels convert any kind of sunlight into electricity, whether it comes directly from the sun in the sky or is reflected onto the panels from the surrounding snowscape. 

Any New Englander who has had to wear stronger sunglasses in February than they do in July will attest to just how much sunlight is reflected by snow that is on the ground, in the trees and on the surrounding buildings. All of it can be turned into electricity if it’s reflected onto your solar panels

What if the Solar Panels Are Covered With Snow?

Because of the way solar panels work and the angle at which they are installed, snow rarely covers them for more than a few days at a time. In fact, it’s not unusual, a day or two after a snowstorm, to see solar panels that are completely free of snow while the rest of the surrounding roof is still covered in snow.

Solar Panels In The Snow
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First, there is the angle. In order to maximize sun exposure, solar panels are typically mounted at a fairly steep angle. They’re also made of smooth glass so the snow just can’t stick to them for long.

Then there is the heat. Like any dark surface, the black solar panels absorb heat, as well as light, from the sun. The moment even a small area is exposed, the panels start to operate and, in generating electricity, they also generate a small amount of heat.

That heat causes more of the panels to become exposed, which generates yet more heat. Pretty soon the entire panel is exposed to the sun and working normally.

What’s more, as the melting snow slides off your solar system, it gives the panels a free cleaning. At other times of the year, dust and pollen can also cause panels to be less efficient. In those cases, all you can do is wait for it to rain, which in some parts of the country can be a very long wait. 

With snow, not only is your panel working again in a couple of days, it’s actually working better because it’s both cleaner and cooler.

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Do You Need to Clear the Snow off Your Solar Panels?

No, it really isn’t necessary and it’s certainly not worth the risk. The minimal loss of production caused by the snowfall is easily made up for in the summertime. Remember, when your system was first designed, it was done so based on average sun hours over the entire year.

The algorithm used to calculate sun hours takes into account the expected weather patterns over a typical twelve month period. And in New England, typical means snow in the winter. The system is specifically designed so that:

  • It overproduces in the summer
  • You store the excess summer production in the grid in exchange for Net Metering credits
  • Your “stored” power is saved up precisely for times like this 

So to take the risk of climbing up on a slippery roof in the dead of winter to clear snow off your panels would be a little ridiculous.

Oh, and you might void the warranty on the panels if you scrape snow off with a metal roof rake. Leave the snow up there and let nature take its course. Your solar panels will be working at full “winter” capacity in no time.

Snow On Solar Panels
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Final Thoughts

While it’s true that your solar panels produce less electricity in the winter than in the summer, that’s nothing for you to worry about. 

First, the loss in production is offset slightly by the fact that:

  • Panels are more efficient when they’re cold
  • They absorb reflected light from the surrounding snowscape
  • Melting snow cleans the panels as it slides off

More to the point, the system was designed to produce excess power in the summer and store that power up for use in the winter. And the net metering program is there to make sure you always have access to power, regardless of the weather.

A properly-sized system, based on properly calculated sun hours should be able to provide you with power year round.

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