Let it snow! Solar panels are ready for that

What gets the ball rolling is the sun: solar panels generate electricity as long as photons of sunlight strike the solar cells. If it shines when it's boiling hot, so be it. If it shines when it's freezing cold – even better! In fact, when it gets over 90 °F, solar panel efficiency starts to decrease at a rate of 1% per degree. So, it turns out that PV modules perform best when it's sunny and cold.

Such an advantage of winter months is offset by the fact that the days are shorter, which means less peak sun hours. What's more, in some states it snows heavily in winter. Snow is one of the factors which influence solar panel efficiency, so let's see how big this impact might be.

Forget those frightening images of solar panels with a five-inch layer of snow on top you might have seen on the Internet. It hardly ever happens in real life, because:

• PV modules are usually installed at an angle, which helps the snow slide off. In winter it should be even steeper to catch the angle of sunlight, so snow is unlikely to stay on your panels for long.
  
• Solar panels are dark and thus attract heat, which helps in melting the snow.
  

So, it's very unlikely that there'll ever be such a thick layer of snow which would be able to shut off the entire array. A thin layer of snow won't bring any problems either: sunlight will still be able to move through it. What's more, snow can come in useful:

• Snow has anti-soiling properties: when it melts, it takes away all the dirt with it. What you get in the end are cleaner panels working at a higher efficiency.
  
• Snow around your solar panels can boost their performance due to the albedo effect. Snow covered areas reflect a lot of radiation, so you can end up with a bigger amount of electricity generated.
  

Different things happen, c'est la vie. If you go out in the morning and can't find your panels in those piles of snow – don't worry! PV modules will survive, as most of them are designed to withstand 5400 Pa snow load, which is about 0.8 lb/in².

We do not recommend clearing the snow from the arrays. You can easily damage the panels, which isn't going to be covered by the warranty. Just wait until it gets a bit warmer or just sunnier at noon, and the snow will slide off itself.

What we do recommend thinking about is snow guards. Unlike standard roofing material, solar panels don't offer much friction for the snow that collects on them. So, there's always a risk of large chunks of snow sliding off all at once. It isn't about catastrophic thinking, but again, different things may happen. Snow guards will allow the snow to fall off gradually, so you'll be sure your belongings and, more importantly, your loved ones are safe.