How Snow and Clouds Affect Solar Panels

Many homeowners interested in investing in solar energy worry about things like clouds or snowfall. Will it block the sunlight? Do solar panels work in the winter? Does the winter season make solar panels worth it? Will cloudy days disrupt the level of energy I need to power my home?

Snow

Many people believe solar panels don’t work well in winter, but just the opposite has proven true. Snow helps clean dirt or debris off solar panels as it melts. In addition, the snow can act as a mirror, reflecting more sunlight on the panels and therefore generating more energy for your home.

There usually isn’t anything to worry about for just a light dusting or graupel (snow pellets or “dippin’ dots” snow). The snow typically won’t have time to stick or build up before the wind blows it away. Even a sparse layer still allows light to reach the solar panel. 

If snow does build up, it may begin to slide off the panels on its own. Solar panels are built at an angle, partly to help snow or other debris slide off easily. Even if it only slightly exposes the panel to sunlight, power generation will still occur again, though not as efficiently as if completely uncovered. If you live in an area where snow typically melts quickly and doesn’t build up, you won’t need to worry about cleaning off the snow.

However, if the snowfall levels in your area do gradually build up throughout winter, you’ll need to regularly clean the snow off so your solar panels have access to sunlight. Places like Amazon and Walmart carry extendable snow rakes or squeegees that work for most people in removing their rooftop snow, without damaging the panels. 

Clouds

Solar panels always perform most efficiently when basked in direct sunlight, so constant cloud cover in a day will lower your panels’ intake.  However, same as with snow, sunlight can still reach the panels when only thinly blocked. 

Only during extremely cloudy, stormy and rainy days will the energy levels noticeably drop. According to CleanTechnica, solar panels will still yield 10-25% of their typical output on even the cloudiest days. Ironically, even on extremely warm and sunny days, too much heat also reduces solar panel output by 10-25%.

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