It’s almost winter in and you know what that means: cold temperatures, gusty winds and plentiful snow. And while those conditions are great for skiing, sledding and snowball fights, how do they work for generating solar energy? The answer might surprise you. While it’s true that solar systems do not generate energy during storms that block out the sun completely, solar PV (photovoltaic) systems can be quite efficient during the winter months.
First, it’s important to remember that the output for your system is calculated on an annual basis, and already accounts for stormy periods (which can happen throughout the year, not just during winter) and short daylight hours during the winter months. So those storms that cause variations in output have already been accounted for in the design of the system.
Second, solar panels, like most electronics, work best in cooler temperatures. The output of solar panels goes down slightly in very hot weather.
Third, Mother Nature helps out when snow accumulates enough to blanket the panels. Snow on roofs with solar panels actually melts faster than snow on roofs without solar panels because of the reflection. The sun naturally reflects on the solar panel and then onto the snow-covered roof. It’s the same reason skiers can get bad sunburn on sunny winter days.
Fourth, melting snow is a natural panel cleaner, removing the layers of pollen, dust, bird droppings and leaf debris that accumulated during the fall. When it snows a significant amount, it’s tempting to go up on the roof to try to clear off the panels, but should you? Removing snow can help aid production if there are several storms in a short period. The panels do emit heat, allowing the snow to start to melt and slide off, but generally Mother Nature will take care of the melt for you, saving a trip to a potentially slippery roof.
Lastly, the structure of the roof has been reviewed as part of our initial design to account for “snow” load before the project is permitted to proceed by the local building department. We also work an ‘avalanche zone’ in to our design, leaving roof space below the panels for the snow to slide down then melt off slower.
If you or a friend or a neighbor have solar, take a look this winter – chances are good that the first part of their roof to clear will be their solar panels!