10 Nov Rainy Days and Solar Panels are OKAY!
As we all know sunshine is needed for solar panels to produce energy. But what happens on rainy days? That’s a great question, because while it may seem to be the worst possible thing for your solar panel system, it’s actually one of the best things for your annual energy production.
Annual energy production is the system’s total output over a full year. In the midst of it all, a single rainy day does hinder your system from maximum annual production—but ONLY for that day.
Solar panels spend the majority of their time in sunny, dry climates. These climates also make the air dry, giving way for dust and dirt particles to become free moving in the atmosphere, which we call soiling. Slowly but surely, those particles begin to land on your solar array and build up into a thin layer of dirt that the sun must penetrate before being absorbed by your solar panels. In places like California and Arizona, where it rains only a handful of times a year, homeowners contract out cleaning services to have their panels sprayed down and cleaned. If homeowners in those climates choose to not pay additional money for these services, their system could face up a 5% drop in their annual output—and even up to 10% in desert climates.
But in New York, rain is more frequent. And the occasional very heavy downpour acts as your own personal solar panel cleaning service. Solar panels are made of tempered glass that becomes very slippery when wet, so the dirt will slide right off. The next time the sun rises, your system will be producing 1% to 2% better than it did with soiling present on the panels.
And since soiling does more damage for annual output than a single rainy day does, an average of one rainy day a week is a healthy and optimal environment for a solar system.
(Read how power optimizers help produce more power on cloudy days »)