Will Solar Panels Produce in Cloudy Weather?

Anything that stands between your panels and the sun, be it clouds in the sky, fog on the surface, or shade from a nearby tree, reduces the amount of solar energy your system produces. But just like you can still get sunburnt on cloudy days, your panels could still be producing electricity, depending on how thick the cloud coverage is.

On a partly cloudy day, your production can drop by 10% to 25%, depending on how frequently the clouds pass over your system. But something called the “edge of cloud” effect can actually intensify the sunbeam and can lead to a brief increase in electricity production. If fluffy cumulus clouds pass in front of the sun, the wispy edges act as a magnifying glass, causing a stronger beam of sunlight to hit your panels!

What about overcast days? A quick way to check if your system is producing energy is to look for shadows outside. If you can see objects casting a shadow, your system is probably producing in some capacity. If you don’t see a shadow, it’s likely that the cloud coverage is too thick to produce electricity. 

All in all, estimates are that your panels will produce about 10 – 30% of the electricity on cloudy days as you would on sunny days, but don’t let that keep you from going solar. Even if you live in an area that has less sun than Southern California and Arizona, it still could be a lucrative investment. 

Portland, Oregon and foggy San Francisco both rank on the US’s top 20 cities for solar. And despite being much cloudier and 1/28th of the size of America, Germany produces 45.9 GW to the US’s 49.6 GW. 

Solar installers should take into account cloudy weather when calculating your system’s production in your solar quote as well, so you’ll be prepared to make a well-informed decision based on your situation. And if you live in an area with net metering, you’ll be able to use the electricity your system overproduced on sunny days to cover electricity on cloudy days.