It’s typically one of the first questions people have about solar panel systems: “What happens when it gets cloudy? Do your solar panels still work?”

The answer is simple. Solar panels work just fine on cloudy and foggy days. The only difference between a foggy day and a sunny day is the amount of energy that is gathered. In fact, there are scenarios in which a solar panel system in a cool, cloudy area will work more efficiently than one in the hottest, brightest desert.

Long Term Sunshine More Important

One of Mark Twain’s best known quotes was about the weather — even though there’s some debate over whether or not he said it at all.

“The coldest winter I ever spent was a summer in San Francisco.”

For anyone who has even been to Fog City in mid-June, this quote from Twain (or whoever said this gem of a line), rings true. The thick fog greets morning risers, recedes for a few glorious hours, then slowly creeps back into view as the sun sets. This wouldn’t seem to be the best scenario for a solar panel system.

In fact, this can be the ideal scenario for solar panel efficiency. Contrary to popular belief, solar panels actually work most efficiently when they are cool. In a place such as San Francisco (or Portland, Ore., or Seattle or Nebraska), the key isn’t that every day is sunny but rather that the solar panels are positioned to gather sun at the best times.

In the case of San Francisco, while the fog is legendary, it does not completely stifle energy production. Through the thickest cloud banks, solar panels may only be working at 5 percent to 10 percent of capacity, but they do collect energy.

When the fog lifts, however, is the key. In many cities — even including such sun-drenched places as Los Angeles and San Diego — fog and clouds come in the morning, then subside for a period of bright sun. These sunny times are often the best times of day for energy collection, so while the solar panels might be working at optimum productivity for only a short period, they will be able to collect plenty of energy.

Cloudy Day’s Silver Lining

On cloudy days, there can also be opportunity for solar panels to collect even more power. Even though this might seem counterintuitive, there truly can be a silver lining on a cloudy day.

It’s called the “edge of cloud effect,” and it can help to balance out the production of a solar panel system on days when clouds are rolling through the sky.

In its simplest terms, the edge of cloud effect occurs when the sun shines through the outer edge of a cloud. The sunlight during that time is magnified, and solar panels can actually work at higher efficiency than they would on a clear day.

No matter which way the clouds roll in, a homeowner’s solar panels will continue to collect energy. Over the course of a year, most areas of the country will provide enough sunlight to make the benefits of solar power available to almost any household.

If you’d like to find out how installing solar panels on your roof can help you drive your electric bill down to zero, contact us today for a free quote.