Solar Energy on a Cloudy Day

Many Bay Area Homes are in the Fog. Should they get Solar?

Will my solar panels work on a cloudy day?

If you lived in a perpetually sunny city, you might not think twice about installing solar panels on your home, condo, or business. What about the Bay Area?

By Parvathisri (Own work) [CC-BY-SA-3.0], via Wikimedia Commons

So you live and work in the Bay Area, which is notoriously shrouded by fog and clouds in the fall and winter months. You fear that the weather might impede the efficiency of a prospective solar solution. While it’s true that fog can blunt the amount of irradiance that your panels get, the situation is more complicated than you may realize.

Even on cloudy days, for instance, typical panels can extract up to 25% of normal capacity. Certain panels are better at extracting energy during cloudy days than others. In a few years, the next generation of panels may even be able to capture ultraviolet rays, which are not affected by cloud cover. But even when it’s cloudy and raining, you can still extract significant power from the sun. Witness, for instance, the amazing solar electricity production in Germany (25 gigawatts!), despite the fact that Germany is notoriously overcast and collects as much sunshine, annually, as does Alaska. Likewise, Portland, Oregon solar arrays are also extremely efficient.

At the end of the day, you need to pay attention to averages: one ridiculously cloudy dark day doesn’t mean much in the grand scheme of things. You want to pay attention to the “insolation” rating of your house to make a more informed decision. Partly cloudy days can actually be useful, thanks to a phenomenon known as the “edge of cloud effect,” in which the sun’s radiance temporarily gets amplified by the edges of clouds, much like a magnifying glass focuses light.

Surprisingly, San Francisco and the Bay Area are wonderful habitats for solar panels: our region is more “solar-friendly” than places like Sacramento, since our moderate all year temperatures put less stress on the materials in panels and allow them to work more efficiently.

For more information about how to design and install the perfect solar solution for your needs, get in touch with the expert team at Save a Lot Solar. Or call 510-332-4971 for a free solar power saving estimate.