January 2017 | Shine Solar

Month: January 2017

 

Cloudy Days and Solar Output

Let’s be real…The winter months are here in NWA! It’s cold, cloudy, and the first snowfall is due any day now. With these overcast days we typically get asked if our solar panels are producing energy, and we have some great news! We listened, researched the facts, and came back with some answers for you.
Typically, a dream scenario for a solar panel is a magnificent cloudless sky just overflowing with uninterrupted sunlight every hour of the day. But this dream is often unrealistic and by no means is it necessary to produce solar power. Solar panels can thrive in cloudy conditions, and even with a cloudy or overcast sky, usable sunlight is getting through even though the sun might not be shining.
There are a few different types of sunlight you should be aware of that your solar panels can convert to electricity. The most straightforward (and most powerful) fuel for a solar panel is “direct sunlight,” which arrives in a direct line from the sun. But solar panels also use “diffuse sunlight,” which is sunlight that has crashed or bumped with other things in the sky – such as clouds, haze, and dust – and as a result, has been broadly scattered before reaching your roof. There’s also “reflected sunlight,” which is sunlight that has bounced off snow, buildings or the ground before hitting your solar panels.
Although diffuse sunlight is less powerful than the direct kind, it does get converted to electricity – just less electricity than what would result from pure direct sunlight. For example, on an overcast day (when most of the sunlight hitting your rooftop is diffuse), a solar panel might produce only 20 percent of its maximum capacity. This isn’t ideal, but not insignificant either – and important to the overall structure of a solar power system. What really matters is the solar panels’ total annual output, which can be large despite extended cloudy days.
A cloudy month or even a cloudy season does not eliminate the value of solar panels. Rather, a solar rooftop’s success is based on how much it reduces your overall use of costly grid electricity. And it makes the most sense to evaluate that on an annual basis, rather than daily or monthly, since even the cloudiest climates get several clear days over the course of a year. We see many cloudy areas in the U.S. get more than enough sunlight (direct, diffuse, and reflected) that produce more than a thousand dollars worth of electricity each year, while also preventing thousands of pounds of carbon pollution.
Also, the technology has arrived to use solar-based electricity even when the sky is cloudy, overcast, or even pitch black. By using a battery that stores excess power during sunny periods, you can tap into that stored energy during times when your solar panels aren’t able to provide enough power.
In some cases, a cloudier climate can actually be linked to more solar power production.
Here’s an interesting fact: a solar panel in famously foggy San Francisco can produce slightly more energy per year than a solar panel in sunnier and hotter Sacramento. A key reason is that San Francisco has relatively cooler temperatures, while still getting a healthy amount of sunlight over the course of the year. That’s good news for solar power, because solar panels actually operate more efficiently in cooler conditions due to the nature of semiconductor materials. So, although Sacramento gets more sun overall, its higher temperatures limit solar panel output. (Thanks to SolarPowerRocks.com for the example!)
The great thing about living in NWA or SWM is we have humid hot summers and cloudy, snowy winters which makes solar power the perfect option for our climate. Due to our location, both extreme weather conditions allow us to consistently produce a sustained amount of energy through the course of the year helping us save money while reducing our carbon footprint.