Are you seeing rocketing solar production in the summer? That’s normal. Are your solar panels going to bed early in the winter? That’s okay, too. A solar system’s production varies month-to-month and even day-by-day, just like the weather.  We take this seasonal variation into consideration when we designed your system.

Want to know more?  Here are the main factors we look at when we estimate how the changing seasons impact your solar production:

1. First, we measure the sun’s position relative to your solar system.

The sun’s position in the sky matters for two reasons: it affects how long the sun is shining each day, and it affects whether the sun hits your panels.

The first point is intuitive: the longer the day, the longer the sun is shining on your panels. That makes June 21st, the northern hemisphere’s summer solstice and longest day of the year, a cause for celebration among solar homeowners!

The location, orientation and tilt of the panels also help us optimize for solar production; solar panels don’t like shade, and they operate most efficiently in direct sunlight. We adjust the tilt and location of your panels so they are exposed to as much direct sunlight and as little shade as possible.

2. Second, we evaluate historical weather patterns in your location.

You guessed it – sunny days result in more solar electricity production than cloudy days, though the difference is not as significant as you’d expect: in cloudier climates such as Portland, Maine, the same solar system can generate 95% of what it would in sunny Miami, Florida.


Source: National Renewable Energy Laboratory

Your solar production is unaffected by air temperature, except in extremely hot temperatures. One study found that solar panels started to lose operating efficiency once air temperatures began to exceed 87 to 91 degrees Fahrenheit. For that reason, it’s possible for a solar panel to produce more electricity per hour on a bluebird winter day than on a painfully hot summer day.

3.  Third, we account for historical snowfall in your location.

The last piece of the puzzle is snowfall. Snow differs from rain because it can pile up and prevent sunlight from reaching your solar panels. We analyze historical snowfall in your location to try to account in advance for these lost days of solar production.

In sum, it’s normal to see seasonal variation in your solar production!

Source: U.S. Energy Information Administration, Electric Power Monthly, Table 1.2E, 6.1B Source: U.S. Energy Information Administration, Electric Power Monthly, Table 1.2E, 6.1B

Don’t fret about shorter days or drab winter weather; you’ve got the upcoming summer production to look forward to and Sungevity’s team of experts on your side.

Posted by Leslye Penticoff

Leslye is the Content and Community Manager for Sungevity. She's also an avid coffee drinker and rock climber, and serves on the Board of Directors at Margination, a nonprofit in Troy, NY.