Does solar power still work in the depths of winter?

Tom Griffin, of Duluth, sweeps away snow from the solar panels in his backyard in 2019. He had nine solar panels installed to help provide electricity to his home. Duluth News Tribune file photo

By Hunter Dunteman | West Central Tribune

Minnesota winters are long, cold and dark, which don’t sound optimal when it comes to saving money on a power bill. But industry experts agree that even with shorter days, solar power could still be a cost-effective measure to reduce expenses for residential, commercial and industrial consumers.

The amount of sunlight that reaches the ground in Minnesota drastically varies depending on the time of year. On the summer solstice in June, the state sees roughly 15-16 hours of sunshine whereas on the winter solstice in December, Minnesotans will only see about eight to nine hours of light.

In a state that’s rapidly increasing both its solar power capacity and consumption, it’s worth wondering what impact shorter days have on solar power. But according to Logan O’Grady, executive director of the Minnesota Solar Energy Industries Association, it’s less than one might assume.

“Do we have as much sun as Florida?” O’Grady asked rhetorically. “We don’t have quite as much but we do compare in terms of days of sun and hours of sun to other southern states.”

Though the National Weather Service no longer tracks the amount of sunshine that falls on their stations in a given time period, a 2004 report from the National Oceanic and Atmospheric Administration (NOAA) tracked the percent of possible sunshine that fell on larger U.S. cities.

For a 100% score on the NOAA report, a city would need to experience virtually no cloud cover during regular daylight hours. The report found that in the five decades leading up to 2004, Minneapolis saw 58% of possible sunshine reach the ground, comparable to cities like Atlanta Houston.

Yuma, Arizona, topped the report with a score of 90%, while Juneau, Alaska, scored lowest at 30%.

The percentages do not reflect the number of actual sunlight hours experienced, as cities in the southern United States have longer winter days than cities to the north.

“Clearly Minnesota’s not the sunniest state in the union, but we’re definitely not the darkest,” O’Grady said. “Just because it’s cloudy or darker doesn’t mean that your system won’t deliver decent results at any given time of the year.”

Beyond the amount of sunshine in the state, O’Grady said colder temperatures actually make solar panels more efficient.

“One thing that people don’t know is that winter is good for solar,” he noted. “Keeping the panels colder, keeping the infrastructure under the panels colder is actually more efficient. It transfers energy more efficiently with less loss.”

Most solar companies agree that solar panels begin to operate less efficiently in temperatures higher than 77 degrees, as energy can carry a stronger flow without overheating.

However, whether it’s snow, ice or trees, O’Grady recommended keeping solar panels free from anything that may obstruct sunlight from falling on the array.

“It’s very rare that [solar panels] won’t work,” O’Grady said.

In 2021, solar power made up roughly 3.2% of all power produced in Minnesota, enough to power 200,000 homes for the year. Industry experts forecast growth in both production and consumption in the years to come.