Do solar panels work with snow on them?

You don't have to live in the sunny southwest for solar panels to work. Solar is popular even in snowy climates, but that doesn't mean you'll generate electricity all the time.

Example of electricity production with snow covered solar panels.

My solar-powered house is located in Buffalo, which is pretty famous for snow. The biggest one-day record for snow in Buffalo? 34 inches.

Despite that reputation for the white fluffy stuff, we also get plenty of sunshine - even in the winter. In fact, clear and cold days in the winter can be great for solar production.

Still, there are multiple weeks a year when my solar panels are underneath a blanket of snow. What happens to solar panels then? Do they still generate electricity when they’re covered by snow?

Solar panels will work if they’re covered with only a light dusting of snow, but once the snow depth exceeds about half an inch, solar panels will stop generating electricity. Wind will sometimes help sweep some of the snow off, but most of the time you’ll need to wait for the temperature to rise and melt the snow before your solar array will generate electricity again.

What your solar electricity production will look like in the snow

The picture at the top of this article is a screenshot from my Enphase solar monitoring system. Enphase microinverters tell you how much electricity each panel generates, and the screenshot shows how many watt-hours of electricity each panel generated over the course of the day.

While this was an overcast day, there was still enough light for the top row of panels to generate a decent amount of electricity. But as you can see from the pattern of light and dark panels, some panels had snow on them while others remained covered.

It had snowed the day before, but there was enough wind and sunlight to clear most of the snow off the top row and a couple other panels. But the bottom row of panels were still completely covered in snow, and several others remained partially covered.

As you can see, the completely covered panels generated basically no electricity - 6 Wh might power a small flashlight for the day, but that’s it. But the top row of panels still generated significantly more.

Do solar panels melt snow?

Solar panels don’t generate heat, so snow isn’t going to melt off them much faster than the air temperature allows.

However, they are dark colored, so they passively absorb energy from the sun and get warmer. This is sometimes enough heat to help clear the panels if there’s only a light dusting of snow, but in my experience this passive heat from the sun can’t be relied on to keep your panels clear of snow.

How does roof slope help keep your solar panels clear?

Snow is surprisingly sticky, especially if it’s a wet rather than a dry, powerdery snow. My roof pitch is 5:12, which is a 42°. That’s pretty steep. Even so, the snow doesn’t really slump off until the temperature warms up.

I also have something working against me, which is that the bottom row of my panels is mounted on a flat section of roof that abuts the pitched section. That’s a recent addition to my home. Before that addition, if I had a few inches of snow on my panels, the snow would slide off the roof once the temperature warmed up a little.

This would sometimes happen in dramatic fashion: the snow would slide off in dramatic fashion, like an avalanche. This is something to keep in mind if you have solar panels on a pitched roof. Be prepared for snow avalanches off your solar array to happen, so you might want to keep the area underneath clear of things like patio furniture or vehicles.

If you have a roof with a very steep pitch, you probably will have better luck with clean panels in the winter. Conversely, a flat roof will remain snow covered for longer.

When does snow melt off your solar panels?

There are a couple main ways that snow will clear off your solar panels.

The first is wind. If it’s very windy, even an inch or so of snow will blow off them. But in my experience, wind isn’t very reliable for keeping your panels clean if you have more than an inch or two.

The main way that panels get cleaned of snow is melting. Once the temperature nears 32°F, the snow will start to soften and slide off.

Should I manually clean the snow off my solar panels?

I can’t reach my solar panels from the ground with an extension pole, so the only way that I could manually clean the snow off is to get on a ladder.

Getting on a slippery aluminium ladder and climbing up to my roof in the middle of a Buffalo winter isn’t something that I want to do, especially because it snows throughout the winter and it’s something that I would have to do probably multiple times a week if I wanted to keep the panels clear.

A potential hospital bill isn’t worth the two or perhaps three weeks of winter electricity generation that I would gain.

If your panels are easily accessible from the ground with an extension pole, feel free to go ahead and sweep the panels. Be very careful and use only soft tools. Our article on solar panel cleaning has tips and links to products that work well for this.

How much solar electricity can you generate in the winter?

While you might hate the idea of losing solar electricity in the winter due to snow, if you live at higher latitudes your winter days are relatively short, which limits how much power you can expect to generate anyway.

You can use The Solar Nerd calculator to find how much. Toward the bottom of the report is a chart that shows how your electricity generation will vary from month to month. We also have an article comparing solar power generation between summer and winter.

Learning more about solar panels and snow

If you want to look at a real world example more closely, feel free to explore the public data for my solar panels.

The screenshot at the top of this article is from February 7th, 2021. If you click around, you’ll see that the day before was partly cloudy but all of my panels were completely covered in snow. By the next day (February 8th) the snow had cleared off most of the panels except the bottom row (which are on the flat roof) and were generating a decent amount of power.

You’ll see that pattern repeat throughout the winter as the snow came and went.

It’s not something I worry about. I just wait until spring, when the snow is gone and sunny days return. Want to see an example? Go to my data for March 19, 2021. It’s a cloudless cold spring day - perfect conditions for solar panels.

#Homeownership #Weather

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