By the end of the day on Nov. 10, the snow had melted off our solar panels. But we lost up to 20 kWh of production before it was gone.

A quick winter tip for your home solar system: If you get a dusting of snow, you might want to get up on your roof and sweep the snow off your panels.

I’m sure wishing I’d done that today.

Last night (Nov. 9, 2010), about one inch of snow fell here in the Denver area.

The snow stuck beautifully to all the three branches – and to our solar system.

When I left the house this morning, I figured a very sunny day would quickly melt the snow off the panels.

Five hours of sun to melt one inch of snow
I was wrong. It took until about 2 p.m. this afternoon for the snow to melt off, even on an almost completely sunny, 40-degree Colorado day, and even on our fully south-facing, un-shaded roof.

We lost nearly 20 kWh of power production thanks to this dusting of snow. That’s 80 miles in an electric car, or about $12 worth of “gasoline” at $3 per gallon and 20 m.p.g.

I’m sure it would have melted off much more quickly if I’d scooted up on the roof and swept it off – being very careful, of course, not to break my neck and not to damage the panels (I’m assuming, hopefully correctly, that a nylon brush broom won’t damage the panels).

I had no idea it would take five hours to melt the snow off of our 26 solar panels on a bright, sunny Colorado day.

Now that I know how much of a hit snow can make on our 5.59 kW system’s production and how long it can take for even a tiny bit of snow to melt on a sunny day, I’ll be up on the roof after every snow dusting brushing things off – and, once again, being very careful when I do it.

While it’s frustrating that we lost about 20 kWh of energy we could have produced today, it’s definitely not worth breaking an arm – or worse – over.

The plan now:

1. Check the weather forecast.
2. If a dusting of snow is going to be followed by a sunny day, get up there and brush it off.
3. If it’s more than a dusting, and several gray days are forecast, I might wait. Then again, I might just be too impatient to wait.

Solar snow experts who have experience with the home solar system/snow dilemma: What do you do?

Other articles about snow & solar systems on the web-->

• A tale of solar panels, snow, and roof rakes (CNET.com, Feb. 2009)
• How will my home solar hold up in the winter? (SunRun)
• Solar panels in the snow and other shading events (Solar Feed In Tariff, March 2010)

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