snow-and-tededitors-blog-entry3Yes, the snow is still falling here on Colorado’s Front Range in mid-March. We got about 1/2 inch of the white stuff last night.

However, snow on solar panels in March is vastly different than it is in January. The sun’s way more powerful and the temperatures typically much warmer.

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That didn’t stop me from trying a new approach to getting snow off of our 5.59 kW solar system yesterday morning, though. This time, I used the garden hose. I wouldn’t do this in January. It’s too cold and I, not to mention the water itself, would freeze — not a good idea for the solar system, or for the roof.

Yesterday, though, had a forecast for temperatures in the 50s. So there I was, at 8 a.m. standing on a ladder (no, I’m not getting up on a snowy roof anymore!), shooting water onto our 26 REC panels. It took about eight minutes to completely clear our lower 13-panel string of snow plus about 1/2 of our upper 13-panel array (I couldn’t get the hose to shoot the water far enough to clear the entire upper array).

Water or Mr. Longarm?
I’m not sure if it was worth it, although it was actually kind of fun — more fun than reaching around with a Mr. Longarm, and a lot less work. Overall, I’d say we generated about 3 kWh we wouldn’t have if I’d let the snow melt on its own.

The moral of the mid-March solar system snow story here in Aurora, Colo.: Don’t bother to clear snow if a clear, sunny and warm day is forecast in the middle of March for the day after the snow. It will melt quickly enough that you won’t lose much production (though you’ll lose some).

Of course, it’s a very different story if you’re talking about a sunny, but cold day in January or February following a snowstorm, as the table below clearly illustrates. Then, you may well want to clear the snow from your solar system.

Sweeping the snow off solar – An ongoing tally of kWh gained & lost

Snowfall date(s)

Snowfall Amount

Date and time of snow sweeping (lower of 2 13-panel strings of 5.59 kW system only)

Estimated kWh gained from sweeping (gain may have been across multiple dates)

Dec. 30-31, 2010

2 ½ inches

Jan. 1, 2011
12:30 p.m.

7.3 kWh

Jan. 9-10, 2011

6 inches

Jan. 10, 2011, 8:30 a.m.

33 kWh

Jan 19, 2011

1 inch

Jan. 20, 8:15 a.m.

6 kWh

Jan. 31, 2011

2 inches

Feb. 1, 9 a.m. (roof too icy; failed to sweep much snow off)

0 kWh (failed snow clearing attempt due to icy roof conditions)

Feb. 5-6, 2011

5 inches

Feb. 6, 9 a.m. (from ladder with 23′ Mr. Longarm)

13 kWh

Feb. 7-8, 2011

6 inches

Feb. 9, 8 a.m. (from ladder with 23′ Mr. Longarm)

29 kWh

(12 kWh of additional production missed on 1st day due to slivers of snow left on on few panels — minuses of central inverter system)

March 6-8, 2011

1 inch

March 8, 8 a.m. (from ladder with 23′ Mr. Longarm)

0 kWh

(waited too long to sweep snow away and it turned to ice, which was unsweepable)

March 18, 2011

1/2 inch

March 18, 8 a.m. (from ladder with water hose)

3 kWh

Running total kWh saved as a result of sweeping snow off 13-panel garage roof string

91 kWh

Running total kWh lost as a result of not sweeping snow off 13-panel upper roof string

108 kWh

Running total of additional kWh lost as a result of limitations of central inverter system

20 kWh

Running total of estimated kWh that could have been produced with immediate, 100-percent post-storm clearing of snow from entire 5.59 kW system

220 kWh

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