Eight straight days of solar system snow cover

snow-neighbors-systemThis is another short entry about snow on solar panels and, no, it’s not a complaint – at least not as I see it. It’s simply an attempt to highlight, albeit in anecdotal fashion, that snow on solar panels does have a substantial impact on solar production.

That might seem like a “duh!” observation. However, since, as far as I know, few people are yet measuring actual instances of solar electricity production lost to snow cover, I see this as an interesting and important contribution to knowledge production and, hopefully, long-term change.

Since we now have neighbors who have a 5.1 kW solar system – ours is 5.59 kW – I can actually show, in a small, but also concrete instance, how lost solar electricity production is both very real here in Colorado, and how it starts to add up.

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8 days of snow cover
It’s been eight days since the Denver area was hit by about two-feet of snow. In those eight days, our neighbor’s 5.1 kW system has remained snow covered for the entire time. In fact, it looks like by the time it begins producing again it will have sat for 10 days under enough snow to prevent any solar electricity production at all.

That’s right: Ten days in a row without any solar production whatsoever, many of them blue-sky, sunny days, but also fairly cold.

I cleared the bottom 13-panel string of our 26-panel of snow last Saturday. However, I cannot safely reach our upper 13-panel string, even with a 23-foot Mr. Longarm. That string hasn’t produced any electricity for eight straight days.

We have a TED (The Energy Detective) system that monitors our solar production and our electric consumption. According to our TED data, we produced 69 kWh of solar electricity during the past eight days – via just half of our 26-panel string.

snow-8-days-coverLost solar production
Had I not cleared half of our solar system of snow, we’d have produced 0 kWh of electricity in that time. Similarly, had I’d been able to clear the upper 13-panel string of snow as well, we’d have produced 138 kWh of electricity.

Meanwhile, our neighbor’s 5.1 kW system likely would have put up very similar numbers, let’s just say 125 kWh. I don’t think they’ll produce any solar electricity for at least another full day, so let’s up the 125 kWh figure to 145 kWh. And let’s also up our own total lost potential kWh to 158 kWh.

If you add it all up between our two homes’ solar systems and say that I hadn’t cleared ours of snow at all, we’re looking at 303 kWh of solar electricity production lost to snow cover – and that’s just one storm, and two small solar systems in the Denver, Colo. area.

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Again – not complaining here – just documenting, in a concrete way, how solar kWh are indeed being lost to snow cover.

Finally, to put the 303 kWh in interesting perspective, our May – September monthly kWh use is about 230 – 300 kWh per month (no, we don’t have an electric car yet). This means that the 303 kWh of solar electricity production lost [by sweeping part of our system, I’ve prevented about 1/4 of that loss] to snow cover sitting on two solar systems in our neighborhood could cover a full month’s worth of electric use by at least one four-person household in that very same neighborhood.

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