Monthly Solar Production – Winter 2012-13 and Loss Due to Snow


The winter of 2011-12 was a complete dream for those of us in New England.  And what I mean by that is there was very little snow. We had one big storm just before Halloween (many towns actually moved Halloween to the following weekend) and then a small storm in March, but that was it. And even better, it turns out that it was a perfect baseline to measure loss of solar panel production due to snow this year.

I haven’t posted my monthly production in several months. This is the slow time of the year for solar production so it’s hard to get excited at the small amounts of electricity I’ve been producing lately. And those numbers have been even less due to snow loss, meaning production lost because either it’s actively snowing or because my panels are buried under a few inches of snow and are hardly producing anything.

We had an average amount of snowfall this winter near Boston.  December and January were pretty tame but we got clobbered in February and March.  Well now that that snow has almost completely melted, I figure it’s time for a review of this winter’s solar production plus an analysis of this year’s snow loss.

Also, for reporting my production from now on, I am only going to be reporting on the last 12 months. That way you’ll always be able to see a current snapshot of what I’ve saved over the last year.

So, on to the numbers:

Period Ending Production As % of Usage Savings
Apr 24, 2012 663 kWh 116.1% $145.86*
May 21, 2012 536 kWh 117.3% $81.62
Jun 22, 2012 707 kWh 121.8% $107.72
Jul 23, 2012 767 kWh 75.1% $116.86
Aug 22, 2012 660 kWh 67.9% $98.93
Sep 21, 2012 616 kWh 77.6% $92.34
Oct 23, 2012 449 kWh 69.7% $67.32
Nov 23, 2012 313 kWh 50.2% $46.93
Dec 21, 2012 188 kWh 33.2% $28.19
Jan 23, 2013 195 kWh 35.0% $30.05
Feb 22, 2013 259 kWh 47.9% $40.02
Mar 22, 2013 325 kWh 60.4% $50.52
Overall 5,678 kWh 72.2% $906.40

*NStar 100% Green Energy rate

If there seems to be some inconsistency, it is due to monthly usage fluctuations, differences in the number of days per billing period and NStar price changes.

I still have one month on the books at NStar’s 100% Green Energy rate, which is roughly 50% higher than their normal rate. So it looks like my annual savings is going to come in right around $900 going forward.

My electric bills were pretty high this winter, with December’s through March’s bills coming in at $63, $62, $50 and $40 respectively. December through February were the 3 most expensive months of the year for me. I’m glad the winter’s over and my panels can really start producing again. Last year I showed a surplus starting with April’s bill so I’m hoping that trend continues!

Regarding snow loss, my baseline period is from December 22, 2011 through March 23, 2012. We hardly got any snow during this time-frame and I showed an average daily production of 12.8 kWh.

The period I am comparing it with is from December 22, 2012 through March 22, 2013.  All the snow we received this winter was in between those two dates.  During this time-frame, I showed an average daily production of 8.6 kWh, almost exactly a 33% reduction from the baseline year.

This resulted in a loss of about $61 in production compared to last year. If you check the numbers yourself, they will appear larger but that is because last year I was still on the inflated NStar 100% Green Energy rate.

Over the entire year, I show a little less than 7% of my production lost due to snow. This number is so low because little of my production occurs during these winter months anyway. I also think this number has room to decrease as most of this year’s snowfall occurred during the months of February and March, which typically have much higher production numbers than December and January.


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2 thoughts on “Monthly Solar Production – Winter 2012-13 and Loss Due to Snow

  1. Hi Gary,

    Very helpful information. I just installed a 24 panel system (5880 Max output) in the Boston area. How large is your system? I’m trying to gauge what my yearly production will actually be.


  2. Hey Mike,

    Glad you like the site! My system size is just under 5 kW, so I’m thinking your system should produce between 6.5 and 7 MW annually, depending on the weather.

    I hope you enjoy earning money with your solar panels! I know I do. :)


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