Monthly Solar Production – May 2012


May was a pretty rainy month in New England.  Plus with all the pollen accumulating on my panels, I was forced into my first maintenance.  In any case, I was not optimistic about my electrical production.

But it turned out to be a pretty good month nonetheless, with a $5.62 net metering credit appearing on my bill, my second consecutive month of producing more electricity than I’m using.  Although I don’t think I’ll make it three in a row since I put in my window air conditioners last weekend.

So here’s my production summary thus far:

Period Ending Production As % of Usage Savings
Dec 21, 2011 223 kWh 32.5% $45.05
Jan 24, 2012 288 kWh 34.5% $59.26
Feb 23, 2012 419 kWh 72.2% $86.81
Mar 23, 2012 484 kWh 87.7% $106.48
Apr 24, 2012 663 kWh 110.4% $145.86
May 21, 2012 536 kWh 105.0% $117.92
Overall 2,613 kWh 69.4% $561.44

If there seems to be some inconsistency, it is due to monthly usage fluctuations, the number of days per billing period and NStar price changes. I also under-reported my Usage % last month because I forgot to subtract the $6.43 NStar flat fee before calculating it.

Note that my production dropped almost 20% from last month.  That shows you how important sunny days are and why solar probably wouldn’t do so well in a place like Seattle.

Although that is a little deceiving since there were 5 fewer days in my NStar billing period this month than last.  So, on a daily basis, my production dropped less than 4%.  This is mainly because the sun is still rising in the sky and the days are still getting longer so on a day-by-day basis, I am producing more energy than I was a month ago.  So while there were a lot more bad days, the good days were that much better.

Looking at my Enphase reporting, I can see that my top 6 energy producing days were all in this billing period, with the highest day being April 28th when I produced a full 33.0 kW.  I assume that my biggest day of the year will be around June 21st or whenever the longest day of the year is, depending on the weather.


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