Seven Years of Solar

I just received in the mail the PG&E yearly true up bill.  After seven years of solar, my usage seems to have stabilized to the right amount to match my panels. In this true-up period through mid October 2013, I had a credit of $16.33.  Perhaps 2014 will be the true comparison with the Tesla Model S in use for a full year.  Also I hope I get the new firmware soon without the Model S vampire drain.

I have a 27 panel system with the rated output of 3.8 Watts and an estimated energy usage of 6,884 kWh / year.  I have had the system in use for seven years with a somewhat varied energy usage.  The first two years, the panels were not supporting an electric car and PG&E got a lot of free electricity.  I got the Tesla Roadster during 2009.  In the 2013 true up period, I sold the Roadster and bought the Model S.

With PG&E, you cannot directly find out how much energy you produce or how much energy you use.  You can only know the “net” energy.  Even this data is complicated and broken down into daily chunks of time as the cost of electricity varies per time of day and time of year.  Also, PG&E changes the rates every few years to make a complete statistical analysis difficult.  Other factors include the weather and how dirty your panels are.  I found a substantial increase in production after having my panels professionally cleaned one time.  The second time I had them cleaned I did not notice a particularly significant drop in production.   I did an exhaustive analysis of how much I generated and used in this report.

In summary, my costs or credit for each of the seven years is listed below:

  • 2007    -88.47
  • 2008   -162.98
  • 2009   -29.55      Roadster mid true-up year
  • 2010    381.75
  • 2011    154.27
  • 2012   -123.22
  • 2013   -16.33      Roadster sold Model S purchased
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8 thoughts on “Seven Years of Solar

      • Agreed that $250 for a monitoring device isn’t cheap but we’ve found the information it provides useful. We bought our TED in the context of our PV install so it didn’t seem like much in the way of added cost.

      • If I had a new solar system, I probably would have thrown in a monitoring device primarily to check my production and usage. I am not too interested in the other data as the house is quite new and built with energy consumption in mind.

        The TED has mixed reviews on Amazon.

      • I bought my TED direct from the manufacturer on the recommendation of my solar installer. Seeing the Amazon reviews has me second guessing this decision..

        We had some initial difficulties with the PLC but they were cleared up after installing an inline filter. Hopefully the system will keep running for a while.

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