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