Eight Years of Solar

I recently finished my annual electric true up period for my solar panels last month. After eight years of solar and the Model S, I am actually paying PG&E at the end of the year a modest amount of $157.56, so I clearly have the right number of panels for the usage on both my house and the car. The seventh year of solar I had a tiny $16 of credit but for several months of that solar year I was driving the Roadster.

Although last year I put a lot more miles on the Tesla than normal, those extra miles were all supercharged and paid for by Tesla. In any given year, probably 1/4 of my miles are supercharged. Each year I take two trips to Oregon and several more to other areas in California.

I started to look through the spreadsheet, the data, the current PG&E rates, my old blogs and it was simply not worth the trouble to re-estimate my estimates. The big black hole with PG&E is that the solar panel owner has simply no good way to know how much energy the panels generated. And although I have kept my Trip A on the Model S since I first got the car, I have no record of miles driven during my PG&E true up period, which ends in mid October each year, or my annual mileage, or the amount of energy I used from charging at home. One could joke that this is all simply a conspiracy to not encourage the adoption of solar panels! Yes there are after market products you can put on your house to monitor your actual energy generation, but I have not chosen to do so.

In early 2013 I went through the very painful task of trying to best estimate when my panels will be fully paid for.  Then I concluded it was likely at the end of my true up period in 2017 and I still believe that estimate holds merit.

On top of the difficulty in measuring things with great accuracy, I am also charged monthly $7.80 in local utility taxes.  California also gives a California climate credit twice a year.  In October my bill was credited for $31.76.  The credit is uniform among all customers in a given area and not dependent upon electricity usage.

“The Climate Credit is from a program designed to fight climate change by limiting the amount of carbon pollution our largest industries put into the atmosphere. Under California’s climate law, power plants and industries must pay for permits when they put carbon pollution into the air. Some of that money is used by the state to fight climate change, and some goes to households and small businesses to assist them with the carbon pollution costs in electricity that comes from non-renewable resources, like coal and natural gas. The credit on your electricity bill is your share of that money, and you can use it to save money today, and to save money in the future when you invest in energy-saving devices and home improvements.”

Regardless, I earlier made some valid assumptions that are still holding merit:

  • If I did not have solar, my outlay per year for the car at about 7,500 miles charged at home per year would be close to $2,000 with PGE rates.
  • I have the correct amount of solar panels on my house which is 3,825 Watts with an annual estimated production of 6,885 kWh
  • The total cost of the system after rebates, permits and non-regular cleaning was $17,750
  • In three more years, my system will have been paid off and all electricity will in a sense be free.

Here’s my annual bill. Positive numbers are charges, negative numbers are credits.

Annual Solar Charges

Annual Solar Charges

5 thoughts on “Eight Years of Solar

    • I know, but after so many years and reasonable estimates, I haven’t bothered.

      I like to analyze data but didn’t realize I should have bought one of these 8 years ago.

    • I track my generation on a daily basis to a spread sheet. With 18 panels, I have generated about 7.1 Mwh per year for the past 4 1/2 years. The SCE rebate, up until earlier this year, was about 3 cents per Kwh. Since that time it has been the retail price of about 13 cents per Kwh. This drastically advances the system payoff time. They pay me the same rate as I pay them if I use more than I generate (tier one, of course).

      • You live in a different area as we only got payback for one year. Our electricity provider is not well liked but hopefully the local laws will change requiring them to buy our extra energy.

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