Big smile as electric bill arrives post-Tesla solar install

[WSE51]

Los Angeles DWP invoices every two months.

My first two month invoice fully on Tesla Solar/Powerwall arrived today, and it worked out just as I hoped.

Due to my home orientation and roof gables, I was limited in the amount of solar panels I could install.

Even though the solar system only produced about 36% of the total electricity used, 88% of the High Peak usage was eliminated. Tesla's time-of-use algorithms nailed it.

My invoice was 54% lower than last year’s August invoice.

Hurray for Tesla, and my thanks to them for sticking it out through the tough LADWP and City of LA regulatory maze.

 

[Big Dog]

sorry to rain on your celebration, but I hope that you realize that this SoCal summer has been cooler than last, by several degrees. (My August bill was much lower as well, even without solar panels.)

 

[WSE51]

Big Dog, you are correct that a more careful statistical analysis is in order. Thank you.

I just did it, having downloaded the daily usage and production statistics from Tesla for the exact dates covered by the DWP invoice. My home usage for the 59 days ending 8/23/19 was lower than for the same period in 2018 --- but only 6.1% lower. My invoice was 54% lower.

There was one additional factor - in 2018 I was not on TOU and the great majority of my invoice was at the price of 28.71 cents per KwH. In 2019, I was on TOU rates, and the High Peak Rate was only 26.08 cents. So even without any solar/Powerwall system, and even if all my usage was at High Peak, I would have saved about 9.2%

So perhaps 15%-16% of savings was not attributable to the solar/Powerwall system and around 38% savings was solar/Powerwall.

One final statistic. DWP says that my home usage was about 1.7% higher than Tesla says it was. While that is close enough for me, I am curious how this compares with others' experience.