miimura said:
So I went ahead and added an equivalent Off-Peak charging amount of 13kWh/day to Jan-Apr to more accurately model the period before I got the RAV. It drastically changes the picture in the winter. Adding that usage when the solar is generating so little pushes the usage way into the upper tiers. The Tier-Less EV rate schedule then comes very close to E-9A. Adding in November and December will probably make EV-A clearly less than E-9A.
It turned out that for the full year E-9A was still cheaper than EV-A in my situation. At one point, early in my analysis, I thought I might go back to E-6 when I'm kicked off E-9. According to these numbers, EV-A will be much better for my situation.
Summary of Calculated Annual Energy Charges:
E-1: $1,468.85
E-6: $1,129.21
E-9A: $817.32
EV-A: $837.35
The Excel spreadsheet to generate this from your own SmartMeter data is on Google Drive here:
PGE Electric Rate Calculator_V1.6.xlsx.
I also did one more calculation to back out my solar generation to see how much my bill would be without solar. Now, I know this is not a very good or particularly valid comparison because no sane person would stay on E-1 with an EV, but here it is.
The main reason I did it this way is that I currently have no way to extract the data for my solar generation by TOU period. If I spent a bunch of time on it, I could probably extract the data from Enphase Enlighten. Anyway, according to this, my annual energy cost would be $2,342 higher on E-1 without solar. Even for the Jan-Apr period when I didn't have an EV, my bill would have been $462 more. For the first 4 months, my interest payments on my HELOC for the amount of my solar system were only $254, so I saved $52 per month more on my energy bill than the interest on the solar system. Actually, now that I think about it, my ACTUAL savings is E-6 with solar vs. E-1 without solar. That comes to almost exactly
$60/mo savings after interest expense because the E-6 bill is lower than E-1 with solar.
One more note about solar true-up. When PG&E installed my NEM SmartMeter after my solar install in December 2012, the usage continued to go to the conventional billing system, not the Solar NEM billing system. When they finally got my account set up in the NEM billing system and backed the charges out of my regular bill, the TOU usage amounts were obviously wrong. I complained to Solar Customer Service and had to talk to 3 people before I convinced them to go back to the original SmartMeter data and recalculate it. They finally did and I got a revised true-up statement. Several months later I noticed that there was no dollar amount accumulated for that first month in my true-up. I got the automatically generated full year true-up bill and paid the balance after it was transferred to my regular bill. Then I received another "corrected" true-up statement, actually 12 envelopes in the mail with each of the 12 monthly true-up statements. Since I have been doing all these crazy calcs based on my SmartMeter data, I also replicated the calculations for my actual billing cycles and found a significant discrepancy, 30kWh, between what I was billed and what was in the SmartMeter data. It turns out that PG&E is missing the SmartMeter data for one 24 hr period in March. It seems like they estimated the missing data by repeating the usage for the prior 24 hours. The problem is that the prior day was a particularly low generation day and was the highest net usage of the whole month. The average of the 6 days surrounding the missing day was only 22kWh. I called the PG&E Solar Customer Service Center and they said they will get back to me regarding how they "interpolated" my usage for billing purposes.