PG&E Charging - Solar and EV

[cciesingh]

I am a PG&E Customer in CA and have recently had solar installed and activated by PG&E

I have also switched to the EV Rate.

I have no idea what is the best rate to use for me, but I usually tend to charge my vehicle at night every 2-3 days. There is also an E6 rate.

Any suggestions what would be my best options?

 

[Khatsalano]

This is a complex question. First, some background: rates are hard to understand because it's not like buying cake. When you want cake, you buy cake. While there are dangers to having too much cake, you can buy as much as you'd like pretty much since there is no way you can out consume the supply of cake. With rates, there are not only supply and demand factors, there are also social policies (energy efficiency, subsidies for lower income, equalization of use due to climate, etc.) that influence how rates are structured.

Ok, now to the good stuff. For me, I drive enough that a tiered E-6 rate would have been super expensive. On a tiered system, the more kWh you use per month, the more you pay per unit of energy. EV-A, is more like per-pound deli food-- no matter how much you eat, it's the same amount per unit. I'm going to take a wild guess here, but assuming you are good about time-of-use (like charging at night, doing laundry at night, no one is home during the day with the A/C blasting in San Francisco), E-6 is better if you're a Tier 1 or Tier 2 customer. If you're a Tier 3 customer and up, EV-A is probably better. You can see what tier you're in by your bill. If you're not a time-of-use flexible customer, E-1 may be even better, provided you don't drive very much, which it sounds like you don't if you only charge every 2-3 days. Good luck!

- K

 

[miimura]

If your net usage is dominated by Off-Peak like mine is, you are almost guaranteed to save money on EV vs. E-6. The Off-Peak EV rate is less than the Tier 1 Off-Peak on E-6. This is the comparison for my house which has an under-sized solar system with two EVs. Maybe it would be close to zero dollars on the annual true-up with no EV charging on E-6. With EV charging, there's no question what is the cheapest. With one EV, E-9 was cheaper, but that's not available any more and in the winter it's significantly more expensive for me.

This is from my spreadsheet, which uses data you download from PG&E. However, it takes some effort to use. If you want a quick and dirty answer based on historical PG&E data, you can use the iOS app "PG&E Toolkit". However, that app requires your PG&E login credentials to download the data.

 

[Merrill]

If your net usage is dominated by Off-Peak like mine is, you are almost guaranteed to save money on EV vs. E-6. The Off-Peak EV rate is less than the Tier 1 Off-Peak on E-6. This is the comparison for my house which has an under-sized solar system with two EVs. Maybe it would be close to zero dollars on the annual true-up with no EV charging on E-6. With EV charging, there's no question what is the cheapest. With one EV, E-9 was cheaper, but that's not available any more and in the winter it's significantly more expensive for me.

View attachment 108795

This is from my spreadsheet, which uses data you download from PG&E. However, it takes some effort to use. If you want a quick and dirty answer based on historical PG&E data, you can use the iOS app "PG&E Toolkit". However, that app requires your PG&E login credentials to download the data.

No sure how this would work considering the peak times are later in the day and go til 9pm, so if you cook during that time your paying peak rate plus you lose the peak rate net generation from earlier in the day. Are the rates for EV that much better?

 

[miimura]

No sure how this would work considering the peak times are later in the day and go til 9pm, so if you cook during that time your paying peak rate plus you lose the peak rate net generation from earlier in the day. Are the rates for EV that much better?

Look at one specific month to see why EV is cheaper. Let's take August in the table above. You are right, that E-6 gets more Peak credit because the evening usage goes into Part-Peak instead of Peak. You see E-6 Peak is -104.23kWh while EV is +10.55kWh. That is a spread of $40.05 in favor of E-6. However, the EV charging in Off-Peak has a difference of $42.99 in favor of EV. The net difference for that month is $17.34 in favor of EV. I'm sure if you had a significant A/C load during the day, this would not be the case. Then again, you would probably have a lot more solar than I do if you had a lot of A/C usage.