California EVA Gas/Electric Cost Calculator

I used a similar spreadsheet, but instead I downloaded my usage each day, each hour from the PG&E website and compared the EVA rates versus my E-1 rates. I even tried the EVA rate for 3 weeks before switching back to E-1. For my usage pattern, I found that:

1) The PIP is unable to charge enough electricity to take advantage of the lower EVA off-peak rates and offset the higher mid-peak and peak costs during the rest of the day.
2) To really save money, I'd have to do laundry on weekends only, or after 11 pm on weekdays, which wasn't feasible with a family of 4.
3) The high peak rates discourage me from charging during the day, meaning that on weekends, it's cheaper to use HV mode even though I could have done the trip in EV mode if I had charged.

I think the EVA rates are better if you have a Tesla, Leaf, Volt, etc. and a long enough commute where you can really "load up" during off-peak times.

 

I agree. the EV-A rate does not provide any benefit for the modest amount of kWh used by the PiP. Depending on your usage pattern the later Peak usage schedule may make EV-A more expensive than E-6. However, if you have a Tesla or other car with high electricity usage EV-A is a good deal. My calculations (similar to the OP) show that E-6 provides only a small advantage over E-1 because my solar panels keep me within the baseline (Tier 1) for most months. I'm considering going back to E-1 next "NEM year" to avoid the inconvenience of Time of Use.

 

Phil, that is a really great spreadsheet! I have a couple of nit-type comments. The battery capacity from 20% SOC to 85% SOC is about 2.86 kWh. (4.4 kWh battery total) Charging efficiency considering power from the wall is probably more like 90%. The word "Tier" is normally used in the progressive rate increases based on monthly totals. You might want to use Peak, Partial Peak and Off Peak per the PG&E rates. Many people get better than 48 mpg after the electricity is used up. On long flat freeway trips I get about 53 mpg. For mountain/hilly trips I get closer to 62 mpg due to the great regeneration charging of the PiP.

Needless to say putting my numbers in the spreadsheet doesn't make much difference. With my solar panels and considering either E-6 (charging mostly at night) or E-1, my charging cost is about $0.14/kWh.

 

I developed a mini-version of this for my own use and agree that most of the time during summer (May-October) it doesn't make sense to charge between 10 AM and 9 PM. I just bought my Prius and switched to a time-of-day plan but think I'll switch back in May. Thanks for posting this!

 

can you switch back and forth whenever you want?

 

No at least for folks with solar. I was allowed to switch in the middle of my first year to EV-A but that was an exception as far as I know. At the end of the year I switched back to E-6. As discussed above E-6 is somewhat better for the modest requirements of the PiP.