Electric Rates (where you live)

Thanks for pointing out my mistake in calculating the full battery capacity. After recalculating it with 2.7kWh for 11 miles, the gap between electric vs gas is more with electric being cheaper. I definitely understand that there are quite a few variables to juggle for a good comparison, but I just wanted a general comparison.

My electric costs is about 7-8 cent per kWh, however, the high cost is due to the delivery service and state/local taxes and surcharges that are scaled proportionally to the amount used, that is why I used the total bill cost for analysis. See the attached files for my bill.

 

With SoCal Edison, petro gas has to drop to $3.80/gal and then I break even with tier 4 Edison electric rates at $0.31/kWh.

 

Right you are -- other than $7.87 fixed charges, the other charges are per kWh.

It looks like you have two tiers that apply to your bill -- the first 576 kWh, and then a higher charge afterwards.
Since a PiP would add on from the top, your marginal kWh rate is:

Code:

0.0030200 +
0.0274900 +
0.0027600 +
0.0000100 +
 
0.0001490 +
0.0006200 +
0.0064890 +
 
0.0898000
 
----------------
 
0.130338

~ 13 cents a kWh

 

Our solar panels generated ~ 4500 kWh per year. We use ~3800 kWh of for our 2100 sg ft home. I can not imagine using 985+ kWh. He must be heating with electric resistance heaters.

 

It is misleading to use the EPA number of 350 Wh/mile or the 400 Wh/mile. Their test has a hill after ~6 miles which kicks on the ICE and isn't reporting accurately EV miles and HV miles. No matter how hard I try I cannot get even 3 full kwh into the battery. At 400 wh/m that would be a total range of 7.5 miles. Virtully everyone exceeds this going fast in winter. At 350 wh/m that would be a total range 8.6 miles.

Yes, I get much better than that. For example yesterday/today I went 2.2 + 5.4 + 5.8 with 1.8 miles left over. So that is ~15.2 miles. Yes, this was at 35 - 50 mph on city streets and not 70 mph on the freeway. But I've measured on the freeway as well and at 62 mph I get more like 10 miles per charge or 275 - 300 wh/mile.

And unless you have charged and measured and charged and measured many times you wouldn't know that when driving ONLY on EV for many days you can only charge about 2.7 kwh per charge (you need to go into HV and run the battery down a few more percent to even get to 3 kwh) But when you do this you skew the onboard kwh consumed numbers by mixing in some gas to sometimes recharge the battery and EV charging sometimes goes to battery used in HV for gas mpg.

Battery only, for days, driving 35-50 mph will get 200-225 wh/mile for most people IMO. (For me it is ~180-190 wh/m indicated before charging losses). I've measured this and the charging kwh compared to the reported number shows losses are ~8-9% for 240v...about 12-13% for 120v. For 80% of the weeks I've had the PIP I've logged the weekly EV ratio stats and I see a minimum of 150 wh/m, a maximum of 270 wh/m (mostly a few freeway trips) and an average of 185 wh/mile. Most typical weeks where I just have my daily commute it is 180-190 wh/m.

And, sure, if you jack rabbit start/stop and have the seat heaters and A/C on you will get different numbers. But in any car you will degrade mpg with A/C and/or heat/defrost. The degradation in an EV will be much greater because there is so little waste energy to start with.

Mike

 

This is a great site. Appreciate the link. BTW - check out the Hawaii comparison: it's practically a wash.

 

So if the PiP pulls 2.7 kWh, then I had my previous figure incorrect. Petrol gas has to drop to $3.10 per gallon in order to break even with SoCal electric's tier 5. In Tier 1: $1.20/gal; Tier 2: $1.60/gal; Tier 3: $2.70/gal; Tier 4/5: $3.10

 

There is nothing wrong with comparing EPA to EPA, but we can use your driving too

ok. I know from years of driving an HV Prius that on a temperate day, decent roads, and no wind the car returns about 60 mpg at 62 mph, meaning at a fuel cost of $3.60 each mile costs 6 cents. This implies a breakeven point of electricity of 20 - 21.8 cents a kWh. Isn't that about tier 3 pricing in many parts of CA ?

Let's for a moment assume that the PiP owner is paying low marginal rates of 10 - 15 cents a kWh. Then your 300 Wh/mile costs between 3 and 4.5 cents a mile, for a average savings of 22 cents a day. That would be about $6.6 a month savings off your lease. Hopefully your lease did not cost more than $6.6 a month over an HV prius ?

LOL. I never fail to be irritated by this spin. The central powerplant has already thrown away the waste heat; the Prius uses it in the cold winter. So while any car uses more energy on cold days, the penalty is more severe in an EV as cabin heating is increasingly utilized.

 

That is a very good point. The heat in winter from an ICE is essentially free. It is just a matter of where the waste heat, or more accurately a portion of the waste heat is shunted to.

The denser air, higher rolling resistance, etc will, as Sage mentioned, have some effect, but not as much as the effect on BEVs.

With our Prii we tended to get about a 20% drop in efficiency over the winter. In our Tesla it is about 30%.

 

I wonder if the Tesla has better cabin insulation than a Prius, implying that the increased winter energy use in a less expensive EV would be even more.

One thing is for sure: An EV that relies on ambient cabin heating rather than electric heated seats and wheel is going to be punished in the winter.

 

If you are going to use CA electric rates, you need to use CA gas prices also.

In CA there are several electric rates. There is a EV night rate that get you down to about 7-8 cents, IIRC. I investigated and if I didn't charge for free at work 80% of the time I would have switched to that. My rate is about 10 cents/kwh (a couple of cents discount for being in the summer Smart Rate...in which a dozen days I get charged a lot 2pm-7pm when they ask people in the program to cut back. This has zero affect on my EV charging.) I'm in the lowest tier 99% of the time anyway...but people who use A/C a lot or run pool pumps all the time should just get the EV TOU plan. There really is no excuse for paying more than 13 cents for EV charging...and it is usually less than that.

Lease? No I puchased. That gives me the federal and state rebates, which made the cost just a bit over the regular Prius...and I get the HOV stickers. And I get free charging at work about 6-7 times per week (5 days plus various work trips and lunch).


Mike

 

IIRC, What you and I call a lot of electricity use is somewhere in the 450 - 600 kWh/month range depending on the locale. Those people might like the rate at night, but they usually run away when they see their daytime charges.

I think I can remember two people deciding on a TOU EV schedule of all the threads that have discussed TOU here on PC.

 

All depends upon your utility.
I have a 5.7c/kWh rate on just my garage. So as long as I don't charge between 4pm - 8pm I'm golden.
I suspect even for whole house TOU plans there are a lot more people on those plans than you think.

 

I wasn't using NM -- we would be horrified at $3.63





Hard to eyeball this chart -- perhaps 3.8 since 2011 ?
If that is the case, add on 5% to your savings -- you are closing in on $7 a month

Purchase once again puts you in the definite minority of owners, and I don't know what 'a bit' means, but you will presumably break even on costs in about 10 years if the difference was $1000. I ignore your free charging at work since that is certainly an anomaly.

No doubt about it, the HOV stickers are worth thousands to some people. <<shrug>>

 

I don't know if I am one of those two people, but the EV TOU rate has saved us a bundle even given the added overnight PiP charges. During May-October, the peak time, where the rate goes up 51cents/kwh in the tier we end up in, is 2-9pm M-F. So we just don't run the high-usage appliances during that time. Set the dishwasher timer to run after midnight, when the lowest rate kicks in; do the clothes wash/dry before 2pm to get the middle rate. Do ironing before 2 or after 9. In the south Bay Area, we only have a few days a year where we really need to run the home A/C, so we just set it to 80F, and maybe it runs for a hour or two before it starts to cool off in the evening.

 

Hi Charles,

I don't remember if you were counted, but thanks for the interesting post. I had no idea that tier rates reach 51 cents a kWh in the Bay area. Perhaps you might be interested in PV on your home or in a collective, at least for that tier and perhaps the one below it. Your post does emphasize an aspect of Prius I have noticed in myself and in your home too: other behaviors change with the car. After all, nothing really prevented you from time shifting some of your electricity use before the EV purchase. That does however confuse the issue of savings from the TOU, doesn't it ?

 

The rate that I am on is contingent on having an EV. The electric company asks what qualifying car you have, but they don't really dig to verify it. Before I had the PiP, I didn't have TOU, so time shifting wasn't relevant.

 

Is there a TOU choice that is similar to the one you have for EV owners that does not ask ?

As you say though, a simple lie will suffice for anyone who wants that TOU.

 

Sagebrush:
When you include all incentives and the tax credit many of use purchased PIPs for <$24k or about the same cost as a Prius III.