Comparing EV and HV energy costs

Looks OK but here is a little critique.
EIA - Electricity Data

Your ave. electricity cost is the base ave. of utilities not of households. A utility serving a smaller population area has the same weight as a large utility say NYC area or Calif. These larger utilities are also likely to serve areas where fund, fee, charge, and tax could be equal to or greater than the base KWh charge. We pay more than $0.10 but exactly what per household is a complex calculation that I have never verifiably seen done.

Ave. gas price also doesn't factor in the volume of gas sold at any given price.

Need a chart or graphic calculator maybe like an aviation e6b to relate the real cost of electricity, gas, and mpg.

 

Your numbers are off. Can't see where the 5.43 mi/kWh came from, but the battery has 4.4 kWh to go typically 11 miles, which is only 2.5 mi/kWh. If you consider the charging losses, it's probably less than 2 mi/kWh.

In my area, electricity is over 20 cents/kWh, and with all the hills around here, I get less than 10 miles/charge, so I pay more to charge than to run on gas. But I do it anyway for carbon-reduction purposes, since my electricity comes from renewables and I have solar panels.

 

Your numbers are off. You have less than 2.7 kWh of usable battery storage. Nobody in a PiP has 4.4 kWh at their disposal. At my 4.8 mi/kWh measured I'd get darn near 21 miles of EV. If you want to add the typical 15% charging loss then it's closer to 3 kWh for each charge.


Unsupervised!

 

another factor is speed. ev is much more efficient at low speeds, hv on the highway. these equations only work on an individual basis, not globally. mostly dependent on kWh cost, which varies much more widely than gasoline.

 

I multiply my electricity cost by 12 to get my per gallon equivalent gasoline cost. Below is the way I do the calculation. The givens are thusly:

3 kWh per charge
12.5 miles per charge
50 miles per gallon gasoline EPA

3 kWh / charge X electricity cost / kWh X charge / 12.5 miles X 50 miles per gallon

Simplified it becomes
3 X electricity cost X 50 / 12.5 per gallon

Or

KWh electricity cost X 12 per gallon

My marginal cost for tier 2 electricity in the summer is currently at $0.24 per kWh. Plugging in is costing me the equivalent of $2.89 per gallon. I just filled up this morning at $2.13 per gallon. If you only get 10 miles per charge then you multiply by 15.

My average electricity cost is significantly lower but that's how electric car companies trick you into thinking you're saving money. All my PiP charging comes from the top at marginal rates. I think it's misleading to use average electricity to calculate costs. It's like using average income tax rates to calculate how much refund you get. No one does that.

I get $1.25 per gallon at the $0.1042 US average so I am $0.25 off from your calculation.

 

and to answer your friend honestly, you need local costs.

 

I recall doing this math when I got my PiP. Based on local electricity kWh rate the regular (not high octane) would have to come down to ~$1.35/gallon before it cost same to drive in EV mode only or use HV (assuming Prius gets 50mpg) mode.

 

life is good in utah!

 

The first thing I did was run the math to see cost in EV vs HV. I arrived at almost the exact same figures.

$0.02 per mile in EV
$0.04 per mile in HV

Gasoline would have to be $1 / gallon to be as cheap as electrons, and this doesn't factor in the added wear on the engine itself.

I'm in the Portland area.

 

I'm paying the equivalent of about $5.40 per US gallon (€1.27/litre) and 11c per kWh (€0.09 at night rates) - gas will never be the cheaper option for me

 

The EPA lists shows for the PiP it takes 29 kWh/100 miles of driving, so I multiply my per kWh rate times 14.5 to equal one gallon of gas (costwise, not energywise).

I switched to TOU rates when I bought my Leaf, which means since then I only plug in the PiP during super off-peak rate times. However, Southern California Edison raised the nighttime rates this year from $0.11/kWh to $0.13/kWh (summer) and $0.14/kWh (winter), or $1.89 (summer) and $2.03 (winter) compared to about $2.40/gallon of gas at Costco.

With tiered electricity rates it can easily get more expensive to drive on electricity as opposed to using gas. Southern California Edison's Tier 2 costs $0.23/kWh (I don't know anyone who stays in Tier 1), which would be the equivalent of $3.34/gallon, which we haven't seen in a very long time.

 

Sadly, paying the true price for gas isn't going to happen anytime soon. There's so much excess capacity, we likely won't see oil going up either.

It's an uphill battle, even with ever improving tech.

 

This underscores how corrupt of an idea it is to allow single occupant HOV access for PiP owners. Hardly anyone buying them will plug them in, yet they will clog the HOV lanes even though they are the most efficient vehicles and consume no fuel when stopped in traffic.

I'd install solar pronto if I lived in CA. The electric rates are silly expensive.

 

Yet we are pretty cheap compared to many places in the NE.

 

That's one way to look at it, and I guess the thought process could be extended to all PHEV vehicles which allow you a choice of fuel type. Why bother plugging in a BMW i3 REX (or Chevy Volt) when you can drive it with the gas engine for cheaper with the current low price of gas in California?

Another way to look at it is that it convinced me to trade my 17mpg Mustang in for a significantly more efficient vehicle, and opened the door for me to discover the world of plug-in electric vehicles. This led me to adding a Nissan Leaf a year later to the family lineup, retiring our aging minivan that also got less than 20mpg, and putting a deposit down for a Tesla Model 3, removing my earlier interests of getting a BMW M3 or similar performance inefficient vehicle. The HOV Stickers program helps change consumer preferences towards a more efficient fleet, which outweighs the minor bump in HOV lane usage (roughly 5% of HOV users during peak hour are HOV Sticker users, as compared to numbers as high as 40% of carpool lane "cheaters").

And I don't mean to throw solar under the bus, but in my experience it's hard to justify solar when my TOU rates allow me to power my house, Leaf, and PiP for about $80-$90 per month. It's hard to truly calculate the ROI on solar with the unpredictability of utility company rates, and deal with getting permission from a pain in the @$$ HOA (California law might stop them from preventing me to do it, but they'll definitely make the process much more annoying than necessary). Perhaps someday I'll get solar, but probably not before replacing my windows with double pane and replacing my 30+ year old AC unit.

EDIT: After nearly 3 years with the Prius Plug-in I've done about 55k miles at 57mpg plus another 9k miles on electricity. Not bad for one of those people that bought the PiP solely for HOV access who can't plug in at or near work.

 

It's interesting you have a Leaf and still find ROI from solar isn't worth it.. I always thought it was a no brainer but with so many variables, I haven't looked into it myself. I do know I won't be getting solar until there is a BEV in the garage.

 

The Leaf is EPA rated for 30 kWh/ 100 miles, so for 50 miles it costs about $1.95 (summer) $2.10 (winter) compared with one gallon of gas in the Prius on my current nighttime TOU rates. Compared with gas prices when I bought the car, that was good enough for me. Again, I only ever charge during the cheap nighttime rates, and only run the AC during those hours too, hence my daytime usage is low and my overall utility bill is generally $80-90.

In the past 2 years or so, I've seen Southern California Edison do two things to screw over solar owners. First, they shifted their on peak hours back by 2 hours. It used to start at noon, now it starts at 2pm. That's 2 hours of prime solar generation than you now get paid for off-peak generation rates instead of on-peak. Second, they adjusted their rates so that super off peak costs more and on-peak costs less. I'll admit since I don't have solar I don't know the exact specifics, but I'd assume this means they pay less for generation during the on-peak hours. The combination of these two could significantly increase a previous estimate of ROI years, yet there is literally nothing to be done about it.

I'm sure solar can be cost effective for some, but I just don't see the benefit yet for my specific circumstance (at least until I upgrade my windows and AC, then I'll get quotes). Hopefully by the time I'm ready to do it the costs will have dropped significantly too.

 

PG&E is no picnic up in NorCal. I had EV TOU rates right after I got the PiP but last year they decided to do all of us a "favor" and get rid of tiers. Naturally, without tiers, non-peak rates tripled or something like that... rates are always in flux, I can't keep track. In effect, my usage now costs more to be on EV rates than to be on non TOU tiered rate. Thank you, PG&E. I was happily charging at night off peak but now I charge during the daytime to spite them (and for spontaneous use after work).