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Total cost per mile for hybrids and plug-ins

Discussion in 'Prime Fuel Economy & EV Range' started by Joe Lopes, Jul 23, 2017.

  1. Joe Lopes

    Joe Lopes New Member

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    Having a regular Prius, and having had a plug-in hybrid and now a Prime, I was curious as to how they fared compared to each other in terms of cost per mile. For a regular Prius, at 50 mpg, that is simple - just divide miles per gallon by 50. at $2.50/gal it's 5 cents per mile. Cold-weather (winter mileage) is about 10% less.

    For the regular Prius plug-in, I got about 12 miles in the summer and 10 miles in the winter for the range. I also have a meter on the electric, so that shows 2.9 kWh for a full charge. At an average electric price of 20 cents, that means 58 cents for 12 miles in the summer, or 4.8 cents per mile and 5.8 cents per mile in the winter. This confirmed my thought that the plug-in electric operation was only marginal at a gas price of $2.50/gal.

    When my Prius Prime, I am now getting 33 mile range in the summer and 30 miles in the winter, with 6.5 kWh for a full charge. That comes out to $1.30 for a full charge at 20 cents/kWh, so 3.9 cents per mile in the Summer and 4.3 cents per mile in the winter, definitely much better than the earlier version of the plug-in hybrid.

    Anyone can do these calculations, since the electric capacity should be about the same, your electric price can be calculated by dividing your electric bill (less fixed customer charge) by the kWh, which may vary by summer/winter, and the current gasoline price can be calculated by dividing $/gal by mpg.
     
  2. bisco

    bisco cookie crumbler

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    well done joe! at 24 cents/kwh, i'm paying around 70 cents for 15 miles = 5 cents/mile year round average.
    at $2.40/gallon for 60 miles = 4 cents/mile.
     
  3. Oniki

    Oniki Active Member

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    PV can reduce the cost of EV miles dramatically.
    Our two *EVs run about 0.5 cents an EV mile. No typo -- half a penny a mile
     
    #3 Oniki, Jul 26, 2017
    Last edited: Jul 26, 2017
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  4. kevinwhite

    kevinwhite Active Member

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    It may be more realistic to use the marginal price of electricity if you need to determine how much your electric bill would go up when adding the EV.

    My average price is about 25 cents/kWh but the marginal rate is 40 cents/kWh since the charges are tiered. The lowest tier is only ~18 cents/kWh.

    kevin
     
  5. ArcPrime

    ArcPrime Active Member

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    How did you get 0.5 cents per mile? I paid 4-5 cents per mile at my tier 1 16 cents per KWh rate.
     
  6. Oniki

    Oniki Active Member

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    1. PV array cost
    2. Lifetime generation estimated by PVwatts
    3. 5 miles per kWh
     
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  7. ArcPrime

    ArcPrime Active Member

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    Sorry, still don't understand how you get that?
     
  8. Oniki

    Oniki Active Member

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    <<scratches head>>

    PVWatts estimates my PV array will generate 50 kWh over its lifetime for each watt;
    A watt cost me $1.5 to install
    So, a kWh costs ~ 3 cents

    I drive about 5 miles on a kWh
    So, 3 cents divided by 5 miles = 0.6 cents a mile
     
    #8 Oniki, Aug 5, 2017
    Last edited: Aug 5, 2017
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  9. ArcPrime

    ArcPrime Active Member

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    I see.
    I also have a 5.421 KW AC PV system. Here in So Cal we paid $4.19 watt/AC. Our levelized cost of solar system is $0.104 per KWh. Doesn't matter what sales talks about PV life time. The way I looked at is PV supplies electricity to the whole house. Since we are using more electricity than PV generated during summer time. PV keeps us in Tier 1 which we are paying $0.16 per KWh, full charge Prime will cost me $1.00 for 25 miles. So true cost is $0.04 per mile. If no PV I will be in Tier 2 $0.25 per KWh that will cost me $0.063 per mile. So during other season when PV generates more electricity power than we use. Then I will use my levelized cost $0.104 per KWh, Extra charges for Prime will be $0.027 per mile.
     
    #9 ArcPrime, Aug 5, 2017
    Last edited: Aug 5, 2017
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  10. Oniki

    Oniki Active Member

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    I'm not sure why you use the term levelized cost for home PV, but 10.4 cents a kWh from the PV array sounds ball-park based on your installed cost per watt. However, it does not make sense to vary the cost of PV generation by your home consumption. In your case it just means that part of your consumption is not covered by PV.

    Incidentally, is your home net metered ? Or on a TOU ?
    And is the $4.19/watt cost inclusive of tax credits ?
     
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  11. ArcPrime

    ArcPrime Active Member

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    Net meter. $4.19 including tax credit. Levelized cost is the cost sales used to calculate 25 years of power generating PV system loses its power each year. Which doesn't mean too much, true cost is the SCE charges I paid each month for the extra 6.3 KWh everytime I charge my car.
    For instance last month I charged my Prime 16 times I had extra 100 KWh charges I paid $0.16 per KWh. It doesn't matter what I paid for my PV system. However if my PV system didn't generate 922 KWh. I would have been in Tier 2, those extra 100 KWh to charge my Prime would have cost me $0.25 per KWh.
     
  12. Oniki

    Oniki Active Member

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    You are arbitrarily assigning the Tier 1 charges to the car use instead of to e.g, your home A/C use. Or your refrigerator. Or your TV ... ...