JFon101231
Active Member
Figured before I spent some time making one in spare time I dont really have I'd ask 
Anyone have a calculator that shows at what gas/electricity prices it makes sense to use which fuel?
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petteyg359
Well-Known Member
Honda claims 42 mpg. I usually get closer to 50. Take 45 as a pessimistic average guess. 45 miles is close to a pessimistic electric-only range, too. Your easy napkin-calculation is to divide the price of a gallon of gas by the 17 kWh of a full charge.
A gallon of gas near me costs $1.68. Divided by 17 kWh that's 9.8¢ for even prices. However, given my electricity is free, it never makes sense to get that gas unless I'm going beyond electric range
A gallon of gas near me costs $1.68. Divided by 17 kWh that's 9.8¢ for even prices. However, given my electricity is free, it never makes sense to get that gas unless I'm going beyond electric range
fusioncutter
New Member
I'd like for you to create it! 
Here's a very simple one. G for cost of one gallon of gasoline, E for cost of 1kWh. It's set for 42 mpg and 47 miles/charge, but you can adjust those numbers to suit your efficiency numbers if you like.
https://www.desmos.com/calculator/qc8ppx28fr
https://www.desmos.com/calculator/qc8ppx28fr
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fusioncutter
New Member
Has anyone done a detailed calculation of the price to charge the car using HV charge mode?
That's a good question. I would imagine that with conversion losses it would be upwards of 15% more expensive than the cost of gasoline. Next time I need to use HV Charge mode I will crunch the numbers.
JFon101231
Active Member
@MrFixit Any chance you could blow up the quadrant under $4/gal and $0.25/kWh? Sadly with CT electric rates around $0.18 kWh and gas around $2.20/gal seems it confirms my suspicion gas is actually cheaper right now.
Yes, at those prices gasoline is between $0.005 and $0.01 cheaper than electricity in your area.
jdonalds
Well-Known Member
Same here. If I had to pay the city electric utility $0.15/kWh my break even price would be about $2.00. But as we charge with solar it will never pay to use gas.Honda claims 42 mpg. I usually get closer to 50. Take 45 as a pessimistic average guess. 45 miles is close to a pessimistic electric-only range, too. Your easy napkin-calculation is to divide the price of a gallon of gas by the 17 kWh of a full charge.
A gallon of gas near me costs $1.68. Divided by 17 kWh that's 9.8¢ for even prices. However, given my electricity is free, it never makes sense to get that gas unless I'm going beyond electric range
Allantheprinter
New Member
Even if you have solar panels, electricity is not free if you have "net energy metering". Any excess power your panels generate gets sold back to your utility. On that basis, your electric charging of your PHEV "costs" you the amount that your utility (PG&E in my case) would pay you for the power you sent back to the grid if you didn't use it for your Clarity.
Ray B
Active Member
Just to add that in two hypothetical cases of 80% EV : 20% HV versus 20% EV : 80% HV the maintenance costs would be quite different over say 150K miles. In the first scenario the engine would only have 30K miles, and the other case it would have 120K miles. The extra wear and tear over the 90K miles would add up. Based on our other Honda I'd say we'd spent ~$2-3K over the past couple of years on power related issues above regular oil/filter maintenance once it got above 90K miles (sensors, plugs, belts, hoses, alternator, etc.).
There may be some maintenance on EV related stuff but I think the safe bet is that it will be much less and/or less common. Too early to tell.
I also enjoy the quiet ride on EV and not visiting the fuel pumps, but it is tough to put a number on those.
So I would add a thumb to the scale if one was inclined to switch to predominantly ICE strictly on the basis of gas vs electricity. You can debate how hard to press on the scale...
There may be some maintenance on EV related stuff but I think the safe bet is that it will be much less and/or less common. Too early to tell.
I also enjoy the quiet ride on EV and not visiting the fuel pumps, but it is tough to put a number on those.
So I would add a thumb to the scale if one was inclined to switch to predominantly ICE strictly on the basis of gas vs electricity. You can debate how hard to press on the scale...
Clarity Dave
Member
That's true only if you use more energy than you generate year-over-year, at least here in Seattle. Seattle City Light doesn't pay for excess solar energy generated but instead zeroes the "kWh bank" every April 30th. Our PV array is sized to provide, in an average year, 100% of the energy we use plus about 3,000 EV miles, so I figure the first 3,000 miles are free (ignoring amortization of the cost of the array, of course...).
MrFixit
Well-Known Member
I am by no means a solar contrarian, and don't want to start a firestorm.
But... Solar power is far from free until the cost of the array has been completely offset by your energy savings.
This process takes time. Dave included the caveat (ignoring amortization), but it is definitely a little misleading for anyone to claim they "drive for free" because they have solar panels.
But... Solar power is far from free until the cost of the array has been completely offset by your energy savings.
This process takes time. Dave included the caveat (ignoring amortization), but it is definitely a little misleading for anyone to claim they "drive for free" because they have solar panels.
I had a similar finding when I calculated this over a short term last year. As I recall, HV Charge mode reduced my gasoline mileage by about 3 mpg in non-winter weather until I reached the 50% SOC when I would shift back to HV or EV. My age-addled brain told me that I could start getting some cost benefit on longer drives from using HV Charge if gasoline is over $2/gallon with my electric cost about $.12/kWh. MrFixit's chart provide more perspective of the degree of benefit as gasoline costs increase (thanks, MrFixit).
Clarity Dave
Member
You're right, but it would also be misleading to say one "drives for free" with a non-EV if one happened to somehow win a year of free gasoline fill-ups, since one is also amortizing the cost of the car too (not to mention maintenence costs).
On the other hand, once we bought the array, the marginal cost per mile is zero until we use more energy than we generate for the year. The array cost the same whether or not we use all of the kWh it generates.
Also, whatever one feels about them, the tax credit and generation credits speed up the payback on the PV array considerably. This varies greatly by state and year of installation, but in my case, the array we installed in 2013 will have paid for itself in 2023, and the second array we added after buying our Clarity in 2018 will have paid for itself in 2031 or thereabouts. That said, there are so many factors going into whether to get a PV array and its size, so YMWV (will vary, not may). I admit I partially justified the second array purchase by telling myself I was spending the money I saved by not buying a Model 3
.
MrFixit
Well-Known Member
Well, we agree in principal, but you can't amortize the cost of the car for the non-EV and not do the same for the EV. Therefore, the cost of the car is basically a wash (ok, you can argue that the ICE car requires more maintenance than the EV - Of course the Clarity is the worst of both worlds because of the dual powertrain).
This is off-topic, but here in the Mid-Atlantic, we have heat pumps. They are the major driver when it comes to total electric usage. It is relatively 'easy' to have a reasonable PV system that covers 100% of your needs if not for the heat pump. In my case, I would roughly need a 10 kW system to meet the entire need. What is the total capacity of your PV setup?
Clarity Dave
Member
True. I didn't mean to imply otherwise, but just to state that amortizing the cost of the PV array is one of several costs of driving, regardless of the energy source of the car.
Our house is mostly heated using a mini-split ductless heat pump (we also have a gas fireplace), and our PV arrays have a total power output rating of 7.8 kW.
I have a spreadsheet with a simple formula. I know how much it costs to do a full charge - $2.50. I enter how many miles that gets me. I enter mpg. In Michigan both of those vary with the season. The spreadsheet then calculates the breakeven cost per gallon.
(mpg / mi per charge) * cost per charge
Example: (44 mpg / 53 mi per charge) * $2.50 cost per charge = $2.08 break even.
In the winter when the mpg = 35 and the mi per charge = 35. the break even is $2.50
(mpg / mi per charge) * cost per charge
Example: (44 mpg / 53 mi per charge) * $2.50 cost per charge = $2.08 break even.
In the winter when the mpg = 35 and the mi per charge = 35. the break even is $2.50