EV Explorer Calculator Concludes Solar Is The Cheapest Transportation Fuel


Sungas Is The Least Expensive Transportation Fuel

“The future’s so bright, I gotta wear shades”
Tom Cruise

Just pinch me!

Here is a handy dandy calculator from UC Davis called EV Explorer.

We thought it would be fun to compare our last two gas cars to our two BMW i3’s. We slid the mileage bar to get a cost of fuel for the BMW i3’s that is slightly less than the EPA sticker of $500 calculated at $0.12 per kWh. This slight reduction is because we drive slightly less than the EPA annual average.

We used the cost of gasoline, which in our area is at $4.00 a gallon

Lastly, we reduced the cost of electricity to $0.08 per kWh which is the levelized cost of electricity for our solar PV system throughout its lifetime. Our solar PV system was installed in 2007 and was paid off in utility and gasoline savings in April of 2012.

We are saving $5,700 a year driving our two BMW i3s fueled by sunshine. That annual savings is nearly the annual cost of one of the BMW i3s.

Solar-Power EVs... That's The Cheapest Way To Go...And Go....And Go

Solar-Powered EVs… That’s The Cheapest Way To Go…And Go….And Go




*Editor’s Note: This post appears on Peder’s blog.  Check it out here.

Categories: BMW


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30 Comments on "EV Explorer Calculator Concludes Solar Is The Cheapest Transportation Fuel"

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This makes a strong case for EV’s. There are many EV’s available that are less expensive than the BMW i3, which means many can run off solar and actually make money off their cars from day 1.

This comparison is difficult to do in California because the rate structures preclude a flat rate.

Conceptually the approach should be to divide the total cost of the electricity by the total used for all purposes. That produces a $/kWh number for everything including cars. Now multiply this $/kWh number by one third of the miles driven per year (for three miles per kWh).

If you have a solar system you need to get the cost per year by depreciating the system plus upkeep and replacement over the number of years of its expected life. For example, if it cost $10k plus $200/year for replacement of the inverter, and the expected life is 10 years, then the cost is $1200/year.

If you claim the PV system was free then nothing will beat the cost of driving an EV. But that’s not realistic.

I calculated a kwh rate based on the cost of my PV system, estimated life (25 yrs), and % of electric that comes from it … which knocked my effective rate down from $0.13/kwh to $0.085/kwh. I then used that rate for my EV costs using the wall kwh usage, plus the capital cost of the car over its expected lifetime, and … it’s just as expensive to own/drive (from a total cost of ownership standpoint) an EV, even on solar, than a comparable gas car, about $0.32/mile, YMMV.

The good news is that as EVs become cheaper and gasoline more expensive, this spread will widen in favor of EVs. For now we have to be content that we’re improving EV economies of scale and avoiding external costs (like pollution and geopolitical costs of obtaining oil) which is definitely worth something, even if it’s not yet a savings benefiting the EV driver.

Electric Car Guest Drive

That seems amazingly high Dan. How is fueling an EV any more the 1/4 the cost of gasoline?

$200 per month, or even $260 month (Volt, Focus electric) is less than an average new car.

If you are purchasing, your monthly cost may be higher for 3-5 years, but lifetime costs will be about the same or lower considering residual value.

Maybe I wasn’t clear … but on my old Mazda Protege5 I calculated a per mile cost (including EVERYTHING: gas, insurance, maintenance … depreciation (straight purchase cost – sales price)) and came up with $0.31/mile. I don’t drive a lot of miles, so depreciation was a pretty big % of the costs. I did the same thing with my 2012 iMiev (assuming similar ownership timeframe [8 years] with a guess on how much I could get for it then [$8k]), and came up with $0.33/mile. Again, my low miles and the high capital costs (that for a 2014 iMiev are a bit lower now and would already beat the TOC for the Mazda) make it kind of high.

Fuel costs ARE much cheaper in an EV. Only about $0.02/mile in the EV vs. $0.11/mile with the ICE. My old Mazda got ~ 30 mpg and I used $3.50 gal gas and my $0.085/kwh PV reduced rate for electricity for those numbers.

Electric Car Guest Drive

Ok. No state or federal incentives?

PV systems will last much longer than that: modules from reputable manufacturers come with a 25-year warranty, and I have no doubt they will outlast it.
For inverters, warranties are between 10 and 25 years, but even if one craps out after say 15 years, it can often be repaired for a few hundred $$, and even an outright replacement remains cheap: mine was ~1400$ for 6kW AC, so that’d add, what, 4$/month, for a total of 30 years of service. Big whoop.

Numbers for my PV system, assuming inverter replacement:

16k$ purchase incl incentives + 1.4k$ inverter
—————————————————– = 6 c/kW·h
30 years * 9.3 MW·h/year

Current average consumption of my EV, incl charging losses: 281 W·h/mile

=> Fuel cost: 2 c/mile or ~1 €/100km.

Unbeatable. Plus it’s squeaky clean. ‘Love it.

I hope my PV system and Inverter lasts past 25 years, but these are kind of guesses, and I’m being conservative – I’d rather over-deliver on an estimate than the opposite.

But, again, in my case going from $0.022/mile to $0.018/mile is not nearly as important as getting that initial $22k purchase price (after incentives) down to $15k or lower in lowering my TCO.

Wow, that’s an impressive cost per kWh. Too bad we only ever get sunshine in the summer here, or my kWh per year might actually compare. 😉

I assumed hydro was the cheapest for the homeowner. Tom Cruise? Timbuk 3.

+1 …. that’s a Timbuk 3 song (not Tom Cruise). First song my wife (of 26 years) and I danced to.

My plan right now is to get a EV first and then get solar panels later to break my dependance on the gas stations and the grid.

In that I was reading there is a thing called energy poverty where the rising cost and lack of access energy causes people and economies to fall apart.

It sounds like this investment in solar is paying better then some bank CD’s and stocks.

Cool, go for it. Even though IMHO both plug-ins and solar are great on their own, together they really shine.

Re PV, if you’re in the US, keep in mind that the 30% federal tax credit ends Dec 2015, so you probably want everything finished by then.

As PV systems easily outlast most roofs, for minimum hassle down the road, you might want to also allow some time (and budget) to repair/refresh your roof first unless it’s already in top shape.
Ideally, roofer and solar installer could even work together.

Anyway, I hope you’ll enjoy the results just as much as Peder, Dan, Zoé-driver, myself and so many others have! For me it’s been absolutely liberating.

The 30% Investment Tax Credit (ITC) for solar ends December 2016 (NOT 2015). Also, if the ITC is not extended, it will change to 10%.


PV and E-Car is perfect. I do that for more than a year now with ZOE and Panasonic HIT Panels. PV produces 9500 kWh per year and ZOE needs just 2800 kwH.

Well that was a useless exercise. It costs me $73/year to commute in my Insight and $38/year in the Leaf. That’s a savings of a whopping $35/year!

So that’s, what, at most 20 miles/week?
Could bicycling be practical in your situation? That’d beat any car hands-down…

Yes, exactly. In fact I do try to bike to work whenever possible. Unfortunately that doesn’t really eliminate the need for a car. Commuting is such a small part of my driven mileage, I was hoping that the link would consider a little more than that.

My summarizing impression of the current economics (with large individual variations glossed over):

Fuel costs: EVs are much cheaper than ICE vehicles
TCO: EVs are comparable to ICEs
TCH (Total Cost to Humanity, which includes, e.g., the cost of cleaning up our atmosphere): EVs are much cheaper than ICEs

I think this is an unfortunate ordering, as many EV supporters will tout fuel savings, and be countered by the EV opposers with TCO, and given the huge uncertainties of calculating TCH, the arguments lose traction. If TCO can be reduced, then the economics will be removed from the arguments, leaving conveniences as the last major hurdle.

Gene … I like it. We just need to include some of the TCH into the TCO, like a pollution fee.

Re TCO: I’d say that for comparable comfort, or like demonstrated here, with the addition of solar, EVs already beat ICEVs.

Unfortunately, agreed, it’s hard to put an exact price on the silence, smoothness and responsiveness of an electric drivetrain, the convenience of at-home refueling, or the satisfaction of “growing” clean fuel on the roof.

Take Edmunds conservative estimates: the Leaf tops even econoboxes half its price.

5-year total:
2014 Leaf S: 36k$
2014 Versa S 1.6: 37k$


And that’s before state incentives, or any of the advantages mentioned earlier, most importantly cheaper electricity from PV.

This is a VERY cool tool, for sure, and I am soooo glad it was made!

Important Note: However, this EV range calculation does not factor in elevation changes coupled with the ‘actual’ speeds of the road traffic and the fact that you need to go faster than 55 to not be run over, and so you will not get the advertised range stated by the manufacturer, by a long shot.

Example: My EV is rated at about 85-90 miles to the charge, but if I want to move with traffic instead of getting the middle finger all the time, I can only get about 55 miles before turning into a 3000lb paper weight.

Yeah, until the sun runs out of power and somebody has to go and refuel it. Then where will we be? In the dark! And then Big Oil and Big Coal will sit back and say “I told you so!”

Time to adjust the straps on my tin-foil hat.