EVs Powered with Solar Panels: Panacea of Hardcore Greens:
Economics, Logistical Issues, Incentives, and Disclaimers
Many of the more hardcore and well off greens have the goal
of getting off fossil fuels so they are willing to do what it takes. Here in
Southeast Ohio there are a handful of those who praise the practice of powering
EVs with solar panels.
The most useful comparison is perhaps one to a comparable
gasoline-powered vehicle. There are many variables to doing the economic
comparisons: local electricity prices to calculate charging costs, gasoline
prices, local solar energy availability, availability of solar-powered charging
station, cost of purchasing a charging station to be charged by one’s own
panels, etc. Which electric vehicle one buys is also a factor. The avg. KWh/50
mile charge for electric vehicles is about 15. The range goes from the Chevy
Spark EV at 11.5 KWh/50 mile charge to the Tesla Model X at 18KWh/50 mile
charge. The most popular EV is the Nissan Leaf at 2016 MSRP of ~ $29120 minus
the $7500 federal tax credit makes the net MSRP ~ $21620. The 2016 Leaf has a range of 107
miles per full charge, an improvement over previous models at 84 miles.
Let’s look at a scenario of charging the 2016 Leaf with
solar panels, from say a 5KW system. With taxes and other costs the Leaf will
cost at a minimum before tax credit $30000. The solar system, assuming a
grid-tied system without battery backup, would cost about $16500 before tax
credit. Total cash upfront for a cash purchase would be about $46500. Add in a
home charging system installed for about $1200 so the total comes to $47700. For
a couple of Tesla power walls for backup add another $7000. The federal tax
credits and the state SRECs (they trickle in slowly over time but let’s assume
them all at once) would come to about $13500 (paid by the government, or rather
the taxpayers). That cuts the total to $33000. Let’s compare to a Toyota Camry
at a cost with taxes etc. of about $22500 and running on gasoline. I read one
comparison that showed that the EV would save $550 per year over the Camry with
gas aroun $2.20 per gallon and electricity at 0.13 per KWh. Gasoline will
likely increase a bit more than electricity over the next 5-10 years so we will
consider that as well. An EV is expected to have lower maintenance costs than a
gasoline vehicle, no oil changes, etc. Savings are estimated at about $500 over
5 years and $1000 over 10 years. So let’s say 20-30 % gradual cost increase in
gasoline or we can just add 25% to the savings. With no change in prices the
savings over 5 years would be $2750. Add in 25% and you get $3437. Add in the
maintenance savings and you get a 5 years savings of $3937 over the Camry and
for 10 years you might get $8500 or more in savings. That would bring the cost
of the EV plus 10 years of operations savings over the Camry at 12000 miles per
year avg to likely below $24400. (I would say also add in about $830 over 10
years for excess solar produced beyond the need of the EV – if a 5KW solar
system made 4000 KWh per year and the Leaf takes 14 KWh to go 50 miles that
would mean it would take 3360 KWh to charge it for the year. That leaves 640
KWh at $0.13 per KWh elec savings, or $83 per year to help power the house
and/or grid – not much excess) That brings it down to $23570 over 10 years. Not
bad but still slightly more costly than the $22500 Camry. However, if gas
prices rose more the Leaf could conceivably cost less than the Camry and at 15
years it would definitely be significantly less.
The above assumes that you are only charging the EV with the
solar panels which is not really feasible. There are logistical issues. For one,
without battery backup, you would have to charge during the day when the sun is
shining so you couldn’t really drive it during the day. Spread over the year
the avg. daily solar production in this area for a 5KW solar array would be
somewhere around 11KWh per day. Remember the Leaf takes 14KWh to charge for 50
miles. With a range of 107 miles it would take right on about 30 KWh to get a
full charge. At 11KWh avg. output for the system it would take 2.7 days on avg.
to give it a full charge. Now there may be sunny days in season where you could
conceivably do it in a day or close to it. With ideal panel angle and
orientation and no shading it might be possible. However, some days in the
winter and even on cloudy rainy days in any season you could get as low as 1 or
2 KWhs or even less if snow covers the panels. It could conceivably take a week
to charge the EV! You might be looking at an absolute max of about maybe 3.5
full charges or about 375 miles allotted for December – but probably much less. This
would be inconvenient to say the least.
Another issue is charging times. The chart I saw gave a rate
for the Nissan Leaf and Chevy Spark at 11 miles added per hour of charge for a
home charging system. That would mean it would take nearly 10 hours to get a
full charge – all during the day with solar. Winter days would not be nearly
long enough but even summer days would require charging pretty much all day
unless you found a fast charging station to use that charged with solar. The EV
charged with solar is really starting to look like a vehicle to drive only at
night as it would really have to be charging during the daylight hours!
Another issue and perhaps the main reason EVs are not more
popular is the range. Although that has been increasing, especially with the
Tesla Model X with a 200 mile range, it is still a big barrier. With a 107 mile
range road trips are pretty much out. Versatility is not at present a feature
of EVs. They are great urban vehicles for short trips and have applicability as
city buses and trains (with bigger battery banks) since they are pollutant-free
and smog-free. Thus for practical purposes they are a niche market. That is why
they have not sold as expected in the U.S. since we tend to like our vehicles
to be capable of ‘going the miles.’
There are a few other advantages to the solar setup: a hedge
against electricity rate increases, increase in the value of the home or
property, and possibly an increase in roof life. Other than that it is just a
lot of work, inconvenience, and cost to taxpayers, for the hardcore green to
lay claim to those emissions reductions which are indeed real. In reality much
of the time the EV would have to be charged by the grid which in Ohio is
powered over 60% by coal so that would significantly offset the emissions
reductions. I would have to say that due to these issues the myth of charging
an EV with a reasonably sized rooftop solar system (5KWh) being economic over a
comparable gas or hybrid vehicle is pretty much busted since if it were to be
optimized it would take away significantly from the convenience of owning a
vehicle and severely limit driving opportunities regardless of the range. Using
a battery backup system would be quite helpful to alleviate the inconveniences
but it would also take away any cost advantages.
This was just a quick look estimate based on a few sources
and others’ ‘mileage may vary’ as they say.
References:
How Much Does it Cost to Charge an Electric Car with Solar Power? – by Ben
Zientara, from solarpowerrocks.com , 2016
Electric Car Charging 101 – Types of Charging, Charging Networks, Apps,
& More – by Zach, at EV Obsession, evobsession.com , Sept 10, 2015
Electric Vehicles vs. Gas vs. Hybrid Cars: A Comparison of Maintenance,
Fuel, Insurance, and Other Costs – by Jeffrey Chu, in Nerdwallet, Sept 15, 2015
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