Electric Cars Vs. Solar Panels: Which One's The Gateway Drug?

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Photovoltaic solar power field at Volkswagen plant in Chattanooga, Tennessee

Photovoltaic solar power field at Volkswagen plant in Chattanooga, Tennessee

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Among the 100,000 or so U.S. drivers with plug-in electric cars, it's widely noted that a lot of them charge their cars using photovoltaic solar arrays.

But which comes first, using solar power or buying an electric car?

Remember that environmental concerns are just one of several reasons to buy an electric car.

Thus far, we've not seen any surveys that address which comes first, the plug-in car or the solar panels (hint, hint).

But we do have a few data points showing the crossover between electric-car ownership and having solar power on your house.

One set of figures comes from the California Center for Sustainable Energy.

That entity processes the state's rebates for both its solar incentives and the Air Resources Board purchase incentives for plug-in cars through its clean fuels program. So CCSE has both data points.

It first published data on solar installations in a February 2012 survey of 1,419 plug-in electric car owners--when California had just 12,000 plug-in cars on its roads.

Of those, a remarkable 39 percent then currently owned a solar photovoltaic system. Moreover, a further 17 percent were seriously considering a solar installation within the next year.

The vast majority of survey respondents were then Nissan Leaf drivers, meaning the survey was not limited to owners of $109,000 Tesla Roadsters.

The number of plug-ins on California roads is higher now, and CCSE is continuing to survey owners.

Unfortunately, a May 2013 update to the plug-in owner survey did not include new numbers on solar photovoltaic installations.

A second data point comes from BMW, in a survey of the drivers who participated in its first electric-car test program, in which a few hundred MINI E converted minicars were leased to drivers both in California and in New York and New Jersey--meaning the data comes from both coasts.

slide deck presented in April by Peter Dempster of the BMW Technology Office in Mountain View, California, says on page 19:

"More than 30% of BMW EV customers invested in residential solar."

2011 Nissan Leaf and 2011 Chevy Volt, with roof solar panels visible; photo by George Parrott

2011 Nissan Leaf and 2011 Chevy Volt, with roof solar panels visible; photo by George Parrott

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So from early data, it appears that electric-car owners are far more likely to have photovoltaic solar panels to generate power than the average U.S. household.

In fact, residential solar is dropping as a percentage of total installed solar generating capacity, as large utility projects start to come online.

The results are skewed to California, of course, but then so are electric-car deliveries. The state is expected to buy as many plug-in electric cars as the next five states combined.

So, tell us: Which comes first, installing solar panels on your home or buying an electric car?

Does buying an electric car lead to the desire for photovoltaic solar panels?

Are California electric-car drivers fundamentally different from those in other states?

And are the next 100,000 electric-car buyers equally likely to have solar panels installed on their homes as the earliest pioneers?

Leave us your thoughts in the Comments below.

EDITOR'S NOTE: Our thanks to the members of the BMW ActiveE owners group and other electric-car advocates who helped point us toward much of this data.


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Comments (64)
  1. One data point. I have my solar panels, but no electric car...yet

  2. We're counting on you eventually, John. When it makes sense for you, of course. I'll get working on solar for our house, too, let's see who gets there first... I'm thinking 2015 to time it for the end of my Volt lease, which I know I've written here too many times lately.

  3. I'm strongly considering a backyard pergola that's large enough to handle ~10kW, under which I could have a lounge area. My roof's layout is not conducive to that much of an array, and the house could use at least 8kW during summer months.

  4. John I have my electric car but no panels, to bad we are not neighbors.

  5. There are more comments in this thread
  6. If it was me I would go electric car first... save my 400 bucks a month (gas bill) then apply 50% of that savings at year end towards solar.... and do the same thing the following year and so on... thus the electric car will eventually pay for its own electricity...

  7. That's a good plan. In California, where the data is from, why wait for one when you can have both.
    You could lease a solar PV system for $0 down, have a lease payment less than the old electric bill and have someone else responsible for maintenance. You could also lease a Leaf for $200/month and get a $2500 check from the state of CA to cover the down payment.
    You'd have a new car, solar PV, and pocket more than 200 bucks a month right away. The ecological and economic arguments now favor Solar and EV ownership.

  8. Let me correct that - The ecological and economic arguments now favor Solar and EV use.

  9. While leasing solar might seem like a good idea, you need to be aware that you'll be stuck with monthly payments for 20 or 25 years which will total significantly more than purchase + maintenance would have.
    The only way to "cancel" is often to buy the system from the leasing company, which obviously then has no reason to price it attractively.

    A much better option IMHO is to fund solar with a specialized loan or mortgage, like the FHA powersaver program:

    Other options exist, and vary by state; installers know.

  10. The option to buy is in my solar lease. I would be able to purchase the system after 8 years leasing. The cost would be $6500.00. I am installing an 8.08 Kw array.

  11. There's no such thing as a PV system for $0 down with a solar lease. You fail to mention that the homeowner must forfeit the 30% federal tax credit worth thousands of dollars as well as any other financial incentive to the leasing company. And second, what maintenance? There is no maintenance with a properly installed grid tie solar system. A solar lease is absolutely one of the worst ways to finance a solar system, not to mention that you'll pay up to 3 times in lease payments what you would have paid if you purchased a solar system instead. And good luck ever selling your home with a lease attached to it. What homebuyer will want to assume your lease payments when they can buy and own a brand new solar system for tens of thousands less?

  12. Leased my LEAF in October 2012 ($150/mo!), solar panels went online in March 2013. Chose a panel array that would essentially offset the LEAF electricty usage, so that I'd be driving completely emissions-free.
    I chose to go with Sun Run, and will have my investment $$ back in 3 years, so the array ends up being free.
    In addition, my office reimburses @ the gas rate for some driving when it's company business, so my driving is not only zero emissions, but essentially free as well.

  13. Yep,

    For most, solar PV generating the same kwhs as the ev uses will pay for itself in three years compared to the use of gasoline.

    Then, for basically the rest of your life, your power is provided essentially for free by Mr. Sunshine.


  14. "rest of your life"

    That is a bit stretch. Solar efficiency reduces by about 0.5% per year. You need to have a solar installation that is about 20%-25% higher than your EV daily requirement to cover it for the rest of your life.

  15. Depends how old you are :)
    Micro inverters are going to have no problems lasting 50 years. That's about right for degradation.

  16. Micro Interters lasting 50 yr is a bit an unknown at this point. I believe it is possible. But it depends on how the packaging is designed, operating temperature and amount of derating.

    Not all solar installations are microinverters though. Many of them aren't. Micro inverters's biggest contribution is when individual panels are shaded. If you have no shading impact, then micro inverter is really just an expensive cost to the system. The efficiency gain is arguable.

  17. I built a 4 175w module array a few years back on a 6 module rack. I used the original Enphase inverters. A year and a half later, I finished populating the rack, and the new Enphase inverters are no longer US manufactured, they are Chinese. A year later, one of the Chinese manufactured Enphase inverters failed. Was replaced under warranty. I'm hopeful for longevity, but I expect the occasional problem.

  18. That's rediculous. We've operated an inverter repair business since 2001 and I can assure you that most inverters, will fail by year 10 to 13. And micro inverters are no exception. Failure rates for micro inverters will be worse because they are subjected to the higher temperatures found on hot roofs with little air circulation. And good luck removing all those solar modules to get to your failed micro inverters. Trouble is, they won't all fail at the same time. Maybe one at year 10 and three at year 12 and 2 at yeat 14 and so on and so on. Just wait till the electrolytic capacitors in you micro inverters start to dry out because of the heat. Good luck. The warranty only covers material, the labor will be on you.

  19. Or add a(much cheaper)solar panel every six years or so.

  20. assuming you have spare roof space/sunny space for it.

  21. Your solar array will not be free because you don't own it. You're just renting it. Add up your lease payments and throw in the tax credit worth over $10,000 for an average sized system when valued at the leasing company's system price. also add in any cash rebate that you gave to them and you'll find that you paid far more for renting their solar system than you would have if you purchased it instead at today's low price of $3.15 a watt installed before incentives. And the worst part is that for all you'll pay, you won't even own the system. It will still belongs to the leasing company.

  22. You gave Sun Run the 30% federal tax credit worth about $10,000.00 on a 6 kW system at their much higher pricing. The tax credit would have gone into your pocket instead had you purchased your system at less than $3.00 a watt installed before any incentives. So how do you figure that you'll get your investment (your tax credit and any other incentives that you forfeited) back in three years? That's simply not possible.

  23. I wanted to get both at the same time, but complications arose for both...

    I had to wait for spring 2013 to get a Leaf with efficient heating (I live in the Northeast).

    My utility company gives solar installation rebates for capacities up to 105% of past 12 months use, which meant the additional panels to handle EV were not rebated (exceptions can be granted for upcoming home additions, but they considered the EV too separable from the house). I also had to wait for the rebate to be prorated based on efficiency (orientation+shading), as it was a all-or-nothing threshold at 80% efficiency until this spring (my system is 78.7% efficient - no south-facing roof).

    In the end, I got the Leaf in early April, and my panels went live May 31st.

  24. In my case, I installed a 10.5kw solar plant on my house over two years, 2010-2011, with the expectation of, someday(2014-15), buying a plug-in vehicle. Wasn't sure if it would be a Leaf-type or a Tesla-type, but definitely a plug-in.

    As fate would have it, our Lexus GS (road car) was totaled back in Aug, causing us to accelerate our "electric car" decision. We survived with our remaining 1999 ICE until our Model S arrived in early March............power bills remain at the lowest $10.50 per month ("service charge plus tax") and expected to stay there for a long time until we use up our "banked" Nevada Power credits.

  25. For me, the Volt came first (for its hi tech, not promise of gas saving) and now after reading the forums for 6 months, I'm considering the choices of 240 v dedicated wiring or a solar array that does it all. I hope that in my lifetime, home PV and battery exchange will make electric driving the norm.

  26. We got a solar panel system on our house 2 years ago when the Chevy Volt was only available in limited distribution and not in NM. We got the Volt last Dec. and love the concept of using the sun to power our car. We've got 4,000 miles on it so far and used less than 12 gallons of gas in mostly around town driving.

  27. Bought the solar array first. Chevy Volt the following year.

  28. We have not gotten an electric car yet but I think a plugin hybrid or straight electric will be the next car.

    We did install a 4 kw PV array on our roof in July of 2012 and we wish that we had done it earlier. It has returned 900 dollars worth of electricity in 10.5 months. The system will pay off in about 6.5 more years.

    I have too many good gasoline cars to go electric yet. What I really want is a good handling, good looking, roomy, comfortable, plug-in diesel electric car. Think Mercedes sedan or possibly a diesel Volt.

  29. I have 17 PV Solar panels on my roof just north of Chicago. It has gone beautifully this past 18 months, frequently watching my electric meter run backwards and crediting my account with the power company, while supplying my neighbors with my over flow on sunny days.

    This last 12 months alone, I've produced 7.5 million kWh of power from the roof. I have my eye on the electric cars and would love to run it on the power of the sun, and as little on the coal/nuke combo that predominates in Illinois ,(Just some wind energy).
    With the next generation of cars, I'll be ready to buy.

  30. 7.5Million KWh? for 17 PV solar panels? in 12 months?

    Do you mean 7.5MWh?

    7.5Million KWh for 12 months is 20,547 KWh/day. Unless your panel is 1000x larger than the typical panel, it is NOT going to happen.

  31. "This last 12 months alone, I've produced 7.5 million kWh of power from the roof."

    Either this is an error, or that is a fantastic amount of power. My best 1 day production, with 24 240w modules + 6 175w modules has been 49 kWh. Multiplied out by 548 perfect solar days, I could produce 26,803 kWh.

    I'm chomping at the bit for a BEV, but had to upgrade our family car first. Since it had to have a year round 90 mile range, I bought a Prius. As soon as that note is paid off, I plan to buy an EV.

  32. Got the LEAF in August of 2011 and PV array went live in August of 2012.

  33. We've had solar panels for over 2 years & finally picked the 2013 C-Max plugin Hybrid.

  34. I have installed solar panels as the first step. The house uses power 24/7 so the panels generate more savings per dollar than the vehicle. Last month's electric bill was $12.00. Since November, not the best month for sun power in the Midwest, our system has generated 2,735 KwHrs as of today. I have a hybrid car but not a plug-in model.

  35. How can the house generate more savings per dollar than the vehicle when gas is $3.45 a gallon and kWh's are only 13 cents? In california each additional kWh can be 34 cents though, so either way solar has huge advantages here, especially for peak hours.

  36. We began a house renovation in Hawaii this spring & examined the 40cents+ kwh electric rate we face in the islands. So we elected to add solar panels to cover all the power needs of our home. Then we discovered that with more panels we could also power 2 electric cars in a state where gas approaches $5/gal. So add a Volt for my wife & a Tesla for me. Anticipated total annual costs for both electric power for our home plus for our 2 cars = $240.00. It's not a quick payback given the capital costs, but is dramatic long term. Most things in Hawaii are expensive, but the sun remains very cost efficient.

  37. That's great Doug!! Better than $4000 or so on utility power and gasoline. Far better actions for the island's air quality too.

    And for people with a good line of credit the payback is immediate, on a cash basis!

    I'm thinking the next appliances I get (after installing solar)will be all electric as well. It gets colder here in the winter and I could run a dryer on solar and vent the hot air into the house in the winter. I'll have solar drying whether the clothes dry on the line or in the machine!

  38. Solar first for us. We installed our 7.5kwh system in 2007. Started driving a BMW Mini-E in 2009.
    Best news is the system was paid for ii full with the savings in July of 2012 :)

  39. I had the solar panels installed in the summer of 2010 when I first placed a deposit on a Fisker Karma. I bought a Volt in October 2011, received delivery on the Karma in February 2012, and then bought a Leaf in June 2012. We have 2 teenagers, so 4 drivers. I am awaiting the delivery of our Tesla Model S in 2 weeks. The solar panels combined with switching our house lighting to LED have covered the electrical demand of charging the 3 cars we currently have.

  40. The Tesla came first, primarily because of my disgust with sending oil money to the Middle East, funding oil wars there, and Exxon's attempts to discredit legitimate global warming science. Ironically, bogus "long tail pipe" arguments have pushed me toward solar panels. The great return on investment has pushed me over the edge.

  41. Darn Norm, poor Exxon. I suppose instead of $40 billion in profit they will have to put up with $39.9999999999 billion or so. Who was it that said the stone age didn't for for a lack of stones?

  42. Bought the 6.4kw solar system first (2+ yrs ago). Received Model S 2+ months ago. First electric bill after charging for a full month (May, in OR) - $3.35 higher than last year w/o Model S. Probably won't have enough credits to offset energy usage in the winter as before, but panel payback period is faster w/electric car since it covers the incremental kwh costs. After a year of both, will investigate time of use pricing to minimize EV charge costs. Does not include $100 custom license plate fee for PV2EV (due to arrive this month).

  43. Invest in rooftop solar and save enough money to pay for your EV.

    * Size your solar system to zero out your electricity bill including the energy for your EV
    * Electricity cost offset by rooftop solar can be applied to your EV payment (The amount being whatever your bill was before going solar)
    * Monthly gas savings can be applied to your EV payment because you are using free energy from your roof to fuel your vehicle
    * Electric Vehicle "cost to own" savings which include lower depreciation and lower repair and maintenance costs can be applied to your EV payment

    In this time of low interest rates a $20,000 investment in the bank will get you less than $200 / year in interest or invest in solar and get a much bigger return.

  44. The two came together for me. The gulf oil spill was the push to do what I had been thinking about anyway, which was to drive my daily 40 mile commute without burning anything. To do that I had to have an electric car (a converted MGB) and add PV solar to the house to generate the electricity to charge the car that would have otherwise come from burning coal or oil. For me it was all one project.

  45. Got my solar panels March 2011, (9.24 KW) and then got the Leaf March 2012. both cost about $30,000 but the panels displaced my electric bill and my gas bill. The car only displaced the gas bill.

  46. I got my Volt about 1 year ago. I installed solar about 6 months ago. So, the car came first and then the solar panels. With the current tier pricing of Calfornia, the solar panels make even more sense after the increased demand from EVs.

    Remember this, the more miles you drive each day, the more $$$ you save over gasoline cost. The more EV miles you drive, then more KWh you use. The more KWh you use, the faster the payback for solar panels and the less cost on per KWh installation is.

    However, the actual return varies depending on the location and the miles driven per year.

    If you only drive 5 miles per day, and use very little power per month and leave in the northern lattitude states, then solar/EV make less $ense.

  47. There are other factors too. My wife & I commute to work together 7 miles each way in a northern state, and were averaging just 8 kWh/day of electricity...

    ...but we live where gas is in the upper range of prices (push towards EV), and electricity costs twice the national average (push towards solar). Also, I think these low usages were penalizing in that fixed overheads became more significant: the short commute meant ICEs don't get warm (efficient) until half way there; the low electricity usage meant the fixed monthly fees were a larger fraction of the bill. Of course, I've traded those overheads for the even bigger up-front costs of EV & solar, but time will minimize their fractional costs.

  48. Solar came first, then a Leaf and a ModS.

  49. Started my BMW Active E lease in March 2012 and my solar panels were installed two weeks ago. I had thought about solar before, but my electricity use was too low to justify it. Now, with the AE and a new Model S, my 4kW system will meet 100% of my annual electricity needs.

  50. One of the fears of potential EV owners is the idea that when the electricity goes out from downed power lines or electrical storms, as happens somewhat frequently, they will be stranded. When there is no grid available to attach yourself to, what then? It's another version of range anxiety.

  51. What?? First, without electricity, gas won't pump either. Next, if past events are any indication, gasoline supply is more easily disrupted than the grid.


    (now the trillion-dollar question: how many such extreme weather events will be needed for the public to realize that maybe those 97~98% scientists are right indeed and we really ought to do something to curb green-house gases emissions, and that the solar+EV combination is great for that too?)

  52. The electric car came first then solar. It was the only way I could really consider my LEAF was zero-emission from the perspective of pollution produced by power plants generating electricity my car requires.

  53. About 3 months after I got my first EV I started getting quotes for a solar array. Eights months later it was on my roof. I've now been driving on sunshine for over 3 years, you can't beat it!

  54. My roof mounted 15kWp PV System has been in operation for five years. Within the next two years I'll definitely be an owner of an EV.

  55. 15.7?? I am curious, how many panels are there? We have a 6 kW system (30 panels) and that covers home and two EVs. You must be using quite a lot of electricity (not that I object).

  56. In my case the solar carport came first. We charge both our Tesla Roadster & Nissan Leaf from solar arrays at our home an office.


  57. Why is the ability to produce most of our own energy, and the cars that make it possible to drive on locally generated renewable energy - equated with drugs? This is not a helpful thing, in my opinion.

    Independence from oil is a wonderful thing - fossil fuels are ruining the only planet we have, and we all need to make this critical change from fossil fuels to renewable energy.

    We depend on the sun and the rest of our environment for everything, so let's not denigrate the early adopters - let's all learn from them instead!


  58. I leased my Leaf but then leased a PV system that is currently being installed at the house.

  59. Got my Volt last year. Hard to justify solar in SF, as almost half of the time it's cloudy/foggy. Last quote I got, I break even in 17 years. But definitely will consider it when I have to replace my roof, if not sooner.

  60. We did consider solar panels for a long time but waited until we had our Leaf for a while, mainly to be able to estimate the size of the system. However, since the panels were installed we have also leased a Ford Focus EV, although we knew we would get a second EV so the system was up-sized for the additional car.

  61. Solar panels: August 2010
    4.6 kWh system
    Plugin Prius: October 2012

    Our utility limits system size to a 110% of previous years usage from grid. To assure we had sufficient capacity for an EV/PHEV after our system was approved we worked hard to reduce our usage and cut down a few trees that shaded our panels. We cut usage by ~20% and increased production by 15%. We have enough capacity to charge second EV/PHEV.

  62. Ok,
    I love that many of you like the solar and BEV both approach. I however like only the solar at home (fresh 6KW system just waiting on smart meter, since my dumb one CHARGES me to give them power) However I have no intention of using clean power for an BEV when I do purchase, as I fully intend on plugging in at work only! Of course I may need to plug in now and then on my days off... Loving the 17 hour days in the summer up here in Canada! I bet my peak day will be any 6KW system in the US :)

  63. will BEAT any 6KW system, sorry for typo

  64. There's absolutely no such thing as a $0 down solar lease or PPA and here's why. A requirement of either of these rental programs is that you agree up front to give the leasing or PPA company your 30% federal tax credit worth thousands of dollars as well as any other financial incentives. The CEC currently reports an average system price of $6.19 a watt. Even if you subtract a gracious 50 cents per Watt rebate, that's $5.69 per Watt. At that price a 6 kW solar system would yield a federal tax credit of $10,242! With a $0 down solar loan instead of a lease, you'll get to keep the 30% federal tax credit as well as all other applicable financial incentives for yourself and you'll own your solar system for a much greater return.

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