Wednesday, September 7, 2011


The premise of this article is that every American household with a place to plug in an electric vehicle (EV), and a place to put in solar photovoltaic system (PV), should plug in that EV and put up that PV, because then you drive for free and thereby save a minimum of over $60,000. This opportunity might apply to 100 million of America's 256 million vehicles. In addition to saving a great deal of money, you’ll be supporting the American economy, reducing global warming, and improving health, and even helping to bring peace to the world (dare to think big). And, it’s more fun.

According to the EPA, Americans drive an average of 12,000 miles a year, or 33 miles a day. The average vehicle in the US gets about 22.5 mpg: that means the average car uses about 533 gallons of gasoline every year. The average cost of a gallon of gas this year is $3.83, and so this year the average American will spend $2043 on fuel. (Yet, it’s been reliably estimated that the true cost of gas is about $15.00, not even including the blood and military and aid money we spend to try to ensure a supply of oil). We know the cost of gas is only going to go up, and with “peak oil” a certainly in the coming years it will likely go up astronomically due to declining production (in the last survey year 30 billion barrels were pumped out, but only 5 billion new barrels were identified). For the sake of argument we’ll be ridiculously conservative and simply use current figures as our basis for demonstrating savings -- but remember, as gas prices increase, the comparative savings increase.

First, a word about the stuff in gasoline-powered cars. Engines contain hundreds of pieces of various types of metal struggling to grind each other into dust as they deal with friction, toxic gases at thousands of degrees, and hot pressurized fluids, including myriad shafts, gears, pumps, bearings, bushings, and rings designed with thousandths-of-an-inch clearances: it is not surprising when something goes wrong. The Automobile Association of America estimates that maintenance costs (ex: tune ups, oil changes, brakes, etc.: not including tires) is $.045/miles, or about $540 per year. And this is not to mention catastrophic failures: have you ever had to replace a transmission? So, the average American spends a total of about $2500 a year for the care and feeding of a gas-powered car.

Let’s contrast this with an EV. The motor is the only moving part, and it turns on a couple of unstressed life-time bearings: aside from tires and windshield wipers, it may never need maintenance. It is quieter (no engine or exhaust), smoother (no transmission), sporty (immediate acceleration and makes its own energy when slowing), and handles better (low centralized mass). Because the brakes are only lightly used they may last forever. No, an EV can’t handle all the trips you will ever take in your life, but it will likely handle 99% of the trips you take every day. If you have two cars, think about how unlikely it is that you’ll need to go more than 100 miles in both cars at the same time. If you don’t have a second car for long-distance occasions, then you can get a plug-in hybrid like the Chevy Volt which will be 100% electric for the very great majority of all your trips.

How much electricity does an EV need? The first mass-produced EV is the Nissan Leaf (I say this with sincere apologies to Tesla, which has sold 1500 Roadsters since 2008, but Nissan is selling about 20,000 Leafs this year). The Leaf received a government mileage rating of 2.9 miles per kilowatt-hour. (Quick primer on electricity: A kilowatt-hour (KWh) is the electrical “energy” unit: 1 KWh is the amount of electricity energy needed to light ten conventional 100 watt light bulbs for one hour, and an EV battery pack is rated in KWh. A kilowatt (KW) is the electrical “power” unit: 1 KW is about 1.3 horsepower, and an EV motor is rated in KW.) From my experience, the government rating seems quite conservative, as I drive my Leaf hard and yet I’m averaging about 4 miles/KWh (but fast highway travel does bring it down, and there is a small amount of loss from the plug to the battery). However, to stay on script, we’ll use the government figure, which means that to go 12,000 miles you need about 4000KWH annually.

There are several ways of calculating the cost of 4000KWh. (And, in the first place, it’s even an assumption that you will be paying for all of that electricity: there are more and more businesses and commercial locations where you can charge the car for free.) But assuming you do pay for charging, you have three options, from the really great to the unbelievably great: you can charge the EV on your existing electricity rate plan; you can change your rate plan; or you can have PV installed (along with a change in your rate plan). Here a quick breakdown of each.

If you pay for the electricity without changing your rate plan then electricity to charge your EV is likely to cost between $.10/KWh and $.40/KWh: there are a number of variables, including where you live, how much electricity you already use, the time of year, etc. For instance, in California the likely cost might be about $.30/KWh (this figure is likely to be lower elsewhere). For 4000KWh, this means an annual cost of about $1200 to charge your EV -- a tidy savings of about 50% off the fuel and maintenance cost of a gas car. Wow.

But wait, it gets even better. If you pay for electricity and have the option to change to a “time of use” (TOU) rate plan, you save more. With TOU, you pay more for electricity when it is expensive, which is mostly during daytime when many people are not home, and less at night -- which is when you will be charging your EV. In a study, 75% of all Californians were found to have about a 10% savings with TOU: but, more importantly, TOU electrical rates during the “off peak” hours of midnight to 7am are only about $.06/KWh, and this is when the EV is timer-set to charge. Therefore, if you have a TOU option, charging your EV may only cost about $250. This is a huge savings of about 90% off the fuel and maintenance cost of a gas car. Wow wow: how can you top that?

You top that by paying absolutely nothing, when you have PV installed and put the TOU plan into effect. The lone issue with installing a PV system is whether you having sufficient sunny exposure on your home or property. And, PV obviously makes terrific sense for replacing the purchase of some or all of your utility electricity as well -- which is why millions of people around the world have already installed PV (more on that later).

To generate 4000KWh a year requires a PV system that can be expected to have a final cost (i.e., after rebates/tax credits) of about $12,000. This estimate is based on a typical final cost of about $5.00/watt for an installed residential PV system, and reasonably estimating that about a 2500 watt system is needed to generate about 4000KWh/year (also: installing PV substantially increases home value, yet property taxes cannot be raised for PV). As in all things, good shopping can yield better deals: my San Francisco PV system was installed for $3.84/watt. Moreover, PV system costs are getting ever-cheaper, and this trend is forecast to continue.

Now, PV necessarily generates its electricity during daytime, when under a TOU plan the value of the electricity is either peak (about $.30/KWh) or partial peak (about $.10/KWh). Using a peak and partial-peak average of $.20/KWh, the annual generated value of 4000KWh is about $800. With TOU, using that same amount of “banked” electricity at night to charge your EV only costs you about $250. The remaining $550-worth of electricity that you generated goes toward paying back the cost of your PV system (you actually take the savings by offsetting some of your home electrical bill). PV panels are guaranteed for 25 years (they will likely last even longer, albeit with some reduction in efficiency), and so the system completely pays for itself! The net result? You’ve been driving 25 years absolutely for free, not paying a penny for any fuel. The savings? $2500/year not spent on the care and feeding of a gas car, for at least 25 years: about $62,500.

Granted, gas cars will, of necessity, get more efficient, and therefore the comparative savings (at today’s gas prices) will seem to shrink. Yet, on the other hand, the cost of these fancy-pants gasoline cars, with their 9-speed dual-clutch, million-moving-parts transmissions and their turbocharged, high-pressure direct-injection systems and their weight-shaving exotic material parts, will only go up -- and remember: the cost of gas will be going up up up. By contrast, the value, range, performance, and abilities of all EVs will only improve (still, there’s an advantage in being an early-adopter: with incentives, the net cost of my very nice Nissan Leaf was only $22,000).

At the beginning of the article I mentioned not only saving money, but also supporting the American economy, reducing global warming, and improving health, and even helping to bring peace to the world. I’ll start with the last of these subjects (if controversial to some, let’s take it head-on). Here’s the thing: I hate terrorists. Big deal, you may think: you hate terrorists, too. Yes, but I’m doing something about it -- I’m cutting off the terrorists at their knees by cutting off their financial support. The majority of the terrorism in the world today is wrought by Islamic extremists who are ultimately funded by oil-selling Muslims (to quote the ironic bumper sticker: “What’s our oil doing under their sand?”). To be clear, not all oil-selling Muslims support Islamic extremists: but those who do are doing it with your patriotic, terrorist-hating dollars. But not with mine. Make the world more peaceful by defunding terrorists. EV+PV = no jihadi.

PV and EV help our economy in so many ways. You can install American-made PV panels, mounted on American-made racking systems, connected to American-made inverters, all of it installed by American workers. Renewable energy is the fastest-growing source of domestic employment. Also, American manufacturers are all developing EVs, and the main Nissan EV manufacturing facility is in Smyrna, Tennessee. I take pride in knowing that I have employed my fellow Americans. Further, we spend hundreds of billions of dollars on oil each year, and the export of all that money weakens the value of the dollar. Lastly, and again let’s be real about this, we have spent a hell of a lot of blood and money fighting multiple wars halfway around the world because that’s where the oil is (here’s a breath-taking statistic: our cost for keeping an aircraft carrier in the Persian Gulf for the last 30 years is $7.3 trillion -- yes, trillion). EV+PV = better economy.

As to health and global warming, the benefits are obvious. Gasoline is a terrible toxin, poisoning our water, our air, and our bodies. The estimated health cost attributed to fossil fuel pollution is $120 billion annually. PV+EV = healthier me. Finally, global warming is of course caused in largest part by carbon dioxide pollution from fossil fuels: in only a couple of hundred years, burning fossil fuels has increased the amount of carbon dioxide in the atmosphere by nearly one half(!), and our carbon dioxide pollution is increasing faster than ever (and our planet’s population of 7 billion humans has added the last 5 billion within the past century and has ever-more acquisitive people). Observation: if we do not quickly evolve from a scavenger species to an intelligent species that can engineer for sustainability, we’ll use up the earth’s resources until we’ve gnawed the bark off the last tree. Finally, to bring this home as objectively as possible: the cost of global warming is estimated to be $2 trillion annually. Replacing just one gas vehicle with an EV running on PV will prevent over 10,000 pounds of carbon dioxide pollution a year. If 100 million vehicles took advantage of this, it would reduce America’s carbon dioxide production by a whopping 1 trillion pounds -- nearly 10% of our CO2 pollution. EV+PV = survivability.

And here’s a bonus: guilt-free performance. Go ahead, mash the accelerator: you’re only burning photons, and the sun will be making more for the next several billion years (if you are asked whether you like nuclear power, just nod and point up). I like to drive fast briskly, and even though after a lifetime of working on car and motorcycles I kinda miss the smell of hydrocarbons, driving with electricity is simply better performance. Even if you get your electricity from our dirtiest fuel, coal, it’s still much cleaner than driving with gas, and each year there is less and less coal powering the national electrical grid (this year it’s down to 45%). And here’s a strange but amazing fact: more electricity is needed to make the gas for a gas car to drive 100 miles than the electricity needed to drive an EV 100 miles -- because there is so much electricity used in the pumping, transportation, and refining of petroleum (not to mention unbelievable amounts of fresh water). So, go ahead, drive with a lead foot: you’ll only leave a lithium footprint! EV+PV= smiley!

Tidbits: Products coming to market will let the EV charge from an induction mat lying under the vehicle, so the driver will never need to ever again touch anything to fuel the car. Products coming to market will let your EV run your home electrical system for a few days: much cheaper and better than buying a generator. There are thousands of charging stations being installed and doubtless hundreds of thousands to come. We are starting to install fast chargers that allow EVs to get over a 50% charge in 15 minutes (and there is a new patent that says it can charge an EV in 5 minutes). With far more competitors in the field, much greater manufacturing volume, and considerable attention to research and development, batteries are seeing dramatic improvements in cost, performance, and lifespan, and all signs indicate that batteries will continue to dramatically improve. EVs can be as fast as the fastest gas vehicle, and motors are more efficient as they grow more powerful. If you think about it, for EVs this is like the era of the Ford Model T one hundred years ago: we are at the leading edge of huge technological advances.

An important concluding note about residential PV: logically, when installing PV to offset EV electrical use, one would also install additional PV to offset expensive home electricity use. Think of it as locking in your electricity cost at about $.12 per KWh for the next 25 years, and really much much less when you consider the positive implications of Time Of Use metering. It is absolutely certain that the cost of utility electricity, typically higher than $.12 per KWh now, will be significantly higher in the years to come: for example, in California the cost of electricity is projected to increase an average rate of about 7% annually (at an annual increase of 7%, in 25 years the rate will be over 500% higher!). Generally, residential PV pays for itself in electricity cost savings in about 10 years -- this really means about the same thing as this article proves regarding PV for fueling an EV, but without getting too involved in the calculation of the annualized increased cost of electricity and cost of capital. Also, residential PV can be obtained through a lease arrangement that does not require the homeowner to spend any money at all: in net effect, the installer pays for the system and simply charges you less for the (clean) electricity then the utility would charge you for (dirty) electricity. No matter how you look at it, this is a good deal -- obviously, this is why people install solar, regardless of whether they were considering EVs. And as we’ve learned, with an EV, you drive for free. In fact, I undersold the whole thing: it’s really, EV+PV = a win-win-win-win-win epiphany. But that’s a clumsy headline; “free” gets right to it, don’t you think?

[The original of this article is heavily-hyperlinked: feel free to email me and I will send along the article with links]


  1. You fail to mention that manufacturing PV panels is far from free. You fail to mention that manufacturing cars of any kind is far from free. You fail to mention the need to mine, process, replace, and recycle lithium batteries is far from free. You fail to mention that a complete and total reconstruction of the nationa electric grid would be required to make your proposal work. You fail to mention that much of the nation is under cloud cover for half or more of the year. You fail to mention that it would probably cost at least $100,000 per household to acquire an electric car and a large-enough EV installation.

    Bottom line: You are not a serious thinker on this vital topic.

  2. Michael, I read the post, and Jason did in fact mention the cost of his EV and the cost of PV. Since EVs would often be charged in the middle of the night when there is much unused capacity, it is not clear that "complete and total reconstruction" of the grid is necessary, although for many reasons grid upgrades are likely.

    Just this morning I viewed a presentation from Ford outlining their vision of the EV future, and the synergies achievable from utility/auto manufacturer cooperation. They and other auto companies are quite serious thinkers on this vital topic.

    Given that Jason lives in San Francisco, has a PV system and an EV, he seems to have a bit of real world experience living in often cloudy weather.

    In the interest of full disclosure, I drove to work today in an EV converted from a diesel rabbit in 1996. I purchased it in 2007 (<$4500). 100% of my electricity (for home and driving) comes from a 2 kW PV system installed in 2004, and I live in a city that sometimes seems like the foggiest place on the planet (fog just rolled in as I write this).

  3. "aside from tires and windshield wipers, [the EV] may never need maintenance".

    What about replacement of batteries? Even lead-acid accumulators have a limited lifetime - Li-Ion deteriorates even faster. (A fully charged Li-Ion cell not being used can typically permanently lose 20% of it's capacity pr year). I'm also concerned that prices for rare-earth metals, and even lithium and lead may get out of control if everyone was to go PV+EV.

    Next, replacing the gas-guzzlers with EVs would curve local pollution, cause less CO2 to be released, less noise and would to some extent (as long as we can cover their energy needs with PVs, other renewables or nuclear plants) be resilient against "peak oil" - but it's not a "magic bullet" for everything that is wrong with cars. Here are some other problems:

    * Traffic jams - EVs won't help (more electronics to get the traffic flowing more smoothly and packing the cars more densely may help, it's a lot cheaper to sit it out in an EV than in a gas-guzzler, and if everyone had EVs one wouldn't need to suffer so much from the noise and pollution)

    * There will still be a serious risk of injury and death when using the roads (this risk is often underestimated, but it would be totally unacceptable in most other areas of the western society). The risk of hitting pedestrians is even higher due to the lack of engine noise. There are actually proposals floating around for introducing artificial engine noise from EVs to alert other trafficants :-(

    * Actually, I think it's a quite big health problem that people live their lives without doing much walking/running/biking. I think there would be massive health benefits from promoting more walking and biking. I've been thinking a bit that car-ownership is both contagious and addictive. In a society where "everyone" has cars, one gets dependent to go quite far to get to shopping centers and other services needed, and since very few would use public transport the offer gets crappy ... hence it gets very difficult to manage without a car. When driving a car daily, it gets unacceptably hard and painful to get around using any other mode of transportation. I really have first-hand experiences with this, on my best I decided to bike for 20 minutes simply because I was too lazy to remove a layer of hard ice from the windows of the car. Some years later, doing such a bike trip was simply unthinkable.

    * I think it's a problem when people end up driving their kids wherever they need to go just because the traffic is too dangerous for the kids to move around on their own

    * It's needed to pave lots of areas for roads and parking. Property prices have a tendency to deteriorate when there are highways built in the neighbourhood (though, maybe less so if the road is covered by EVs than gas-guzzlers ... but still, in high speeds there is much more noise from the tires and air than from the engine)

    * Locally I think that the biggest problem of it all is in the winter time ... lots of salt dumped on the roads so that people wouldn't have to use studded tires ... and lots of asphalt dust in the air because people use studded tires anyway. The snow simply gets black as soon as it hits the ground, the snow that is cleaned away from the street is so badly polluted that it has to be treated as hazardous waste, it's a big problem because they don't know where to dump it all anymore :-(

    * Roads needs plenty of maintenance, asphalt and gravel. The boilers for melting asphalt tends to smell really nasty, and quite some nature is destroyed to create gravel.

    (Talking about fog - most of my life I've been living so far north that the sun disappears completely for two months during the winter time)