Sun Follows the Solar Car

Bill Storage once got an A in high school Physics and suggests no further credentials are needed to evaluate the claims of most eco-fraud.

Once a great debate raged in America over the matter of whether man-mad climate change had occurred. Most Americans believed that it had. There were theories, models, government-sponsored studies, and various factions arguing with religious fervor. The time was 1880 and the subject was whether rain followed the plow – whether the westward expansion of American settlers beyond the 100th meridian had caused an increase in rain that would make agricultural life possible in the west. When the relentless droughts of the 1890s offered conflicting evidence, the belief died off, leavings its adherents embarrassed for having taken part in a mass delusion.

Model TWe now know the dramatic greening of the west from 1845 to 1880 was due to weather, not climate. It was not brought on by Mormon settlements, vigorous tilling, or the vast amounts of dynamite blown off to raise dust around which clouds could form. There was a shred of scientific basis for the belief; but the scale was way off.

It seems that the shred of science was not really a key component of the widespread belief that rain would follow the plow. More important was human myth-making and the madness of crowds. People got swept up in it. As ancient Jewish and Roman writings show, public optimism and pessimism ebbs and flows across decades. People confuse the relationship between man and nature. They either take undue blame or undo credit for processes beyond their influence, or they assign their blunders to implacable cosmic forces. The period of the Western Movement was buoyant, across political views and religions. Some modern writers force-fit the widely held belief about rain following the plow in the 1870s into the doctrine of Manifest Destiny. These embarrassing beliefs were in harmony, but were not tied genetically. In other words, don’t blame the myth that rain followed the plow on the Christian right.

Looking back, one wonders how farmers, investors and politicians, possibly including Abraham Lincoln, could so deeply indulge in belief held on irrational grounds rather than evidence and science. Do modern humans do the same? I’ll vote yes.

Today’s anthropogenic climate theories have a great deal more scientific basis than those of the 1870s. But many of our efforts at climate cure do not. Blame shameless greed for some of the greenwashing; but corporations wouldn’t waste their time if consumers weren’t willing to waste their dollars and hopes.

Take Ford’s solar-powered hybrid car, about which a SmartPlanet writer recently said:

Imagine an electric car that can charge without being plugged into an outlet and without using electricity from dirty energy sources, like coal.

He goes on to report that Ford plans to experiment with such a solar-hybrid concept car having a 620-mile range. I suspect many readers will understand that experimentation to mean experimenting in the science sense rather than in the marketability sense. Likewise I’m guessing many readers will allow themselves to believe that such a car might derive a significant part of the energy used in a 620-mile run from solar cells.

We can be 100% sure that Ford is not now experimenting on – nor will ever experiment on – a solar-powered car that will get a significant portion of its energy from solar cells. It’s impossible now, and always will be. No technology breakthrough can alter the laws of nature. Only so much solar energy hits the top of a car. Even if you collected every photon of it, which is again impossible because of other laws of physics, you couldn’t drive a car very far on it.

Most people – I’d guess – learned as much in high school science. Those who didn’t might ask themselves, based on common sense and perhaps seeing the size of solar panels needed to power a telephone in the desert, if a solar car seems reasonable.

The EPA reports that all-electric cars like the Leaf and Tesla S get about 3 miles per kilowatt-hour of energy. The top of a car is about 25 square feet. At noon on June 21st in Phoenix, a hypothetically perfect, spotless car-top solar panel could in theory generate 30 watts per square foot.  You could therefore power half of a standard 1500 watt toaster with that car-top solar panel. If you drove your car in the summer desert sun for 6 hours and the noon sun magically followed it into the shade and into your garage – like rain following the plow – you could accumulate 4500 watt-hours (4.5 kilowatt hours) of energy, on which you could drive 13.5 miles, using the EPA’s numbers. But experience shows that 30 watts per square foot is ridiculously optimistic. Germany’s famous solar parks, for example, average less than one watt per square foot; their output is a few percent of my perpetual-noon-Arizona example. Where you live, it probably doesn’t stay noon, and you’re likely somewhat north of Phoenix, where the sun is far closer to the horizon, and it’s not June 21st all year (hint: sine of 35 degrees times x, assuming it’s not dark). Oh, and then there’s clouds. If you live in Bavaria or Cleveland, or if your car roof’s dirty – well, your mileage may vary.

Recall that this rather dim picture cannot be made much brighter by technology. Physical limits restrict the size of the car-top solar panel, nature limits the amount of sun that hits it, and the Shockley–Queisser limit caps the conversion efficiency of solar cells.

Curbing CO2 emissions is not a lost cause. We can apply real engineering to the problem. Solar panels on cars isn’t real engineering; it’s pandering to public belief. What would Henry Ford think?



Tom Hight is my name, an old bachelor I am,
You’ll find me out West in the country of fame,
You’ll find me out West on an elegant plain,
And starving to death on my government claim.

Hurrah for Greer County!
The land of the free,
The land of the bed-bug,
Grass-hopper and flea;
I’ll sing of its praises
And tell of its fame,
While starving to death
On my government claim.

Opening lyrics to a folk song by Daniel Kelley, late 1800s

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  1. #1 by Bruce Vojak on January 25, 2014 - 11:34 am

    Great piece, Bill! I really appreciate the balance you strike when you write. I recognize it as submitting to reality, not spinning an argument. Such writing is always very persuasive to me, as I expect it might be for many others.

    BTW while I was at Motorola working piezoelectric components about 15 years ago, we looked into what it would take to attach some PZT transducers onto a person in order to power a cell phone based on the vibrations generated by that person’s movement throughout the day. Not surprisingly, it was the same story.

    Hope all is well with you,


    Bruce A. Vojak | Associate Dean for Administration College of Engineering | University of Illinois at Urbana-Champaign 306B Engineering Hall, MC-266 | 1308 West Green Street | Urbana, IL 61801 USA E | T 217.333.6057 | F 217.244.7705

    co-author of Serial Innovators: How Individuals Create and Deliver Breakthrough Innovations in Mature Firms (Palo Alto: Stanford University Press, 2012) Stanford University Press web site for Serial Innovators | Sloan Management Review book review | Fast Company expert blog ________________________________

    • #2 by Bill Storage on January 25, 2014 - 8:55 pm

      Thank you Bruce! I’m hoping to get your help on my solar powered helicopter project.

  2. #3 by Mike Karg on February 1, 2014 - 5:38 pm

    Makes sense, Bill, that solar alone is insufficient. But, doesn’t it also make sense to use solar power as a supplemental way of charging the batteries? If this energy can be stored, and the car is parked outside, it seems like it would pay for itself at some point.

    • #4 by Bill Storage on February 1, 2014 - 8:28 pm

      Thanks for the comment, Mike. It might make sense to get the kilowatt hour or so that you could reasonably capture. The reason to do this, in my view, would be to reduce CO2 from oil or (worse) coal-based electricity generation. All life-cycle analyses I’ve seen of solar-panels in this type of usage profile conclude that the CO2 “cost” of the panels greatly exceeds that of the non-renewable energy it would eliminate. The embodied energy of solar panels is also quite high. These factors are particularly relevant to usage profiles impacted by things like shade and garages.

      See Ozzie Zehner, among others, for more details on solar cell life cycle. Ozzie, who is no white-collar capitalist, recently noted what should be obvious to anyone familiar with life cycle cost analysis:

      “When solar industrialists claim that their electricity is approaching cost parity with conventional energy, they are implicitly admitting that so far, at least, it has taken more conventional energy to fabricate, install, and maintain a photovoltaic system than that system ever produces.”

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