Whorled View

April 14, 2008

Solar Cells on Cars … wouldn’t it be … lame?

Filed under: conservation,earth,ecology,economics,energy,environment,solar,Technology — lullabyman @ 6:31 am

“Solar cells on cars! Wouldn’t it be great?! I can’t wait to get mine and stick it to the man and never have to pay for gas ever again!”

This is probably one of the most common things I hear when I talk to most people about electric cars or solar technology (both subjects I know just a little about). I admit … it is a great dream. It is also a dream based on the assumption that solar cells are getting somewhat close to being about to provide the power to operate a car, which incidentally consumes a tremendous amount of energy to transport you from “A” to “B”. This is a concept that most people have no clue about: gasoline packs an amazing amount of punch. The energy density found in this liquid that you just pump out of the ground is phenomenal.

Then you have solar cells, the alternative. The sad fact is that the best commercially available solar cells only convert 20% of the sun’s energy to electricity. Try this: go outside when it’s sunny and notice how hot the sun feels on your face. Then stand behind some tall trees that filter out about 80% of the sun’s direct rays. Suddenly get cold? That’s about how much of that energy is available to you with the very best (ie. ugly) commercially available solar cells. Sexy solar cells (black and curvy) are at best half as efficient (less than 10%).

So the next question is: how far will that take you if you tile them all over you your Tesla Motor’s Roadster (a super efficient Electric Vehicle)? I’m thinking around 4 miles/day. Tesla Motor’s did the analysis though and said you don’t want to put them on the hood, so you’re looking at 2 miles/day. See the math for yourself (they did it so I don’t have to )<:).

So using the best commercial solar cells possible on a very efficient road-worthy EV you get a range of 1 mile per day from where you live (remember you have to drive both ways).

Hmmm … One mile? Why don’t you get a bicycle instead.

But what if …. what if some quantum-dot nano-particle super-ultraconducting-lattice PV solar cell was invented that was 80% efficient? Yeah, that would be cool… very cool. You’ll be able to drive 16 miles per day in your Tesla Roadster (up to 8 miles from your house)! Of course, you could only do this when it’s at least moderately sunny. Also, your car is going to be hot and muggy inside because it sat in the sun all day. Plus, your car would probably cost a million dollars and won’t be available for 50 years or more when just such efficient solar cells are invented (not being a pessimist … just a realist).

But hey … you’d get bragging rights. 😉

“My car is powered by solar. Neener-neener.”

“Oh is that right, Smarty pants?”

“Yeah, powered by solar, you knuckle dragging galoot.”

“Actually I’m more of a car-pounding galoot”. [smack!] “He he he … Now what is it powered by, Smarty pants?”

Yeah, Ouch! High efficiency solar cells are quite fragile. That’s also why you don’t want to put them on the hood of your car. Or on the trunk. Or … maybe anywhere on your car.

So what about the solar car challenges that schools compete in every year where they race their solar cars over 100 mph and travel like 100’s miles/day? Have you seen those things? They’re marvels of engineering.

They’re also very fragile, designed for one very cramped person with extremely limited visibility, maneuverability (designed to only go straight), no AC, no heat, no lights, and no safety (relatively speaking). Consider this … in 2004 Andrew Frow, (from U-of-Toronto) was driving the winner of the American Solar Challenge Safety Award when he unexpectedly swerved into oncoming traffic and was instantly killed. A tragedy for sure that should never be trivialized. What’s important though is that similar accidents happen at events like this on almost an annual basis (although that was the only one to collide with a car resulting in a death) and the racers and designers are indeed as careful as they can be but these cars are built only to win competitions, not save lives.

No, using the Solar Challenge Cars as justification for Solar powered commuter cars is kind of like jettisoning airplane passengers over destinations because people successfully sky dive. I’m thinking you probably want your car to be 1) comfortable, 2) fit multiple people, 3) have AC, heat, air, 4) windows, 5) good visibility, 6) maneuverability, 7) safety features, 8) survive a crash from any side, 9) have room for groceries, 10) look good, 11) be in your favorite color, and 12) be functional after a basketball bounces off it.

BUT YOU CAN HAVE THAT IN A SOLAR POWERED CAR TODAY! Just get an electric vehicle and charge it’s batteries with solar panels on your house. Go with the Toyota Prius (or hold out for the Chevy Volt if you want to look cool). Better yet, if you live near the Mojave desert in California then forget about solar panels because the electricity in your house is already solar powered.

A MUCH CHEAPER WAY TO DO IT: Yes, in fact, if you put solar panels on your house you can sell the electricity back to the grid at a 2:1 price. So why would you put solar panels on your car anyway? You save twice as much $ putting them on your house.

NEV: Now, admittedly I’ve been a curmudgeon about this issue, and I should at least throw the “pack your own solar” fans a bone. There is a viable “pack your own solar” Car in the form of a “NEV” (Neighborhood Electric Vehicle), but I’d be scared to drive it on any of our streets. Still, if you like electric golf carts and you live in a leisure neighborhood and you don’t like to walk it might be just what you’re looking for: http://www.sunnev.com. It’s cheap too!

They say it does 3 mi/day. The economics works because it’s so light, and it’s light because it’s a glorified golf cart. With increased weight the power requirements will go up porportionally. A comfortable sedan is about 10 times heavier and will additionally have a lot more friction (internal and against the road).

Don’t get me wrong. Solar is great. I personally think it will play a very major part in the future of the world’s energy solution, including mobility. Just not in the way that you probably envisioned it.

In fact, eventually some (may be all) cars will have solar cells embedded in their design but they just won’t really do anything other than keep your battery from going dead, or maybe power a fan that will keep your car cool on the hottest days while it’s parked in the sun (they’ll probably be integrated into your rear window). They already sell after-market window units that do this (you have to slightly unroll your window where the device is located).

In short, sometimes it’s good to remember that when you take the best of all technologies and mix it all together into a single unit, the sum is less than the parts. Solar is one of those things that sometimes acts that way. I’d gladly be proven wrong though by some genius who figures out how to cheaply squeeze a lot more energy out of the sun than our current commercially available solar cells do. Until then, have an extension cord ready, because EV’s will be giving internal combustion engines a run for their money within the next 5-10 years and you’re going to need a lot more juice for them than an affordable solar array will provide.



  1. If I enter clever comments and lots of them will you give me a prize for best comment of the week, like Robin (http://robinblogz.blogspot.com/)
    does on her blog?

    Comment by Mom — April 17, 2008 @ 2:55 am

  2. Yes! Though the prizes will be distributed on a millennial basis starting in 3008.

    Comment by lullabyman — April 17, 2008 @ 2:32 pm

  3. Alan has been reading about bio diesel and he’s about ready to set up his own processing plant. I begged him to wait until he moved some of his stuff for his myriad other projects to Clear Creek. This hillside and driveway and garage is starting to look like a salvage yard.
    It’s a good idea though: relatively simple and cheap.

    Comment by Linda — April 17, 2008 @ 8:01 pm

  4. Bio-diesel is such a slam dunk right now.

    Comment by lullabyman — April 17, 2008 @ 8:40 pm

  5. I would like to have solar power at the cabin. I am glad you posted this article because I would have been one of those dorks complaining about why we can’t have solar panels all over the car.

    Comment by robin — April 21, 2008 @ 6:30 pm

  6. Brent drives a Diesel Jetta and it gets 45 miles to the gallon- I’m a fan of bio diesel.

    Did you notice that it’s now cool to drive ugly cars? What’s up with the prius being a status symbol?

    However I did rent a prius to drive from LA to San Diego- I made the 120 mile trip and didn’t have to fill up the rental car because it was still full. That was pretty cool.

    Comment by salt h2o — April 25, 2008 @ 1:43 pm

  7. This is a very interesting post to me–we just watched “The Death of the Electric Car” not too long ago, and I was very stubborn about NOT being sucked into it’s pursuasiveness, but I was in the end ticked, just as the producers want me to be.

    I totally confused about bio-diesle cars. Does this include ethonol cars that require us to grow large crops of corn, use all the energy and land that is require for that process, to then get the ethonol to fuel our cars effieciently (and expensively)? It seems like a trick to pacify the public’s demand for more alternative fuels.

    Can your next post sort this out for me? Can I give you post assignments? Will you please continue to make them funny like this one so as to help keep my short attention span?

    You make me laugh–even when writing about solar energy!

    Comment by Jolly — April 25, 2008 @ 6:25 pm

  8. Yes, bio-diesel is very cool, and has potential to be very wonderful, and yes, bio-diesel has the potential of being very very very bad for the reasons you mentioned.

    Right now it is somewhere in the middle of wonderful and bad and you can blame congress for the bad.

    Same with ethanol, and yes, these are indeed two different things. Bio-diesel is much better. Ethanol requires tons of processing, which releases more carbon in the atmosphere than the gas it’s supposed to replace. Think Ethanol = Evil. Bio-Diesel beautiful. Bio-diesel can go straight into your *diesel* car without extra processing – straight from used (and filtered) vegetable oil from your nearest McDonalds. Very very very cool. That’s when bio-diesel shines.

    When it replaces cheap crops that go to feed the needy then it doesn’t shine. And that’s what’s happening now. Massive hunger in Africa right now is due in large part to ethanol production due to senseless government mandates that costs billions in taxes.

    The really bad thing here is that corn is used instead of other options simply because congress made it so after prostituting themselves with agricultural lobbyists. Corn is one of the least efficient ways to make bio-fuel. Switchgrass produces 4X more per acre. See this:

    There’s a tree in South America called Brazilian Copaifera langsdorfii that produces bio-fuel nearly as well as switchgrass but without needing any processing (from the sap to your tank), and it offsets all the carbon by producing oxygen. You tap it like a maple tree, so it lives for 50+ years. http://www.nextenergynews.com/news1/next-energy-news4.3.08d.html

    Researchers are engineering algae ponds that produce combustionable fuel comparable in concentrations that are 15X higher than what corn produces. Problem is, farmers can’t use it, so Willie Nelson doesn’t sing about it, and there are few if any lobbyists that are pushing for reform in the bio-fuel industry. Instead they want to keep the status quo. It’s sickening. 5 years ago a 5 gallon bucket of wheat cost $5. Now it costs $25.

    But I’m all for bio-fuels. We just need to do it the right way.

    Comment by lullabyman — April 25, 2008 @ 10:54 pm

  9. Putting all the technical stuff on the side, the reality here is this: If its new, tons of people will be on line purchasing a car just because it has solar panels attached to it. The entire “want to go green” has made business people hippies and hippies into business people.

    Comment by Neon — July 20, 2008 @ 3:34 pm

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