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USA Today Misreports New Solar Prius Feature

  1. Jul 7, 2008 #1

    russ_watters

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    http://www.usatoday.com/money/autos/2008-07-07-prius-solar-powered-air-conditioning_N.htm

    A quick gut-check of the numbers shows that 2 kW is impossible and 5 kW is just downright laughable. A high quality panel such as THIS one generates about 140 w/m^2 and costs $5.5 per watt. That means that to generate 2 kW, the Prius would need 14 m^2 of panel facing directly toward the sun. The Prius is a hatchback, with a total length and width of 4.4x1.72= 7.57 m^2. Nevermind that at $5.5 a watt for 2 kW, the panels alone would consume roughly half the cost of the car.

    I wonder who this unnamed source is?
     
  2. jcsd
  3. Jul 7, 2008 #2

    berkeman

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    Re: Nikkei Duped by Solar Prius Hoax

    Funny typo. But you mention hoax -- is it more than just a typo?

    BTW, if you think about it, using rooftop solar panels to power the car's air conditioner has a basic flaw. The solar panels generate the most power when the sun is directly overhead, when the interior of the car is in shade. When the sun is off to the side at an angle, heating the interior of the car the most, the rooftop panels are at an angle, which degrades the effective insolation and power output.
     
  4. Jul 7, 2008 #3
    Re: Nikkei Duped by Solar Prius Hoax

    Good point. It's also likely that solar panels charge batteries to be used later. So at night you can still run the air-conditioner after a days worth of charge.
     
  5. Jul 7, 2008 #4

    LowlyPion

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    Re: Nikkei Duped by Solar Prius Hoax

    Maybe they mean that it generates enough to operate the power windows?

    Maybe to store up enough energy you have to leave the garage lights on or park under a street lamp* overnight?

    [*street lamp - theoretically a way to get the city to pay for part of your transportation?]
     
  6. Jul 7, 2008 #5

    Moonbear

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    Re: Nikkei Duped by Solar Prius Hoax

    This one says it's 215 watts.
    http://www.ubergizmo.com/15/archives/2008/05/solar_roof_for_the_prius.html

    I wonder if it's a problem of USA Today reporters trying to read a Japanese newspaper and messing up the translation? There's an inherent flaw in one newspaper reporting what another newspaper wrote and calling it reporting. :uhh:
     
  7. Jul 7, 2008 #6
    Re: Nikkei Duped by Solar Prius Hoax

    Solar powered air conditioning. Are they even aware of how much torque is required to turn an A/C compressor when the clutch is engaged?... quite a bit more than anything powered by solar can provide.
     
  8. Jul 7, 2008 #7

    lisab

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    Re: Nikkei Duped by Solar Prius Hoax

    That was my first thought, too. Maybe it could run the fans, but the compressor? I don't think so.
     
  9. Jul 7, 2008 #8
    Re: Nikkei Duped by Solar Prius Hoax

    Yeah. Even if whatever device they were using to turn the compressor was already fully spun up, i'll be willing to bet that the shock of engagement (if it still had a clutch) would be enough to stop the device or at least drag it to a slow crawl. Definitely not enough to maintain proper compression.

    Transient response. That's the word I was looking for.
     
  10. Jul 7, 2008 #9

    russ_watters

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    Re: Nikkei Duped by Solar Prius Hoax

    I don't see any way there could be a typo there. The entire concept is flawed. Perhaps it could just be a false rumor, but it is awfully specific for a rumor.
     
  11. Jul 7, 2008 #10

    LowlyPion

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    Re: Nikkei Duped by Solar Prius Hoax

    From another account:

    "The solar panels will be available on the most expensive models of the Prius and will supply a portion of the electrical power required to run the air conditioning system in the hybrid.

    The symbolic gesture is part of Toyota's effort to maintain a green image as the leading producer of hybrids."


    http://www.consumeraffairs.com/news04/2008/07/prius_solar.html

    This account appears to bring a bit more realism to the table.
     
  12. Jul 7, 2008 #11

    russ_watters

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    Re: Nikkei Duped by Solar Prius Hoax

    Well that makes more sense. But how do they go from a low-wattage battery charger to something that could power the A/C? 2-5 kW sounds about right for what would be required to power the A/C.
    Wow, that's a pretty horrible bit of translating then! Maybe I should change the thread title...
     
  13. Jul 7, 2008 #12

    russ_watters

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    I think you guys are right - just bad translating/reporting. So I changed the title.
     
  14. Jul 7, 2008 #13
    Heard this on the local news this morning without any numbers. First thought was "Wow, that will be an EXPENSIVE upgrade."

    But on the other hand, Toyota might be getting a cut of car wash fluid revenues, since it probably won't work if the sun panels are dirty.
     
  15. Jul 7, 2008 #14

    LowlyPion

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    I suspect it will be a "special" cleanser too.

    "Special" being a synonym for "expensive, high margin".

    I can see the commercial already, with the ShamWow talking head. "Are you following this camera guy?"

    They might even recommend against car wash machines to encourage cleanser sales.
     
  16. Jul 7, 2008 #15
    I think it was all wishfull thinking on the part of the media. They should have stated:

    emphasis mine

    http://www.nowpublic.com/tech-biz/toyota-plans-prius-solar-panels
     
  17. Jul 7, 2008 #16

    OMG this will mean that the pan handler on the corner will want to wash more that just the windshield.
     
  18. Jul 7, 2008 #17

    LowlyPion

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    With what you will be saving on the air-conditioning you can afford to pay him.
     
  19. Jul 7, 2008 #18

    Moonbear

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    Yeah, it's one of the worst I've seen in a while. They're citing another newspaper, which they state did not cite sources, and Toyota won't discuss anything still being planned. :uhh: So for all they know, they're just spreading bad rumor (or have a bad translation...hard to tell which).
     
  20. Jul 7, 2008 #19
    I assume the process isn't direct, in which case you don't need 4kW of power.
    Just charge some batteries while you're at work for 8 hours, should be plenty. Gives you free AC on the hour ride home.

    4kw @1 hour = 14.4 Megajoules

    14.4 MJ / 200 (J/s) = 20 Hours of charging, for one battery.

    So about 6 hours for 3. Assuming they together can output 1.3kWHour.

    If they have a smaller car, more efficient air conditioner, better insulation from the outside, and a couple of decent batteries I don't see why this is a big deal.
     
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