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Model 3 may have Solar Roof that can charge the vehicle

Discussion in 'Model 3' started by X-Auto, Nov 25, 2016.

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  1. X-Auto

    X-Auto Member

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    Yes, I am not drunk my friends, Elon Musk confirmed this will be offered as an option for Model 3 ! and It might provide more power when built like a retractable roof, see below tweets;

    elon-tweets-solar-glass-roof-model-3.jpg
    So what you guys think? Also if interested I have written about this and more updates on my blog here: Tesla Model 3 Will Have A Solar Charging Roof - More Updates From November

    Happy Thanksgiving and Black Firday weekend !!! Cheers !
     
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  2. JeffK

    JeffK Well-Known Member

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    #2 JeffK, Nov 25, 2016
    Last edited: Nov 25, 2016
    As far as "charge the car" let's be clear that it'll simply add a (very) small amount of charge... for all intents and purposes though I'd refrain from saying it'll "charge the car" as people might misinterpret this not needing to plug it in at all.

    Let's also be real about charging... I'll use a Model S as an example because it's bigger and we know the dimensions. The area from the top in sq meters is roughly 10 sq meters. at 20% efficiency this would yield 2 kWh Model 3 will be even less. Chances are that only the roof would be solar panels and not the entire surface area of the car. This puts you closer to 1-1.2 kWh

    In addition, you need to leave it in the sun, this causes the interior to heat up and once it hits the max temp, the car will start to cool itself drawing power. Let's be very generous and say this leaves you netting 1 kWh.

    Where I live the average is 4.21 sun hours per day, this means if I leave the car out all day in perfect sun I'd get about 4.2 kWh. This would save me about $0.50 of electricity per day.

    Now realistically, I have a garage and I park in a parking garage at work. I also drive to work in the early morning when it's dark and I drive home early evening. Maybe it'd get 30 min of sun so that $0.06. If I worked 365 days a year then it would add up to $21.90 per year. If a solar roof on the car is a $2000 option then it would take 91 years for it to be worth it (in my particular situation).

    For someone who only parks outside then in my area it'd take them nearly 11 years to break even if energy prices stayed the same assuming a $2000 solar roof option.

    It'd be cool if it worked better or was cheaper but right now it's not all unicorns and rainbows.

    That said, if I lived in a very small town and drove a small amount every day with no garage at any destination then it'd be fantastic. Might even skip getting wiring done to charge with high current at home to offset the initial solar cost.
     
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  3. BluestarE3

    BluestarE3 Active Member

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    Probably more accurate to say, "add some charge to the car". As for the "deployable" comment, I think that was just Elon thinking out loud in response to the previous tweet, rather than a declaration that he wants to offer such.
     
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  4. Watts 4 Me

    Watts 4 Me Member

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    I think they may look into it in the future. Realize it's not worth it and not go with it.
     
  5. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    That just reads like Elon thinking out loud.
     
  6. ecarfan

    ecarfan Well-Known Member

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    I think Elon is just joking. Really. His second tweet about the "deplorable" roof reads like humor to me.
     
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  7. Troy

    Troy Active Member

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    #7 Troy, Nov 25, 2016
    Last edited: Nov 25, 2016
    Elon is not joking. The more important quote is the following. This feature will allow leaving the car unplugged at airport car parks. The energy generated just needs to be more than the vampire drain.

    [​IMG]
     
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  8. BluestarE3

    BluestarE3 Active Member

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    I think the smiley at the end of Elon's response belies that. ;)
     
  9. ecarfan

    ecarfan Well-Known Member

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    His use of the :) emoticon leads me to believe he is not being serious.

    Seriously...the amount of power that a Tesla vehicle roof (and even the hood) covered with solar cells could generate is minuscule. It's a nonsensical way to charge the battery pack.

    Even if Tesla embedded transparent solar cells in the windshield and rear window as well as in the roof and the hood the total power output (even at midday) would be tiny.
     
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  10. Chuq

    Chuq Active Member

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    I spoke to a Tesla employee at an event a couple of weeks ago and he said "The only Tesla with a solar roof at the moment is Elon's own car." Make of that what you will... further discussion implied that the technology used with the tiles (where the solar cells are visible at certain angles but not others) would be useful in other products.
     
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  11. S3XY

    S3XY Member

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    I'm with you on this. I don't think Elon dismisses anything out of hand but he will dismiss it if research shows it is not feasible or cost effective.
     
  12. Topher

    Topher Energy Curmudgeon

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    I am reasonably certain that Elon has done the math. He is that kind of guy. It is also possible that he will offer it at a huge cost, for the few people that actually park in the sun at the airport for months at a time, and posers who are willing to do stupid things to look fashionable. Depends on how big his marketing people tell him the poser contingent is.

    Thank you kindly
     
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  13. Haxster

    Haxster Member

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    Perhaps it's a battery "maintainer" for the 12V battery. I think the Karma did something like this.
     
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  14. Troy

    Troy Active Member

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    #14 Troy, Nov 25, 2016
    Last edited: Nov 25, 2016
    In other threads, I wrote a lot about why Tesla will deploy lots of city-superchargers for people who park on the street and have nowhere to charge at home or work. That's 90% of car owners in Hong-Kong (source) and China is most likely very similar.

    When those people go on holiday and leave their car parked on the street, what will happen to it if the battery runs out because of vampire drain? There was an incident with a Roadster left unplugged at a museum. At that time, Tesla said the following:
    I think the solar car roof idea makes perfect sense as long as it can generate more energy than the vampire drain.
     
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  15. ecarfan

    ecarfan Well-Known Member

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    That is a possible reason for such a feature, but when you consider the engineering resources that have to be spent creating that feature and implementing it into the vehicle and balance that with the potential number of customers who would be willing to pay very likely thousands of dollars for that feature as an option, I doubt there is a rational basis for Tesla to do it.

    If that is the reason for offering a solar roof option, basically Tesla is saying "EVs have this weakness that they drain the 12V battery faster than ICE vehicles so we are providing this expensive option for those who will leave their EV unplugged for many weeks at a time, something that we firmly advise not doing".

    I think the potential market size for such an option would be minuscule. The fact that Fisker did supports my reasoning. Fisker did a lot of dumb stuff.
     
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  16. X-Auto

    X-Auto Member

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    elon-tweet-expensive-solar-roof-no.jpg

    No Sir, not huge costs,,,,, :) and since He already has this on his vehicle, he should have done the math ! :p
     
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  17. Troy

    Troy Active Member

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    According to my calculation, the solar car roof would add $144 to the cost. This article says a 3,000 square feet asphalt roof would cost $20,000. Tesla's solar roof is cheaper than a normal roof. That's 278 square meters. Per square meter would be $72. Two square meters would be $144. Tesla would be selling this option for $500, cheaper than the obeche wood upgrade. Seems like a cool feature to have.

    @X-Auto, thanks for that screenshot. I think it further demonstrates that Elon wasn't joking.
     
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  18. X-Auto

    X-Auto Member

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    'impossible' is a mindset my friends and Elon doesn't have that mindset so this will be done and it will charge the vehicle, maybe enough to get a few miles to reach home or in a situation where batteries totally drain and it puts you out of that emergency situation...
     
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  19. Troy

    Troy Active Member

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    It turns out there was another Elon tweet about this (source). It looks like they have been testing things.

    [​IMG]
     
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  20. BluestarE3

    BluestarE3 Active Member

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    Isn't he just saying that solar glass tiles (for house roofs) will have built-in defrosters analogous to what is used in a car's rear window? He's not saying that Tesla cars will have solar glass roofs that can generate electricity. At least I don't read that in this Twitter exchange.
     
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