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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. Troy

    Troy Active Member

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    @BluestarE3, you are right. On Oct 28th when he sent this tweet, it was unclear whether the same ice melting technology would be used in cars as well. However, a few days later on Nov 1st Elon said, "It is using a lot of techniques from the automotive glass business and, in case it wasn't obvious with the announcement, Tesla has created a glass technology group with some really phenomenal people" (source). So it looks like Tesla hired people from the automotive glass industry who know about rear defrosters on cars and they have done some tests on prototypes.

    After the conference call, there were multiple articles about the Model 3 having an ice melting glass roof. This was before his second set of tweets on Nov 4th when he confirmed solar roof on cars:

    Elon Musk: The Model 3 Will Incorporate Tesla's Solar Roof Technology
    Expect Model 3 glass to share features with Tesla's Solar Roof tiles
    The Tesla Model 3 could feature an ice-melting solar roof

    Quote from the third article: "Musk all but gives away the plans for a paneled roof and windshield that can defrost and melt snow efficiently."
     
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  2. eSpiritIV

    eSpiritIV Member

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    I agree with most people that this will be something they may offer in the distant future, not the first vehicles off the lot, Im sure the M3 will also have a tow package, but again not for a long while.
     
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  3. Model 3

    Model 3 Active Member

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    Why not? It was after all promised already at the Unveiling #1.
     
  4. Topher

    Topher Energy Curmudgeon

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    This is a guy who charges $4500 for different wheels... I am not convinced his definition of 'not super expensive'
    matches mine.

    Check the price of raw solar cells in bulk, and you will see how silly this is. Even the article you cite say that the roof will cost $73,000 not $20,000.

    Which shows you shouldn't believe what the press says. The efficiency of a standard windshield defroster is that of a resistance heater (i.e. 100%), same as Tesla's version.

    Thank you kindly.
     
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  5. Cattledog

    Cattledog Active Member

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    I resemble that remark.
     
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  6. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    No, the standard windshield defroster is not 100% efficient. It uses the same system that provides cabin heat and defrosts by blowing air up the windshield. What the article is suggesting is that they're aiming to have heated glass, as found in some Fords in the 1980s.
     
  7. Topher

    Topher Energy Curmudgeon

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    My mistake. I meant REAR window defrosters.

    Thank you kindly.
     
  8. ecarfan

    ecarfan Well-Known Member

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    I could be wrong...but I think many journalists have gotten this completely wrong.

    It appears to me that Elon is saying that the upcoming Tesla Energy solar tiles will have built in heating elements to melt snow and ice and that this is desirable because the energy required to do that melting is more than offset by the energy produced by the solar roof tiles once they are cleared of snow and ice.

    That is not the same thing as saying that future Tesla cars will have "solar" PV roofs that generate energy and can melt snow and ice. The reason being that the surface area of a car is very small compared to the surface area of a house roof and the car already has a huge battery in it that cannot be effectively charged from the tiny car roof area whereas the house has a huge roof area that can be used to easily charge a relatively much smaller home storage battery.

    If Elon is in fact driving a Tesla with a glass roof and windshield and rear window with embedded heating elements in them, of the type that Tesla Energy plans to include in their solar roof tiles, that would be to test the capability of the heating elements, not to test how useful a PV car roof would be to provide power. Elon and JB have done the math and they know that the available surface area of a car roof is much too small to generate a useful amount of power and certainly not enough to recharge the vehicle battery.

    The flaw in my reasoning is that Elon lives in LA and there is essentially no snow or ice on car roofs in his neighborhood! :cool: Which makes me question whether or not he really does have a Tesla test car with solar cells or embedded heating elements in the roof.

    If next year Tesla offers a car option with solar PV cells embedded in the windows and roof I will be very surprised. Which won't be the first time that Tesla has surprised me...
     
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  9. Troy

    Troy Active Member

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    In this video after 6:10 they talk about the Karma Revero. That's the car that will be released by the Chinese company that bought the rights to Fisker Karma at a bankruptcy auction. The guy says the Fisker Karma solar panels in this video generate 125 Watts of power and the Karma Revero will generate 200 Watts. In 10 hours that would be 2 kWh energy. It seems enough to cover the vampire loss. In terms of mileage, that's equal to 265*2/75.9= 7 miles range.

     
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  10. ecarfan

    ecarfan Well-Known Member

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    Yes, and those roof solar cells will only produce their peak output of 200w at midday for a few hours on a sunny day in the summertime with the car parked outside in an unshaded location.

    In the real world that means even if the car is parked outside all day (and how many Fisker owners are likely to leave their very expensive car outside all day on a regular basis?) on a typical day with some clouded and not during the summer the amount of power generated will be much less than 2kWh and likely only about 4 miles of range. And if the car is parked in covered parking or its a cloudy day in late fall to early spring (half the year) the roof solar cells will produce almost no energy at all.
     
  11. Topher

    Topher Energy Curmudgeon

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    Ten hours of sun requires about 2 days of actual time. The best solar insolation locations in the US get less than 6 solar hours average. The worst, half that.

    Yes, it is probably enough to offset the vampire losses. But that implies that it adds little range.

    Thank you kindly.
     
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  12. Jayc

    Jayc Member

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    I just don't see the point in a solar roof which at best will add a few percent points of charge under ideal conditions. Sunlight intensity varies from region to region and some owners will park their car indoors or sheltered car parks so essentially you have a feature that some can benefit from sometimes. One thing that distinguishes Tesla from the rest IMO is their ability to put money exactly where it matters and with Model 3, that will be even more critical as margins are limited.
     
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  13. ohmman

    ohmman Maximum Plaid Member

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    mod note: edited somewhat click-baity thread title in exchange for accuracy.
     
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  14. X-Auto

    X-Auto Member

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    7 miles is enough to get you going after office all day !
     
  15. Dan Detweiler

    Dan Detweiler Active Member

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    Personally, my belief is that integration of the Tesla Roof technology (Tesla Glass) into future cars won't be for putting charging cells in the roof but will be used to allow for windshield wide heads up display technology working towards autonomous driving capabilities.

    Dan
     
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  16. JeffK

    JeffK Well-Known Member

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    I think this is spot on because I can't see obscuring a perfectly, good, clear roof with solar cells. The view from the interior would suck.
     
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  17. Chuq

    Chuq Active Member

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  18. JeffK

    JeffK Well-Known Member

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    I'm assuming that no matter what, from inside the vehicle you'd see the panels ... and since that's undesirable, you'll not get the panels.

    I'd rather see clouds, blue sky, or stars than the back of solar panels :( especially if my cost/benefit ratio is high.

    If it's going to cost more than the electricity I'd gain in use and it's going to obscure my view then I can see very little personal benefit.
     
  19. Topher

    Topher Energy Curmudgeon

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    Another possible innovation would be hydrophobic glass. Might make up for the lack of a rear wiper.

    Thank you kindly.
     
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  20. 3Victoria

    3Victoria Active Member

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    I think there are possibilities of Tesla glass. They might incorporate clear solar cells, soevial coatings etc. Including solar cells might be incredably cheap for Tesla, and might auto defrost windows, charge 12V battery, cause auto darkening for bright sunlight. I will be happy to see what they come up with. :D
     
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