Featured Toyota testing new solar powered Prius

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by Prius Pete, Jul 5, 2019.

  1. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    Can you explain how you are going to get this?

    I have had solar PV for 4 years. Today was sunny all day, but not perfectly clear.
    I generated 19 kwh...my best ever is just over 20. I get about 4100 kwh per year.
    This is with 12 panels, not perfectly oriented...they are 10-12% less than optimal.
    Of course the panels are probably better oriented than those on a car, on average.

    Each of my 12 panels is 39" x 65", so maybe you'd get about one of these on a car.
    If you fit more than this they will be sub optimal, in any case.

    Summary: you might get about 1.5 kwh per day, if in the sun all day, during the long summer days and 1/4 of that in the winter.
    Based on my 4100 kwh/yr for 12 panels...maybe 340 kwh/yr in a car. And you have to be sure and keep the car clean.

    At $.10/kwh that would be $34/yr or ~$500 for 15 years.
    Even if you could double the solar area...it is still just $1000.
    And you haven't taken into account being partially dirty or shady. (Check out micro inverters and how much more they cost to partially solve this)

    Finally, most people usually want to NOT park in the sun during summer because it degrades the interior faster and heats the car more and causes you to use A/C more.

    Mike
     
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  2. Rmay635703

    Rmay635703 Senior Member

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    I have no choice but to park in the sun all day, I live in Wisconsin though
     
  3. drash

    drash Senior Member

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    Unfortunately, I have no choice but to park in the sun all day. No shade, but the parking lot is almost perfectly North-South oriented. Typically I change how I park based on weather and time of year. Summer time I point the car North. Winter time I point to the South, to take advantage of the big windshield and whatever sun we get to warm the car.


    Unsupervised!
     
  4. drash

    drash Senior Member

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    Well what caught my eye about this article is that these ATJ cells are germanium based and they were getting 25% efficiency. While cheaper to manufacture than silicon they are nowhere’s near silicon in efficiently converting solar. That and the fact these are smooth surface and “the silicon cell has micro-pyramidal textures in its surface, feature that increases the absorption of light from a broad range of angles of incidence”. And you mean this chart: upload_2019-7-7_10-35-2.png

    Unsupervised!
     
    #44 drash, Jul 7, 2019
    Last edited: Jul 7, 2019
  5. austingreen

    austingreen Senior Member

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    Just to help your math a little - your panels are 1.64 square meters. I just installed 19.8% efficient panels (happy independance week for me from most fossil electricity at home), and if we take toyota at its word of 34% efficiency then I come to 2.56 square meters for the key of 0.86 KW. This is definitely possible if you cover the rear window as they have done in the illustrative picture. Solar One is designed for solar and gives 5 meters in better orientation so toyota should be able to do around half on an already designed shorter car.

    For the year they are estimated that I will get 1412 kwh AC from each kw of solar panels. I'm in austin which is not as good as california and angles are slightly off optimal, but better than a lot of the country for solar like where drash is located. YMMV. My guess is this is wired to just dc to dc converter and charging losses would be less efficient than converting to AC, but given the angles its gong to come out worse, but lets use that for 1215 kwh/year or 3.3 kwh per day. My guess from their numbers they are talking about getting 5.3 kwh on the best day, but you need to average this down for cloudy days, storms, etc.

    Figuring 80% efficiency of charging that 1215 kwh (again not best case but close to it) would require about 1520 kwh per year ac or about the amount from 1 kwh of solar panels on the roof. For 10 years @$0.28USD japan/kwh = $4256 USD (we are talking expensive power in japan relative to the US, but cheaper than some european countries). My guess is if they wanted to put it on a car 3 years from now that is about what they would have to charge. The numbers make little sense with less expensive electricity prices in the US and the likelihood I am over estimating the real world generation over a decade (cells will likely degrade, parking must be close to perfect).
     
    #45 austingreen, Jul 7, 2019
    Last edited: Jul 7, 2019
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  6. Tideland Prius

    Tideland Prius Moderator of the North
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    The 2019 RAV4 Limited and XSE Hybrid have this feature.
     
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  7. fuzzy1

    fuzzy1 Senior Member

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    Do keep in mind that this chart does not display actual power output. The "radiometric cosine effect" mentioned in the paper is factored out of this data, but is an essential part in figuring the device's total power output as the solar incidence angle changes.
     
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  8. drash

    drash Senior Member

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    Yep, just conversion efficiency, and much to my chagrine this paper was published in 2005, ancient by the way technology moves forward. I was going to use this graph to figure out how Toyota got 860W in Japan but being old tech, germanium, and a smooth surface, probably not possible to recreate a curve that would use the efficiency loss in calculating useable power over a (useful) days span on Toyota’s solar skin.

    Would this mean I would get a Prime with Solar Cells? No, probably not because this would be something like a Limited Platinum version of the Prime. A novelty more than a necessity since I have access to Community Solar.


    Unsupervised!
     
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  9. Prius Pete

    Prius Pete Active Member

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    Toyota says the car can get 44 km from a day of charging. Since this is about the EV range of a Prime, I assumed the solar panels could charge the 8.5 KWhr battery from zero to full on a sunny day. It was just a back of the envelope calculation to show that, under ideal conditions, a solar car like this could pay out depending on the price they charge for the option. Obviously your solar mileage may vary.

    NEDO, Sharp, and Toyota to Begin Public Road Trials of Electrified Vehicles Equipped with High-efficiency Solar Batteries | Corporate | Global Newsroom | Toyota Motor Corporation Official Global Website
     
  10. William Redoubt

    William Redoubt Senior Member

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    In my world, the 0 to 60 elapsed time is not a factor. Nor are these, "performance" modes, fancy door latches, self-driving, or video games. My issues are cost to procure, cost to own, range, availability of service/repair and parts, and reliability. I could care less if I can beat a Corvette, play Cuphead or have a touchscreen for everything in the car.
     
  11. William Redoubt

    William Redoubt Senior Member

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    Bendy bus? Is that the way ya'all talk in Pennsylvania? Jolly good, governor.
     
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  12. bisco

    bisco cookie crumbler

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    toyotas ideal conditions are unlikely to be experienced in the real world
     
  13. Tideland Prius

    Tideland Prius Moderator of the North
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    I’d like to point out that this prototype charges while in motion too. So you will gain miles while out on the road. The current Prime/PHV does that but it’s only to run accessories like the nav or radio.

    On a road trip, this can help extend the range by 20-50% based on the current Prime before needing a charge.

    And to expand your scenarios...

    Waiting at the border? Charging (easily 2-3 hours on long weekends)
    Waiting for the ferries? Charging
    Crawling on the freeway? Charging

    Most people in the sunshine states have dark tinted windows anyway so they just need a windshield one to reduce interior wear and tear.

    Another benefit? Remote A/C to cool the interior. On the Prime, it only works if there’s EV range left. If you’re depleted and are in HV mode, remote A/C doesn’t work. Therefore having the solar panel top up your battery so that you can have remote climate is definitely a plus.

    Solar panels on the roof is like a PHV. Sure it’s not like a BEV but it can significantly reduce your gasoline usage. Solar panels can help reduce your impact on range by topping up while you’re driving or parked. Its opportunistic charging.
     
    #53 Tideland Prius, Jul 7, 2019
    Last edited: Jul 7, 2019
  14. bisco

    bisco cookie crumbler

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    that's a great feature. i love the forward thinking and r&d. i would expect a production car in n/a by gen VI or VII
     
  15. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    If Toyota truly has solar panels and a design that can do this...AND can make them at a price that plenty of people will pay to get, then they should, instead, go to mass production right away and sell them for home solar installations. I'm guessing the claims are exaggerated and/or the price is way too high.
    But we will see, I guess.

    Mike
     
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  16. William Redoubt

    William Redoubt Senior Member

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    Wait a minute Mike. This is Toyota. Not Tesla. This is Akio Toyoda. Not Elon Musk. But I wonder if Mr. Toyoda is contemplating rocket boosters on the higher trim levels? :rolleyes::rolleyes:;)
     
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  17. alanclarkeau

    alanclarkeau Senior Member

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    Lots of Bendy Buses here:

    upload_2019-7-8_14-10-58.png
     
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  18. Prius Pete

    Prius Pete Active Member

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    PriusChat member E-GINO in Italy has the existing solar roof option on his Prius Plug-In

    Prius Prime Solar Roof | Page 3 | PriusChat

    He says, on a good day, he can get 7 km of solar range -- this is in line with Toyota's statement of 6.1 km. However, he has only generated 96 KWhr in 14 months, so it seems real life solar generation might be quite small.

    The new solar roof design must be doing something else to increase solar range. They are claiming 7.3 times the range of the current solar roof but have only increased the solar cell power by 4.8 times (180W to 860W)
     
  19. Rmay635703

    Rmay635703 Senior Member

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    Some solar panels are much less affected by being at the wrong angle.
    I have a cheap thin film 60 watt panel that seems to collect more juice than a 60 watt monocrystal unit at the same angle.

    My guess is the future will be multi-structural harmonic radiation panels that collect more of the spectrum including some direct thermal energy . Get the “directional” nature of panels somewhat fixed (so output matches the amount of cross sectional sunlight and IR intercepted) and there will be a lot of happy campers
     
  20. austingreen

    austingreen Senior Member

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    I doubt the claim of 0.86 kwh is exaggerated, but yes the claims that people will get those miles are clearly exaggerated as they are assuming jc08 mileage which is almost impossible to achieve in any real world conditions and numbers appear to be about leaving the car out in a sunny place like texas all the time. They are partnered with sharp on this and they had the tech back in 2013. The reason triple junction cells are not used is the cost. I'm sure if sharp had a big cost breakthrough they would be selling them for home solar, but again there is a reason I put up 20% efficient panels and not higher, and that is all about the price of a system. A vehicle has limited real estate so perhaps it is not as cost sensitive, but I doubt this is a cheap system. US's DOE and Japan's METI are funding reaserch to lower cost, but I haven't heard of any big breakthroughs there.

    Sharp Hits Record 44.4% Efficiency for Triple-Junction Solar Cell | Greentech Media

    Let's use the 7.3 and consider that is about 600 kwh/year. That is about half of what I calculated for ideal so its likely in the ball park for real world. Its likely the new cells and design let it charge at lower light levels and are more efficient charging. That's 1.64 kwh/day on average, and I still think the best days are around 5.3 kwh.

    Let's say you increased the battery size to 12 kwh from 8.8 kwh instead. That likely would cost toyota around $200/kwh or $640 (+ profit, markup, etc), and tech has moved so it would likely fit in the same space. Say you can charge 80% of the added energy or 2.6 kwh, that would improve range and power more. For those who want solar they can likely purchase it in a different way. Still this may be a cool gadget for japan which has expensive electricity and not much possibilities for most to put up solar panels.
     
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