Using Super-Efficient Solar Cells To Keep Your Electric Car’s Battery Topped Up

Who hasn’t thought of sticking a couple of solar panels onto an electric car’s roof to keep its battery at 100% charge while it’s parked out in the sun? While usually deemed impossible due to the large number and weight of PV solar cells required to get the necessary amount of energy, this hasn’t kept Toyota’s engineers from covering one of their Prius cars with 34+% efficient solar cells.

Some may remember the solar roof option which Toyota previously offered years ago. That system produced a mere 50 W and was only used for things like running the AC fans, indirectly extending the battery charge. In 2016 Toyota brought back this system, in a much improved version. This upped the power output to 180 W, allowing it to power all secondary electronics in the Prius, even allowing it to add a few extra kilometers (roughly 6.1 km/day) to the Prius’ range if one were so inclined.

This newest prototype pretty much goes for broke, reminding us of the cars used in the World Solar Challenge, such as the Dutch Stella and Stella Lux positive-energy solar cars by the team at the University of Eindhoven. Who coincidentally have done a spin-off, setting up a company to produce the Lightyear One, which at least on paper sounds amazing, and potentially may never have to plug it in.

With super-efficient solar cells producing about 860 W of power, the Toyota prototype Prius should be able to add roughly 44.5 kilometers to the car’s range. Maybe not as amazing as the Lightyear One, but Toyota has what appears to be a working prototype. With this additional range added just by having the car parked or driving in the sunshine, it could make it a very interesting proposition for a lot of people, depending on how much it’d add to the total cost of the car.

Admittedly, the current Prius prototype looks rather rough: the solar cells don’t blend in well with the rest of the car. But maybe that’s what’s so reassuring about Toyota’s efforts. Their engineers are improving performance and features as PV solar and other technologies improve, without a lot of focus on glossy CGI renders and marketing.

Would you be interested in adding nearly 50 km of range to your (hybrid) electric vehicle with a PV solar option like this? How much would you pay for it? Or would you rather get some 25+% efficient cells and glue them on your current electric car? Have you, or someone you know, ever blended PV solar and cars like this before? Please let us know in the comments.

Hat tip to [Qes] for sending in this tip!


96 thoughts on “Using Super-Efficient Solar Cells To Keep Your Electric Car’s Battery Topped Up

  1. Yay, good to see the trend moving on. I haven’t used starter batteries in one of my car’s for over 5 years just 6 off 3500F super caps in series. Lighter than the old battery and with higher starting current too. Not enough Ahr discharge to worry me when not run since I drive car once or so a week. Could use a top up solar trickle charge just in case…
    Thanks for post, might prompt others to go similar route for older cars as more lead free super caps on market etc cheers..

      1. Indeed, my alternator charges to 14.4v (headlights off) and after about 5-6 days the caps drop to approx 11.3v or so, enough to start the car normally (twin cam 4 cylinder) even down to just over 10.5v or so if bit longer – last checked that about 2 years ago. I got stuck once leaving headlights on but, on a hill there was enough juice to tickle the alternator field for a rolling start lucky its a manual. The radio backup and ecu still connected but, no remote I still use a key. I do have an isolator switch next to the set of caps under the bonnet in case I’d like to leave it couple of days longer. On long trips like to country where I might be a few days just in case I carry one of those red Hawker 12v SLA battery’s – the high grade pure lead one in a box with isolator and jumper leads incidentally dated 1996 from the local university’s UPS regular service maintenance, got a few of them around 2004 or so, they are one of the best lead SLA type I’ve ever come across made in France and iirc used on private jets to start the APU.
        I definitely need some solar trickle charger and voltage limit as the caps are about 6 years old by now probably starting to dry out next few years, these days getting easier to make your own…

        1. Cool, that sounds amazing – thanks for the information! Do you balance the individual cells to 2.7V, or is it okay to trust the ~2V of headroom?

          For what it’s worth, Harbor Freight sells a small 12V / 1.5W panel designed to stick on the inside of your windshield and plug into a cigarette lighter adapter. It’s a miniscule amount of power, but it might help with leaving the headlights on for a few hours.

          Also, I hadn’t realized that the cigarette lighter adapters were bidirectional before I saw it – I always guessed there was a rectifier somewhere in there.

          1. True, I was initially concerned about balancing then measured the resistivity change turns out they are pretty much self balancing within that 2v or so total headroom. Occasional checks as they operate show they are within about .2 to .3v variance – a data logger for each cap in the sequence would likely point to which one might go open circuit first which is far more likely than any cap shorting unless physical ingress. Has been a while should check again soon. Haven’t ever wanted to go up to that max 2.7v per cap, though if I was to do that given the amount of stored power re possible catastrophic failure then sure I’d put in some means to manage that. Even then though the failure mode is only gassing which increases resistivity not any serious heating.

            The only wiring change I made from battery to caps was the series isolator, just a cheap 100Amp rotary switch such as used on small boats. Unfortunately, though a fair safety issue is all standard auto cig lighter plugs only ‘on’ when key in place in ignition or accessory position and don’t want to do that at all. Ideal is to add, wire in a diode (in series with suitable fuse) from cig positive to battery positive on back of ignition switch or where convenient. I have a 3v solar panel ah lah cheap garden light type and tiny SMPS to lift to 14v and will wire that tidily into dash leaving the plug for my ph charger when driving. Have a pic somewhere of the caps in the car can upload to soon where I check stuff daily…

        2. I have been very interested in doing this myself. I’ve seen YouTube videos of people that used super caps, plus a supplemental battery comprised of some 18650 cells. The caps are good for much longer times of inactivity.

    1. I would love to have a vehicle like this. And I would pay to have this feature. I am in sales ajd drive quite a bit. But I think if solar covered half my usage it would phenomenal. I hate having to go to the pump, and I dont have a place to charge am EV. I see a lot of negative and also many very ignorant comments on here and I dont understand it. I am American. I didnt realize that so many Europeans are also like that. Why do you need nuclear fusion power to charge a car? Only if you dont understand how solar works I guess. And it works pretty damn well. Someone mentioned Germany having 2 grids, one for renewables one for coal. That’s one of tge dumbest things Ive ever read on the internet.

      1. I too would love to buy/drive a solar Prius. I work from home and typically drive < 10 miles a day a few days a week, just dropping off/picking up my son from school when I sleep too late to get him on the bus. If those numbers are correct, I'd probably cover all my driving with solar spring, summer and fall. Mostly likely buying a Prius Prime anyway when my car bites the dust, as long as this option wouldn't cost an arm and a leg, I'd definitely get it.

        (I'm American too, BTW)

        1. Prius Prime will get you ~22miles plugged in all electric. I have a Chevy Volt, sadly discontinued, and get 50-60 miles all electric which covers my daily commute. I save about $150/month in gas versus the Mazda 3 I used to drive.

      2. A quick check of wikipedia says that Germany has one grid for electricity, like most countries (and it’s interlinked with the countries around it). Interestingly they do have a second grid running at 16.5Hz, which is used for powering railways, it’s joined to Austria and Switzerland. Neither grid is 100% renewables, they’re both mixed. Basically, you shouldn’t believe everything you read on the internet.

        As for why solar isn’t as well loved in Europe, well, in the UK we typically get about 10% of the theoretical maximum of power, if you average over a whole year. (Due to the latitude and the clouds). So that purported 50km of extra range a day becomes more like five.

  2. “How much would you be prepared to pay for it?”

    Not much. Those 860W of solar cells probably produce about 5kWhr on a really good day, being a bit generous. Something like 75p worth of electricity. So this might save you, maybe, £275 per year, if you drive at least 50km every single day of the year (driving 100km one day an 0 the next doesn’t count).

    Of course that’s not the whole point; being able to go a bit further without recharging is also worth something, though the amount that it’s going to add to your range *while you’re driving* is going to be pretty small cheese.

    So, £500 maybe? At a stretch?

      1. We’ve spent way too much money saving his butt!

        Neat idea, would ease some of the range anxiety if you aren’t pressed for time. If they could build this into something like a Hilux or a CR-V with a bit more ground clearance, I could see this being useful in countries with less infrastructure, or large deserts.

    1. Your electricity is too cheap! We pay between 0.30 and 0.35 euronies per kWh. If the thing produces 860 W/sunny hour, and we get 1709 sunny hours per year in Munich (
      0.86 * 0.35 * 1709 ~= 500 euros/year. Times maybe a ten year life for a car?

      Could be worth 3000-4000. That’s not nothing, but then if you price out ultra-efficient solar cells…

      It’s moot though. We park in a garage or under shady trees.

      1. Yes at Germany people pay 2x price of electricity because all infra are build twice. First solar/wind for saving green souls and then coal/gas to produce real electricity. I think Germany is great example how to not do your energy politic if you want save resources and nature. It is quite great global joke of failure Germany “green” things are.

          1. I remember seeking shelter in the city when it started raining a few days after Chernobyl. Don’t need that again. Also, google for Asse nuclear storage, disposal fail. Don’t mock us for at least trying to keep a climate target, instead of just having none at all.

        1. Sorry, but BS. A good couple of days a year roundabout 50% of the energy comes from renewables. It’s a very small list of countries that can show something similar. We could join your party and do nothing. But I’m not for wishes and prayers, I’d rather do something and fail.

    2. It’s not just about electricity cost, it’s the fact that you can keep going in a blackout, even if the gas stations are down. This would be worth thousands for a dedicated preparedness type.

        1. Diesel, as does gasoline, cannot be stored more than a year or else it goes bad. Hardly useful for a prepper unless he has access to a natural source of fat that can be processed easily and converted to biodiesel.

    3. You forget that first, electricity is not as cheap everywhere. Second: chargers/easy access to electricity cant be found on every corner. For example the closest charger is 2-3km away from my workplace’s parking lot.
      So having to not spend time charging the car, looking for a charger and generally forget that I need to “fuel” the car every day worth more that £500. A normal person is not driving 50km a day every day.

      1. This assertion “a normal person is not driving 50km a day”, that very much depends on where you take your sample. I live on the outskirts of London and I expect most of the cars I see each morning and evening are travelling 25km or more. London has a commuter belt that stretches out for tens of kilometres beyond its already quite expansive boundaries. I’d sure be grateful if there were less oil being burned in order to achieve this transport.

        1. Nice, you picked a sample size of 1 and extrapolated from it. Look, look, I can do the same!
          I live in a capital city, I have a car, and I drive 0 km on average on weekdays and still live 10km from my workplace. If we extrapolate this single data point we can assume that no one drives a single km in their entire life.
          Or I take another single data point:
          My friend drives 300-500km a day. If we extrapolate this we can assume that everyone drives 300-500km a day.
          Most of the people dont live in cities that are as large and huge as London. Most of the cities are smaller in diameter than 5-8km. Also villages exist. Average city contains less than 35k people.
          If I would have to travel more than 1-1,5h a day I would move closer to my workplace or look for another job.

          50km of daily free range is plenty for the average. According to this study its enough for over 95% of the people.

          1. >”50km of daily free range is plenty for the average.”

            Except you’re not getting 50 km because the numbers are a sham. The 860 W is the peak power output of the panels, not the average output, and you’re really looking at 8-9 extra kilometers on an -average- day.

            The Toyota PR team is basically cheating by using dubious testing standards to achieve the low energy consumption, and “extrapolating” the energy gain from the data sheet of the solar panel supplier rather than any real world testing. It’s just complete nonsense. See below.

          2. “The Toyota PR team is basically cheating by using dubious testing standards”

            Yes, those dubious testing standards that are the required testing standards in Japan. Those sneaky bastards.

          3. Nice, you wilfully misinterpreted their statement to go on an elaborate nitpicking rant. Look, look I can do the same!
            They didn’t provide a sample size of one, they made an estimate based on a set of assumptions that seemed valid based on their personal experience and observations and extrapolated from that. You could simply have said “Here’s a study that says you are incorrect” instead of pounding out reductio ad absurum drivel, but then you then you might have realised that you are both essentially saying “50km of daily electric driving for the average driver would be a good thing.”

          4. “They didn’t provide a sample size of one, they made an estimate based on a set of assumptions that seemed valid based on their personal experience”

            Which is what a normal person would call a “reasonable estimate,” but what you called “dubious testing standards.” What part of the estimate that they’re making involves dubious testing standards? Everything they quoted is from industry standard testing methodologies.

            That’s the entire point that I’m making. I don’t disagree with you that the mileage estimate as an actual number is probably noticeably high, but I doubt that it’s 5x too high. JC08 testing tends to give numbers that are about 50% too high in terms of mileage (which sounds *horribly* bad, but most other testing standards are way off too), which would imply that you’re talking more about 25-30 km per day, rather than 40-50 km.

            Plus, like I said, the numbers basically pass the sniff test, definitely within a factor of 2. Their interim report ( ) has similar numbers, all spelled out, although it’s focusing on the economic benefit/emissions reduction rather than usable range.

          5. >Yes, those dubious testing standards that are the required testing standards in Japan. Those sneaky bastards.

            Dubious testing standards for this purpose. The JC08 cycle isn’t representative for average driving in the US or EU because it’s designed for urban driving in Japan. It’s only going up to 82 kph for a short burst and the average speed over the test is 34 kph.

            Electric cars do great in urban driving because they idle at zero power – in theory. The trick is that when you’re actually driving the car, you have fans, lights, radio, AC, heater, etc. turned on and those consume a significant amount of energy per kilometer because you’re moving so slowly. But, for the purpose of the test, you’re allowed to turn everything off.

            For example, to get 140 Wh/km at 34 kph average speed, your power budget is 4.8 kW or 6.6 HP, which isn’t much. That’s already telling how far you have to optimize if you want to make the trip. If you turn on your AC, lights, etc. you immediately add at least 50% to your power consumption. An electric heater to keep the windows from frosting up at -20 C can gobble up 3-5 kW.

            This phenomenon is known as the MPG gap – basically, all car manufacturers cheat the mileage tests. EV manufacturers are just in the happy position that they can cheat more because the testing standards happen to be favorable to EVs and hybrids.

          6. > but I doubt that it’s 5x too high

            One part of the cheat comes from using an easy mileage test standard, the other part comes from exaggerating the solar panel output.

          7. >JC08 testing tends to give numbers that are about 50% too high in terms of mileage

            For regular cars. For electric cars it’s even worse and 100% off isn’t uncommon if the manufacturer pulls all the stops they could.

      2. I live in the UK. My daily commute is about 35miles round trip, so just over 50km.
        But I also like to doit as fast as possible because nice country roads & sports car. So that would sap the range of an electric somewhat too.

        This electrical experimenting is nice but until someone discovers fusion it’s a dead end.
        Or we need to build hundreds of nuclear power stations in each country and massively upgrade the grid to support charging every car outside your house.
        And everyone is forgetting about trucks…
        And that the public dont own energy but we sold it to commerical enterprise like a bunch of morons selling our souls to the devil for the promise of dividends.

        Or, we make battery packs all modular and able to be bolted into a car chassis within 5 mins by robots – then you pay for the level of charge in that battery as if you were paying for litres of fuel.
        We get them from these places called “filling stations” which look after the charging of the batteries in the background so we aint waiting around.
        Some cars might take one pack, some “high performance” might take 3 packs. but requires all manufacturers to accept standardisation – inset XKCD here.

        This has been tried and it failed because at small scale there are other options like recharging.
        Mass charging of 100’s of vehicles in any location is not scalable. Wireless charging is insane – we might as well go back to trolley bus style gantries feeding power to all cars.
        Give me a more logical way forward for rapidly getting 25Kwh++ of energy into 1000’s of cars that are otherwise queuing for their turn to use a charger for 4 hours.

        Or hydrogen as a fuel
        But which is realistically more practical? A hydrogen filling network or battery charging everywhere?
        As ever the costs involved with hydrogen make battery electric cars look cheap. But sadly that short sighted lack of investment is why we have a global warming problem in the first place – business / traditional for profit companies wont fix this problem
        Massive investment required to make hydrogen production (spliting water) efficient and without using natural gass as the feedstock like we do today.

        Or we capture all the exhaust emissions from the tailpipe back into a tank (fuel tank could be dual duty with/without a flexible seperator inside the tank). When we fill with petrol/diesel we pump this out at the filling station. When the trucks come to resupply they take away all that captured gas to a central location where it’s either used for other purposes, transmuted, or sequestered.
        ^^^ minimal infrastructure changes.

        insert your workable idea which isn’t as crazy as believing all vehicles can convert to electric without at least 50% of traffic somehow being removed from the roads entirely through rationing, taxation or loss of “freedom”.

        1. “And everyone is forgetting about trucks…”
          Not “everyone”…
          Some companies are experimenting with solar panels on the roof of the semi-trailer for supplemental

        2. “capture all the exhaust emissions from the tailpipe back into a tank”
          Try running the numbers on the size of the tank required combined with the pressure of the stored exhaust including nitrogen from the air. It’s so impractical it’s not even funny.

          1. Internal Combustion Engines should be called Hot Nitrogen Engines. The fuel and 20% oxygen from the air mainly serves to heat and expand the 70% nitrogen (plus a smidge of other gasses) content in the air. If you tried to run an ICE on gasoline + air minus all the nitrogen, it either wouldn’t run at all or would run very poorly with little power. If the gas volume was increased to match air volume, then the mostly oxygen “air” to fuel ratio would have to be changed to get the engine to run.

            The combustion isn’t perfect. Even at the ideal stoichiometric ratio for gasoline and air (or diesel and air) it doesn’t use all the oxygen available in air and the fuel. There’s also oxygen bound up in the tiny % of air that’s carbon dioxide.

            No matter what, there’s always some free oxygen left in the combustion chamber to combine with some of the nitrogen, making nitrogen oxide. Combine nitrogen oxide with water vapor under the right conditions, you get nitric acid. Same thing with sulfur compounds that are released/produced. Nitrogen oxides, sulfur compounds, and carbon monoxide are the three main things catalytic converters work to alter to less noxious forms.

          2. [Gregg Eshelman] says:
            “f you tried to run an ICE on gasoline + air minus all the nitrogen, it either wouldn’t run at all or would run very poorly with little power.”

            No, attempting to run an ICE on straight O2 and gasoline would probably weld the rings to the cylinder walls and the pistons, and the valves to the heads…
            Basically you’d be making an oxygen cutting torch that would start to cut itself from inside out.

            That is why racers use NOx, it allows more oxygen for combustion, while minimizing the welding.

          3. Surely you meant N2O and NOt NO or NO2 :-(
            Btw: The N2O displaces some of both O2 & N2 by relevant proportion, end result is rather more heat produced for more power generated in that you can increase fuel flow as the simplest method with N2O ie don’t need turbo/supercharge – you have to be careful as it does produce higher temperatures. Look up engine damage from nitrous; melted pistons, valves etc
            From highschool chemistry and reaction energies (assume fuel as octane or proportion mix with methanol) and simple gas laws you can craft an excel function in only a few lines to play with the numbers and graph them – probably already done on the WorldWide Electronic Link ;-)

        3. IIRC one of Ford’s hybrids uses lithium ion cells that are similar in size (if not the same) as a standard “D” cell. Figure out a way to unload and load small cells – like how the ammunition in the magazine of an A-10 Warthog is exchanged. That airborne cannon sends its empty shells back to the magazine instead of dropping them.

          Imagine pulling up to an EV filling station and getting a fill up of 100% charged cells while the depleted ones get cycled into the station’s testing and charging system. In and out fast, just like with liquid fuel.

          Tesla built one battery swap station for the Model S in California but it was never opened. After seeing videos on Youtube of what’s involved in removing and replacing the battery in a Model S, and the potential to crunch the electric contacts, I don’t see how an automated system would be reliable. Then there’s all the fasteners and the wear and tear repeated swapping would put on the threads.

          Without quick release latches and far more robust connectors, Tesla battery swapping stations were never intended to be a real part of the company plan.

          Such *could be* done but there would have to be a universal standard for mounting and connecting modules.

          1. “That airborne cannon sends its empty shells back to the magazine instead of dropping them.”

            Dropping expended cartridges on civilians is forbidden by NATO.

      3. I am not a “normal” person, (gee whiz, who woulda thunk it?)
        My daily commute is ~124 Km/day.
        My employer, which is making a big stink about being “green”, does not have plug-ins available for electric cars (even though they manufacture EV charging ports).
        If they did, I would consider buying a plug-in hybrid, and willingly pay a “reasonable, daily” charging fee.

    4. My willingness to pay would likely depend on how close I already was to the limits of battery range.

      Going with the cheapest, lowest capacity, battery and then trying to salvage the situation with some(relatively expensive if they are using the top shelf very high efficiency ones rather than the ‘optimal price/performance for volume install’ ones) solar panels makes very limited sense; but if you are already at the limits of available range the option that adds some tens of kilometers on a good day starts to look a lot more interesting.

      1. I could see other reasons you’d pay. Perhaps you don’t have access to a charging point at one or other ends of your regular journeys, perhaps you just don’t like fetching the cables out of your car.

    5. >Those 860W of solar cells probably produce about 5kWhr on a really good day

      I saw he calculations somewhere else; the average output would be more like 2 kWh per day in the US/EU.

      But the elephant in the room is that 2-5 kWh is NOT enough to drive the car 44.5 km without cheating. The average electric car uses up about 200-250 Wh/km without the usual tricks like taping up the body panel gaps and disconnecting all the electric devices like they do on EPA/NEDC testing. In the most optimistic scenario, it would add 25 km to the range, but realistically you’re lucky to do 8 km per average day of solar charging.

      So how did Toyota come up with the number? Easy: they cheated. They used a Japanese light vehicle testing cycle which gives you a lot more mileage than the other standard tests, and with all the usual tricks as mentioned above, you can make an electric car go twice as far as you’d ever hope it to go in real driving.

      1. So what they’re really saying is, “If you happen to live somewhere near the equator, and you leave the car to charge all day, and then you hypermile it on flat level roads while maintaining an average speed of 34 km/h, you can travel 45.5 kilometers on sunshine.”

        Also, the futility of putting solar panels on cars: the power grid needs customers in the summer to soak up the extra electricity from solar panels that nobody can use at that moment. If only there were some device where you could store it for later use…

        1. According to the press release, the mileage per day was calculated from:

          1) average per-day solar radiation for Nagoya times the panel area times the overall charging efficiency, to get the total energy stored in the battery
          2) conversion to mileage is from the Prius JC08 testing data (8.74 km/kWh)

          To get to ~44 km, you need 5 kWh, which doesn’t sound crazy for a peak daily output of around 3+ square meters.

          The criticism of the JC08 test is fine, but this isn’t Toyota specifically cheating – they’re a Japanese company, and the JC08 test is the standard in Japan. You’re free to argue that Toyota might have influenced the creation of that test, but I highly doubt they did it to make the miles that you get from a prototype solar panel equipped car look higher.

          “Also, the futility of putting solar panels on cars: the power grid needs customers in the summer to soak up the extra electricity from solar panels that nobody can use at that moment. If only there were some device where you could store it for later use…”

          That argument doesn’t work. You could also say that adding solar panels to cars reduces the battery size that vehicles need to carry around to meet a mileage requirement in a day, and the battery capacity that’s saved there could be put into fixed storage where it can better soak up peak demand at all times. Cars are a terrible load dump because they’re likely unavailable when the sun’s up because that’s when they’re going to be most mobile.

          1. >(8.74 km/kWh)

            That’s 114 Wh/km. Real world electric cars do about twice that.

            >average per-day solar radiation for Nagoya times the panel area times the overall charging efficiency

            Which is false. The average solar radiation doesn’t account for the angle of the panel, or the temperature of the panel, or shading of the panel etc. which all affect the efficiency. They’re making unrealistic assumptions.

  3. Wow, I didn’t even know that efficient solar cells were on the market yet mainstream consumer level… are they really?

    I recall when looking at for my Prius, the reason for not implementing more than the air circulation fan was due to the interference the solar cells caused with AM radio reception. I think the logic was to keep the temp down on the inside by circulating in the cooler outside air.

  4. Could be interesting…. if, when parked, the car can re-position itself (or even just tilt the solar cells) to improve exposure to the sunlight. At the very least carry an on-board smarts using AI to predict your likely movements and therefore tell you the best place to park in the lot.

    e.g. (kinda…)
    “OK Betty, you’ve arrived at work.
    No scheduled trips in your diary today.
    The sun is out now, but its going to cloud over ’till 2pm,
    The left hand corner of the lot will therefore catch more sunlight – move to row F, spot 27, which is free.
    You have to walk an extra 210 metres, but you will not be in the rain.
    BTW, reverse in – I’ll catch more rays like that.”

  5. Wish that Toyota would just go ahead and make BEVs! The demonstration shows that electric vehicles are so efficient that a couple years worth of gasoline would pay for a Cars lifetime (25+ years worth) of electricity.

  6. 860Wp, 34+% efficient solar cells….. at 25C (77F) and 1000W/m2 called Standard Test Conditions. With ~0.46% power drop for silicon devices (here we have multi-junction ones) with every extra degree over 25C we end up at max 700W. Still impressive but I guess such custom cells must cost a fortune.

    1. Lets be honest… Few vehicles have had a useful one, at least in the US, since about 2005.

      Last passenger vehicle had a windscreen mounted rearview that can not, no matter how it is adjusted, make the road surface behind the vehicle visible unless the boot is full. The lower of the rear window is above the midline of the mirror at the highest position. Current pickemup has the same issue due to the gate height, but a full bed load does help. Useless side mirrors, though, due to the body flare (mostly styling, but also to make space for the PPE built into the doors and pillars)

      Test driving a few dozen trucks and passenger cars during 2016 and 2017 showed me that this is pretty much the norm. There were only a few exceptions, and I don’t recall which, as the vehicles were otherwise not memorable.

    2. This is a concept car i.e. the impractical outfits that runway models are wearing. They do not reflect the actual products for real life. The panels won’t survive a fender bender, vandalism in rough hood or a bit of mud/slush. :P

    3. “Who really needs a rear window, amirite?”

      Those without rear view cameras?

      One company is experimenting with rear view side cameras, with the displays hanging on the “A pillars”.
      The rear view side cameras have less wind resistance than the mirrors they replace and, and placing the displays on the A pillars doesn’t block the driver’s view any more than the pillar itself.
      (I think the displays should show the areas the pillars block, if the vehicle is stopped, such as a traffic light or stop sign, and then switch to rear view when the vehicle is moving (forward or reverse).)

  7. We call our Prius the big grey slug. Functional, but not interesting looking or fast. Somehow, this solar install turns it from epically bland to quite ugly. Whereas the Lightyear One looks awesome. Well done Toyota!

    1. Is a Prius not exactly the same speed as all other cars when you take traffic and… the law… into account? I have a 14 year old Peugeot, it goes the same speed as all the cars from this year.

      1. I had a 2005 Prius. It would do 0-60mph in 10 seconds which was more than adequate. Also, everyone’s become spoiled over time. Arguably the most beloved car of the 1970s was the Volkswagen Beetle. It had a 0-60 time of 20 seconds, yet people were OK with that back then.

    2. I don’t know, I personally kind of like the look of the panels on the prototype. Though I will admit that the first thing that popped into my head was Wayne Szalinski’s van in Honey I Blew up the Baby.

    1. The Sion boasts about its power sharing ability.
      Once in 1979, I did “power sharing” with my Ford F-100.
      Its battery was dead, so I popped the hood of a car parked next to it and jump started the F-100.
      (I left it attached for several minutes after getting it started, to “repay” some of the power I’d used.)
      The owner of that car (a Mustang?) probably didn’t know I’d touched it.

  8. I wonder how long those solar panels would last during my normal daily commute. Living in the Southeastern US with all the construction going on (and people who can not figure out how to secure their load before they drive), there is a good bit of debris on the road (and I mean paved interstates too.. I do very little back-country driving). I have had my car 7 years and have had to replace two windshields (and the current one has pits and chips) , the hood & roof has dents and dings from road debris, and I have lost 4 ham antennas (sheered clean off!) due to flying debris.

    1. Jeez… are those roads very busy? Here in England you’re supposed to clean up any mess you make on the road, although that’s problematic on the extremely busy roads.

  9. I’d gladly sacrifice the extra mileage to have an actively vented car during the summer. Imagine not having to step into an oven when there’s no shady spots to park at.

    1. This. I’ve often wondered how much power would be required just to keep my car near ambient temperatures in the summer. The mirrored window shades help a lot, but not enough.

      1. a long long time ago I rewired my heater fan to run with the engine off to try and reduce the summer heat build up – all I achieved was a flat battery ….

        I have seen small solar powered ventilation fans that slot into a partial open window but i cant say how effective they would be

        1. “I have seen small solar powered ventilation fans that slot into a partial open window but i cant say how effective they would be”

          I think they were a “great idea on paper”, but were implemented too cheaply to be effective, and increased the possibility of vandalism/theft with the small opening.

          I leave the sun/moon roof partially open on my car on hot days, but the sunroof also provides an extra avenue for sunlight to heat up the interior. (Not too mention the rain that got in last month during an afternoon T-storm.)

    2. The trouble is, you have to leave your car in the sun to have enough power to run the AC (not just a fan), but the car then soaks up more heat from the sun than what the AC can remove with the power it has.

      860 Watts isn’t much considering there’s 10 kilowatts of sunshine beating down on your car.

      1. For comparison, car AC systems come in between 180 to 7000 Watts with a “typical” car AC drawing about 3000 Watts from the engine at full output. At the lowest end, it’s just the fans.

  10. There’s a german start up “Sono Motors” that sells a car with solar cells that will go into production this fall.

    35 kWh Battery (~250km WLTP)
    120 kW Motor
    148 solar cells with 1.2 kW peak
    220V power outlet and charging other BEVs
    4 Seats / 4 doors
    all standard equip

    R. Schmidt

    1. >35 kWh Battery (~250km WLTP)

      Not likely. It needs to have an exceptionally small drag area/coefficient (tiny car), or low speed to achieve that energy consumption. No proper size car has managed less than about 200 Wh/km in real world motorway driving. (35 kWh / 175 km)

  11. They aren’t. The only way you get 34% efficiency is with the sort of triple-junction cells that power satellites. The cells on that car probably cost about ten times as much as the car.

  12. yeah, nice try, but this is as ridiculous as just sticking a “0 emission” sticker on a all electric car. this is just a drop of water on ha hot plate. let me put this in the “keep on dreaming” box on the top shelf. if you really want to make a difference, just take the bike if you can.

    1. My car is zero emission. It’s charged via a home solar system and battery system.
      Also the electricity used from pure coal generation is still much more efficient and better than petrol. It’s not great but it’s a start.

  13. I suggested this would be a good idea, when I was doing IT contract work at Toyota Au HQ, 12 years ago. It may be 20 years before they perfect it but at least they are taking the idea seriously now. IT means an autonomous car could slowly cross an entire continent one solar charge at a time, but they need a minimum of 100km per day to be useful for some tasks, such as cars that deliver themselves.

  14. I wonder where they parked the car to get that much out of solar cells that do not move. If I were the skeptical type I would guess they added up the best case from all of the cells to get that number and the real world number would at best be considerably under half of what they say is possible. And that is assuming you have no trees or buildings etc.

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