14 ms·

Toyota testing improved solar roof for EVs that can charge while driving

158 points by JaakkoP 7y ago

lettergram 7y ago
They are claiming up to 27.7mi per day left in the sun. If true, my 5mi commute each way would be possible without ever charging the vehicle in the summer... That being s said, curious how this holds up to weather (hail, snow, etc) and whether those numbers are accurate.
- agumonkey 7y ago
  I think it will make a lot of sense for light vans. A lot more surface.
- penagwin 7y ago
  Given the small surface area of the roofs, the efficiency of existing solar panels, and how much car companies exaggerate when it comes to miles (do they mean 27.7mi with all the seats removed, etc.) I would expect it to be a practical no-go for anything except sunshine. I'm from michigan, so in the winter assuming you park your car in the open for your job, you can easily expect it to be covered in snow - whenever it snows - which is all winter. So it'd only be beneficial here during the summer, except when it's raining which is currently 3/7 days of the week. I mean it'd be a nice bonus I guess, but at least for my situation it wouldn't make a ton of sense to spend extra on.
  - adrianmonk 7y ago
    It would be very climate dependent. Here in Texas, typically I'd have 0 to 5 days per year with snow on my car. And nobody drives on those days anyway. And there are 228 sunny days in an average year. I would be worried about hail, though. I know a lot of people whose cars have been damaged or even totalled by hail.
    - Marsymars 7y ago
      Insurance companies here have worked out that they save money by cloud seeding outside of the cities to minimize hail damage in more populated areas.
- Johnny555 7y ago
  If true, my 5mi commute each way would be possible without ever charging the vehicle in the summer If you're interested in reducing environmental impact, a bicycle would also let you do that commute without charging and with much less environmental impact than an EV covered in solar cells... though it may be less pleasant in hail and/or snow. If you're just interested in saving money for electricity, then I'd be surprised if the extra cost in adding all of those solar cells is cheaper than paying for the electricity.
- chris11 7y ago
  The one exception is parking. This isn't as useful if you use covered parking. And with a new car I'd rather use covered parking.
- jillesvangurp 7y ago
  It's probably going to fluctuate quite a bit. But for a lot of people on average they'd find their car charged of nearly charged when it's been sitting out there for hours/days. The exception would be longer trips, which most people don't do every day.
gameswithgo 7y ago
If you run the math on this, even assuming 100% efficient conversion to electricity, it doesn't seem very useful.
- hn_throwaway_99 7y ago
  > The new system will provide up to 44.5 km (27.7 miles) of additional range per day while parked and soaking up sun That seems like a big deal. Most drivers actually drive in the 30-50 mile range per day (IIRC Chevy said that over 80% of commuters would be able to only be on electric with their 53-electric-mile-range Volt). So for most drivers this amount of power could reduce their external electricity needs by somewhere between 50-100%.
- bochoh 7y ago
  >>The new system will provide up to 44.5 km (27.7 miles) of additional range per day while parked and soaking up sun, and can add up to 56.3 km (35 miles) of power to both the driving system and the auxiliary power battery on board, which runs the AC, navigation and more. As someone with nearly 100 miles of round trip commute (and who parks in a usually very sunny parking lot) I would certainly appreciate 27+ miles of "free" range. Certainly enough to be useful for me. In the case of a Tesla I'm sure it's more than enough to negate the continuous usage of sentry mode as well.
  - SketchySeaBeast 7y ago
    I wonder if it'll provide enough power so that you can park and wait with AC or the stereo (admittedly two very different loads) running without worrying about it cutting into your range.
    - bochoh 7y ago
      I think that would wholely depend on the setup for the AC compressor. If it's entirely electric and sized appropriately it can be a fairly efficient mechanism. A friend of mine uses the AC in their tesla to keep pastries cold from lunch to evening commute for < 10-20 miles of range depending on ambient temperatures. Meanwhile my gas SUV idles at .3 - .5 gallons per hour depending on engine load. (4 cylinder 2.0 liter, non-turbo).
driverdan 7y ago
This is like any other concept car. It's a cool concept but won't make it to production. The commercial viability of this is far off. 34% solar is prohibitively expensive. You won't see these on cars until costs come down significantly.
- realityman 7y ago
  Covering an entire Prius with exotic semiconductors is not the road to brisk sales.
- Theodores 7y ago
  I thought the same about defect free LCD panels. Now they are cheap enough to make a house out of them and they have replaced billboards that used to be made from paper. One thing that has changed is the structural value of the roof of a car. In the olden days the roof was a vital part of the safety cell. Now it is not quite the same. The A-pillar has been toughened up and the engineering for the roof is different, hence the all-glass affair on the Tesla Model 3 and other marques. Elon Musk said there was no point in having solar panels on the car and that those would be best kept roadside for generating power that goes into the grid. He was right. But you are not going to persuade your supermarket to cover their entire parking lot with solar cells so your car can park in the cool shade underneath them whilst getting free power. If solar cells can be as good as printed and be an integral plart of a car in the place of steel, paint, glass or carbon-fibre then they don't have to make commercial sense in the rational way that Elon Musk outlines. When I get my EV campervan in 2025 I hope the roof is festooned with solar panels that are not some bolt on but integrated into the design. If I am parked up somewhere and they give me enough power to make myself a cup of tea and power my laptop then I would be happy with that. If they were a $5K option then they would also be a $3K add-on to the resale value of the campervan. If I kept the van for ten years then $200 a year for that month of use I get out of the van might be more expensive than supercharging the EV for pennies but I would still just like having such a space age feature. Nothing really makes sense with autos. There isn't such a thing as a stripped down utilitarian auto. It is all a matter of degree. Some people pay for carbon-fibre cup holders. Or fake carbon fibre hood scoops. Or extra titanium bits for the exhaust. Or, perhaps more relevant, a cabriolet top that retracts at the touch of a button at speeds up to 25 mph. If that makes sense to people - and it does - then solar cells on the bonnet and roof can easily be foisted onto the marketplace.
mtgx 7y ago
I'll start thinking Toyota is serious about EVs when it actually starts saying so -- only recently it said the future are hybrids. Yeah, right. Good luck with the bankruptcy/firesale in 10 years Toyota!
- nradov 7y ago
  Hybrids are the future for most of the market worldwide. It will take decades to build out the charging infrastructure necessary to support battery electric vehicles. Some industrialized countries will move faster.
  - dougmwne 7y ago
    I wonder if you can expand on why you think it will take decades to build out the charging infrastructure. I've seen it suggested that technology adoption S curves have been getting faster and faster over the last hundred years. The power grid exists everywhere you'd want to charge a car already. It seems a petty simple job to go the last hundred feet to the parking space. My perception was that the liming factor is the price of batteries more than anything else. It's widely expected that once batteries reach $100/kWh, electric cars will cost less than an ICE car. At that point, I'd expect these cars to really take off quickly.
    - kevin_b_er 7y ago
      The moment you consider apartments, it does not. There are few if any apartments to get where you can charge your car. This is an area many overlook, but if you don't own a home, you might not have a good place to charge. This does not fit when the big mantra around EVs has been "charge at home!" instead of "fueling up" at a station. Even now, the DC charge stations aside from Tesla are not fast enough.
      - WrtCdEvrydy 7y ago
        We priced an electrical charging system for our apartment (2 spots), and the biggest cost was installation with energy coming in at a second (less than 5% of cost)
hourislate 7y ago
I wonder if there is a market for a car cover that acts like a flexible solar blanket. Here in Texas it could offer your vehicle some protection from the Sun while charging it at the same time.
- cagenut 7y ago
  it'd be a great way to donate solar panels to local teens
temporaryvector 7y ago
I live in a pretty hot city (My car's outside thermometer showed 48°C yesterday at midday). The extended range is nice and all, but if somebody makes a car that can run the AC without running/draining the battery while it's parked, even if it's just a little to keep the car interior at 35°C or so, I would, without exaggeration, buy it the day it's released here. Hell, I'd consider it even if it would just keep the fans on to vent the hot air out. Parking in the sun while doing errands, which often involve multiple short trips where the car's AC doesn't get enough time to cool it down, seems to be a very common cause of heat-stroke among white-collar workers here. I've had to go to the ER twice about it this summer alone.
- agumonkey 7y ago
  how much power does an AC use (say on medium settings) ?
  - temporaryvector 7y ago
    I'm actually not sure in terms of car AC. Local wisdom says that on hot days your AC will sap up to 10 HP from your engine. Not sure how accurate that is. Looking around on Telsa forums and the like, I'm seeing numbers between 1 and 3 kW. My house's mini split AC unit draws around 9 amps (according to documentation, anyway), so around 2 kW. Actual numbers seem to be closer to 3 kW in the summer.
    - agumonkey 7y ago
      hmm, gets me wondering if that's why my car can't climb hills when on AC.
      - fencepost 7y ago
        "Hang on, I'm hitting the turbo button." (turns off AC)
        agumonkey 7y ago
realityman 7y ago
Does the math check out? You would need about 10kW-h to get the claimed distance, times three for the efficiency (by the way, there are NO mass-produced cells with 34% efficiency; they must be using GaAs or multijunction cells to achieve 34%) means solar input of 30kW-h per day. The projected horizontal area of a Prius is 8m^2 (including the windows) so we need about 4 hours of 1000W/m^2 insolation. Which I guess isn't totally impossible. Typical average insolation at populous latitudes is around 200W/m^2.
- SigmundA 7y ago
  Yes looks like GaAs: https://global.toyota/en/newsroom/corporate/28787347.html https://global.toyota/en/newsroom/corporate/28787347.html
  - walrus01 7y ago
    If they can bring the cost down on that, for other types of panel manufacturing for non automotive markets, that would be pretty amazing. 22% monocrystalline silicon 156mm cells are a commodity now (such as to build a 60 or 72 cells panel with and sell it under $0.60/watt), but 30 to 34% GaAs cells are incredibly expensive. Until very recently GaAs triple junction cells have been so costly they are only used on satellites and other spacecraft.
    - realityman 7y ago
      If they can make them as cheap as silicon then obviously people will buy them instead, but it's not clear to me that panel efficiency is a relevant factor in the economics of commercial solar power.
      - kirrent 7y ago
        Interestingly it is, but more because of the associated costs. Extra panel efficiency means you need less land, less mounting hardware, and fewer installers for the same power solar farm.
    - 7y ago
SigmundA 7y ago
Triple junction GaAs based panels for a whole 860 watts of power in full sun at the right angle, no mention of cost. Anybody know how much a panel like that goes for per watt now days?
- singularity2001 7y ago
  Doesn't answer your question but I just saw that you can get ordinary 100W panels for 65€ on eBay now (in pack of 2)!
- walrus01 7y ago
  I've never seen triple junction GaAs raw cells sell for less than $6/watt stc rating. For comparison I can buy pallet loads of 72 cell, 370W panels built from high efficiency mono Si cells for under $0.55/watt stc.
kevin_b_er 7y ago
They covered the car, including the back window, in triple-junction solar cells. Last I heard, those were made of expensive stuff like indium gallium arsenide junctions. They were popular on satellites because they do really really well outside of atmosphere and much worse in shaded and indirect light conditions than silicon. I'd like to know how much those cells really cost and how much power is left when you can see out the back window again. 860W sounds like a high number. Fancy 30+% triple junction solar cells cost something like $200-$300 per _watt_ years ago. As a result, those solar panels might be worth more than the car itself! Even if they've got the fancy ones down to $50/watt, that's still $43000 in solar cells. Sure they've got grandiose claims about how little they'll cost in the future, but I'd like to know about today. This is same bunk as hearing they've made a new crazy high efficiency solar cell, but it can't be manufactured outside a lab with a mountain of grad students doing the work. Sounds cool, but it won't come to market any time soon.
- walrus01 7y ago
  I will literally believe somebody has successfully commercialized triple junction GaAs cells, when I can pull out my Visa card and order a pallet of 20 assembled modules from a distributor. As I can do now for 54, 60 and 72 cell panels built from high quality 156mm monocrystalline Si cells. Until then I think triple junction GaAs is going to see the most use in experimental UAVs funded by research money, and satellites.
cellular 7y ago
We used to fight for the shady parking spots. Imagine the future when you fight for the sunny ones.
benj111 7y ago
Who wrote this? "This demo car’s prototype cells can convert solar energy at 34% and up" 34% what? "Using a redesigned solar battery cell film that measures only 0.03 mm" 0.03mm wide? Long? And what's a solar battery cell film???
- et2o 7y ago
  The efficiency percentage on a solar panel refers to the amount of radiated energy from sunlight that can be converted into electricity. https://en.m.wikipedia.org/wiki/Solar_cell_efficiency https://en.m.wikipedia.org/wiki/Solar_cell_efficiency Less sure about the 0.03mm but I'm guessing the relevant metric would be thickness or depth.
  - benj111 7y ago
    I know that, its sloppy writing not to state it though.
    - et2o 7y ago
      Kind of an asinine comment then. Presumably anyone reading that article would know about efficiency.
      - benj111 7y ago
        If you want to take that approach to journalism they could have cut down the length by about 90%, they cud prbly ms ut mst ltrs frm wrds nd yd stl no wht ws sed. And I still don't know what a solar battery cell film is.
        et2o 7y ago
        https://en.m.wikipedia.org/wiki/Thin-film_solar_cell https://en.m.wikipedia.org/wiki/Thin-film_solar_cell I think you're being a bit performative with your greivance! Took a few seconds of Googling :-)
myroon5 7y ago
See also: https://lightyear.one/ https://lightyear.one/ https://en.wikipedia.org/wiki/List_of_cities_by_sunshine_duration https://en.wikipedia.org/wiki/List_of_cities_by_sunshine_dur... Using those I found Lightyear quotes "271 days of carefree range" for Marsa Alam, Egypt. Interested if anyone finds a city with a higher quote
mikeash 7y ago
There’s no way it’ll charge while driving. It might discharge more slowly while driving and charge while parked.
CalChris 7y ago
This is interesting because the solar strip on the Nissan Leaf SL was just a do hickey, 9 watts max. It was capable of trickle charging the 12V starter which meant less draw for charging the 12V coming from the traction battery. Not nothing but really not much. I don't think it even rounded up to a mile of range. I'm not sure what's up with the visibility out the rear window of the Honda as pictured.
- usrusr 7y ago
  > It was capable of trickle charging the 12V starter Enough to increase the utility of a rarely driven ICE car tenfold.
williesleg 7y ago
I'd need a roof the size of a football field to give me enough charge to get back home from work.
mixmastamyk 7y ago
Always wanted this, makes a lot of sense in the desert. Is Toyota still turning on the headlights in the daytime? Seems like it would negate this advancement.
- Johnny555 7y ago
  You mean DRL's? They lead to a significant reduction in crash rate - and since much of a car's carbon impact is tied up in the manufacturing of the car, that is likely a far greater impact than running the DRL's all day. Plus, with LED DRL's becoming more common, the power drain is much less significant than the old incandescent lights. My old car ran the 55W headlights at around 40W each for DRL's. My new car has a DRL LED module that uses around 3W.
  - Marsymars 7y ago
    How'd you figure out the draw from your various headlights? Bulb specs?
    - Johnny555 7y ago
      I measured it once, kept reading about how OEM wiring was under spec'ed and led to voltage drop at the headlight, so I measured the voltage + current, and got a bit over the 55W rating for the regular headlight. After the first measurement I thought I proved that the wiring was seriously undervolting the headlights when I only measured around 10V (and just under 40W), then I realized that was the DRL's. To find the 3W spec for the LED DRLs on my current car, I just looked up the specs on an replacement module - I don't crawl around the hood with a multimeter anymore, too much expensive stuff in the way. (the reason I measured in the first place was because I wanted brighter headlights since I was doing a lot of night driving in mountain roads, and thought that replacing the wiring harness would be an easy upgrade. I ended up adding a set of driving lights which looked kind of dorky, but worked great)
  - mixmastamyk 7y ago
    No, the headlights were unable to be turned off on a friend’s old carolla. Was a while ago though.
pcurve 7y ago
Without clicking, I was going to post a sarcastic comment about also putting battery on hood and trunk lid. Then I saw the picture. lol
fri_sch 7y ago
There's also Sono Motors, a start-up from Munich, Germany. They aim at delivering something they call a SEV (Solar Electric Vehicle) in 2020. They have an interesting concept and more than 10k reservations. https://sonomotors.com/?lang=en https://sonomotors.com/?lang=en
- masonkay 7y ago
  Thanks for sharing the Sono Motors link. The Sion model is to be available in 2021 (or at least that is what I read on their website.) I like this practical little car with energy interface considerations at its core. Solar body panels can add up to 34km range per day, this seems to be a major incremental improvement to the EV model, I think. Sticker price of 25.5k Euro (16k for base and est. 9.5k for battery) and they let you buy the battery separately or you can lease one. It seems it will be manufactured in Sweden (Trollhättan). I want to learn more about their (export) US market strategy. Needless to say I do like this SEV concept.
  - fri_sch 7y ago
    > The Sion model is to be available in 2021 (or at least that is what I read on their website.) 2021 will probably be more realistic for delivery. Though they say in their FAQ that they will start production in the second half of 2020.
newnewpdro 7y ago
I once used an 85W portable solar panel to charge my battery while driving after the alternator failed. It was surprisingly effective at keeping the car operable, at least until the sun went down. I didn't have any accessories running, so it was just the ECU/fuel pump/injectors/ignition it had to keep up with. The experience left me wondering what MPG improvement it would be to embed solar cells in the trunk lid and hood for charging the battery in the daytime, offloading the alternator.
ngcc_hk 7y ago
The solar one of worked meant I do not have to charge the car for most of the trips I did!!! Shocking.
scotty79 7y ago
Meanwhile I just discharged 12V battery of my hybrid toyota by sitting inside with phone plugged in and fans running. There was no warning and now I have to fiddle with cables and second car to get my car to start. All while there's still charge in hybrid batteries that I assume could trickle charge my 12V to help me start the car. But it won't.

158 points by JaakkoP 7y ago

They are claiming up to 27.7mi per day left in the sun. If true, my 5mi commute each way would be possible without ever charging the vehicle in the summer... That being s said, curious how this holds up to weather (hail, snow, etc) and whether those numbers are accurate.

agumonkey 7y ago
I think it will make a lot of sense for light vans. A lot more surface.
penagwin 7y ago
Given the small surface area of the roofs, the efficiency of existing solar panels, and how much car companies exaggerate when it comes to miles (do they mean 27.7mi with all the seats removed, etc.) I would expect it to be a practical no-go for anything except sunshine. I'm from michigan, so in the winter assuming you park your car in the open for your job, you can easily expect it to be covered in snow - whenever it snows - which is all winter. So it'd only be beneficial here during the summer, except when it's raining which is currently 3/7 days of the week. I mean it'd be a nice bonus I guess, but at least for my situation it wouldn't make a ton of sense to spend extra on.
- adrianmonk 7y ago
  It would be very climate dependent. Here in Texas, typically I'd have 0 to 5 days per year with snow on my car. And nobody drives on those days anyway. And there are 228 sunny days in an average year. I would be worried about hail, though. I know a lot of people whose cars have been damaged or even totalled by hail.
  - Marsymars 7y ago
    Insurance companies here have worked out that they save money by cloud seeding outside of the cities to minimize hail damage in more populated areas.
Johnny555 7y ago
If true, my 5mi commute each way would be possible without ever charging the vehicle in the summer If you're interested in reducing environmental impact, a bicycle would also let you do that commute without charging and with much less environmental impact than an EV covered in solar cells... though it may be less pleasant in hail and/or snow. If you're just interested in saving money for electricity, then I'd be surprised if the extra cost in adding all of those solar cells is cheaper than paying for the electricity.
chris11 7y ago
The one exception is parking. This isn't as useful if you use covered parking. And with a new car I'd rather use covered parking.
jillesvangurp 7y ago
It's probably going to fluctuate quite a bit. But for a lot of people on average they'd find their car charged of nearly charged when it's been sitting out there for hours/days. The exception would be longer trips, which most people don't do every day.

gameswithgo 7y ago

If you run the math on this, even assuming 100% efficient conversion to electricity, it doesn't seem very useful.

hn_throwaway_99 7y ago
> The new system will provide up to 44.5 km (27.7 miles) of additional range per day while parked and soaking up sun That seems like a big deal. Most drivers actually drive in the 30-50 mile range per day (IIRC Chevy said that over 80% of commuters would be able to only be on electric with their 53-electric-mile-range Volt). So for most drivers this amount of power could reduce their external electricity needs by somewhere between 50-100%.
bochoh 7y ago
>>The new system will provide up to 44.5 km (27.7 miles) of additional range per day while parked and soaking up sun, and can add up to 56.3 km (35 miles) of power to both the driving system and the auxiliary power battery on board, which runs the AC, navigation and more. As someone with nearly 100 miles of round trip commute (and who parks in a usually very sunny parking lot) I would certainly appreciate 27+ miles of "free" range. Certainly enough to be useful for me. In the case of a Tesla I'm sure it's more than enough to negate the continuous usage of sentry mode as well.
- SketchySeaBeast 7y ago
  I wonder if it'll provide enough power so that you can park and wait with AC or the stereo (admittedly two very different loads) running without worrying about it cutting into your range.
  - bochoh 7y ago
    I think that would wholely depend on the setup for the AC compressor. If it's entirely electric and sized appropriately it can be a fairly efficient mechanism. A friend of mine uses the AC in their tesla to keep pastries cold from lunch to evening commute for < 10-20 miles of range depending on ambient temperatures. Meanwhile my gas SUV idles at .3 - .5 gallons per hour depending on engine load. (4 cylinder 2.0 liter, non-turbo).

driverdan 7y ago

This is like any other concept car. It's a cool concept but won't make it to production. The commercial viability of this is far off. 34% solar is prohibitively expensive. You won't see these on cars until costs come down significantly.

realityman 7y ago
Covering an entire Prius with exotic semiconductors is not the road to brisk sales.
Theodores 7y ago
I thought the same about defect free LCD panels. Now they are cheap enough to make a house out of them and they have replaced billboards that used to be made from paper. One thing that has changed is the structural value of the roof of a car. In the olden days the roof was a vital part of the safety cell. Now it is not quite the same. The A-pillar has been toughened up and the engineering for the roof is different, hence the all-glass affair on the Tesla Model 3 and other marques. Elon Musk said there was no point in having solar panels on the car and that those would be best kept roadside for generating power that goes into the grid. He was right. But you are not going to persuade your supermarket to cover their entire parking lot with solar cells so your car can park in the cool shade underneath them whilst getting free power. If solar cells can be as good as printed and be an integral plart of a car in the place of steel, paint, glass or carbon-fibre then they don't have to make commercial sense in the rational way that Elon Musk outlines. When I get my EV campervan in 2025 I hope the roof is festooned with solar panels that are not some bolt on but integrated into the design. If I am parked up somewhere and they give me enough power to make myself a cup of tea and power my laptop then I would be happy with that. If they were a $5K option then they would also be a $3K add-on to the resale value of the campervan. If I kept the van for ten years then $200 a year for that month of use I get out of the van might be more expensive than supercharging the EV for pennies but I would still just like having such a space age feature. Nothing really makes sense with autos. There isn't such a thing as a stripped down utilitarian auto. It is all a matter of degree. Some people pay for carbon-fibre cup holders. Or fake carbon fibre hood scoops. Or extra titanium bits for the exhaust. Or, perhaps more relevant, a cabriolet top that retracts at the touch of a button at speeds up to 25 mph. If that makes sense to people - and it does - then solar cells on the bonnet and roof can easily be foisted onto the marketplace.

mtgx 7y ago

I'll start thinking Toyota is serious about EVs when it actually starts saying so -- only recently it said the future are hybrids. Yeah, right. Good luck with the bankruptcy/firesale in 10 years Toyota!

nradov 7y ago
Hybrids are the future for most of the market worldwide. It will take decades to build out the charging infrastructure necessary to support battery electric vehicles. Some industrialized countries will move faster.
- dougmwne 7y ago
  I wonder if you can expand on why you think it will take decades to build out the charging infrastructure. I've seen it suggested that technology adoption S curves have been getting faster and faster over the last hundred years. The power grid exists everywhere you'd want to charge a car already. It seems a petty simple job to go the last hundred feet to the parking space. My perception was that the liming factor is the price of batteries more than anything else. It's widely expected that once batteries reach $100/kWh, electric cars will cost less than an ICE car. At that point, I'd expect these cars to really take off quickly.
  - kevin_b_er 7y ago
    The moment you consider apartments, it does not. There are few if any apartments to get where you can charge your car. This is an area many overlook, but if you don't own a home, you might not have a good place to charge. This does not fit when the big mantra around EVs has been "charge at home!" instead of "fueling up" at a station. Even now, the DC charge stations aside from Tesla are not fast enough.
    - WrtCdEvrydy 7y ago
      We priced an electrical charging system for our apartment (2 spots), and the biggest cost was installation with energy coming in at a second (less than 5% of cost)

hourislate 7y ago

I wonder if there is a market for a car cover that acts like a flexible solar blanket. Here in Texas it could offer your vehicle some protection from the Sun while charging it at the same time.

cagenut 7y ago
it'd be a great way to donate solar panels to local teens

temporaryvector 7y ago

I live in a pretty hot city (My car's outside thermometer showed 48°C yesterday at midday). The extended range is nice and all, but if somebody makes a car that can run the AC without running/draining the battery while it's parked, even if it's just a little to keep the car interior at 35°C or so, I would, without exaggeration, buy it the day it's released here. Hell, I'd consider it even if it would just keep the fans on to vent the hot air out. Parking in the sun while doing errands, which often involve multiple short trips where the car's AC doesn't get enough time to cool it down, seems to be a very common cause of heat-stroke among white-collar workers here. I've had to go to the ER twice about it this summer alone.

agumonkey 7y ago
how much power does an AC use (say on medium settings) ?
- temporaryvector 7y ago
  I'm actually not sure in terms of car AC. Local wisdom says that on hot days your AC will sap up to 10 HP from your engine. Not sure how accurate that is. Looking around on Telsa forums and the like, I'm seeing numbers between 1 and 3 kW. My house's mini split AC unit draws around 9 amps (according to documentation, anyway), so around 2 kW. Actual numbers seem to be closer to 3 kW in the summer.
  - agumonkey 7y ago
    hmm, gets me wondering if that's why my car can't climb hills when on AC.
    - fencepost 7y ago
      "Hang on, I'm hitting the turbo button." (turns off AC)
      - agumonkey 7y ago

realityman 7y ago

Does the math check out? You would need about 10kW-h to get the claimed distance, times three for the efficiency (by the way, there are NO mass-produced cells with 34% efficiency; they must be using GaAs or multijunction cells to achieve 34%) means solar input of 30kW-h per day. The projected horizontal area of a Prius is 8m^2 (including the windows) so we need about 4 hours of 1000W/m^2 insolation. Which I guess isn't totally impossible. Typical average insolation at populous latitudes is around 200W/m^2.

SigmundA 7y ago
Yes looks like GaAs: https://global.toyota/en/newsroom/corporate/28787347.html https://global.toyota/en/newsroom/corporate/28787347.html
- walrus01 7y ago
  If they can bring the cost down on that, for other types of panel manufacturing for non automotive markets, that would be pretty amazing. 22% monocrystalline silicon 156mm cells are a commodity now (such as to build a 60 or 72 cells panel with and sell it under $0.60/watt), but 30 to 34% GaAs cells are incredibly expensive. Until very recently GaAs triple junction cells have been so costly they are only used on satellites and other spacecraft.
  - realityman 7y ago
    If they can make them as cheap as silicon then obviously people will buy them instead, but it's not clear to me that panel efficiency is a relevant factor in the economics of commercial solar power.
    - kirrent 7y ago
      Interestingly it is, but more because of the associated costs. Extra panel efficiency means you need less land, less mounting hardware, and fewer installers for the same power solar farm.
  - 7y ago

SigmundA 7y ago

Triple junction GaAs based panels for a whole 860 watts of power in full sun at the right angle, no mention of cost. Anybody know how much a panel like that goes for per watt now days?

singularity2001 7y ago
Doesn't answer your question but I just saw that you can get ordinary 100W panels for 65€ on eBay now (in pack of 2)!
walrus01 7y ago
I've never seen triple junction GaAs raw cells sell for less than $6/watt stc rating. For comparison I can buy pallet loads of 72 cell, 370W panels built from high efficiency mono Si cells for under $0.55/watt stc.

kevin_b_er 7y ago

They covered the car, including the back window, in triple-junction solar cells. Last I heard, those were made of expensive stuff like indium gallium arsenide junctions. They were popular on satellites because they do really really well outside of atmosphere and much worse in shaded and indirect light conditions than silicon. I'd like to know how much those cells really cost and how much power is left when you can see out the back window again. 860W sounds like a high number. Fancy 30+% triple junction solar cells cost something like $200-$300 per _watt_ years ago. As a result, those solar panels might be worth more than the car itself! Even if they've got the fancy ones down to $50/watt, that's still $43000 in solar cells. Sure they've got grandiose claims about how little they'll cost in the future, but I'd like to know about today. This is same bunk as hearing they've made a new crazy high efficiency solar cell, but it can't be manufactured outside a lab with a mountain of grad students doing the work. Sounds cool, but it won't come to market any time soon.

walrus01 7y ago
I will literally believe somebody has successfully commercialized triple junction GaAs cells, when I can pull out my Visa card and order a pallet of 20 assembled modules from a distributor. As I can do now for 54, 60 and 72 cell panels built from high quality 156mm monocrystalline Si cells. Until then I think triple junction GaAs is going to see the most use in experimental UAVs funded by research money, and satellites.

cellular 7y ago

We used to fight for the shady parking spots. Imagine the future when you fight for the sunny ones.

benj111 7y ago

Who wrote this? "This demo car’s prototype cells can convert solar energy at 34% and up" 34% what? "Using a redesigned solar battery cell film that measures only 0.03 mm" 0.03mm wide? Long? And what's a solar battery cell film???

et2o 7y ago
The efficiency percentage on a solar panel refers to the amount of radiated energy from sunlight that can be converted into electricity. https://en.m.wikipedia.org/wiki/Solar_cell_efficiency https://en.m.wikipedia.org/wiki/Solar_cell_efficiency Less sure about the 0.03mm but I'm guessing the relevant metric would be thickness or depth.
- benj111 7y ago
  I know that, its sloppy writing not to state it though.
  - et2o 7y ago
    Kind of an asinine comment then. Presumably anyone reading that article would know about efficiency.
    - benj111 7y ago
      If you want to take that approach to journalism they could have cut down the length by about 90%, they cud prbly ms ut mst ltrs frm wrds nd yd stl no wht ws sed. And I still don't know what a solar battery cell film is.
      - et2o 7y ago
        https://en.m.wikipedia.org/wiki/Thin-film_solar_cell https://en.m.wikipedia.org/wiki/Thin-film_solar_cell I think you're being a bit performative with your greivance! Took a few seconds of Googling :-)

myroon5 7y ago

See also: https://lightyear.one/ https://lightyear.one/ https://en.wikipedia.org/wiki/List_of_cities_by_sunshine_duration https://en.wikipedia.org/wiki/List_of_cities_by_sunshine_dur... Using those I found Lightyear quotes "271 days of carefree range" for Marsa Alam, Egypt. Interested if anyone finds a city with a higher quote

mikeash 7y ago

There’s no way it’ll charge while driving. It might discharge more slowly while driving and charge while parked.

CalChris 7y ago

This is interesting because the solar strip on the Nissan Leaf SL was just a do hickey, 9 watts max. It was capable of trickle charging the 12V starter which meant less draw for charging the 12V coming from the traction battery. Not nothing but really not much. I don't think it even rounded up to a mile of range. I'm not sure what's up with the visibility out the rear window of the Honda as pictured.

usrusr 7y ago
> It was capable of trickle charging the 12V starter Enough to increase the utility of a rarely driven ICE car tenfold.

williesleg 7y ago

I'd need a roof the size of a football field to give me enough charge to get back home from work.

mixmastamyk 7y ago

Always wanted this, makes a lot of sense in the desert. Is Toyota still turning on the headlights in the daytime? Seems like it would negate this advancement.

Johnny555 7y ago
You mean DRL's? They lead to a significant reduction in crash rate - and since much of a car's carbon impact is tied up in the manufacturing of the car, that is likely a far greater impact than running the DRL's all day. Plus, with LED DRL's becoming more common, the power drain is much less significant than the old incandescent lights. My old car ran the 55W headlights at around 40W each for DRL's. My new car has a DRL LED module that uses around 3W.
- Marsymars 7y ago
  How'd you figure out the draw from your various headlights? Bulb specs?
  - Johnny555 7y ago
    I measured it once, kept reading about how OEM wiring was under spec'ed and led to voltage drop at the headlight, so I measured the voltage + current, and got a bit over the 55W rating for the regular headlight. After the first measurement I thought I proved that the wiring was seriously undervolting the headlights when I only measured around 10V (and just under 40W), then I realized that was the DRL's. To find the 3W spec for the LED DRLs on my current car, I just looked up the specs on an replacement module - I don't crawl around the hood with a multimeter anymore, too much expensive stuff in the way. (the reason I measured in the first place was because I wanted brighter headlights since I was doing a lot of night driving in mountain roads, and thought that replacing the wiring harness would be an easy upgrade. I ended up adding a set of driving lights which looked kind of dorky, but worked great)
- mixmastamyk 7y ago
  No, the headlights were unable to be turned off on a friend’s old carolla. Was a while ago though.

pcurve 7y ago

Without clicking, I was going to post a sarcastic comment about also putting battery on hood and trunk lid. Then I saw the picture. lol

fri_sch 7y ago

There's also Sono Motors, a start-up from Munich, Germany. They aim at delivering something they call a SEV (Solar Electric Vehicle) in 2020. They have an interesting concept and more than 10k reservations. https://sonomotors.com/?lang=en https://sonomotors.com/?lang=en

masonkay 7y ago
Thanks for sharing the Sono Motors link. The Sion model is to be available in 2021 (or at least that is what I read on their website.) I like this practical little car with energy interface considerations at its core. Solar body panels can add up to 34km range per day, this seems to be a major incremental improvement to the EV model, I think. Sticker price of 25.5k Euro (16k for base and est. 9.5k for battery) and they let you buy the battery separately or you can lease one. It seems it will be manufactured in Sweden (Trollhättan). I want to learn more about their (export) US market strategy. Needless to say I do like this SEV concept.
- fri_sch 7y ago
  > The Sion model is to be available in 2021 (or at least that is what I read on their website.) 2021 will probably be more realistic for delivery. Though they say in their FAQ that they will start production in the second half of 2020.

newnewpdro 7y ago

I once used an 85W portable solar panel to charge my battery while driving after the alternator failed. It was surprisingly effective at keeping the car operable, at least until the sun went down. I didn't have any accessories running, so it was just the ECU/fuel pump/injectors/ignition it had to keep up with. The experience left me wondering what MPG improvement it would be to embed solar cells in the trunk lid and hood for charging the battery in the daytime, offloading the alternator.

ngcc_hk 7y ago

The solar one of worked meant I do not have to charge the car for most of the trips I did!!! Shocking.

scotty79 7y ago

Meanwhile I just discharged 12V battery of my hybrid toyota by sitting inside with phone plugged in and fans running. There was no warning and now I have to fiddle with cables and second car to get my car to start. All while there's still charge in hybrid batteries that I assume could trickle charge my 12V to help me start the car. But it won't.