Toyota testing improved solar roof for EVs that can charge while driving
techcrunch.com
techcrunch.com
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.
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.
It also says that the most efficient photovoltaics yield 175W per square meter. (Though I've seen figures as high as 200W.) https://en.wikipedia.org/wiki/Solar_panel#Efficiencies
That's also the peak power, and a motorized A/C will instead be turned on and off leading to a much lower power draw that also depends less on the peak power. Typically a 50-30% duty cycle, so 200-300 watts very roughly. More depending on the insulation, sun, and outside temperature.
the best bet with solar panel AC... is to cover all windows with them so sunlight doesn't heat the inside of the car when parked. :cough:
Running on Max A/C, the screen reads just under 1/8 gal/hr. With the A/C on and with the fans at 50%, consumption is a little less but still around 1/8 gal/hr. Consumption drops too low to get a reading when A/C is off with fans 50%.
[1]: Like a fridge. Refrigeration systems are most efficient at full power. IIRC it's due to the restrictor plate separating the hot and cold radiators- it's designed to work at a certain rate of flow, so you'll get gas and liquid mixing at lower power.
You can't use LCs, as they don't have a real "clear" mode- they always block a very significant amount of light. You'd have to use electrochromatic paint or similar, as some trains and airplanes do. It's expensive and a chipped windscreen would be awful. You also can't get great resolution. I still wish somebody would do it.
I'm all for EVs but I find these types of comments distracting and underscoring a fundamental misunderstanding
Where is the misunderstanding?
a) has a transmission window in the range that's useful for PV b) has high emissivity in the atmosphere's IR window c) has high reflectivity in the rest of the spectrum
Edit: third possibility described by the interesting reply below: there could be an out of visible band reflective coating over the panels.
I have read research papers about such coatings, but I don't know whether they're in commercial use.
Tesla's dog mode does this. Draining the battery isn't really something to worry about; AC uses <300 watts over long periods (turns on and off at <1 kW). Leaving it on for 8+ hours you're talking about <5% capacity loss, at a cost of <50 cents. For short trips you could leave the AC on full blast without even noticing a drop.
Having a car with remote start alleviates the problem a little bit, but I'd rather not run an ICE engine while I'm not in the car for obvious reasons.
> but it is probably the only reason I'm considering a Tesla if it ever comes to my city
Hmm, Telsa should be pretty reachable. Perth and El Paso look like some of the only neglected hot cities.
https://www.tesla.com/findus?v=2&bounds=67.51085725091038%2C...
I'm pretty hopeful that we'll either get Tesla in a couple of years or other manufacturers will come out with something.
Though this would depend upon the humidity, would not work in high humidity and equally work better in low humidity.
However, based on this thread, utility mode requires the key fob, so someone could just break a window and steal the car. I wish manufacturers other than Tesla would think about these use cases:
https://www.insideevsforum.com/community/index.php?threads/u...
That said, even if it is time-limited, 15 minutes is usually enough to cool down the car without leaving the AC on all day.
As global temperatures rise, there are places becoming increasingly uncomfortable to live in. There may be cases where it's cheaper to wait out the hottest days in your car, instead of retrofitting a cooling system onto a building.
Dog mode is the main thing keeping me from trading in my Tesla for something else.
Sounds like this “dog mode” does exactly what you’re wanting. I see a new Tesla in your future :)
“If you want to activate the solar powered ventilation system before you get out of the vehicle it is a simple process. On the left side of the steering column, you will find a small square button with a car and fan on it. Press this button before you turn off your vehicle and you are all set. Next time you get in your Toyota Prius it will be nice and cool.”
Edit: apparently it’s limited to running the fan, there’s also a remote a/c option that’ll run for a few minutes off of battery before you get to the car.
You can easily hit ~85c (+/-) in very little time then; sadly lots of children / pets are killed all the time as people are just dumb, ignorant, or forgetful.
http://www.smartglassinternational.com/electric-switchable-g...
Just regular tint would be good too. I'm not sure if there are tints which block depending on the angle of the sun.
Temperatures could be reduced significantly with a car modification that uses very little energy: a small fan to circulate and replace all inside air with outside air, and a one-piece reflective foil cover on top of the car, covering the entire windshield + roof + sides + rear windshield.
In case you wanted to feel like you were in a blast furnace instead of an oven?
https://priuschat.com/threads/solar-powered-fan-is-it-workin...
I believe hybrid Volvos can do this while using the battery.
Now I have a tesla which can just run the AC at will, which is even better :)
from reading your comment it sounds like you just don’t want the interior to ever get over 35c, which is exactly what the Cabin Overheat Protection mode is. Basically this is a set it and forget it setting that ensures the inside will never go over 100F. You can choose to use ac which kicks it on and off every so often using minimal range, or you can choose for it to only use outside ambient air, granted it if it’s 48c then you are only getting as cold as that.
check out this article and video https://insideevs.com/news/340230/how-much-does-cabin-overhe...
Until very recently GaAs triple junction cells have been so costly they are only used on satellites and other spacecraft.
You also have to ask if the $ spent on these solar panels might be better spent on your house, where they will never be in an indoor garage, and maybe cheaper/simpler to install.
The Tesla model 3 is rated as 237 watt-hours/mile, but this article shows 218 wh/mi at 65mph
https://forum.abetterrouteplanner.com/blogs/entry/13-model-3...
Using that exact figure would require 6kwh, and driving slower would require less.
That being s said, curious how this holds up to weather (hail, snow, etc) and whether those numbers are accurate.
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.
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.
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.
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.
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.
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.
Until then I think triple junction GaAs is going to see the most use in experimental UAVs funded by research money, and satellites.
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
Imagine the future when you fight for the sunny ones.
I'm not sure what's up with the visibility out the rear window of the Honda as pictured.
Enough to increase the utility of a rarely driven ICE car tenfold.
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.
Anybody know how much a panel like that goes for per watt now days?
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.
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.
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.
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.
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.
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)
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.
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%.
"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???
Less sure about the 0.03mm but I'm guessing the relevant metric would be thickness or depth.
And I still don't know what a solar battery cell film is.
I think you're being a bit performative with your greivance! Took a few seconds of Googling :-)
I searched for battery on that page so this isn't the fabled solar battery cell film.
This does seem to be the case. It's embedded in a laminate.