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

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

#41

Post by temporaryvector »

hwillis wrote: post #29
temporaryvector wrote: post #12

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 fa…

> 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. 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…

I'm not sure how true that would be in extremely hot weather, but it is probably the only reason I'm considering a Tesla if it ever comes to my city, my commute is really short so even if it cut 200 miles off the range it'd be worth it for me.

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.

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

#42

Post by DonHopkins »

devoply wrote: post #16
temporaryvector wrote: post #12

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 fa…

It would also be cool, pun intended, to add windows with liquid crystals that can darken when parked to keep additional heat out.

Wouldn't darkening just absorb more heat? How about turning white, or a reflective coating? (Maybe not something liquid crystals could do, but a car with mirror shades would look cool.)

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

#43

Post by agumonkey »

redwall_hp wrote: post #33
agumonkey wrote: post #13

Earlier quoted context omitted.

how much power does an AC use (say on medium settings) ?

Wikipedia says 3kW https://en.wikipedia.org/wiki/Automobile_air_conditioning#Po... 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

yeah forget it, 3kW is small house scale

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:

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

#44

Post by realityman »

walrus01 wrote: post #28
SigmundA wrote: post #19

Earlier quoted context omitted.

Yes looks like GaAs: https://global.toyota/en/newsroom/corporate/28787347.html

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 satel…

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.

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

#45

Post by redwall_hp »

bdcravens wrote: post #34
mtgx wrote: post #10

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!

Yes, a company that will have a $23B profit in FY2019 will be out of business in 10 years. I'm sure if they really want to get serious about EV's they can find a scrappy little startup to acquire. I hear there's at least one that could use their production expertise that is struggling each quarter to turn a profit.

Literally the largest automotive company by volume, as of 2017 lol. https://en.wikipedia.org/wiki/List_of_manufacturers_by_motor...

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

#46

Post by agumonkey »

temporaryvector wrote: post #26
agumonkey wrote: post #13

Earlier quoted context omitted.

how much power does an AC use (say on medium settings) ?

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.

hmm, gets me wondering if that's why my car can't climb hills when on AC.

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

#47

Post by devoply »

DonHopkins wrote: post #42
devoply wrote: post #16

Earlier quoted context omitted.

It would also be cool, pun intended, to add windows with liquid crystals that can darken when parked to keep additional heat out.

Wouldn't darkening just absorb more heat? How about turning white, or a reflective coating? (Maybe not something liquid crystals could do, but a car with mirror shades would look cool.)

Probably true that white or reflective coating would be better, but even with black there would be much less green house effect inside the car. The windows would heat up though and would be cooled by the air outside.

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

#48

Post by hwillis »

temporaryvector wrote: post #41
hwillis wrote: post #29

Earlier quoted context omitted.

> 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. 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…

I'm not sure how true that would be in extremely hot weather, but it is probably the only reason I'm considering a Tesla if it ever comes to my city, my commute is really short so even if it cut 200 miles off the range it'd be worth it for me. 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.

Even on constant full blast with the smallest battery Tesla sells, it's only gonna use ~2-3% per hour. Over 8 hours that would be 44 miles off the 220 mile range.

> 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.

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

#49

Post by seltzered_ »

temporaryvector wrote: post #12

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 fa…

2015 and later variants of the Prius already have this via the solar roof option: https://www.jpauleytoyota.com/blog/how-does-the-toyota-prius...

“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.

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

#50

Post by dougmwne »

nradov wrote: post #32
mtgx wrote: post #10

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!

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.

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.
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