The title doesn't really tell you what they're actually doing. Toyota is basically running a program to put 34% efficient solar panels on a Prius to charge the battery during the day.
Using typical panels on roof, hood, and trunk only nets you 4-6 miles / day of solar energy if you do the math. They're increasing surface area of panels here and using what are probably multi-junction (i.e. really expensive) cells for a fair boost in potential range / day. The claim of 18 miles per day of sun seems like a stretch and in actual production and real-world conditions you'd be more likely to get three quarters of that, but I could be wrong. Still impressive, though.
How far is the average commute? There are a lot of places where this level of additional range for "free" could potentially halve your charging needs.
Might also mean that people start looking for uncovered airport parking. Or that it's a lot harder to get really stranded with an electric car.
Even at 100% efficiency (which we'll never get) I think electric cars will still have to charge off of something. But dragging the panels around with you so that you always have some kind of charging seem pretty reasonable.
> But dragging the panels around with you so that you always have some kind of charging seem pretty reasonable.
It might prevent the worst case scenario of being stranded in a desert without fuel. But for everyday driving, dragging around that extra weight has a real cost, which could quite plausibly outweigh the benefits to everyday driving.
Remember, our auto industry has moved to the point where spare tires are starting to become uncommon and full-size spares are almost unheard of. The market isn't trying to optimize for the worst case scenario.
You may be underestimating how much people dread chores like manually plugging their car to the electric outlet, and many people don't have those special garages with chargers on them, and if the house is a rented one modifying it is out of question (and renting is not only a poor people problem, a lot of people pay an insane amount of money renting, ask anyone in NYC).
> You may be underestimating how much people dread chores like manually plugging their car to the electric outlet,
I'm simply assuming that, for the foreseeable future, solar panels on your car won't put a noticeable dent in the frequency of those chores compared to with a current production Prius. If you can already go for two weeks of commuting and grocery runs without topping off the gas tank in your hybrid, stretching that by another day or two doesn't meaningfully change the ownership experience even if it does have a long-term impact on the economics of owning that vehicle.
When I first read your comment, I thought that there was no way that solar panels could be heavy enough to affect your mileage. So I did some quick calculations.
Estimates of solar panel weight I found say that solar panels tend to weigh 2-4 lb per sqft.[1] Note that estimate is for roof-mounted solar panels, but if anything, car-based solar panels should be lighter.
A Prius has dimensions of 180"x69".[2] The sqft of the solar panels will be less than that, since the panels don't cover the windshield, and they don't go all the way to the edge of the hood, etc. That's 86.25 sqft, so that puts an upper bound on the weight of the solar panels at 345 lb. If we assume the lighter end of the scale for solar panel weight, that becomes 172.5 lb. That's 6-11% of the curb weight of a Prius. That's pretty substantial! For reference, a 50 lb spare tire kit can reduce fuel economy (and presumably mileage, for EVs) by 1%.[3]
Although that does imply that you're breaking even if the solar panels can increase your range by ~5%, not accounting for the weight. If you live somewhere like Arizona, that might work out. If you live in Seattle, maybe not.
These are thin-film, light-weight, and flexible. Hanergy owned Alta Devices has a Gallium Arsenide lift-off process that produces the world-record efficiency for single junction PV.
172lb is a lot! Thanks for doing that. But I think solar panels meant for rooftops have a lot of weight in the aluminium frame, and are think glass. I can't imagine a car manufacturer putting thick glass above the aluminium skin of the car if they didn't have to.
Maybe we'll get cool solar panel crystal car roofs in the future!
> So you’d leave the generator running when you park the vehicle, unattended?
I use a generator frequently. I leave it outside, unattended. So do the neighbors (when the power goes out). I never leave an idling car unattended because I worry about it. It's a much bigger deal than a little gas engine.
> It would be like leaving a vehicle idling when you park it. Noisy, polluting, and potentially deadly.
It certainly is a bad idea to run any sort of combustion engine in a poorly ventilated area. Perhaps I presume too much that people will have some common sense.
As for the noise, that's a design issue. ICE car engines are pretty quiet these days. There's no particular reason why a small ICE has to be loud like a chainsaw.
> That's essentially what a plug-in hybrid is, modulo the "small."
Not exactly, Prius uses two drive trains and some fancy gearing to be able to use both engines. The gas engine actually propels the vehicle (either alone or together with the electric)
Some 'hybrids' like the Volt only have EV drivetrains. The gas engine is just a generator and does not turn any wheels. Which also means that it can be much simpler – no transmission to worry about, you can run at whatever the ideal RPM is. And so on.
Most Prius-es are simple hybrids; the car they're testing with is a Prius Prime, a plug-in hybrid with ~25mi of all-electric range from an 8.8kWh battery, that's what they're trying to add range to. If that battery is exhausted you just drive on the gas engine as usual (I have a 2017 Prime). So this would just be a small boost, though to be fair I often can go a few days on a charge (but I don't drive a lot).
Thermo-photovoltaics are a reasonable alternative to the internal combustion engines for the hybrid car of the future. Would probably run off methane or a 90/10 methane/hydrogen mix.
That's the thing. Unless the option costs ~$1k extra, you will never ROI until after at least 10 years.
In that time you'll be paying for replacing the glass on the solar panel when a rock inevitably cracks it.
The claimed range would meet easily meet my mileage five days of the week – it's a big win! I'm in a fairly sunny city in Australia so I imagine I'd get a decent charge much of the time. I don't think this'd work so well in say, Vancouver, but then every place has to use the renewable energy sources locally available :-)
If you don't park in the shade. If your parking space doesn't tilt slightly away from the the sun.
For the same money you would be far better off installing some solar panels permanently somewhere along with a battery that can transfer that power into the car when you get home.
Or, better yet, skip the batteries and plug the solar panels into the grid. The more solar panels attached to the grid the better. Anyone who cares about the environment would put panels on their house, lawn, driveway and pets long before their car. This is a fashion statement, a fancy paint job.
(And most people would be shocked at how much solar power is available in Vancouver. Without dust in the air, droughts most summers, and the lack of mountains to the south, Vancouver does fairly well in terms of solar.)
+1 for the idea of putting solar panels on the pets. Pretty sure of the same marketing people who think putting solar cells on a car roof will be cost effective would love that idea.
Most people who live in big cities in the EU dont have a house (and they make up >50% of the population). They live in apartments. Isnt this the case for the USA too?
I think you’re confusing 5 miles / day with 5 miles each way. 5 miles per day is 2.5m each way which is about 45 minutes each way of walking and 90 minutes total walking per day (not each way)
90 minutes per day not each way if the commute is 5 miles per day. That’s walking distance of you’re motivated, but if I lived 2.5 miles from work I think I’d commute on my OneWheel at least when it’s not raining.
In my particular case I work from home, and my 'commute' is back and forth from church in the morning; I give a lift to a friend who isn't terribly mobile, so the car is necessary – otherwise I'd be on the bicycle. Unusual, I'll grant :-)
5 * 365 > 1500 miles. I'd take that. And if I perchance ran out of fuel and battery, it'd be nice to know I could eat at a cafe for an hour in the afternoon and probably get it to hobble to a gas station.
That's the kind of peace of mind that's worth maybe an extra grand.
No, the public will pay much more than that because it is now a car part. Brand specific car parts are sold way above what an equivalent part would cost at retail. There was an interesting business model that consisted of buying brand new cars and breaking them up for parts.
Why did you say "No"? Clearly it will only be more expensive if you buy it as a part instead of as a car. Your own line explains it to yourself if you think about it: "There was an interesting business model that consisted of buying brand new cars and breaking them up for parts."
What happens when it gets hit by a bit of flying debris on the highway? Screwdriver, piece of wood, rock, etc? Do I have to call insurance to get the panel replaced? Or just hail. Can I own this car in the midwest?
Seems like an odd complaint to me. What happens if your mirror gets hit by a rock on the highway? Or the front windshield? The solar panel is just another part of the vehicle that can be damaged, no?
If your car is being assaulted by solid objects at highway speeds so often that it becomes a serious concern to factor into your next car purchase, I very strongly suggest moving somewhere safer.
Windows ... generally ... aren't high-power electrical equipment.
Solar cells aren't simply inert panels of glass or silicon, but circuits of cells for which damage may affect a large portion of a panel. Solar panels as it is suffer degredation and a lifespan of ~20-25 years, in stationary mounts, due to sunlight, UV, wind, rain, hail, sand, dust, stones, and other forms of degradation.
Road debris, rocks, falling tree limbs, pine cones, other vehicles, birds, insects, and more, could impact or degrade solar panels.
A chipped windshield can be filled or replaced, at fairly modest cost. Trailing-edge rear windows might have integrated defogger wires or radio aerials, generally front glazing doesn't. Solar panels are rather more fussy.
Body nicks and dings can be effectively ignored. PV damage, not so much.
In hail, you worry more about windshields than anything else. Hail is pretty random, and baseball size does occasionally happen. So for most people, I'm guessing that would just mean throwing a larger blanket on the car to try and prevent impact damage.
The car would not rely on the solar panel for constant operation, so the same thing that happens to escalators when they stop working and becomes stairs—-the solar powered car just becomes a normal hybrid or electric vehicle. Then you get it fixed.
I have a Gen 3 Prius with the "solar roof" option that is used to run ventilation when parked, so you don't come back to a uncomfortably hot car. The solar panels are covered by thick glass (I guess toughened), so there is no more chance of them being damaged than a window.
At 35mpg that’s essentially 43 gallons of gas a year or $111 worth at $2.50/gallon (~national average). So yeah, $1000 seems about right but likely people would pay more just to use less fossil fuels. I would.
It seems like this could be useful for making electric cars more practical for apartment dwellers, in that a car in an open lot would stay indefinitely topped up when unattended and unplugged instead of the omnipresent worry of the battery running down.
Yeah, a lot of people inner city won't drive everyday and often only have on street parking. Or they'll be renting somewhere that has garages without charging stations.
Anything that can minimize the number necessary trips to a charging station or eliminate them completely for people that only drive once or twice would a week be a big win.
Getting those people to use a shared pool of electric cars would be a bigger win. That low utilisation means the initial environmental cost of producing the car is not amortised over nearly as many trips.
4-6 miles? you only read the first paragraph, where the author summarized previous efforts.
"If the car is driven four days a week for a maximum of 50 kilometers a day, there’s no need to plug into an outlet, NEDO’s Yamazaki said."
This car maintains equilibrium at 124 miles per week, so basically anyone with a commute with a 1-way distance up to 12.4 miles, or 15.5 miles if you work from home one day a week, would not need to use a charger.
I just bought a new car. I was interested in a Tesla but don’t have a parking spot with an outlet, among other deterrents, that kept me from spending the initial $10k.
My commute is about 8 miles per day. If a solar panel on a Prius could give me an almost free commute I would have bought it in a heartbeat.
This is an outgrowth from the WSC, the founders are alumni from TU/e.
Now the car is really covered in panels (~5 sqm), it looks like they just replaced the rear window by panels (as well as panelling the hood, trunk and roof obviously).
IIRC they were claiming up to 12km/h solar charging (as in you could crawl along on solar alone on sunny days). According to their calculator thingie, they're expecting about 5km/day in midwinter aberdeen (on average obviously).
That has some value. How many people get stuck for a simple flat battery ? Having a way to avoid that is pretty nice to me. Depending on how costly is the option.
I bet you could get a more useful vehicle by making something more efficient than a Prius - sacrificing some niceties of course. This is a marketing stunt for the Prius brand, but it makes me wonder what you could get if you relaxed that constraint.
Would it be on a leaderboard that included empty frames with no air conditioning units? The Prius is nowhere near the best efficiency you can get with a vehicle. Check out the Wikipedia page on solar cars for a couple of pictures:
I guess leaderboard is defined by "Cars that have sustained the rigors of NTSB-style testing to determine roadworthiness and are available for sale to the mass public."
Cars are nowhere near efficient, they are just in a nice point between practicality and efficiency for their given use-cases.
If you don't turn it on, all the AC unit does is weight you down a bit, no? Googling a bit, the AC-specific parts weight about 20kg. A Prius weights about 1300kg, so the AC is about 2% of its weight. Doesn't seem exactly life changing.
In fact, in a BEV your problem is the 500kg battery, which those solar cars lack. You'd need to reduce it to get solar power to be more viable, but it would be at the cost of getting a lower range when the sun isn't shining directly on it. I'm not sure how many drivers would make that trade.
If you assume 100% efficient covering the entire vehicle and you live in a sunny area and are always parked and moving in the sun and not shade, its kinda sorta worth it.
Very roughly, it looks like the prius has a 1.1sqm hood, 1.7sqm roof and 1.1sqm trunk. That's 750~775W worth of panels.
The prius has an EV range of 25mi with an 8.8kWh battery, that's 2.8mi/kWh, so with the 3.9sqm worth of high-power panels above and assuming full sun (full power production) you'd gain a range of 2.17mi/h.
And continuing the silly hypothetical, it seems like it would leave Toyota with a Gillette Razor business model of supplying you with repair parts for the last car you ever buy.
There are many different reasons to change a car and "not able to drive one" is not the biggest.
To name a few - evolution of the safety standards, better reliability, lower cost of maintenance, even something as trivial as not liking a color and wanting to get a newer model.
If you take a look at the cell phone market, for example, from the functional point of view there are no reasons not to use 80-s nokia brick because it still makes calls, and here we are and mobile market is working just fine.
You already don't want to pay for a repair for a modern car after an accident -- all of the electronics and recalibrations (front camera and calibration, front radar sensor and calibration, blind spot detecting radar/ultrasonic sensor and calibration) adds up to serious money even for a minor accident.
The folks that come up with photovoltaic paint are going to get very rich.
In the mean time a flexible solar charging car cover/blanket would cover the entire area of the vehicle and could plug right into the charging port while the car is parked. Could even be used across same size vehicles or to sell power back to the grid (if this were available) if car is fully charged.
Slide Ranch in Marin County in California has a golf cart with solar panel for roof. The guy who drives it around ranch said last couple years he did not have to plug his cart for charging at all. If it was in’s out of the juice he just leaves it on the sun and comes back at the end of the day. Here is a neat use case how this technology already works albeit he has a pretty corner case.
Solar panels don't have zero environmental cost, I'd be surprised if making them solar powered is a net environmental win, especially when you have to build the charging infrastructure anyway, just in case the weather is not suitable for charging.
The extra solar panels installed on the grid to feed those carts don't have zero environment cost either, though. And neither do the batteries required to hold that energy until the carts are plugged-in, which would likely be at dusk/night, when they're not in use.
(Grid solar -> grid battery -> cart battery) involves more losses than just (cart solar -> cart battery).
Kinda related: in my city they introduced regular solar cells on roofs of public transport to charge the regular battery on ICE buses and apparently that averages 4-5% lower fuel consumption over a year (so - all the weather conditions, indcluding 3 months of pretty cold winter and cloudy rainy autumn), and it makes the batteries lose capacity much slower.
These buses use batteries for lots of stuff - lights, automatic doors, AC, ticket machines, external and internal displays. Apparently there are problems with batteries running empty when the buses have to wait for the next course too long. Also the batteries are losing capacity too quickly when they are charged all the way down often.
They introduced the pilot program in 2013 and in 2017 they decided to put solar cells on all the buses. Links in Polish:
When I lived in the America's desert southwest, the school buses were partially solar powered. The panels weren't on the roof, though, they were where the buses were parked. Each bus had a port on the side for hooking into the panel grid in between runs.
I think the reason there weren't panels on the roof is because the roofs usually had two air conditioners on them. I suspect the solar plug-in wasn't for locomotion, but to power the air conditioners.
Yes. It's a valid technique to keep the temperature on a fleet controlled so you don't waste time cooling down a bus later in the day before picking up students. Solar panels let them make it basically free. And the solar panels on the fixed roofs of the power stations will recoup their cost over time far longer than potential lifespan of a vehicle.
For the cost and mass of the solar panels, you can add more range with more batteries, on normal sized street cars. The math just doesn't work out well until you get to very small/light vehicles with large roof area.
In my layman's understanding of batteries doesn't the resistance of a battery increase with its level of charge? If so wouldn't these large batteries have so much resistance that at a reasonable level of charge most or a large portion of the energy would be lost as heat? Does it somehow charge individual cells as opposed to the whole thing or am I way off base?
It allows running a fan in sunny weather. The more the Sun is cooking the car, the more power there is, so that works out nicely.
It helps with long-term parking, for example at an airport. It's annoying to return to a car that won't respond to a key fob and has lost all the settings.
I drive if the Sun is beating down or there is a thunderstorm. Sometimes I get dropped off, then walk home later in nicer weather. I also drive when I don't have 20 minutes to spare; the drive is only 3 minutes.
I used to drive for a much shorter commute. At the time I could have been urgently summoned to a site 30 miles away at any time so I had to be prepared.
I ran out of gas on my way home one night. If you never drive past a gas station and only fill up every month or two it’s easy to forget.
Another thing this would be great for is pre-cooling or heating the car before you drive it. At a CoP of 3 which is conservative for modern AC heat pumps, the 860W of solar gives you over 2.5kW of cooling.
Even if it just tempered the air whilst parked with fan ventilation through the cabin, it would massively lower the cabin temp which can reach over 90C in sunny locations.
This is a convenience feature for fully electric cars. Charge at home, leave it parked at work and it recharges a fair bit. Won't make as much of a difference on a longer road trip; but will increase the range between mandatory recharges.
If you want you probably could go full martian if you got an external solar array you could deploy when stopped.
The real win is going to be on mid-sized electric vans and RVs since you have more surface area and could deploy a charging array as a canopy.
Think of a 300 ft^3 van ( about the size of a Sprinter )
with full wrap solar panels and an additional 100 ft^2 of solar panel that could be deployed when parked.
If you were using it as an RV you could plan on extended backcountry camping trips without having to worry about recharging.
Full wrap solar panels would be a silly idea. Almost half of the panels would not be producing power. Effective surface area would be about ~130 ft^2. Even with that additional solar panel, let's call it 250 ft^2, it would produce ~4kW on a clear day. Basically, charging all day might get you 150 miles in a Tesla model S. I would rather just charge my Tesla while eating a sandwich for lunch then pay for the additional complexity.
Your numbers are off by a lot. A Sprinter roof is around 100ft^2 (not sure why you're saying cubic feet, solar panels are flat and can't overlap).
I live in a 25ft shuttle bus. I have solar that covers the roof end-to-end, 1800W. It's a lot but nowhere near enough to recharge batteries to drive a vehicle of this size any reasonable distance.
I've though about this. 100 x 100 W solar panels charging for 10 hours per day would give you 100 kWh, which is about 500 km range in a Tesla X or S. 100 panels is a lot — you'd need a small trailer to carry them, and set up and packing away each day would be hard work. But it would be possible.
US Route 66 (4000 km) would take 8 days. Circumnavigating Australia on Highway 1 (14,500 km) would take ~30 days. Drive at dawn and dusk, park during the day and see the sights.
Kia/Hyndai panel produces 100 wh. So it would take about 27 days to charge 64Kwh battery (of course no one expects full recharge with these panels.. but just a comparison.
I think, actually people leaving in areas prone to power outages (due to weather, for example), would appreciate built-in solar re-charge capability of a vehicle that can provide temporary power to household devices.
Napkin math on this isn't great, however, if you park your car outside multiple days a week and don't use it every day this could be a worthwhile upgrade.
I think the problem is that you would have to park your car out in the sun. The sun is hard on cars.
Hot temperatures are not great for batteries, and if there is ever any active thermal management, the costs would subtract from the benefits.
Elon Musk talked about this a couple of times. At first they explored it, but then said cars wouldn't be outdoors enough to benefit.
I have wondered about solar panels on the top of trucks however. A 53' trailer has 450 square feet of roof, which with standard panels works out to be 6kw. Probably much more with the panels toyota is using.
It seems the Tesla Semi specs say "less than 2kwh per mile" so 3+ miles for each hour of sunshine, more with better panels.
Even if this could eventually be done affordably, this only only makes sense for vehicles meant to only go a short distance on electricity, like Toyota's own Prius Prime, with it's 25 mile electric range.
If you have a longer range EV, then you need to plug in anyways to charge the much larger battery, at which point why bother with the solar panels for charging the traction battery?
This seems a bit like an attempt to get more out of their hybrid gasoline powered cars, which is a technology they seem very wedded to.
> If you have a longer range EV, then you need to plug in anyways to charge the much larger battery
Why can't you, say, have a longer range EV but only have a short commute and so not utilise that range usually?
Surely in that scenario, solar is useful on a daily basis, but when you want to go on a long distance journey you can still make use of the charging facilities and longer range.
Given that your short (i.e. 10 miles) commute costs about $1 in utility rate electricity (at 20c/kWh, .5kWh/mi), to be worthwhile, the solar panels would need to cost far less than the $2 per day that such a commute costs. Accounting for rainy or cloudy days, and the inevitable dirtying of the solar panels, it's unlikely to be worth the expense in economic terms, to say nothing of the aesthetics.
It would make more sense to use the money to put solar panels on your house, if generating your own energy for commuting is a priority.
That's why I maintain that the only value of on-car solar panels for daily commute purposes is for hybrids with small batteries (which are Toyotas strategy) since the alternative to electricity in that case is using petrol, which typically costs 2x per mile compared to electricity.
> If you have a longer range EV, then you need to plug in anyways to charge the much larger battery, at which point why bother with the solar panels for charging the traction battery?
Not everybody has a wired garage available, for one. Especially urban communities of europe or japan. Having to go to the public charging stations a bit less is still a boon.
It's a range extender (not a big one, granted) and an emergency charger if you run out of juice as well (that happens).
This is really not going to be charging your battery much. You can barely justify the energy usage in creating the panels. Useless if you park in a garage at home or at the office, or have a tree overhanging the car. The panels themselves have a shelf life too.
I would personally prefer it if you were able to fold out panels (or for extra points, the panels fold out themselves). I think you could quite realistically have a large "sun roof" that folds out panels instead - then you would begin to get some better power returns. Add to that some sun tracking and you can massively improve your efficiency.
But really, just give owners of the car something to install on their garage roof and a plug for the car.
I'm surprised how no one commented about the obvious problems here. These are very expensive high output panels. The ROI would be negative. They'd add thousands of dollars to the cost of the car. Until prices drop significantly you won't be seeing 30%+ solar on a car soon, at least not ones with a positive ROI.
It's far more cost effective and practical to install a stationary solar array to recharge from.
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[ 3.3 ms ] story [ 244 ms ] threadUsing typical panels on roof, hood, and trunk only nets you 4-6 miles / day of solar energy if you do the math. They're increasing surface area of panels here and using what are probably multi-junction (i.e. really expensive) cells for a fair boost in potential range / day. The claim of 18 miles per day of sun seems like a stretch and in actual production and real-world conditions you'd be more likely to get three quarters of that, but I could be wrong. Still impressive, though.
Might also mean that people start looking for uncovered airport parking. Or that it's a lot harder to get really stranded with an electric car.
Even at 100% efficiency (which we'll never get) I think electric cars will still have to charge off of something. But dragging the panels around with you so that you always have some kind of charging seem pretty reasonable.
It might prevent the worst case scenario of being stranded in a desert without fuel. But for everyday driving, dragging around that extra weight has a real cost, which could quite plausibly outweigh the benefits to everyday driving.
Remember, our auto industry has moved to the point where spare tires are starting to become uncommon and full-size spares are almost unheard of. The market isn't trying to optimize for the worst case scenario.
I'm simply assuming that, for the foreseeable future, solar panels on your car won't put a noticeable dent in the frequency of those chores compared to with a current production Prius. If you can already go for two weeks of commuting and grocery runs without topping off the gas tank in your hybrid, stretching that by another day or two doesn't meaningfully change the ownership experience even if it does have a long-term impact on the economics of owning that vehicle.
Estimates of solar panel weight I found say that solar panels tend to weigh 2-4 lb per sqft.[1] Note that estimate is for roof-mounted solar panels, but if anything, car-based solar panels should be lighter.
A Prius has dimensions of 180"x69".[2] The sqft of the solar panels will be less than that, since the panels don't cover the windshield, and they don't go all the way to the edge of the hood, etc. That's 86.25 sqft, so that puts an upper bound on the weight of the solar panels at 345 lb. If we assume the lighter end of the scale for solar panel weight, that becomes 172.5 lb. That's 6-11% of the curb weight of a Prius. That's pretty substantial! For reference, a 50 lb spare tire kit can reduce fuel economy (and presumably mileage, for EVs) by 1%.[3]
Although that does imply that you're breaking even if the solar panels can increase your range by ~5%, not accounting for the weight. If you live somewhere like Arizona, that might work out. If you live in Seattle, maybe not.
[1] https://sunmetrix.com/is-my-roof-suitable-for-solar-panels-a....
[2] https://www.toyota.com/prius/features/dimensions/
[3] https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=...
Maybe we'll get cool solar panel crystal car roofs in the future!
It could still be used as a supplement while driving to extend the range. If the battery was fully discharged, you'd have to wait.
It would be like leaving a vehicle idling when you park it. Noisy, polluting, and potentially deadly.
I use a generator frequently. I leave it outside, unattended. So do the neighbors (when the power goes out). I never leave an idling car unattended because I worry about it. It's a much bigger deal than a little gas engine.
> It would be like leaving a vehicle idling when you park it. Noisy, polluting, and potentially deadly.
It certainly is a bad idea to run any sort of combustion engine in a poorly ventilated area. Perhaps I presume too much that people will have some common sense.
As for the noise, that's a design issue. ICE car engines are pretty quiet these days. There's no particular reason why a small ICE has to be loud like a chainsaw.
Not exactly, Prius uses two drive trains and some fancy gearing to be able to use both engines. The gas engine actually propels the vehicle (either alone or together with the electric)
Some 'hybrids' like the Volt only have EV drivetrains. The gas engine is just a generator and does not turn any wheels. Which also means that it can be much simpler – no transmission to worry about, you can run at whatever the ideal RPM is. And so on.
Yes, the gas engine can turn the wheels.
For the same money you would be far better off installing some solar panels permanently somewhere along with a battery that can transfer that power into the car when you get home. Or, better yet, skip the batteries and plug the solar panels into the grid. The more solar panels attached to the grid the better. Anyone who cares about the environment would put panels on their house, lawn, driveway and pets long before their car. This is a fashion statement, a fancy paint job.
(And most people would be shocked at how much solar power is available in Vancouver. Without dust in the air, droughts most summers, and the lack of mountains to the south, Vancouver does fairly well in terms of solar.)
nope, not doing that -- too hot.
[1] https://www.healthline.com/health/exercise-fitness/average-w...
That's the kind of peace of mind that's worth maybe an extra grand.
If your car is being assaulted by solid objects at highway speeds so often that it becomes a serious concern to factor into your next car purchase, I very strongly suggest moving somewhere safer.
Solar cells aren't simply inert panels of glass or silicon, but circuits of cells for which damage may affect a large portion of a panel. Solar panels as it is suffer degredation and a lifespan of ~20-25 years, in stationary mounts, due to sunlight, UV, wind, rain, hail, sand, dust, stones, and other forms of degradation.
Road debris, rocks, falling tree limbs, pine cones, other vehicles, birds, insects, and more, could impact or degrade solar panels.
A chipped windshield can be filled or replaced, at fairly modest cost. Trailing-edge rear windows might have integrated defogger wires or radio aerials, generally front glazing doesn't. Solar panels are rather more fussy.
Body nicks and dings can be effectively ignored. PV damage, not so much.
If it really breaks, then you have a car just as useful as before, until you get the solar panel fixed.
Whether this is good or bad comes down to how much the panels will add to the cost.
In Europe that’s about €240 or $265
The Europe price doesn’t even cover the externalities of burning oil.
Anything that can minimize the number necessary trips to a charging station or eliminate them completely for people that only drive once or twice would a week be a big win.
I still don't think solar panels will help in this situation.
"If the car is driven four days a week for a maximum of 50 kilometers a day, there’s no need to plug into an outlet, NEDO’s Yamazaki said."
This car maintains equilibrium at 124 miles per week, so basically anyone with a commute with a 1-way distance up to 12.4 miles, or 15.5 miles if you work from home one day a week, would not need to use a charger.
My commute is about 8 miles per day. If a solar panel on a Prius could give me an almost free commute I would have bought it in a heartbeat.
FWIW there's a project to actually do that: https://lightyear.one
This is an outgrowth from the WSC, the founders are alumni from TU/e.
Now the car is really covered in panels (~5 sqm), it looks like they just replaced the rear window by panels (as well as panelling the hood, trunk and roof obviously).
IIRC they were claiming up to 12km/h solar charging (as in you could crawl along on solar alone on sunny days). According to their calculator thingie, they're expecting about 5km/day in midwinter aberdeen (on average obviously).
https://en.m.wikipedia.org/wiki/Solar_car
Cars are nowhere near efficient, they are just in a nice point between practicality and efficiency for their given use-cases.
In fact, in a BEV your problem is the 500kg battery, which those solar cars lack. You'd need to reduce it to get solar power to be more viable, but it would be at the cost of getting a lower range when the sun isn't shining directly on it. I'm not sure how many drivers would make that trade.
You did not specify the time duration, though.
Very roughly, it looks like the prius has a 1.1sqm hood, 1.7sqm roof and 1.1sqm trunk. That's 750~775W worth of panels.
The prius has an EV range of 25mi with an 8.8kWh battery, that's 2.8mi/kWh, so with the 3.9sqm worth of high-power panels above and assuming full sun (full power production) you'd gain a range of 2.17mi/h.
How does that make sense? If this was possible(and patentable), everyone else would go out of business.
To name a few - evolution of the safety standards, better reliability, lower cost of maintenance, even something as trivial as not liking a color and wanting to get a newer model.
If you take a look at the cell phone market, for example, from the functional point of view there are no reasons not to use 80-s nokia brick because it still makes calls, and here we are and mobile market is working just fine.
In the mean time a flexible solar charging car cover/blanket would cover the entire area of the vehicle and could plug right into the charging port while the car is parked. Could even be used across same size vehicles or to sell power back to the grid (if this were available) if car is fully charged.
https://solaractionalliance.org/solar-paint/
It just has very poor efficiency compared to panels, and so is not economically viable and probably won't be for some time.
[1] https://www.solar-estimate.org/news/solar-paint-hydrogen-qua...
Car battery, like a lead acid one? If so, it's a very tiny battery.
(Grid solar -> grid battery -> cart battery) involves more losses than just (cart solar -> cart battery).
These buses use batteries for lots of stuff - lights, automatic doors, AC, ticket machines, external and internal displays. Apparently there are problems with batteries running empty when the buses have to wait for the next course too long. Also the batteries are losing capacity too quickly when they are charged all the way down often.
They introduced the pilot program in 2013 and in 2017 they decided to put solar cells on all the buses. Links in Polish:
http://www.mpk.lublin.pl/imgs_upload/image/aktualnosci_fotki...
http://www.transport-publiczny.pl/mobile/lublin-wszystkie-au...
I think the reason there weren't panels on the roof is because the roofs usually had two air conditioners on them. I suspect the solar plug-in wasn't for locomotion, but to power the air conditioners.
This is def going to be huge down the road
Unfortunately today most street cars are still way to heavy/bulky for this to have a real impact given current solar panel efficiency
For the cost and mass of the solar panels, you can add more range with more batteries, on normal sized street cars. The math just doesn't work out well until you get to very small/light vehicles with large roof area.
Whatever the voltage output of the solar panel is, you can always step that up or down.
The batteries go up in voltage slightly when they are charging, but not much relatively.
For a typical LiIon cell, it may be at "0%" at 3.4V (you don't want to drain it all the way). And "100%" full is around 4.2V.
As long as you can supply at least 4.2V, it will charge up to that point.
It allows running a fan in sunny weather. The more the Sun is cooking the car, the more power there is, so that works out nicely.
It helps with long-term parking, for example at an airport. It's annoying to return to a car that won't respond to a key fob and has lost all the settings.
I ran out of gas on my way home one night. If you never drive past a gas station and only fill up every month or two it’s easy to forget.
My commute was about 6 miles, and I rode my bike 365 days a year for 4 years. Even in the winter. In the Yukon. -48C one nice morning.
Even if it just tempered the air whilst parked with fan ventilation through the cabin, it would massively lower the cabin temp which can reach over 90C in sunny locations.
The first version was just a panel that ran a fan, which ran if the inside temp > outside temp.
The next generation had an actual separate battery for the solar panel, which engaged the car's AC when needed.
If you want you probably could go full martian if you got an external solar array you could deploy when stopped.
The real win is going to be on mid-sized electric vans and RVs since you have more surface area and could deploy a charging array as a canopy.
Think of a 300 ft^3 van ( about the size of a Sprinter ) with full wrap solar panels and an additional 100 ft^2 of solar panel that could be deployed when parked.
If you were using it as an RV you could plan on extended backcountry camping trips without having to worry about recharging.
I live in a 25ft shuttle bus. I have solar that covers the roof end-to-end, 1800W. It's a lot but nowhere near enough to recharge batteries to drive a vehicle of this size any reasonable distance.
I'm honestly surprised that nobody has tried to make a city-block-sized desert vehicle when it's such a common sci-fi concept.
Maybe it'd be too hard to tow when it inevitably got stuck.
US Route 66 (4000 km) would take 8 days. Circumnavigating Australia on Highway 1 (14,500 km) would take ~30 days. Drive at dawn and dusk, park during the day and see the sights.
https://www.driving.co.uk/news/kia-hyundai-cars-will-use-sol...
Kia/Hyndai panel produces 100 wh. So it would take about 27 days to charge 64Kwh battery (of course no one expects full recharge with these panels.. but just a comparison.
I think, actually people leaving in areas prone to power outages (due to weather, for example), would appreciate built-in solar re-charge capability of a vehicle that can provide temporary power to household devices.
Hot temperatures are not great for batteries, and if there is ever any active thermal management, the costs would subtract from the benefits.
Elon Musk talked about this a couple of times. At first they explored it, but then said cars wouldn't be outdoors enough to benefit.
I have wondered about solar panels on the top of trucks however. A 53' trailer has 450 square feet of roof, which with standard panels works out to be 6kw. Probably much more with the panels toyota is using.
It seems the Tesla Semi specs say "less than 2kwh per mile" so 3+ miles for each hour of sunshine, more with better panels.
If you have a longer range EV, then you need to plug in anyways to charge the much larger battery, at which point why bother with the solar panels for charging the traction battery?
This seems a bit like an attempt to get more out of their hybrid gasoline powered cars, which is a technology they seem very wedded to.
Why can't you, say, have a longer range EV but only have a short commute and so not utilise that range usually?
Surely in that scenario, solar is useful on a daily basis, but when you want to go on a long distance journey you can still make use of the charging facilities and longer range.
It would make more sense to use the money to put solar panels on your house, if generating your own energy for commuting is a priority.
That's why I maintain that the only value of on-car solar panels for daily commute purposes is for hybrids with small batteries (which are Toyotas strategy) since the alternative to electricity in that case is using petrol, which typically costs 2x per mile compared to electricity.
Not everybody has a wired garage available, for one. Especially urban communities of europe or japan. Having to go to the public charging stations a bit less is still a boon.
It's a range extender (not a big one, granted) and an emergency charger if you run out of juice as well (that happens).
I would personally prefer it if you were able to fold out panels (or for extra points, the panels fold out themselves). I think you could quite realistically have a large "sun roof" that folds out panels instead - then you would begin to get some better power returns. Add to that some sun tracking and you can massively improve your efficiency.
But really, just give owners of the car something to install on their garage roof and a plug for the car.
It's far more cost effective and practical to install a stationary solar array to recharge from.