Toyota is trying to put solar panels on a Prius to charge battery during the day
bloomberg.com
bloomberg.com
BTW, if you take the ferry to Alcatraz, they will try to impress with you solar panels and a helical wind turbine on the ferry itself. But pay attention, and they admit it doesn’t do anything more than power the loudspeaker. The boat runs on diesel. Because of course it does. If a few panels could power a ferry, we'd have gotten off oil long ago!
Is this actually true? Solar Panels don't have to power 100% (or even 20%) of the car to still be super useful on an EV.
An EV with a solar array that generated just ~0.7kwh during 6 hours of daylight, would still be charging itself an extra ~20 miles of range per day while parked. That's significant enough to be worth it to me. And that range can add up (imagine being parked at the airport for 3 or 4 days, and having an extra 60+ miles of "free" range sitting on your car when you return)
Alternatively, that electricity could power an AC outlet or an air conditioner for camping trips or remote work while parked or whatever. "Dog mode" could keep parked cars safely cooled without draining any range.
My EV sits outside an office, in direct sunlight, nearly every business day. And it's battery covers 70% (but not all) of my daily commute. Even if solar panels aren't the most efficient use of that space, surely they're better than nothing, right? Every watt from that solar panel, is a watt I didn't have to pull off the grid, or an ounce of petrol I did not have to burn.
And that's assuming you're parking outside at all while at work. In suburbia you might be. Good luck in any big city.
Overall I don't see how this is going to be economically efficient any time soon, even in the best use cases. It seems better to have fixed solar and a plug. But I hope I'm wrong.
That's a big "if", though. Photovoltaic paint is currently around half as efficient as commercial solar panels.
https://www.walmart.com/ip/Solar-Sun-Powered-Power-Window-Fa...
What I would love to see is a Tesla that can act as a powerwall and power your house when the grid fails. Some people hack them to do that but it doesn't look simple or without risk.
Not only is this a backup for a rare outage but it makes you money by charging when power is cheap and selling back when expensive. Occasionally the price of power goes negative and you are paid to charge.
https://electricinsights.co.uk/ is good for exploring the energy data and pricing.
A solar panel to make it net neutral energy to keep cool would still be nice.
Basically, mount your panel, and install a block diode if it doesn't already have one, then run the wires (positive and negative) to your battery to keep it charged.
Then, all you need to do is hook up a switch to your blower motor inside the vehicle, along with a simple speed controller (for this, it's best to use a cheap 12 vdc PWM controller - don't try to use the "low speed" resistor if your car uses a resistor pack, as it might not keep it cool enough) - so you can turn it off and on, and control the speed of the fan - while the car is parked and "off" (no-key).
Park it in the sun (of course), set the vent controls to allow air in from the outside (hopefully it stays this way when the car shuts down - if not, you'll have to figure out a way around that), crack your windows slightly (1/4-1/2 inch), then shut off the car. Flip the switch and set the speed control for the fan to something "low" - the fan should run, but not at hurricane speed.
Then get out and close/lock the doors. Air will be drawn in from the cooler outside, blown into the cabin, and exhausted out the windows.
The battery will stay charged from the solar panel.
If you are concerned about the battery being run down when the sun sets, then:
1. You can optionally use a separate battery to the fan, with a blocking diode to keep the fan from using energy from the car's battery.
2. Or you can add a thermostat to detect and only run when the sun is beating down hot (this could be in addition to the PWM control - so the fan doesn't run all the time, only when the cabin gets too hot).
3. Add a photoelectric switch to disconnect the fan from the battery, when the sun goes down.
4. A simple way would be by just wiring a standard Bosch SPST automotive relay (the coil) in series with the panel, and the fan across the contacts - when the sun goes down, the relay would open up, and shut off the fan.
Note that this car ventilation mod does not require an Arduino, so you might not become popular or upvoted on the tubes, but your car might be cooler in the summer...
Assuming 0.7kwh in 6 hours of daylight, that means the solar cells are outputting ~115W. It's hard to estimate exactly how much power is needed to cool a Prius, but 115W seems far less than sufficient. Traditional car air conditioners run directly off of mechanical power from the engine for efficiency. Home window air conditioners typically draw 1000W-1800W. A Tesla user reports [1] that the Tesla electric AC takes 2.4kW when starting up and then switches to a steady state of ~600W. Looks like [2] the Prius climate fans on medium take up 100W without the AC even being on. Coming at this another way, using this online calculator if we plug in 250 cubic ft for an estimate of the Prius internal air volume, assume high-quality insulation, and a 25°F temperature drop, this online calculator says that requires 1500 BTUs or 450Watts. [3]
That said, solar panels would still help somewhat! I also like the idea of exposing more people to solar and increasing general awareness around energy consumption (and how energy-hungry ACs are). Hope they do make it market in some form.
[1] https://teslamotorsclub.com/tmc/threads/how-many-watts-does-...
[2] https://priuschat.com/threads/power-consumption.14026/
[3] https://www.calculator.net/btu-calculator.html?roomwidth=6.2...
An EV uses ~250wh/mile. This varies a bit for some, but none of them are going to come close to 20 miles in .7kwh. Maybe 3-4 at most.
The ability to use something like this when left parked at an airport would be nice, though. Though I suspect that readily available 120V outlets is actually a cheaper option in the long run, relative to deploying panels on every car.
That seems like a very realistic/feasible figure. (Lightyear One's claims their prototype car can pull almost 2kw per hour (7.5 miles of charge per hour), which at 6 hours, earns you 12kWh per sunlight-day)
It’s not “.7kW per hour”.
Watts is a measure of power, it’s already Joules/second.
You just want “.7kW”.
For 6 hours, you still won’t get 4kWh, because you need to adjust for less than ideal angle, and less than full sun days.
But if you got 3kWh on a good day, that’s still 10-12 miles of additional range.
Car environments tend to be worse than that due to the angle and likely regular proximity of even mild shading. Its certainly enough to eliminate vampire drain, which is helpful at times, but I don't see how it will add an appreciable amount of mileage otherwise.
The top of an electric car has maybe 3–5 square meters of flat space.
Solar panels, even at high noon, usually only produce about 200 watt-hours per square meter.
The most efficient production electric vehicles today (probably the Hyundai Ioniq and the Tesla Mod 3) would only be able to travel 2–4 miles on that amount of electricity…in an hour. Most people could walk faster.
Financially, the cost of the panels and electronics, R&D and assembly would never pay for itself in the life of the vehicle, compared to charging from the wall in your garage.
While it might be nice to have for cars that sit there for a while or in the apocalypse. Right now it is better to use home solar panels or charging, as they have more surface area. Or maybe build parking structures with panels that can charge with more area. Maybe one day when they are small enough or can pull in sun into a smaller surface areas it will make sense.
Solar panel cars would probably also really up insurance rates and add more safety work/R&D.
[1] https://qz.com/1482588/why-teslas-dont-and-cant-have-solar-r...
On a car it also acts as a range extender and emergency backup (if you're out of battery and the car is engineered for, you can crawl along at the charge rate or wait a bit for a better charge). It's not great, but being to "walk" with your car might save your ass.
And if the car is designed around this idea (à la lightyear one), you can increase things further (the LY1 folks advertise a solar charge rate of up to 7.5mi/h WLTP with no A/C).
Solar panels in a remote location need to be converted from DC to AC for transmission, then transmitted long distances with associated losses, then converted to DC again to charge the car, stored in batteries in the car with associated losses. A solar roof could actually be a net gain assuming the energy is used while the car is in motion, and it’s used near the equator so no tilt required.
Pulling 600 W/m^2 from a PV panel may be theoretically possible, but the world record efficiency for a PV device is still less than 50%. To get above 40% efficiency you need to use very expensive multijunction devices and solar concentrators (i.e. not going to work on a car).
If you get the plugin Prius, you can already not pay for gas at all with short commutes. And it cost almost half of Tesla Model 3.
The better way is parking it in a garage of small to large size, that has solar on the roof, with a much bigger surface area, that you could plug into.
Another bad part is that since solar is still in heavy innovation phases, you'd need to be able to swap out panels for replacement and newer tech so there would need to be standards there or else it becomes highly cost prohibitive. It would add so much to testing that it would add layers of cost. This would also limit design options and weight.
Even when efficient, you still want to park your car in or under a cover/garage. That is the best place to put the panels because noone wants a hot car.
From your excerpt is seems electric panels still give 2-4 miles of range per hour of charge. Even taking into account the added weight, it's a net positive so why dismiss the idea completely ?
Say I use my car for the daily commute and I'm some 10 miles away from office. I work 8 hours in the office in daytime, and leave my car in the parking. For when I'm going back home, my battery would be topped up.
I'd need to recharge my car much less, once a month maybe.
Also, say you can do 300 miles with a full charge. Depending on how fast you go, you'll do those 300 miles in 5 to 10 hours. So on average, a the solar aid would give you some additional 15 to 30 miles, ie 5%-10%. Which sounds nice to me.
All with the current technology. Obviously there are tradeoffs, in R&D, price and weight.
But it seems like worth pursing, log-term.
You just gloss over the most important part of the question right there. At a charging rate that low, even a small amount of added weight may completely destroy the plausibility of this idea.
> would only be able to travel 2–4 miles on that amount of electricity… in an hour. Most people could walk faster.
> Solar panels, even at high noon, usually only produce about 200 watt-hours per square meter.
> The most efficient production electric vehicles today (probably the Hyundai Ioniq and the Tesla Mod 3) would only be able to travel 2–4 miles on that amount of electricity…in an hour. Most people could walk faster.
From what I get:
- in the best conditions the panels could produce 200W in an hour
- 200W would allow for 2-4miles on the most efficient cars
The author's point seems to be that if the solar panel was the only source of energy the car would be slower that walking. It's different from seeing it as an additional source of electricity, just like regenerative braking is for instance.
50km is just as many kms as I commute to work during a week. Perfect prototype for me already. For longer trips I prefer motorcycle.
What you gain in additional charge will offset the AC power draw you need to cool down your car after you parked it in the sun for a full day.
A more effective solution would be to have a carport with a solar panel roof (10~15m2) that way you have shade, affordable panels, and an actual charge capacity of about 50km. It doesn't move with the car, but since we are talking about work commute your car will probably be parked at the same location for 5 days/week during peak sun output.
Mind you that the panels used on the Toyota prototype are still very expensive. At current prices they probably don't make economic sense.
Right. Or from a pure economics point of view, put the solar panels literally anywhere else in the world other than on top of the moving vehicle that is sensitive to aerodynamics, weight and structural integrity. Deal with the small transmission losses from the grid. Rely on charging stations at home, work or other businesses. The last part is the only piece that isn't reliable at the moment, but is only getting more so.
I'd count on even less than that. Industrial solar farms average a capacity factor of around 20-25%, dropping as low as 10%. And that's with farms built for maximizing sunlight. A car is likely to do far worse, especially when you consider imperfect conditions, and how frequently people park indoors. If it's a tossup between protecting my car from the elements, and getting a few miles a day of charge, I'm going to choose the former.
80 miles (128km) a day is a pretty harsh commute I used to do, the vast vast majority are doing significantly less than this.
Among other things this means you can meaningfully charge the Prius's battery from the solar hitting it on a daily basis, even though it would take weeks to fully charge a Tesla.
Garage is just one example where there is no sun.
The difference with the cells in the article is they are 0.03mm thick so they don't weigh as much and can be curved around more car body parts.
plug in a prototypical 1000W PV system at your latitude and longitude, as if it's on the roof of your house. That would be four 250W panels.
Look at the kWH produced per month in mid summer, and again in mid winter.
Using Seattle as an example, estimated production of 147kWh per month in mid summer, and 34kWh in the worst month of winter.
Now look at how many kWh the capacity of a tesla battery (70 or 90 or 100kWh) is for a single full charge.
147, divide by 31 = 4.74kWh per day
Those estimate figures for pvwatts are pretty rough, but they also calculate based on having near direct sunlight from sunrise to sunset, as if the PV panels are on the roof of a building or an unobstructed ground mount. Cars are frequently in the shade.
Realistically, if you were to somehow magically cover a Tesla in 1000W of PV, and it was all flat-angled optimally to catch the sun, you might get 3kWh a day if you were really lucky.
There is really no practical reason why the photovoltaics needs to be ON the car. Putting high efficiency pv cells on curving surface is expensive and hard. The PV can be on a roof mount covering your closest grocery store, home depot, car repair garage, public school, and so on, feeding the grid.
Why? People are wrong about stuff all the time. Often more committed to worse ideas than this. What about this particular instance of them being wrong annoys you so?
While I can't speak for the person to whom you're replying, I can tell you why it is annoying to me, and that is very simple. In this thread there are basically two kinds of posts:
1. Posts about the physics of why solar on cars is basically a bad idea (or at least a massive waste of money in the face of much better alternatives).
2. "Yes, but have you tried turning your head sideways and squinting at it like this [...]"
For some reason, solar-on-cars brings out the #2 in many otherwise smart people, and it's extremely tiresome to constantly slap down the nonsense. Because, I think, they really, really, really want to believe it can work.
> People are wrong about stuff all the time. Often more committed to worse ideas than this.
Yes, but when you show them why those ideas can't work, using numbers and science, they abandon those ideas.
This is empirically not true: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.357...
https://spectrum.ieee.org/transportation/marine/happiness-is...
It can cruise purely electric, although with just 100 kWh of battery capacity, the net result is a 30% reduction in diesel consumption.
A typical solar panel is 100w in peak conditions. It's then easy to visualise what powering something with solar panels might entail if you can make a guess at the engine HP.
Even a small ferry is likely 2000hp+.
That doesn't mean anything. A standard panel (1m×1.9m) has a peak power of 300W.
What we must compare is the solar radiance times the efficiency of the panel, and multiplied by the surface, would give you your available power
The solar factor usually employed in the UK is about 0.1 to get from nameplate capacity to actual production (accounting for hours of darkness and suboptimal atmospheric conditions) so it would be reasonable to assume your 300w is actually more like 30w.
At least some percentage of solar panels on our hypothetical solar power ferry are likely to be in shade or not pointing directly at the sun. Then you have various conversions and charging losses to get the power into a usable form.
These are roughly the use cases lightyear one tends to cover, under a somewhat ideal 12km/h WLTP (that is in good sun the panels can charge 12km worth of WLTP range per hour, which can extend the range during a drive, recharge a parked car or let you drive at 10~12km/h when the batteries have run out).
You're going to be generating that energy while working out anyway and it has to go somewhere. I think the biggest benefit is being able to direct where that energy dissipates. You can either put those 90 watts into the air as heat through friction, or put it into electricity through some dynamo. The second choice will make it so the place doesn't heat up as quickly.
Do they really tell you how much energy they are harvesting as electricity or do they just tell you how much energy they are dissipating as heat?
Because it is very common for sports equipment to measure/estimate the power applied by the athlete, in watts, all without the slightest trace of harvesting implied.
> Over an 8-hour work shift, an average, healthy, well-fed and motivated manual laborer may sustain an output of around 75 watts of work.
That's before conversion & transmission losses (especially as the converter will need to handle wildly varying inputs)
And even if we ignore these, according to 10.1109/MSPEC.2011.5910449:
> Let’s assume that the average piece of exercise equipment is in use 5 hours a day, 365 days a year. If each patron generates 100 watts while using it, that machine creates some 183 kilowatt-hours of electricity a year. Commercial power costs about 10 cents per kilowatt-hour on average in the United States, so the electricity produced in a year from one machine is worth about US $18 dollars.
Same for these solar panels on a car, too. Solar panels aren't the nicest things to manufacture right now. Putting them on a platform this poor is silly when you could put them somewhere more effective. If they were dirt cheap and harmless to create, opportunity costs might be less of an issue, but even today, they aren't dirt cheap and the aren't harmless to manufacture. They should be used effectively, not for show or feelings.
All I really want is a stationary bike that powers a fan pointing at you to cool you down because I'm a sweaty bastard.
I worked it out and even if I pedal 8 hours / day and somehow convince the wife to join we're only producing 2kWh / day. Our house's power usage is ~11 kWh/day in the winter (worse in summer due to AC)...it's hopeless.
Phones and tablets need 10 watts or less. A notebook somewhere between 25 to 50 watts if it is running at 100% CPU. Why would an exercise machine with a similar screen size need more than that? Even a total beginner can generate far more than 50 watts.
That's... not even wrong?
The "extra energy needs" is 2400kcal, olive oil is 884kcal/100g, that's 270g of olive oil, about 300ml.
That's pounding down half a standard bottle every day, and at least a buck or two. Aside from getting cheap as hell olive oils, you seem to use ladles for spoons.
If your car is hanging out all day at a parking spot, say in front of your office building, or just on the streets, it might actually charge a large battery enough to get you a chunk of the way through your trip.
It could make plug-in hybrids the norm, even if you don't have a place to plug. For many people, their cars sit idle 80% of the day, if not more. Even if it charges enough for a quarter of the way to your house, that's a quarter more of not needing fuel.
Right now I fill up my regular prius once a month. With this I can see that changing to once every 3-5 months. A potential of course, not saying this will work.
That's the idea behind it. Not to power it as it drives.
Plus, installing PV on a car is not new. Half the top tier engineering department in the US have a setup for that, some are nearly 20 years old. But PV have come down in price, they’re still not very efficient, and the benefit will be marginal. I’d rather install PV on every parking lot instead, that way it is always connected to the grid. Unlike the car which is only connected when plugged in.
I found them banal in most cases, at least including 3. Also they are technologically pieces of shit in terms of value for money since it's not worth giving at least $60,000 for a car that isn't even enough for very long trips without stopping to recharge.
https://en.m.wikipedia.org/wiki/World_energy_consumption
Don't buy any coastal property! Unless you're 70 and don't care about leaving anything behind. The sea water will come.
I missed that the time I went to Alcatraz - but it was probably because it was a night tour...
It's true a car surface is ridiculous. Now on a van, bus or truck .. this could make for some nice juice.
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.
That's the kind of peace of mind that's worth maybe an extra grand.
In Europe that’s about €240 or $265
The Europe price doesn’t even cover the externalities of burning oil.
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.
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).
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.
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.
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.
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.
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=...
"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.
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.
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.
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.
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.
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.
[1] https://www.solar-estimate.org/news/solar-paint-hydrogen-qua...
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.
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.
(Grid solar -> grid battery -> cart battery) involves more losses than just (cart solar -> cart battery).
I personally am not sold on the idea of panels on a car. The positioning will probably be subpar to outright bad most of the time and small accident repairs will cost more, as the panel modules will need replacements.
But at lower latitudes closer to the equator, panels facing directly up at the sky will do well year-round.
Most cars are outside all day long and electric cars have a big battery sitting there, ready to accept charge. Car manufacturers are the experts at mass-manufacturing so this is probably the cheapest and lowest impact way to install and use some solar electricity generation. If your vision of the future includes solar PV covering every external, manufactured surface then this is the place to start.
Of course this doesn't do much for the range of the vehicle in question; building and operating cars is incredibly resource intensive and is only ameliorated by making them hybrid or electric. These panels are a concrete reminder that we need to reduce that usage to soften the damage we're doing to the environment.
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.
It's far more cost effective and practical to install a stationary solar array to recharge from.
But it's my impression that there hasn't been an industrial-scale effort on mobile solar panels that optimize power/weight/limited area like this. I guess maybe some of those camping panels.
But if a car can self-power it's daily driving range, and we could get spray-on/paint-on solar (remember that?) with functional yield at reasonable cost... why not?
The ideal intermediate electrification step isn't all-battery, as much as I'd like that. For "consumer" driving it's PHEVs with decent all-EV range (40-80 miles)... that maximizes the somewhat restricted (currently) battery component mineral supply to eliminate daily driving greenhouse gas emissions.
And if a cheap solar paint can reduce the grid impact of that then why not? Throw some research into that.
Yes, generally speaking rooftop solar will be more efficient, but I'm guessing rooftop solar and utility solar will have plenty of uses. There's STILL coal on the grid, and NatGas.
Hm. Perovskite spray-on solar cells... Hard to see how they avoid the perovskite degradation when it contacts air
https://news.energysage.com/solar-news-scientists-invent-spr...
Optional features included the solar-PV roof panels to help cool the cabin interior in summer heat
https://en.wikipedia.org/wiki/Toyota_Prius#Third_generation_...
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.
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).
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.
The big solar cell you park under then shields the one on your roof from charging :)
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.
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.
You did not specify the time duration, though.
This only really makes sense if you never have access to charging, and if that is the case an electric car is probably not a great fit for your lifestyle anyways.
Car battery, like a lead acid one? If so, it's a very tiny battery.
Everyone commutes hours so this is not enough (as always readers assume everyone lives in the US).
Everyone has a house so put them there (see comment about US).
Tesla doesn't have it so it doesn't make sense.