The direct solar-powered car is something of a Holy Grail. A car that can charge itself by just being out in the sun would solve several key objections to EVs: They could potentially never use electricity generated by fossil fuels, living up to the “Zero Emissions” label. And they would make owning an EV without a home charger significantly more feasible, as in apartment dwellers.
Despite common assumptions that car solar panels are essentially useless except to run a ventilation fan to cool down the interior (actually a pretty handy feature), there are two current cars (Prius Prime, Hyundai Sonata HEV) whose solar roofs can add up to 2.2 miles of range per day as well as run the a/c. But that’s just a modest starting point. The Sono Motors Sion (top) goes into production next year in Europe, and its solar panel skin can generate up to 21 miles of range per day. And Toyota has shown a Prius Prime (bottom right) with advanced cells that can add 35 miles. And the ultra-efficient but ultra-expensive Lightyear (bottom left) has some 450 miles of total range, augmented by its solar roof which can add 12 miles.
Of the three, the Sion speaks to me: it’s real, minimalist, affordable, practical, small but roomy, and designed for easy DIY repair; a Sion to replace my Scion?
I’m going to focus on the Sion, not only for the reasons given above, but also because it’s actually going into production late next year. Sono was started by a couple of Germans in 2016; they’ve come a long way since then. And how is it being financed? By crowdsourcing, which just exceeded its €50 million goal in 50 days in order to put it in production.
The Sion is a small and tall EV with embedded flexible polymer solar cells all over its body. In essence, they are the car’s skin, and as such, they’re some 20% lighter than comparable steel panels. In order for them to generate a meaningful contribution to range, the Sion is maximized for efficiency rather than fast acceleration or high speeds (140 kmh/87 mph max). Its battery has a maximum capacity of 35 kWh, which is modest by American EV standards, but then the Sion is clearly targeted for different conditions in Europe, where longer ranges are not considered nearly as important. The stated range is 160 miles/255 km on the European WLTP standard. But then of course it starts adding range as the sun kicks in, up to 21 miles.
Before you pooh-pooh that range, remember that’s what you start with every morning. The average American drives 29 miles per day. No, it’s not going to be for road warriors, but it would be more than enough for most typical commuters.
The 248 solar cells can generate up to 34 km/21 miles per day, in Munich, Germany, for example. This is equal to some 5,800 km/3600 miles per year. The chart above shows the variable amounts based on conditions. Undoubtedly this would be better in a sunnier Southern climate, as Germany is not exactly optimal for solar.
An 80% charge at a high speed charger takes some 30 minutes.
The Sion has a sleek, understated interior. If you’re wondering what that green stuff is, it was solar powered too.
It’s called breSono, a natural moss-based air filter that’s conveniently shown under a clear plastic cover to remind you that you’re driving a really green car. And one whose production will be 100% carbon-neutral.
Rather than try to produce the cars itself, final production is being outsourced to NEVS, the company that took over the former Saab plant in Trollhätten, Sweden. Thanks to the Sion’s black polymer skin, there’s no need for a big paint shop or stamping plant. Any color you want, as long as it’s…solar cells. And Sono is working with various suppliers to provide the bulk of the components, keeping their own development costs very low.
The first Sions are expected to roll off the lines in late 2021, and deliveries start in early 2022. Given that Sono has achieved its crowdsourcing goals, presumably this is not all just hot air.
One of the aspects that intrigued me is that the Sion is designed to be as simple as possible for user repairs of standard replacement parts. DIY is back! Obviously, Sion will be sold directly without dealers, and this is a way to simplify basic repair issues and/or work with independent mechanics. Major repairs will be outsourced.
Then there’s the price, of course. It’s listed at €25,500, which is roughly $28,000. Since that includes VAT, which is 19% in Germany, a more comparable direct comparison would be $22,680. All of these are before EV incentives/tax credits, which are considerable in Germany (€6,000) and most European countries.
Those prices in dollars are of course hypothetical, as there’s no current plans to bring the Sion to the US. The case for the Sion might be challenging in the US, although undoubtedly it would have appeal to a certain slice of the market. If it takes off in Europe, I suppose it’s possible it might find its way here too, although federalizing it could be a bit of an obstacle..
More details at sonomotors.com.
The Lightyear One is also a European project, from the Netherlands. An offspring of the University of Eindhoven’s winning World Solar Challenge projects, the Lightyear is an exercise in ultimate range (up to 450 miles) through ultra-efficiency. That’s the result of a carbon fiber body, the best aerodynamics of any car on the road, and a solar roof, hood and tail. Those panels can add up to 12 miles of range. It also has four small in-wheel motors.
It’s an interesting project, but its prospects are not good, due to an expected price of some €149,000 ($163,000). That’s just way too expensive. But it gives some idea of possible future solar integration on a handsome shape. More at Lightyear.one
Currently, only two cars offer solar roofs, and with rather limited impact on range. The Prius Prime is available with an optional solar roof in Japan and Europe (not available in the US due to roll-over standards), and addition to running the air conditioner or other accessories, it can add up or 2.2 miles of range per day. Not much actual payback for the roughly $3,000 option.
The Hyundai Sonata hybrid (HEV) is available in Korea with a solar roof. Its addition to range is roughly comparable to the Prius Prime.
But this past summer Toyota showcased a Prius Prime with drastically improved solar capability. The new cells, made by Sharp, are up to 35% efficient, and claimed to generate enough juice to add 35 miles (56 km) of range on a good day. That really starts to change the equation. And of course the Prime still has its gas-hybrid drive train, so it would be ideal for someone who has no access to any grid charging and wants zero range anxiety.
Something like the solar Prius Prime would be perfect for Stephanie, as almost all her trips are very short, she would be likely to hate/forget to have to plug it in every night, and it would take her on her several trips to the Bay Area per year with zero stops for gas, as it has a whopping 640 mile (electric + gas) range.
Production outlook for the Prime Solar is unknown; it’s obviously an advanced technology concept for now. I’m pretty convinced we’re going to see something like it before too long; it just makes too much sense. Never plug in, almost never buy gas. What’s not to like? And what’s next; self-driving cars?
Hi Paul, very interesting…as futuristic as all this looks, i doubt that deliveries can start before production, LOL
Aha! Fixed now.
This wouldn’t last one season around here as we’ve been having a lot of hail in recent years…
You’re making assumptions. These aren’t exactly made of glass; they’re embedded in a tough flexible polymer. Do you think typical solar panels break regularly in hail?
When you’ve lived in a place with 300 days of sunshine for a long time you don’t have to make assumptions about what lasts. And yes, solar panels on homes also get destroyed here and they don’t even face straight up.
Solar panels are designed and tested to sustain hail up to 1″ in diameter. They’re much less susceptible to hail damage than cars, windows, roofs, and many other things. More details:
Solar panel manufacturers test their products to ensure that they are capable of withstanding hail storms. In most cases, solar panels are tested and certified to withstand hail of up to 25 mm (one inch) falling at 23 meters per second (approximately 50 miles per hour).
solar panels hailIn fact, not long ago, NREL’s main campus in Golden, Colorado was hit with a severe hailstorm just last month. Of over 3,000 panels on or adjacent to the roof of a net-zero energy building, only one panel was broken during the storm. To get an idea of the intensity of the storm, the same weather system left shattered car windows and dents in vehicles and home roofs around the Denver area. The single broken panel appeared to have been hit simultaneously with several large hailstones in a very concentrated location, leading to micro-cracking of the surface glass. The conclusion: hail may be an impressive physical force, but solar panels are well-equipped to withstand impacts even from large hailstones.
Having said all of that, the solar cells in the Sonos Sion are even more durable than that , as they’re embedded in a very tough flexible polymer. They’re not at all like typical solar panels. That actually is the single most unique and significant IP on the Sion.
It’s going to be much less damaged by hail than regular cars. How great is that?
And if the hail in your part of the world is as big as softballs, than there’s always insurance in case the Sion gets damaged.
All of this is of course highly theoretical, as the odds of you actually having a Sion is less than the odds of such a hailstorm. 🙂
Ha! You are certainly right about that last bit cause I’m into classics. Newest bought car is a 1993.
But besides hail (which can be way bigger than one inch here and is truly a hassle insurance or otherwise) you can’t predict what this high strength polymer will look like in 10 years of direct sun. Will it lose efficiency after getting faded? Because if it’s not glass it’s going to look pretty haggard I think.
The speed at which real solutions to major environmental challenges are coming is incredibly satisfying. The real challenge would seem to be harnessing the optimism and making the political commitment to get behind these changes.
“We have the technology.”
The Six Million Dollar Man (1973)
Wow. I like every bit of the Sion.
Re Prius Prime: there is a good chance that the fuel for the gas engine is going to foul in the tank.
That worry came up with the Volt. It’s apparently not a real one. The engine management system turns it on once in a long while to keep things from stagnating.
The US market Prius Prime was supposed to have solar panels on the roof, but as Paul noted, Toyota was unable to import them because the glass used in the solar panel made the cars unable to pass American rollover crash tests.
Would the US be willing to loosen up safety standards to accommodate some small start up that has not yet to produce a single car? If they did, would people be willing to sacrifice their personal safety to encourage green technology?
The article linked below was from 4 years ago and there is still no solar powered Prius. If a mega corporation like Toyota has been unable to solve the safety issues, then how can we expect a small crowd funded start up to do it?
https://www.autonews.com/article/20160616/OEM05/160619900/next-generation-toyota-prius-has-solar-roof-for-europe-japan
I don’t have the definitive answer, but I do know that the Sion’s panels are different, in that they are embedded in a very tough polymer or such. I suspect that ultimately there’s a solution. Teslas have glass roofs. Keep in mind that the Prius wasn’t designed from scratch to have that; it was an add-on.
That Sion is intriguing to me, not as a car for me personally, but for my wife. She is a preschool teacher with a 1.2 mile commute. We’re already thinking about small CUV for her to carry stuff back and forth to the school. Something like a Honda HR-V comes to mind.
For us, this Sion may never even need to be plugged in based on those solar recharging numbers. We could probably do all of our weekend errand running (if local) with a ride like that. If it could be charged overnight with a 115 volt extension chord that would be cool. I have no garage in which to install a charging station.
But she has range anxiety big time, with a gas engine! If she gets below a 1/4 tank she freaks out. All electric would definitely take some convincing, especially if we were relying mostly on solar power.
The times, they are a-changin’, indeed.
These are the future. By 2030 they will be common
Yes finally an EV that would suit my current situation though that will be changing and to what I dont know yet but it hardly ever rains here I have a short commute and my daily drive lives out doors in the weather.
I feel like in the numerous states that have yet to legalize weed, telling the officer who pulled you over that that wadded green plant lining the entire bottom dashboard tray is just “breSono, a natural moss-based air filter that’s conveniently shown under a clear plastic cover to remind you that you’re driving a really green car” is going to have you waiting in handcuffs for a while as they verify it with the K-9 unit dispatched.
Another feature which appeals me is that it will have* some huge amount of cargo space ( I forget the figure), and will be* rated to tow 750 kg. Also, 250 km of range with a 200 km recharge in 30 minutes is viable for trips of up to 700 km in a day, if there is infrastructure to support it.
* All stats for cars from start-ups get an asterisk from me until a member of the public can buy one.
Never using electricity generated by fossil fuels is great and all, but I suspect that the manufacture of solar panels, electric motors and the rest require quite a few of them.
But that labeling aside, I do like the idea. It would certainly eliminate waxing the roof and hood, the only real PITA areas to do so on a modern car. But the guy who has the luxury of a garage at home and a parking structure at work will see very little benefit.
I also like the idea of the DIY repairs. The direct sales model would be a no-go in the US due to dealer franchise laws in about every state, but I suppose they could follow a Tesla-style model. Really, something like the Sion would serve me fairly well.
but I suspect that the manufacture of solar panels, electric motors and the rest require quite a few of them.
I guess you missed this from the text: one whose production will be 100% carbon-neutral.
Sweden’s power is already well over half from renewable sources, and Sonos will offset any carbon from the manufacturing and production process. These folks are serious about building what will almost certainly be the greenest car available.
Solar panels can maybe, in ideal circumstances have some use to cool or heat the car, but never can give any usefull range. Even if there will be panels that can give 20 miles a day on something small like a car roof, the will only ever produce those miles in perfect weather. Maybe nice in places where the sun always shines, but the cost of the panels and solarsystem will not be worth it. And the roof will be useless for bikes, kayaks and whatever people want to put on their cars.
More gimmick then usefull,imho.
Very interesting, I use to give green architecture tours – the future can be wonderful if people can change their ways of doing things. I thought the Prius with the photovoltaic cooling system was sold in the U.S..
As the chart indicates Photovoltaic/Solar Panels don’t generate as much energy on cloudy winter days, but they still work. Munich is pretty far north – 48 degrees, roughly the same as Minot, ND or Bellingham, WA, just south of the 49th parallel which is most of the Canadian border.
I’m a fan of EVs, it would be great if solar energy could augment or become the power source in the future for all EVs.
Lots of intriguing aspects to this piece amongst them:
– If solar powered cars become popular, will garages fall out of favor?
– Or will home garages be fitted with glass roofs?
– Surely, Toyota will object to a car being called “Sion” so soon after selling Scions
– Interesting use of the NEVS plant. Their original plan, to put Saabs back into production, didn’t work out so well…
– But for me the big story is the decreasing apparent cost of being a startup automaker. For half a century, the costs were considered so steep that almost nobody dared try starting a new car company from scratch; those that did (i.e. Tucker, Bricklin, DeLorean) quickly fizzled. Yet in the years since Tesla proved it was possible, there are now seemingly dozens of automotive startups, and evidently funding is as close as a Kickstarter campaign.
– But the fact that established automakers like Toyota can’t make solar roofs meet US rollover standards doesn’t bode well for an inexperienced startup being able to do same.
– I haven’t followed solar power closely, but a breakthrough in solar panel effectiveness could have major ramifications, making recharging necessary only for backup power or expected long trips, and seriously cutting living costs by making gasoline or electricity to power autos a rare expenditure.
A glass garage roof wouldn’t be helpful in areas with snow and ice – ironically, it would have to be heated.
My father currently drives an electric car powered entirely by solar energy — just in a less direct way than this. The way it works is this: my parents have solar panels on the roof of their house, which captures energy during the day and converts it to electricity that they sell to the utilities company (which itself operates on an all-renewable-energy-sourced power grid, I believe, but don’t quote me on that), and buy it back at night for a lower price to charge the car. Since their house is quite energy-efficient (no air-conditioning), they produce more energy than they use, making the car (in a roundabout sort of way) solar-powered.
Of course, this isn’t an option if you live in an apartment, something that these cars would potentially help address. But then again, (as a few people above have mentioned) many people drive from a covered parking garage at home to a covered parking garage at work, making the net energy benefits of something like this fairly low, I would think. I’m assuming all these theoretical numbers are calculated from the maximum amount of sun possible for the car to receive in day; a better measurement might be how many miles per hour of direct sunlight it would add. Because if your total outdoor commute time is, say, an hour, and you have covered parking both at home and at work, then I can’t see much range being added from something like this.
Great update on actual upcoming electromotive vechicles. Please keep them coming. All that industry coverage on the vaporware Tesla truck is just a nusance diversion to me.
PS: I immediately took a lichen to that dash.
if you think the Cybertruck is vaporware, then I’m not sure you’re the right audience for my posts. 🙂
Interesting. The limits of the Sion point to its greater potential, I think. It’s really an urban runabout rather than a highway cruiser. Tesla broke wide because it met and surpassed highway cruiser metrics (at least in performance), but higher density living/working won’t need these. I like the green moss, but I’m wondering if it turns brown as it accumulates filtered particles.
This is intriguing, there has been significantly more advancement in this field than I was aware of. As is typical, the “safety authorities” are far behind reality, I’d be happy with Europe’s safety specs if it means the other benefits in lighting etc would be kosher as well.
It’s a joke to discuss possible effects of a very low percentage chance of a rollover when there’s a much greater possibility of being hit by a raised truck with a metal bumper replacement that in no way lines up with the stock bumper of a regular car or even a standard truck and nobody has an issue with that.
This is exciting news. A few weeks ago I had been wondering about the current state of solar cars, remembering the bicycle wheeled solar cars seen in various university competitions from ages ago. So this is quite timely.
Gas is great, but so are hybrids and full electric cars. Solar only increases the intrigue and for my current situation a full solar car would fit the need nicely. These are exciting times.
Be warned, the Sion site is a bit of a rabbit hole! Great journey, though. They are, may their gods bless them, spending barely anything on marketing, and it shows. The site is resolutely factual and transparent. There is neither condescension nor proliferation of despoiled verbiage.
They set out exactly the way in which an entirely new vehicle could be put into series production for just 200mill Euro. Use of existing parts from suppliers, no massive tooling needed for body-stamping, no paint, no marketing to speak of. Impressively, to me, they do not claim to have invented anything particularly new: even the solar paneling is a variation on available tech. Funding is about 30% venture capital, the rest crowd-funding and pre-ordering/individual private loans/equity to the company. There is, so far as I can see, no fudging of any sort.
The aim is environmentally-centered transport rather than that chimera of glamourous mobility – meeting the actual dull lolloping about that is the real world of most of our driving, without causing harm.
It is extraordinarily reviving to read of a company reacting to science, and acting with science, clear-minded, and unpretentiously ethical. You can become very dispirited when you live in country where the level of debate feels as if we are still saying Copernicus might be wrong, even as the land literally burns to oblivion around us.
I hope they succeed, big time. Lord knows it’ll be hot enough in Oz by 2022 for one here never to need charging…
Self-contained solar-powered cars have always triggered a skeptical response from me. Solar power is mighty at the scale of houses and farms and planets, but pretty thin soup at human scale. And modern transportation takes lots of highly concentrated energy. Once I got a chance to get behind a computer this evening I had the urge to do a reality check. I pulled together some crude but real numbers. I was surprised by what I saw.
Some solar panel figures to start with: the solar panels on my house put out a maximum of 300 watts for each panel’s 1.7 sq. meters of area. That’s a maximum 0.18 kW per sq. meter.
Looking at the diagram on their website, the Sion’s footprint is 4.3m by 2.1m. Just by an eyeball’s guess let’s say the solar panels cover 50% of that area: 4.5 sq. m. At 0.18 kW/m that’s a maximum output of 0.79 kW. Let’s be wild and assume every day is a clear day and we’re on the equator, so we get max output for 12 hours a day. That’s 9.5 kWh ultra-maximum energy output from the solar panels every day.
Watching the instruments on the Fiat 500e this evening, I saw about 5 kW when running a steady 30 mph on the level. That works out to 0.17 kWh/mile.
Using 9.5 kWh at the rate of 0.17 kWh per mile works out to 57 miles!
There are many things unaccounted for with these crude assumptions. A northern winter’s cloudy day has nothing remotely like the solar input as a day at the equator. (This year our 14 solar panels got 20% as much energy in January as in July.) At a medium latitude like 45 degrees, the sun is at a shallow angle to the Sion’s solar arrays, which are fixed in place facing straight up. We’re assuming 100% efficient batteries, motor and electronics. We’re going a steady 30 mph, which is about ideal for EV range.
But the point is, for a ballpark estimate based on very optimistic but independent figures, my 57 miles is not that different than the claimed 21 miles. It passes the reality check for me.
Maybe it’s not a crazy claim after all. Even if it’s only 4 miles on an overcast winter’s day in Germany, that’s something. And on a clear summer day near the equator maybe it can get 20 miles.
I appreciate the effort, Mike. Thanks for the numbers.
I love every bit of the Sion. I guess it’s intended for young city singles or couples or a car number two for people in the ‘burbs (and Paul it seems). As such it’s damn near perfect.
I love that it’s such a complete package – everything thought out with sustainability in mind.
Nah, it’s intended for rich old people to drive from the home to shopping center. Think Phoenix with all the golf cart people.
Average life of PV solar cells is 20 years with 1% degradation each year so there is that as well…
I think that’s old info, i.e. a decade old or so. In any case since most panels carry at least a 20yr warranty (most are 25 if I am not mistaken) guarding against more than 1% degradation per year your scenario suggests that roughly half of all panels will be replaced under warranty which seems like a pretty good deal from a consumer standpoint. I’d say they last significantly longer than that with less degradation barring some sort of externally caused breakage.
Why would someone need to be rich and old to drive a $23,000 car that can exceed every speed limit in the US? I can’t tell if you are/were being sarcastic or not.
SInce it’s a European contraption, I believe it’s more directed at young people in cities
This, rather than the confiscatory measures dreamed up by city-dwelling members of the Green Party (which we now have in government here in Austria) is the way forward. If Sion’s claims and pricing will turn out to be true, I would seriously consider one in 2-3 years time, as my driving profile fits the projected range – my car is always parked outside and we’re having more sunny days than we used to in the past…