A recent article at Slash Gear attempted to tackle the problem of solar-powered cars. The topic did hit the news last month with cars like the Vision EQXX concept and Hyundai’s hybrid Sonata sporting solar panels, and if those cars were all we had to go on, the science mentioned in the article would be correct. The short take on “why we don’t have solar electric cars” fell far short not because it said anything wrong as much as that it didn’t cover the whole truth.
This got me to thinking about how often I see this happen. The average car enthusiast and automotive journalist can’t see the value of solar-powered vehicles that’s just months from hopping onto the scene.
Why People Keep Getting This Wrong
Honestly, though, we do have to be fair. Solar-powered cars is an easy thing to get wrong. It’s a slow-changing topic that most cleantech fans aren’t on top of. Want some proof? Look at any of the comment sections on our articles about solar vehicles.
The fundamentals of electric cars haven’t changed since the Tesla Model S came out. High-density batteries (usually lithium-ion as of this writing), slung low in a “skateboard” configuration, power at least one AC electric motor (via an inverter) which makes the car move. Sure, battery density has improved. Tesla has exciting plans for the 4680 tabless battery cell that get a lot of attention, too. But nobody has really been able to question whether electric cars are fundamentally viable since 2012, and spurious arguments against them are dying out as prices fall, infrastructure gets built out, and EVs prove themselves.
Solar technology hasn’t changed much in that time, either. Like battery storage, minor improvements have been made since EVs started proving that they could serve as a normal automobile and not as a short-range commuter or impractical weirdbox. So the amount of solar energy you could get from a vehicle’s surface area hasn’t improved by a whole lot. The numbers in the Engineering Explained video that the article linked to are correct.
It’s fair to say that entirely covering the average EV in solar cells still wouldn’t produce enough energy to make a meaningful contribution to the vehicle’s range to be much more than a marketing gimmick. The old Toyota Prii (that’s the plural of ‘Prius’) with a solar panel only used that to run a small fan to ventilate the car while parked to keep it cool, and other electric or hybrid cars that have come with solar panels can only use solar to add fewer miles of range daily than you can count on your fingers, even if you’ve lost a finger or two in accidents.
It’s not stupid for people to think that if the numbers haven’t changed, that solar vehicle technology doesn’t make sense any more today than it does in 2012. Moving a car-shaped object the size of a car through the same air down the same roads wouldn’t be any different today than it was in 2012, right?
What Changed Since EVs Were New
While improved NiMH (blocked by the oil companies) and then lithium-ion batteries made a big difference in the viability of electric vehicles, solar-powered vehicles haven’t had a similar moment where big change happened overnight. Instead, incremental changes have been stacking up under people’s noses over the last decade and leading toward viability too slowly to catch everyone’s attention.
I noticed this happening in 2019. The solar cells you can buy on the commercial market only tend to produce electricity with 20-25% efficiency, and this had risen a little in the decade leading up to that article (from 15-20%). A 5-10% increase in solar efficiency isn’t a huge deal on its own, but Toyota’s test vehicle was fitted with experimental solar cells with 34% efficiency. With that much power (about a kilowatt), Toyota’s test vehicle was able to get 27 miles of range per day of charging, which is pretty close to the average distance an American driver goes in a typical day.
That got my attention. Sure, you’d still have to plug that vehicle in when there’s a cloudy day, or let the vehicle’s gas engine run in the case of Toyota’s test vehicle. That’s not ideal, but for someone living where you can’t plug a vehicle in (apartments, etc), getting most of your vehicle’s miles to run on the sun and only using a gas engine when conditions are bad is head and shoulders above just burning gas full-time. 34% solar cells aren’t commercially available yet, but it won’t be long until they are.
The other thing that has improved since 2012 is vehicle efficiency. For more normal-looking vehicles, like a Tesla, the amount of energy needed to go a mile has been slowly decreasing. Slightly better battery technology, improved drivetrains and electric motors, better tires, and aerodynamic tweaking has all led to just not needing as much energy to drive. This means that the slightly improved solar cells can now add more range to the vehicle’s battery than they used to.
On top of this, companies like Lightyear and Aptera are taking efficiency to the next level. Vehicle shapes are obviously not as conventional as a Tesla, but by looking more like a hypermiling or ecomodder car (like the AeroCivic, or this modified Prius), it’s possible to get a lot more range out of a car than is otherwise possible. When you add this massively-improved efficiency to the small gains that solar has made, it’s possible to get a meaningful amount of range out of solar technology today instead of 10 years from now.
In this case, meaningful range added doesn’t mean the vehicle will never, ever need to be plugged in, but it does mean that it would only have to be plugged in rarely if you’re the average driver. If you’ve got enough range being added from the sun every day to cover a few more miles than you use, then the extra “rollover” miles will get saved up in your battery for a rainy (or cloudy) day.
As I pointed out earlier, this is something we’re pretty close to actually seeing on the road. I won’t get one of the first Aptera models, and they’re projecting mine to show up in 2023 or 2024. Other people who are ahead of me in line are probably going to get theirs early in 2023 (you can use our referral code to get yourself in line here). Lightyear says they’re going to begin production in the second half of this year. Their prices are a lot higher than Aptera, but it’s a more conventional-looking vehicle.
So, if I were to recommend an article to people wishing to cover solar vehicles, they should title it something like, “Why We Don’t Have Solar Vehicles, Yet.”
Featured image by Aptera.
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