Great Video Explains Solar-Powered EVs

A recent video at YouTube not only explains the math behind solar-powered EVs, but also gave plenty of nuance on the subject. More importantly, it’s made to be accessible for people who don’t follow EVs the way that many of our readers do.

For those of you who don’t watch videos, or who are at work or something and can’t watch a video, I’m going to do a quick recap and then provide some of my own commentary.

He starts out by telling viewers the story of EVs themselves, which is important. You can’t just say “solar-powered car” to the average person driving a gas-powered vehicle today and have the topic make any sense. Many people don’t understand that EVs are rising in popularity, and they also don’t understand that they’re far more efficient (because they don’t turn most of their energy into waste heat). He then talks about using solar power to charge electric vehicles using solar canopies and other parking lot solar installations, which makes a lot of sense.

He then leads viewers to the next obvious question: if you can put panels over your car to charge it, why not just put them on the car? And, he does a great job of answering the question in a way non-technical viewers can understand. But first, he takes a tour of solar car history, which is something we’ve done here. The point? To show that solar vehicles have been a thing for decades and that they’re improving as solar and battery technology improves. Arriving back at present, he goes ahead and runs the numbers, starting at the ideal and then adding all of the limitations piece by piece to show why it’s hard to make much power for a solar EV to run on.

But he doesn’t stop there. As he goes through the different solar EV options that are in various stages of production and pre-production, he shows that cars optimized for solar and efficiency can make a useful amount of power that equals a useful amount of range. The two best vehicles for solar-powered driving end up being the Lightyear One and the Aptera, which both produce enough power to cover many drivers’ daily needs using just solar.

His conclusion is that for traditional vehicles with normal shapes and construction methods, solar isn’t very useful. It might add a mile or two of range per day, or just help power auxiliary systems. But vehicles that are made to run on solar through greater efficiency and more solar cells are actually worth making.

Even among readers at CleanTechnica, who tend to be big fans of clean energy, I’ve seen this debate turn sour. There are far too many unbridled optimists and people who think vehicle-mounted solar power can’t possibly be useful. For that latter group, the numbers on solar EVs from 10-20 years ago doesn’t check out, so it’s not possible in their minds. For the unbridled optimists who want to “solar all the things,” solar EVs make sense because they haven’t run any numbers at all and they just think they’re neat.

For solar cars to succeed commercially, we need to calibrate consumer expectations. We can’t just tell people that solar cars are neat, go get one, and expect people to just like the idea. We also need to make it clear that you need a car optimized for running on solar power for it to be more than a virtue signal to other drivers that you care about the environment just a little more than the other EV owners. If people know what they’re actually getting into, and get an appropriate solar vehicle, then we’ve got no problem.

A “yes, but” answer isn’t as fun as a solid “yes” answer, and it’s certainly less satisfying. But complex truths (solar cars are good, but you have to get a very efficient car) are better than misleading half-truths (solar cars are neat!).

This Toyota test car from 2019 had panels with 33% efficiency, and added 10-12 miles/day of range from the sun. Image by Toyota.

One thing that the video didn’t say that is worth mentioning is the future of solar technology. The numbers for solar vehicles didn’t make sense ten years ago, and they’re starting to make sense for optimized designs. But what about 10 years in the future? 20 years?

The best commercially-available panels today are a little over 20% efficient, but that doesn’t mean that solar technology has no room to grow. As I’ve pointed out before, solar test vehicles have been around for years with solar cells sporting better than 30% efficiency. We probably aren’t far off from commercially available panels approaching 50%, either. Researchers are working on even better technology that could get us as far as 90% efficiency, which would more than quadruple the available power.

When we get to the point where a solar vehicle can make 3-4 kW of power from its own roof, that’s basically Level 2 charging speeds. Nearly all EV owners get by great with Level 2 charging today, with only the occasional Level 3 charge for taking long drives. Given that solar cars would still plug in as needed, this would put them on par with today’s EVs, making solar EVs a viable option even if they’re not optimized for maximum efficiency.

At the same time, though, I’m not going to lie and pretend that I don’t “think they’re neat.” I honestly don’t care that much whether the solar panels are useful. Being able to even say that a portion of your driving is covered straight from the sun into my battery is cool. I think it would be even cooler to figure out how much of the drive came straight from sun to motor, too.

One thing I’m seriously considering doing when I get my Aptera (you can get one, too, and save on your reservation deposit here) is taking a lower-speed drive across the country to see how much I can do strictly on solar power. I’d also like to see how much I can get away with on e-bikes.

But I’m an enthusiast and I understand that not everyone is a fanatic like I am. We need to make sure people who just use cars to get from A to B have the information they need and a car they can afford.

Featured image by Aptera.