In a previous article, I reviewed some of the interesting projects people were pursuing for solar cars. Although functional, and even useful in some cases, some solar experiments were rather unattractive. In this article, I want to inform readers of an interesting project that makes it easier for anyone to have a stylish, simple, and efficient solar EV charging setup.

But before I get to the new part in development, I want to address the skeptics a bit so we can all appreciate the value of what’s going on here.

Why solar cars aren’t really a thing yet

I hear people throwing a lot of numbers, and I see a lot of people trying to say that solar cars will either be very useful, almost worthless, not worth the cost, etc. I could explore and confirm or debunk the numbers, but Jason at Engineering explained basically took care of it for us:

When you factor in the losses, you realistically envision getting 2-4 kWh of battery power per day of charge if you cover the whole car with solar cells and keep the charge efficient. 2-4 kWh is not nothing, as opponents say. It’s roughly the same as 2-3 hours of level 1 charging.

Whether this is useful highly depends not only on your daily driving needs, but also on the efficiency of your vehicle. For something like my Nissan LEAF, putting cells on the roof gives about 8-10 miles of range per day. My normal daily driving needs are around 40 miles a day on school days, so that doesn’t make a whole lot of sense. But, if I were to replace that with an Aptera (which only uses about 100Wh / mile), then that same 2-4kWh gives 20-40 miles per day of solar range. So on sunny days it would work (especially considering that it also charges on days I don’t drive it).

As solar cells become more efficient, on-board solar power will become more and more useful, even for vehicles that are not as efficient as the Aptera.

The numbers look good to me. How do I add solar power to my EV?

If adding 8-10 miles per day of range sounds good to you, it’s possible, but it’s usually not a good idea to start putting together different standard solar gear to charge your EV. In another post, I shared the story of Sam Elliott’s solar powered Nissan LEAF. In his case, he had a LEAF with a badly degraded battery, and he was missing a few miles to get home from work every day. So by adding solar charge, he could provide enough charge to get home during his working day.

The problem is, its initial load setup was quite complicated. He had solar panels mounted on the roof of the LEAF, which went into a fairly standard 12-volt DC charge controller. This charge controller has charged a bank of lead acid batteries. An inverter took current from the batteries and converted it to 120 volts of alternating current. This fed the original EVSE, which charged the car as a level 1 load. Unfortunately, it didn’t provide enough juice to make the EVSE happy, so he had to add a timer to the EVSE in order to that it only charges part of each hour.

It worked, but it took the whole trunk with extra batteries, an inverter, etc. Also, converting from DC to AC and then back to DC, along with other conversion losses, meant it was pretty inefficient.

Make a better solar EV charger

What EV drivers really need in order to be able to charge solar energy efficiently is a charge controller that does not waste energy and space by directly converting solar cell power into 400 volts which most EV batteries need it. Fortunately, a new thing is starting to happen. The project of building such a printed circuit board which I have already covered is now ready to be tested by others.

Not only does the board convert the power of two solar panels to 400 volts, it also has provisions to be able to close the battery switches and power any other electronic device you would need to charge the vehicle. In other words, if you wire it correctly, it could add a constant 300 watts of power to your car’s main battery in the most efficient and safe way possible.

It’s not an easy project, but it could still prove useful to the EV community. Most EV enthusiasts won’t have the skills to take this board, bolt some panels, and wire everything securely. Electronics technicians should be able to figure this out, but it’s also something independent EV stores and other EV companies could do. So if you want to add solar power to your electric vehicle without giving up your entire trunk for secondary batteries or otherwise creating a Rube Goldberg Machine, it is now possible.

Why it matters

Like I said, adding 8-10 miles a day might not seem like much to most EV drivers, but it’s enough to make a difference in some situations. It may be a technical challenge or a desire to reduce impacts to an absolute minimum. It could actually cover someone’s very small driving needs. Or, someone can live in an apartment or other accommodation without access to charging. It could even be just for aesthetics or bragging rights. Whatever the reason, there are definitely worse ways to part with your money.

On the other hand, the future utility of solar charging is not to be sneezed at either. The best cells commercially available today have an efficiency of around 24%, which means they convert about a quarter of solar energy into electricity. In the near future, cells could climb up to 30%. 40-50% is in the pipeline, and 90% is theoretically possible. Even if you can’t get all the horsepower you want today, it’s very possible that future cells will require you to add 30-40 miles per day for normal EVs. Even if your experiences only help others to test and work on integrating solar technology, it is well worth it.

Image shown: Screenshot of Real Solar Cars YouTube video (embedded above).

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