Okay, my SiL @victoriousone92 showed me a thread(?) on Tumblr about solar panels and electric cars, and oh wow were there some issues. So without going too far into it, let's go over some of the issues with "simply" putting solar panels on electric cars (thread) 1/

Solar panels are heavy.
With vehicles, weight directly reduces efficiency and this is more important for electric vehicles because electric vehicles are super efficient already (I'll spare you the math but a fundamentally more efficient vehicle suffers more from weight issues) 2/

This weight issue isn't insignificant. In my electric car, I notice a range decrease (albeit relatively small) if I have even a single passenger.
Why does this matter if the solar energy is "free"? *Because it reduces the efficiency of grid electricity which isn't zero carbon.*3/

Next issue: cost.
Currently (haha), the biggest impediment to electric vehicle (EV) adoption is cost. Solar panels are expensive on their own, and the engineering and production to put them on cars increases the cost of already expensive EVs. This is very not good. 4/

Solar panels kinda suck (on a per-area basis).
Solar just isn't efficient at collecting solar energy. The total energy captured by a car *covered* in solar is just not all that useful for most vehicles. Like, I'm talking maybe a couple dozen miles of range per day. That's it. 5/

Solar panel efficiency is already fairly low, and if you spec for putting them on vehicles with curved surfaces designed to be resistant to hail and debris at 70mph, they'll be even less efficient. This conspires to make solar even less attractive for vehicles. 6/

Next issue is safety.
You need to validate the solar panels for occupant safety. Safety is a *huge* factor in vehicle design. Suffice it to say that adding a ton of solar panels to your vehicle will require lots of clever engineering and thought to maintain safety standards. 7/

Solar panel production is already limited, we should use it as efficiently as possible. Production is a limited resource as it ramps up to meet need. All possible production should be used as efficiently as possible, and vehicles are not the most efficient place to put panels. 8/

Think about where you tend to park. Do you actively seek out sunny spots to park your car? No. People park in shade as often as possible (because it saves time/energy/comfort when cooling the interior of the car). This is antithetical to the goal of solar panels (sun = good). 9/

Some companies *are* putting solar panels on EVs, and the benefits are not clear at all. Nissan used to put panels on the Leaf, but stopped. I think Hyundai puts them on some Ioniq trims? Solaris has their EV which is A Thing, and it's covered in panels. They're not great. 10/

Not to belittle the vehicles themselves, but the benefits they claim are small on their own, and if you assume there's some marketing fudgery going on, the benefits are even smaller. Look at the cost difference and calculate the fuel savings. It's a tough sell. 10/

I hate this argument in most contexts because it's often used in bad faith: but manufacturing solar panels has a carbon footprint and that needs to be offset. It takes solar panels a couple years under optimal circumstances to do that, but purting them on cars would be worse. 11/

That's not an outright sin, but it doesn't help when you consider other efficiency hits.
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So, what's the conclusion? Well, solar on EVs just isn't the best use of our solar panels, in my opinion. We need them to be used as fully as possible, and cars are just not it. 12/

Is solar energy great? Yes.
Are EVs great? Yes.
Are they a match made in heaven? Basically.
Do they sleep in the same bed? *No.*
Is this metaphor tortured? . . . yes

TL;DR: EVs and solar are great, but from a distance.

I welcome questions and requests for clarification here.

I should say, this is a very abridged rambling. There is a lot I'm leaving out, and as ever there is an occasional lack of nuance. I tried to capture truth as well as possible, but I couldn't say everything here. This is why I explicitly welcome questions/complaints/etc.

I should also address: the point of this thread is to point out complications.
If after all this, you still want solar on your car for the small convenience, that's fine. But it's a luxury. The supposition that solar *should* be included on all EVs is silly, but wanting it isn't.