Why don't electric car manufacurers put solar panels on the car roofs?

Honestly it seems like a no-brainer to me to put a solar panel on the roof of electric cars to increase their action radius, so I figured there's probably one or more good reasons why they don't.

Also, I acknowledge that a quick google could answer the question, but with the current state of google I don't want to read AI bullshit. I want an actual answer, and I bet there will be some engineers eager to explain the issues.

Boozilla ,
@Boozilla@lemmy.world avatar

This guy heard you:

https://youtu.be/qPENum9DFFA?si=2eOx7mpy6CQwG1sH

Duamerthrax ,

The math doesn't work out unless it's an ultra light car. Check Aging Wheels video on the Aptera for more. The first few minutes, he covers the technical stuff on car mounted pv.

brlemworld ,

Look at the Fisker Ocean, it adds almost no range or energy, and leaves horrible and distracting shadows on the passengers. Youat as well ask why you can't charge a car with a D battery.

manicdave ,

Solar panels on cars are thought of the wrong way. The responses in this thread really demonstrate that.

It's true that they're kind of pointless on EVs, because they're never going to supply enough power to not need a proper charge, which makes the panels redundant.

Where they could be useful is hybrids, sold as something that makes the engine 10-20% more efficient.

AA5B , (edited )

I vaguely remember reading something about a Prius with solar panel on the roof. It was enough to run a small fan to keep the interior a little cooler. In theory it improved efficiency because the air conditioning had less work to do

kaffiene ,

The Dutch have been working on this for ages : https://lightyear.one/

fine_sandy_bottom ,

Everyone saying how little energy a solar panel will produce in optimum conditions.

I don't think anyone has mentioned how difficult it would be to get optimum conditions for any significant portion of the day.

If you think about the places you park, how many of them have uninterrupted line of sight to the entire arc of the sun? Right now my car is parked on the street but it's in the shadow of a building.

Schlecknits ,

Even if you have the option to park directly in the sun, would you?

Being in a car that has been heating up for several hours of direct sun exposure is grueling. Switching on the AC to cool down to acceptable temperatures will probably drain more battery then was gained by the solar panel.

fine_sandy_bottom ,

Another really good point.

... a different way of looking at it is that it's just way more practical to put solar panels in other places, like on the rooves of buildings.

Additionally, there seems to be an assumption amongst middle class suburbanites that everyone should just have roof top solar. Of course, the vast majority of humans to not have any roof space, because they live in an apartment.

I would also point out that my spell checker seems to think that the plural of roof is spelt "roofs" but I'm sure it ought to be "rooves" in the same way the plural of hoof as in part of a horse is hooves.

Successful_Try543 ,

I would also point out that my spell checker seems to think that the plural of roof is spelt "roofs" but I'm sure it ought to be "rooves" in the same way the plural of hoof as in part of a horse is hooves.

According to Wiktionary, both seem to be correct, but 'roofs' is the common variant.

corsicanguppy ,

Being in a car that has been heating up for several hours of direct sun exposure is grueling.

Ahh, beach days with mum. I remember the warm sand, cool lake water, and the layers of flesh burned off my young legs when we got into the car. Those days, we got our exercise writhing in place to avoid the worst of the burns until the car got moving enough to cool the seats down. Thankfully seat belts were optional, then.

Zoot ,
@Zoot@reddthat.com avatar

Yall didn't just put a towel on the seats?

BradleyUffner ,

Bring a wet towel inside the car? Are you mad?!

JordanZ , (edited )

I remember looking at the Prius and it had a solar roof option. I remember reading a MotorTrend article about it. They had to make a lot of assumptions like 12 hours of sun everyday no exceptions and just to break even from the cost of the roof option it would take 5+ years. So not really worth it. You’d be better off just paying for the electricity or putting solar on your house and charging with that.

Edit…words missing

ASeriesOfPoorChoices ,

the solar panel was just to run a 12V fan to keep the car cool in the sun. it didn't charge any batteries.

JordanZ ,

The title of the article I linked and its subtext is

“The 2023 Toyota Prius Prime Could Take 3 Weeks to Recharge—Without Plugging In

Or, put another way, you can get more than 1,000 miles of free range in a year.”

It most definitely charges the battery.

gnuplusmatt ,

on the roof doesn't make much sense. What I did see the CSIRO testing was a portable solar array that you could roll up and store in the boot. IIRC they drove a Tesla across a large swath of Australia stopping and only charing on the portable array as needed

FuglyDuck , (edited )
@FuglyDuck@lemmy.world avatar

I had similar ideas using a VAWT, mount it on a speaker tripod, set it up to catch the evening and morning turn over. Maybe catch a trickle charge.

conrad82 ,

The first generation Hyundai Ioniq 5 had solar roof (at least some models).

The first gen ioniq 5 also had a very low payload capacity, with stories of families who couldn't legally be in the car at the same time without being over the capacity.

The reason, I'm told, is that supporting the solar roof reduced the payload capacity a lot.

Also, solar cells on a car doesn't make much sense like others have already said.

Kolanaki ,
@Kolanaki@yiffit.net avatar

They have them on some international models of Hyundai electric cars. It's not nearly enough to power the car or charge the battery, though. It's more to just slow the battery down while it powers low-power things and look cool (it's part of the trim package). Solar panels need to be way more efficient than they are now for them to really make a difference with such a relatively small surface area.

Daxtron2 ,

I don't remember what car it was but an ex's car had this. It was only really used for keeping the car from getting way too hot while it was off in the summer.

tyrant ,

I think they should put windmills on the roof. If you're going down the freeway that would charge the battery real quick! /s

Maalus ,

Obligatory windmills do not work that way, also that's exactly how an alternator works.

Kolanaki ,
@Kolanaki@yiffit.net avatar

But... That's exactly how a windmill works.

Maalus ,

Windmills don't generate electrical energy. For that you need a wind turbine.

Kolanaki ,
@Kolanaki@yiffit.net avatar

Windmills don't generate electrical energy

What if you used them to grind pizeoelectric materials like quartz? 😌

tyrant ,

https://lemmy.world/pictrs/image/15097518-4b6f-48b1-82cf-2444e04d60ab.jpeg

Doombot1 ,

Doesn’t provide enough power for the cost of the cells, plus having to clean and upkeep them. And the more material you cover them with (to protect them; solar cells are INCREDIBLY fragile), the less efficient they are. I was on a solar car team in college and the cells are so fragile that to clean them, we had to use new microfiber cloths every time. Any dust would scratch and ruin them (which made it quite tough when I drove across the outback in the thing). We kept our cells completely uncovered because we needed maximum efficiency - but even with a super light carbon fiber solar car that’s got very minimal tire contact patches, specialized tires from Bridgestone, and a very aerodynamic shape (plus no amenities like A/C), I think our car could sustain something like 10-15 km/h on a perfectly sunny day in the middle of the outback. It just doesn’t add enough on a huge, heavy EV

Dasus ,

So a solar golf cart might be doable?

GreyEyedGhost ,

A 9v battery powered skateboard is viable if you pick the right combination of weight, speed, and distance. Doesn't mean it's going to change the world.

agressivelyPassive ,

On the other hand: most cars are not moved 23h a day. They just stand around.

A lightweight solar panel could be a worthwhile range extender in at least some climates.

kent_eh , (edited )

On the other hand: most cars are not moved 23h a day. They just stand around.

It doesn't take much shade to have a signifigant reduction in the output of a solar panel.

Unless you are parking in an open field with no trees or tall buildings around, your power generation will be signifigantly reduced.

Not that the amount of power generated by a panel the size of a car roof is all that much, even under ideal conditions.

Doombot1 ,

Exactly. And what’s worth remembering is that solar cars tend to be something like 2X longer then normal cars, and cover the entire surface except for windshield with panels. No rear windshield, either.

Cryophilia ,

I've seen some prototype solar panels that roll up like a carpet for easy storage. Keep it in the trunk, lay it out when you're gonna be parked somewhere for a while.

Sidhean ,

Now THIS is podracing

zbyte64 ,

On the other hand: most trips are made to the exact same place, why move solar panels around when you could just leave them in place (especially if the car isn't moving for 23hr)?

fmstrat ,

And more weight means less range.

morphballganon ,

Having solar cells uncovered by glass is baffling

Steve ,

Because it barely matters. Like putting an extra AA battery in the glove box.

jj4211 ,

Well now the question is why they don't put an extra AA battery in the glove box.

njordomir ,

Then you can use your glovebox battery to jump your main battery when you leave the light on!

Treczoks ,

Solar cells on a car have no real use. You would have to leave the car out in the sun for weeks to months to charge it up just once.

Jarix ,

Seems worth offering as an option. If you can get 10-20 kms out of the solar panel in decent time it might be enough of an emergency precaution to give people who live outside of cities less reason to poopoo EVs

Treczoks ,

More like 5-10km, and then only on a sunny day in the sun, which would make the car uninhabitable due to the heat.

Better put a few square meters on the roof and use those instead of the 2-3m² you can place on a car at suboptimal angles and with the requirement to park in the baking sun.

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