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.

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.

Boozilla ,
@Boozilla@lemmy.world avatar

Thanks for posting the question! Whole point of the community.

I think we'll see more of this in the future as they continue to make progress on inexpensive "solar paints" and the like. It's not a bad idea, it's just that the tech level doesn't show much bang for the buck...yet.

snooggums ,
@snooggums@midwest.social avatar

In addition to the other points about efficiency, there is also the maintenance and added weight in a high location on the car that would impact stability and safety. Keeping that slab or solar cells from majing a crash worse would be a large undertaking for example.

Solar panels now are like tube tvs. If we make a breakthrough on paintable or extremely thin and flexible solar cells like we did with the leap to flatscreen tvs then it would be much more likely as the costs come down even if they still provided only a small charge.

Blubber28 OP ,

That does indeed make sense, thank you (and many others) for the answers!

bobburger ,

The new Prius Prime has an optional rooftop solar panel.

According to an article in Slash Gear you can get about 4 miles of range after 9 hours in the sun.

So it has the potential to marginally increase your range on the scale of a short commute under ideal circumstances, but it's not much apparently.

dgriffith ,
@dgriffith@aussie.zone avatar

Assumption:

Someone crams a 300 watt solar panel onto the roof of their EV and manages to integrate it into the charging system so that it's pretty efficient to use that power.

Numbers:

One hour of good sunshine on the 300 watt panel = 300 watt-hours (Wh).

Average EV energy usage : 200Wh per kilometre these days. Maybe a little more, maybe a little less, depends on how and where you're driving.

Result:

One hour of perfect sunshine hitting the roof of your car equals 1.5 kilometres of extra range, or you can drive your car in a steady-state fashion at a 3-5 kilometres per hour because an EV is more efficient than the average usage at lower speeds.

Conclusion:

Probably better off increasing the storage capacity of the battery as a full day's sunshine will get you about 10 kilometres of range.

stsquad ,

For range it doesn't add much in most cases. But it also depends on how long between journeys you have. If you're traveling in a van and you are going to be stationary for a few weeks at a time then it can start to make sense, maybe with an extra fold out.

ramble81 ,

Once upon a time Audi had solar panels on the roofs of their car and it could only generate enough power to run the cabin fan to try to cool the car down while you were parked.

To give you an idea of the sheer amount of power that an EV requires to move its bulk, look at the sizes of their batteries vs home battery packs. An EV has battery packs of around 100kWH and that can get you a few hundred miles range at most. Now compare that to the requirements of a home battery. The average use for an entire home is about 30kWH per day, and most home batteries only recommend 10-15kWH.

Looking at that you start to see the massive difference in power usage required. To charge a small home battery like that you usually need multiple panels (10+). They just don’t have the space and power generation to offset the sheer amount of power EVs require.

Successful_Try543 ,

Modern EVs such as Teslas have a high power consumption, much higher than some PV panels on the roof could deliver. Thus, it would only increase the weight of the car while not significantly increasing their range.

OhmsLawn ,

In addition to weight, there's cost. They would have to be integrated into the design, not just normal, flat solar panels, so there's a significant cost increase. It's no problem on a delivery van, but anything curvy is probably prohibitively expensive to develop and produce.

setsneedtofeed ,
@setsneedtofeed@lemmy.world avatar

Popsci article.

TLDR solar panels have a lot of inefficiencies, which makes them more of a detriment to mounting on standard commuter cars when you take into account the effects of the added weight.

Boozilla ,
@Boozilla@lemmy.world avatar

This guy heard you:

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

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.

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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