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.
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.
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.
If the solar panels could be efficient enough to run the air conditioning, I’m sold lol
My Prius has this. It literally just runs a small fan in the summer to keep the interior/batteries cool.
Because it barely matters. Like putting an extra AA battery in the glove box.
Well now the question is why they don’t put an extra AA battery in the glove box.
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.
A few of them have. The core issue is it doesn’t add much range, while at the same time adding more cost, weight, and complexity. On a sunny summer day you can expect to get single digit kilometers added to the range, while on a cloudy winter day you won’t get even a full kilometer added.
They do make some sense on hybrids, as they are lighter so the range increase is a bit more and people are less likely to charge a hybrid. But, they still suffer from not adding much range, while adding cost, weight, and complexity.
Bear in mind also that the extra weight and possibly aerodynamic compromises actually reduce range. In some cases, particularly at night, in poor weather, and at high speed, the panels would be a net negative.
They would only be useful if your car sat around in the sun for long periods without access to a charger.
such as parked at work or in a summer traffic jam?
Parked at work it will probably have a building nearby that creates a shadow. In a traffic jam, assuming perfect sun conditions and no shade, a 100W panel will generate around about 500m (or yards) of range per hour. Meanwhile the AC will use about 700W to 1kW of power to prevent your face from melting.
Some tests on YouTube report a realistic addition of 1 mile per day using the car in a typical commute.
Depending on the car and the temperature, AC Is simply not an option (same for heat) in a traffic jam. I drove a 2019 Nissan Leaf (with 12/12 battery bars and normally 80-140 miles in range, depending on the season)for my 19 mile commute for a while, and had an awful time during subzero temperatures (~-20 Celsius) once. I went from fully charged on the work chargers to considering breaking out my reflective emergency blanket in three hour stop-and-go traffic so as not to kill my battery before home. I stopped to charge and it took much longer than usual, to the point that I just gave up and used my hand warmers and hoped on the way home.
I don’t blame the car for that, I was unprepared for the predictable consequences of cold temperatures on electric cars, but it was still super unpleasant.
Leafs have battery packs with no active heating or cooling, which significantly impacts their performance in bad weather and when fast charging. Coupled with very small packs in the early models, and you have a recipe for a bad experience.
While most of the points are covered here, and it’s likely true that the cost to add the panel and micro inverters is high, (I built a small two panel one battery off-grid system for about $4000 to power a chest freezer)… I have a counter point that I feel should be considered.
While it’s true that it isn’t going to extend driving range by much, my thought is that it is still worth it. Take these examples:
Drove to great wolf lodge in the summer, left car in parking lot for 3 days without charge. It lost several %.
Left car in an airport lot for a week lost even more power.
Drove to NorCal, left car at Airbnb driveway, had to find charging despite the car sitting in very bright sunshine for 4 days.
Car camping
Apartment complex parking (literally one of the main negatives about EVs)
All of these would benefit from trickle charging, even if it was just to prevent the drain of sitting.
What car do you have? I worried about this for my Model 3 back in 2021, when it had some vampire drain. But if you don’t open the app on your phone, the car goes into deep sleep and it can be parek for weeks without a single 1% loss.
You seem to know what you’re talking about and I want to piggyback off this question to ask why they don’t harvest energy from the brakes or the wheels spinning. I always heard braking once could power a home for a day or something. And I assume if you put a passive spinning wheel power generator on each of the four wheels, you’d also produce a lot of energy. Are all of these things too heavy to have any benefit? Plus the wind passing the car as it drives…it just feels like there are a lot of missed opportunities for new energy production as the car moves that aren’t taken advantage of. What’s holding these ideas back?
Most electric cars have regenerative braking. It’s not magic though, it takes more energy to speed the car back up than it recovers. Regenerative braking just makes stopping less bad for range. Sure you can go down a mountain and gain a lot of power, but not enough to go back up the mountain.
Electric cars do charge when braking. Obviously the energy recuperated is less then waht was needed to drive that fast in the first place. Using driving wind would just increase the energy needed to drive that speed and would be net negative.
All newer cars do this. It’s called regenerative braking.
The problem is that this isn’t really even trickle charging. Customers would absolutely complain and say it’s not working because it couldn’t charge the battery more than 1-2% in an entire day of sun. EV batteries are 60kWh+ yet getting more than 2kWh/sq meter daily from residential panels is hard for much of the US. Add to that the:
- weight of panels
- cost of panels
- heat trapped in the car from having a roof literally designed to absorb solar radiation
- fragility of panels (although all these glass roof EVs have that problem already) And it’s really not worthwhile.
One solution to the apartment street parking problem is adding charging ports to streetlights (they do this in Europe). But for most of US apartments there’s already dedicated parking space so also space for chargers. The unruly size of new vehicles is a much bigger problem in my mind, if there were actual motivation to fix this problem in government it would already be solved through some tax credits.
the question then becomes how much weight are you adding/energy are you consuming by having to carry the weight. I honestly don’t know and considering how heavy batteries are it is likely not that significant, but if you are only getting a few % charge a day then anything eating into that is going to hurt.
I still see some merit in a more utility style vehicle where you do expect to take it out camping, but for a daily commuter I think most people would prefer the sunroof to the trickle charging.
Also as an apartment dweller… I just wish they’d make normal wall outlets more available. Not everyone needs a proper fast charger but only having a few inconveniently located ones to fight for also sucks. But if more spots could just plug in and slow charge that would be a huge improvement
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.
I have a very vague memory of watching a video where someone calculated the amount of energy produced, which was minimal. The benefit vs the cost is very poor.
The same could be asked with smartphones.
Why don’t smartphones include solar panels on the back side of the phone?
We buy solar phone chargers for use in the backyard. They work ok. It would take a long time to fully charge, but it will keep you from going empty.
Do you usually use your phone in the sun or leave it exposed to direct sunlight?
It would be cool if they were built into the highway and could charge your car as you drive over it. That might make toll roads almost worth it.
The Fisker Ocean has solar panels on its roof. It can add 4 or 5 miles a day if fully exposed to the sun.
Not enough to matter. It’s a gimmick.
If you don’t have an EV, you may think that EV owners are worried about range, and they’d welcome any increase. I have not found this to be true.
It’s more like having a car that starts every day with a full tank. You’re never going to burn through that in a single day. Pretty soon you don’t care about range, efficiency, or pay much attention to the battery meter. It only matters if you’re on a road trip, which for me is a couple times a year.
I would not want to give up a nice full-roof sunroof for a few extra miles a day.
For an extra miles a day… if you park in the full sun all day every day. Garage? 0. Driveway? Probably shadow half a day.
if i park in the shade, and therefore don’t have to turn on the ac as soon as I get in, I think that would be about the same, savings wise.
The newest revision of the prius has an option for rooftop solar. The break even point is relatively long, in the 5-8 year time frame iirc. The energy generation isn’t massive; at 185w it won’t substantially extend the range something like 5 miles per day.
Right. Unless you live in US and have relatives you regularly visit in a different city in the same state only 400km away.
I mean I still don’t care about solar panels on my roof and I’m much happier with a moon roof on my PHEV. Nearly 80km of electric range means I’m driving an electric car 99% of the time and have convenience of 5 minute fill ups when I go further.
While that might not be economically feasible, I’ve always wondered why plug-in electrics couldn’t send power back into the grid. No solar? Send energy onto the grid during the day from the car and recharge during the off-hours at night. Solar? Recharge during the day and send energy onto the grid at night. Just make sure to set a minimum charge that will get you to a charging station.
Some do, but to do this, the point of entry to the grid needs to be set up in such a way as to support this, with an automatic transfer switch for when the grid disconnects, and a meter that reads energy use as both incoming and outgoing, rather than the default of all incoming.
Source: am electrician who has installed batteries on peoples houses
IIRC some car batteries can be used that way, but it wears out the battery.
For LFP batteries it’s irrelevant. They have a 3000 cycles to 80% cap, some of the new ones have 6000. That’s 10 or 20 years assuming full discharges an recharges everyday.
Or in terms of lifespan, assuming a realistic 400km range (250 miles), it’s between 1.2M and 2.4M km before the range reduces to 80% (750k and 1.5M miles). The car will be completely Theseus-ed at the point.
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.
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
There’s two problems with this:
Panels are not free. They cost money to install, weight to move around, and prevent you from a mega-sunroof that most EVs have.
Second, if you think one inconvenient charge per month will make people outside of cities and disparage (for whom EV already offer the most advantages) change their opinion, I think you will be disappointed. Most of them formed their opinion by “but I don’t wanna!”, not by any logical thinking.
This is the exact type of gimmick/bullshit they can utilize to convince people to get over irrational fears. Because people are often irrational when making decisions.
But its also tied directly into the fear of running out of juice in the middle of no where. It not only offers but actually gives people comfort and security. Even its really not meant to actually be used regularily or ever really.
I know one mechanic who has both a Model S and Leaf. He HATES that his model S slowly drains the battery when not used and his leaf does not. And he can explain the difference both why and how. If a company just used that fact to sell their car over any car that also loses charge sitting unused they will absolutely have an advantage for people. Imagine parking your car for weeks and it always being as charged as you left it or more instead of sometimes having to worry if you have a dead car waiting for you because you realized after the fact that you left it with a low charge
I absolutely do think it will change enough minds. I work in the industry from the repair side. But also with people who use their vehicle to pay their wage. I know this can work towards removing that part of the equation because there is a TON of people who dont want EVs to replace ICE and they stoke every dumb fear people have. Having the option, however poorly it performs has always been a net postive as long as it does perform the way its supposed to
Good sales people try to understand what is preventing people from making good choices. Bad ones just lie to you.
Additional costs are exactly what people expect to pay extra for ask in think that’s really a moot point beyond getting the amount in the right ballpark.
I appreciate the long form reasoning, but I disagree. People I’ve met that don’t like EVs, they don’t like EVs first, look for a reason later. There is of course a tiny, minuscule minority that do more than 300 miles of driving a day and cannot spare 15 minutes to charge, but that is well under 0.1% of drivers.
The Dutch have been working on this for ages : https://lightyear.one/
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.
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
