Solar panel to charge car

Solar panel to charge car

It would be nice Tesla can provide solar panels on the roof to increase the milage of the car. The solar panels can charge the car while being parked and increase the milage of the car.

balabanshik | September 30, 2013

As experience showed with Fisker Karma that had such a panel, the power of a roof-sized solar panel is not enough to even power the AC in the selfsame car. And, as you can imagine, the more sun you get to power that solar panel, the more you would need that AC...

Blueshift | September 30, 2013

This comes up a lot, so I have written an answer here which can be referenced in the future:

Brian H | September 30, 2013

Short answer: trivial and stupid.

blue adept | October 24, 2013

The solar panel-roof integration was originally a Tesla idea that was stolen (not for lack of a better word, just the proper one) by Fisker during his time at Tesla when he was suppose to have been working on the design of the then concept for the Model S (but instead chose to steal the design parameters and use them for his own profiteering), which he later deployed on the Karma, ineffectively.

To this end, it is not that it is an impractical accompaniment to the an EV's charging/re-charging capabilities, just an improperly implemented one by Fisker.

Brian H | October 24, 2013

wrong again. The available power is trivial, and vastly overpriced.

Roamer@AZ USA | October 24, 2013

People have a naive understanding of how much energy it takes to propel an automobile and how much energy a solar panel produces.

The weight of the panel and inverter would use more energy to haul around than it would produce. The panel would only generate power, when parked in direct sun, a few hours a day but the weight would be hauled around 24/7.

Roamer@AZ USA | October 24, 2013


Excellent link. Thanks for sharing it.

Timo | October 25, 2013

There are cheap and very light solar solutions. Just the conversion ratio for those solutions are weak so you need large area to get anything from them. Anyway I bet using one of those solutions would be 1/5 of the cost of Fisker solar panel with nearly same power if you just use whole roof instead of just part of it.

Still tiny power though. Maybe just barely enough for keeping charge when it is already low (anti-bricking) in sunny parking lot. Not nearly enough to affect range in any way.

@BlueShift, in your wiki you forgot that car panels would not be tilted toward Sun, so you need to decrease the angle of the Sun too. Realistic amount of Sun from car roof is way less than 2kWh/day even for 2m^2 panel. At least most of the year and for most parts of the world (about 66% of all land is at northern hemisphere, and about 1/3 of that 34% in Southern is Antarctica. Weird, but true).

Blueshift | October 27, 2013

@Timo I added a few words that hopefully make it more clear.

Timo | October 27, 2013

It's better now. Gives a person thinking about adding solar panels to extend range quite good explanation why it wont work.

Car t man | October 28, 2013

@just an allusion

no need to go too far with the stealing assumption, etc. Rooftop solar panels are not someone's design. They are a very old concept and even serial ICE cars had sunroof fitted panels for powering ventilation (Audi A6, etc..)..

Tesla really is too young of a company to have invented it all. One could then argue that Tesla stole suspension design, power steering, AC,.. designs...

No need to over do the guarding of the company. I would assume that if someone did steal their design, they could have just copies a Jaguar even earlier, etc.

blue adept | October 31, 2013

@ Brian H

"wrong again. The available power is trivial, and vastly overpriced."

Relatively speaking, it really isn't a matter of however much power a solar cell/panel can generate, nor is the cost of construction an issue, so much as it is a matter of how it is both constructed and configured that determines its powering/charging capability.

I feel that you are overlooking the innovations attributed to the namesake of the company.

blue adept | October 31, 2013

# Car t man

"no need to go too far with the stealing assumption, etc. Rooftop solar panels are not someone's design. They are a very old concept and even serial ICE cars had sunroof fitted panels for powering ventilation (Audi A6, etc..)..

Tesla really is too young of a company to have invented it all. One could then argue that Tesla stole suspension design, power steering, AC,.. designs...

No need to over do the guarding of the company. I would assume that if someone did steal their design, they could have just copies a Jaguar even earlier, etc."

I'm not arguing that Tesla holds proprietary ownership of the concept of roof-mounted solar panels, I am saying that it was Tesla (and by extension, Musk) who holds/held conceptual ownership of the idea to incorporate the panel into the roof's composition INSTEAD of merely incorporating some type of remote mounting...Fisker STOLE that and a review of the court filings reveals nothing less!

Timo | November 1, 2013

@just an allusion; Solar radiation is weak. You can't get enough for that small area to affect much no matter how good tech gets. It is not matter of construction or configuration, just available radiation, geometry and basic physics.

Nexxus | November 1, 2013


Here's the problem: The most powerful solar panels only produce 345W/panel/hour. They are 30" x 60" each (pretty much the available rooftop area of the Model S).

Where I live there is only 6.6 solar irradiated hours/day average throughout the year. So, you would only get enough power to add an additional 6.6 miles to the battery pack, at best.

Due to the cost/power ratio (not to mention they don't look pretty on the roof surface, even if embedded into the glass panels) solar charging just isn't feasible until the panels efficiency gets much greater than the current 21%. Needs to be 80% efficiency or greater, and that's not going to happen soon, if ever.

Better off putting the panels on your house and use that system to charge with, as the roof square footage is much greater.

Just my 2 cents worth,


blue adept | November 1, 2013


And yet a tree can both bloom and grow, even under a full canopy, with but indirect ambient lighting....

blue adept | November 1, 2013

Thank you for your input, Dave, it is appreciated and reflects the ideology of the conventional understanding of the science.

I guess that my perspective on the matter differs greatly from conventional wisdom...?!

Brian H | November 1, 2013

As opposed to unconventional misunderstanding ...


Timo | November 2, 2013

@allusion, trees don't go galloping 60mph in freeways.

Brian H | November 2, 2013

Leaves do like light cloud, though! Fewer shadows, multi-directional light.

Pungoteague_Dave | November 2, 2013

Three of my boats have cabin-top solar panels. They are much larger than a car roof, are always unshaded unlike a car, and they can barely maintain the house batteries when we are not onboard. Very stupid idea. And the idea of solar panels on any car us an answer in search of a problem.

Brian H | November 2, 2013

I like that: a stupid answer in search of a problem!

bent | November 3, 2013

I should like to have a small solar panel on my Roadster to power the contactors to the main battery in the event of a 12V battery failure. The Model S could presumably also use one to cover for that same eventuality.

valdger | November 4, 2013

IF Tesla S have solar panel with power of 200 W, in the max conditions will charge 85-kWH battery 425 hours)

olanmills | November 6, 2013

@just, I feel like you know this, but that you're just being a contrarian. The amount of energy it takes to move around a 4500 lb car is a lot. It takes way more electricity at once then most people are used to using for other everyday devices.

I use 3-4 times as much electricity than I used to use before I had the Model S.

As others have mentioned, the only use for solar panels on the roof of a car would be if they were dirt cheap and didn't negatively affect any other aspect of the car in a major way. Basically, if there were no costs or downsides, then sure, why not, but that's not the case at all.

Money spent on a solar panel could be spent on extra battery cells which would be far more practical.

Brian H | November 6, 2013

Even perfect solar cells would be trivial on such a small area.

blue adept | November 8, 2013


It is not my intention to come across as a "contrarian", much as it is not my intention to power the car (let alone a 4500 lb one).

Instead, only to "charge" it, as thread starter Jonathongolf originally suggested (though actually POWERING it with solar would be a novel approach and require a good bit more of engineering ingenuity, but it would take a bit more head scratching to pull off than what I am able to commit at this point), as I've some ideas on a more so direct method of powering it other than 'solar'.

But 'charging' it with solar, sure! After all, the batteries dissipate only so much of their charge over the course of their use, the amount of which fluctuates depending on the demands placed on them to motivate the car down the roadway, so I could see a solar trickle charging system being a benefit to the batteries' charge longevity and the cars' range as a result.

blue adept | November 8, 2013

@Brian H

If a device is properly engineered, it wouldn't have to be of such mass that would make its use an imposition/impractical, e.g., have you any idea of what the size of the first computer was?

Picture that, and then look at the iPhone that possesses all the power and computing ability of a great many laptops, and some PC's even, there in the palm of your hand.

It really does all come down to the application of the ideology and not so much its' physical constitution.

Roamer@AZ USA | November 8, 2013

Hard to change the laws of physics. Sunlight contains energy just like gasoline. The amount of energy from the sun that lands on the surface of the car is finite and can not be increased by wishing it was more.

blue adept | November 9, 2013


Each day the Sun shines the equivalent of about 1,000 watts per square meter at noon on a cloudless day.

Granted, the MS's canopy is a lot less than some 10 and 3/4 square feet, but we're only talking about what would amount to "trickle" charging to help replenish the batteries' charge capacity from usage.

I'm not saying that there aren't more readily beneficial methods of increasing charge capacity/battery range than a solar-based one, I'm just precluding its exclusion as but one option of the many I see to accomplish the same goal.

Brian H | November 9, 2013

Expensive and trivial.

olanmills | November 13, 2013

Dang, I made a longish reply which got eaten by some sort of error on the site.

Here's the summarized version:

"Each day the Sun shines the equivalent of about 1,000 watts per square meter at noon on a cloudless day."

This is not very much power compared to what would be needed to charge the car, even just to cover a 20 mile trip, in a decent amount of time, especially after you factor in real-world factors such as solar panel and charger efficiency, time of day weather, etc.

Then there are other practical matters to consider, like how much money such a system would cost, what kind of limitations it would place on the cars styling and functionality (sunroof, etc). Also consider that parking outside for long periods of time on a regular basis is not something owners of expensive cars typically do.

Brian H | November 14, 2013

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ronnussbaum | November 14, 2013

Have we not heard of photovoltaic paint?

olanmills | November 14, 2013

Yes Ron, we have had posts about photovoltaic paint too. The same problems apply with available surface area of the car, efficiency etc. Again, it wouldn't provide that much energy. If it was relatively low-cost, and didn't negatively affect other aspects of the car (like the way it looks, or the shapes you could build or how long it takes to produce etc), then maybe it would provide some benefit, but you have to consider the tradeoffs. And right now, it still seems like if you were looking to add extra money spent towards the car's energy systems, it would be much more practically spent on more battery cells.

blue adept | November 14, 2013


Yeah, I HATE it when that happens, especially when you compose a text rich, data field post that mysteriously disappears when you try to post it...Frustrating to say the least.

Anyway, as I tried to clarify previously, I am not suggesting the use of canopy integrated photovoltaic cells for the purpose of CHARGING the vehicle (not yet anyway - technology will have to advance appreciably before solar capture capacitance on that level is realizable), instead, I'm only suggesting TRICKLE-charging the batteries to assist in replenishing their diminished charge capacity.

Granted, the demands placed on the batteries by the motor(s) varies depending on driving conditions, yet I feel that an appreciable amount of that dispensed charge can be recaptured through solar charging much like the plug-in adaptor for your laptop maintains its' batteries at optimum capacity though you are placing demands on the battery throughout your usage of the device.

It's just a thought really.

Brian H | November 14, 2013

Charging a car with paint or other surface solar will NEVER happen. Even ideal 100% energy capture would still be trivial, due to the small surface area. Fuggedaboudit. (Please)

Roamer@AZ USA | November 15, 2013

I can put solar panels on my house roof and generate power and shade at the same time or I can put a small one on my car and park it in the sun to cook everyday.

I think it would take more energy to cool the car after stating all day in the sun than the little panel would generate. This is one of those ideas that sounds good until you run the numbers.

fancarster | November 15, 2013

For example:
even sun is powerfully shine for 6hr's, and we have to get 85kwt. Solar panels efficiency is about 15%, let's drop a losses during charging process, well we have to 85\6=14,2kwth\150wt(by 1m3)=95 square meters we need on the tesla's roof. Anyone? :)))
Bravo, author =)
P.S. I'm from north Russia. And So funny to read this. Cause unfortunately in Soviet Russia car heats you. ) That's why ICE performance is increasing up to 100% in cold winter )

Mark22 | November 15, 2013

It is also important to keep in mind that the angle of the panels will reduce efficiency by 10-40% depending upon where you live and the season and possibly even which direction the car is facing.

And as mentioned earlier, you are always loosing vehicle efficiency due to the added weight, while only gaining a trickle of power during peak sun hours while the car is under the sun. No cloudy days, no parking under a covered parking space, or tree, etc.

FAR more efficient to put the panels on your roof.

Brian H | November 15, 2013


It's unending. This worthless suggestion comes up over and over. And Fisker actually did it! Talk about appealing to the dumbest common denominator.

Roamer@AZ USA | November 15, 2013

@ Brian

blue adept | November 26, 2013

Technological innovation occurs on an almost daily basis, so I feel that it is presumptuous of anyone to conclude that there won't be any sort of breakthrough in solar charging that would make it more so practical and effective than it is today.

petochok | November 26, 2013

No one has concluded that there won't be a breakthrough, or that one day, solar tech won't reach a point of feasibility for on-vehicle application. It was merely stated that given the current state of solar tech, the yield is negligible.
Food for thought: Fisker's panel would take something to the tune of 400+ years just to pay for itself.

Timo | November 26, 2013

Point is that yield is negligible because of Solar radiation is weak. This doesn't change no matter how good the tech gets unless you somehow make Sun brighter. I would not recommend that.

Brian H | November 27, 2013

100% effective solar panels would still be worthless. Get it?

blue adept | November 28, 2013

I'll just say this...There is far more to 'light' than what we see/the amount of lumens our photoreceptors are able to absorb (the visible portion of the electromagnetic spectrum extends from about 380 to about 780 nanometers) to facilitate the process of seeing.

Timo | November 28, 2013

That fact doesn't change the Sun irradiation. It's still weak.

blue adept | November 28, 2013

I won't argue.

Granted, I've eaten too much to sleep, but I won't argue.