Solar panel roof

Solar panel roof

Have you guys thought about using a solar panel roof for tesla models? The point of the solar panels wouldn't be to fully charge the car but to assist the battery, especially while sitting in traffic or in between charges, while the car isn't plugged in. The sun gives away all that free energy. Might as well put the car to work to be more productive. Sure it will be expensive at first but tesla motors figured a way to make batteries cheaper, why not solar panels?

Timo | 04/04/2014

Too much hassle and added complexity. Solar energy you get for that small area that isn't even pointed to Sun is just too small.

mb30 | 04/04/2014

there is tech actually that can put solar "panels" laminated between glass. I don't know how efficient or cost effective it is to have it make sense, but if they could use that in the pano roof plus maybe the windshield, maybe it could help somewhat?

For me at least, i just finished install on my rooftop solar at the house, and that seems like a way better option. Free charging at home is good enough for me ;)

Justthatkid19 | 04/04/2014

Shouldn't be complex at all. I bought a little solar panel that is hooked up to a USB port . What's the difference between that and just a panel(s) wired to the battery. Curvature of the roof will provide some pointing at the sun, but it doesn't need to. The sun just has to hit the panel. The more solar energy is used the more efficient the panels will become overtime. Say it generates enough power to power the touch screen, radio and the USB ports to charge your phone. That's less reliance on the main charge over night. Resulting in more efficiency.

DTsea | 04/04/2014

Many existing threads. Check

holidayday | 04/04/2014

I'm all for the solar option.

But for the price and hassle to build it into the car, it's currently more price competitive to have solar at home with huge panels that catch more light.

If people are willing to pay for the little panel on the car, then more power to them (pun intended.)

I do hope for a lower price point for the in-glass panels, as the sunroof and back window are huge places where sun can help power the car.

Blueshift | 04/04/2014
Brian H | 04/04/2014

Parked in the sun all day, you might get a few miles. At a cost of hundreds of dollars a watt. Stupid.

nikolateslas88 | 04/04/2014

there was a guy that was working on a paint type solar panel. like paint on the ground part, then paint on the electron sensitive layer and then paint on a protective layer. something like that.there was going to be some type of solar plastic film as well, totally bendable and stick on. i dont know what the efficientcy of it was, but it always seemed interesting to add this to electric vehicles.

DTsea | 04/04/2014

Paint, silicon, whatever. The solar flux is 1 kW/sq m at sea level. There are about 2 sq m available on the car. Commercial solar cells are around 10% efficient (10 W per square foot or about 110 W/sq m.) Assuming average sun angle of 45 degrees, you will get 70% of that or 140 W. After a whole day, you would get a whopping 1 kWh (3 miles) of charge... wouldn't even keep up with vampire drain.

For this princely quantity of power, worth $0.12 PER DAY, you would have to add solar inverters, wires, blah, blah blah adding thousands of dollars to the cost of the car. Remember... backup sensors alone add $500 to the car!!

This is... to be utterly blunt.... a silly and wasteful idea. The only way solar makes sense is a fixed installation with enough area to be useful. Your house's roof is about right.

Justthatkid19 | 05/04/2014

Until those solar panel s become more efficient, and cheaper. Starting an entire electric car company a few years ago while the rest of the world used gas, sounded like a silly and wasteful idea. Always be open to ideas.

Justthatkid19 | 05/04/2014

Also that's 3 miles less you'll have to push your car if your battery runs out.

Timo | 05/04/2014

Solar weakness is not solvable technology problem. It can't be solved without moving out of the atmosphere and closer to Sun.

Mauriziolarranaga | 05/04/2014

Super-thin flexible solar windshield sun shield when parking outdoors through an input port on the dash. Would be a nice branded accessory. Perhaps to charge a portable Li Ion pack or a 12V battery top off

petochok | 05/04/2014

"Also that's 3 miles less you'll have to push your car if your battery runs out."

That's like saying everyone should keep a 1 liter canister of gas in their ICE car, and that it's 5 miles less they'll have to push their car if their gas runs out.
Audi has had a solar panel inegrated into the sunroof of some models for years. Its main function was to run a small fan, just enough to ventilate the interior during hot summer days. Nothing more.

Brian H | 05/04/2014

Bluntly, it's a stupid waste of money. Forever. No miracle technology can add more sunlight than actually falls on the car.

DTsea | 05/04/2014 even at 100% efficiency, the car would make $0.50 worth of power per day... and the most efficient solar panels (for satellites) are 35% efficient or so and cost about $10000 per square foot.

So, as Brian H so aptly put it, it is a stupid waste of money... forever. Cars are too small to be solar powered by onboard panels.

Car t man | 06/04/2014

1. As the OP said, it does make sense for the 12v system.
Ideally, the car would use it simply to spin the vents to
expel heated cabin air out.

2. The roof of the panel S could accommodate a 120-150w commercial
flexible panel, which shouldn't cost Tesla more than 120 or so $.
It could charge the car's 12v battery with 5-10 amps in direct
strong sunlight, or some 2 amps in shade. Enough to cover
some of the drain.

3. This is NOT meant for the propulsion battery and in general, you
can stop regergitated, that this does not make sense, because it
does, but it could make the S look a bit like the Fisker to some,
which I think is much of the reason Tesla doesn't do it currently.

It isn't expensive, difficult, a hassle,.. None of these are true.

It is far more cost effective than the drained battery Tesla needs
to replace continuously. And yes, I speak from experience. This is
cheap, effective and would improve the car. The cost is negligent.

Considering how much energy the car needs to cool the cabin down,
at least venting the cabin built up hot air, would already improve
the situation significantly.

DHrivnak | 06/04/2014

A small solar panel to run a fan to keep the cabin cooler in the summer and to keep the 12v charged would cost VERY little and would be of some use. The Prius, Leaf and Focus have this option. I agree it is more gimmick than substance but the same could be said for most things in life.

Timo | 06/04/2014

As an option it could be used for things like that. I wouldn't choose that option since to me it would be just waste of money.

Brian H | 06/04/2014

The solar roof on Fisker cost about $5000. It must be attractive and robust for that environment, far increasing costs over usual installations.

Functionally, cars are not (by preference) stored outdoors in sunlight. A garaged car has no use for solar panels.

bent | 06/04/2014

The car needs the 12V battery to activate the contactor to the main battery pack in order to start the car. In scenarios where the 12V battery has failed a small solar cell panel would be useful simply to activate the contactor so the car will start. The alternative in this situation is for the car to be temporarily bricked until the 12V battery can be externally charged or replaced and personally I would appreciate having a solar powered fallback to this. For this isolated case I can't imagine you'd need a whole roof panel though, a very modest one should be quite sufficient for the task.

DTsea | 06/04/2014

It is so expensive because even for only 12V system, you need power conversion electronics to step up from 5V to 12V; wire routing; control system and software; stucturally rugged roof specially modified to fit the solar panel; and so on.

As Brian H said... for $5000 you can just replace your 12V battery about 100 times. Cheaper and more effective!

Timo | 07/04/2014

If you produce those in bulk then everything you just said would cost practically nothing barring the actual mounting of the solar panel. Thin film panels are light, cheap and flexible and some are even transparent so that you can mount it inside the sunroof. You won't get much power out of it, but it would be rather cheap.

Those things get expensive (and heavy) if you try to get lots of power out of small area, cost increase is almost exponential with conversion ratio.

$5000 sounds lot to me. I bet that's another thing in Fisker that has gone wrong.

DTsea | 07/04/2014

Ita not volume its variability. The current price point is the actual Fisker option price of $5000. Since TM chargea about that for the tech package its probably similar.

The headliner without pano roof is already low.... this would make it worse. Its a non starter.

Timo | 07/04/2014

Less than millimeter would make it worse? Well, yes, but I would not be able to notice it.

DTsea | 08/04/2014

Its not less than a millimeter. There has to be depth for the wires, substrate, and protective cover too. Would probably need at least half an inch.

Car t man | 08/04/2014


your data on Fisker's roof is either wrong, or for marketing purposes and sense of exclusivity, includes cost of the actual roof, possibly made of
exotic materials.

An automotive grade semi flexible panel with 150w costs me about 200$ on
semi volume order. That is the kind rated for vehicle, yacht and similar
use, the kind you can walk over.

At some 18v, which is perfect for 12v battery use.

So all your assumptions on costs are wrong. If Fisker stated the 5000$ figure,
they just tried to make it seem a very exclusive feature.

Brian H | 08/04/2014

The figure was also cited by analysts and engineers at the time. Car roofs are special; they need to be robust and watertight, amongst other things. Making solar cells either, much less both, is not cheap.

holidayday | 08/04/2014

Nope, not cheap at all.

But hey, people upgrade their stereo at "not cheap" prices too.

Have it as an option. If people will pay for it, the option will stay. If people are not willing to pay for it, it will go away.

DTsea | 08/04/2014

But it would consume Tesla engineering and manufacturing development resources. Better to stay focused on Model X, Gen III, and the high priority upgrade items.

Car t man | 08/04/2014

Brian, cells I use are just that. And the cost is what I mentioned. So cost isn't the issue. Automotive grade water tight flexible thin panels, perfect
for roofs.. If it is priced reasonably, it will definitely be a popular
option. Especially with the dodgy 12v system and battery...

But it is best for venting the car in hot summer days. Just endlessly
keeping cabin heat way below what it would normally reach.

Rocky_H | 08/04/2014

That was hilarious, Car t man, how Brian H seemingly was squinting his eyes shut to make sure not to see your comment about how it was a heavy duty, automotive grade panel, and then he just repeated the same already refuted statements.

nikolateslas88 | 08/04/2014

that is why there is a man making a paint on solar panel as well as a thin sheet plastic stick on panel to make things practical. there are other chemical substances that respond to the solar spectrum better than the solar technology used commercially today. it would increase the practicality of a solar paint on substrate that would be a thin coating, wires are added at the edges so there is no "1 inch space" like a normal panel...

DTsea | 08/04/2014

It still generates a trivial amount of power.

Timo | 08/04/2014

@DTsea, you can laminate it inside the solar roof. That transparent solar cell is less than millimeter thick, but it would require different glass manufacturing.

As long as you don't try to overdo (IE, you don't even try to charge the car main battery with it) it it can be cheap and pretty much unnoticeable to car structure.

You can even paint with solar cells. That would not change car roof any less robust or watertight. Or use solar like the paint protect films Tesla offers. If it breaks, then it would be the solar panel that breaks, not the car. Only thing you would need to figure out then is the wiring. Broken solar panel could be peeled off and replaced.

Those things have advanced far beyond those clumsy squares most homes have in their roofs.

Timo | 08/04/2014

@DTsea, "trivial" for travel, but if it aids against vampiric losses and helps keeping cabin temperature manageable in very hot environment it could still be useful.

As an option. Not as standard. I probably would not take it unless it is practically free, too far north to have any use to it; we might get two weeks over +25C if the summer is a hot one. Usually not though, and most of the time Sun is just too low to be any use.

Brian H | 09/04/2014

TM stated at the time the Fisker came out that the Wh return on "investment" was terrible compared to just adding a few more batteries. Even in sunny Calif. And worthless in a garage, off-season, under clounds, at night, etc. etc. The "ventilation" can be achieved much more directly and cheaply.

Brian H | 09/04/2014

typo: under clouds clounds

DTsea | 09/04/2014

You can just leave the pano roof in vent position.

Red Sage ca us | 09/04/2014

A 16' tall, delta-shaped, dorsal fin covered with solar panels would make an excellent solar sail. Combined with the low center of gravity, this would be a real winner!




Uh... Not really. That would be a horrible idea.

Car t man | 09/04/2014

Note, there is no "glass" on the panels I mentioned. And the power is not trivial, if used efficiently. Using AC to lower the temps is non efficient. Venting air, to avoid heated air accumulating and then using AC for 5 minutes, instead of 15, is already a plus, not to mention, it is better
if the interior of the car reach far lower temps than they do now in sun.

Furthermore, the 12v battery is lead acid. Whenever it isn't 100%full, it
is aging at an accelerated pace. So to keep it topped off, means keeping
it healthy for many many years. Lead acid is very stable and reliable, if
kept full. If not, it is fickle and degrades quickly. In any case, the
assumptions this has to be unsound, are false. Genuinely.

DTsea | 10/04/2014

Genuinely, the chance of TM doing thia are very low.

Car t man | 10/04/2014

Genuinely, I think this is as logical and to be expected of Tesla, as radar cruise control. I think of it only as a question of time, not if.
Same for back to grid, etc..

Timo | 10/04/2014

Tesla likes to keep things simple. Less things to break down. I too see probability that Tesla adds solar panels in their cars very low for at least couple of iterations of current models. It's changing tech though, so one day, who knows.

Brian H | 11/04/2014

Wrong locale for the wrong tech.

Car t man | 13/04/2014

The solar panel to 12v battery hookup is simple tech, all components extremely non complex and maintenance free (much less so than the 12v battery in this application it seems)...

There is no practical or economic reason against it.

Red Sage ca us | 13/04/2014

It's sort of like the sports cars that have exposed carbon fiber hoods... Or the circuit board graphics on entry level EVs... Having a solar panel on a Tesla Motors vehicle would send a message that is not intended. Basically, its tacky.

On the one hand, it gives the appearance that the CAR is solar powered, when it is not. So called tech reporters would either say it's a waste because you can't charge the car ith it, or that Tesla was stupid to use a technology that had limited usefulness. Either way, the intended purpose of the panel would either be ignored entirely or otherwise misconstrued.

Car t man | 13/04/2014

How about not paying so much attention to appearances, speculation, etc and just do what makes sense? What would be wrong with that? Everyone who is
clueless about how much power such a solar panel can actually provide, is
long overdue for a knowledge base update and will be all the more prepared
for an alternative energy future and understand how many panels it takes to power a house..

Red Sage ca us | 13/04/2014

Car t man asked, "How about not paying so much attention to appearances, speculation, etc and just do what makes sense?"

One of the main reasons why I like Tesla Motors is that is exactly what they do... Just because other American car manufacturers have routinely put 20 or more cupholders in seven passenger vehicles, didn't mean they had to follow suit. Just because luxury American cars have held to the archaic traditions long held by manufacturers of horse drawn coaches when detailing the interiors of their cars, didn't meant they had to fall in line. Just because other American car companies have gone out of their way to enforce the 'superiority' of the Internal Combustion Engine, while simultaneously claiming the 'inferiority' of electric vehicles, didn't mean that Tesla should agree.

Making solar panels standard issue on the Tesla Motors vehicles makes as much sense as putting snow tires on them as standard. Not everyone in the world lives in a place with a lot of sun. Not everyone in the world lives in a place with a bunch of snow. Some people routinely park their cars in a garage, or under a carport -- no sunlight. Some EV drivers never park anywhere they can't 'plug in'. Some people drive to work in the wee hours of the morning -- before sunrise. Some people go home at night -- after sundown. The likelihood of any car I operate being on snow is nil to none. Others have to deal with that eventuality six months a year -- they are a minority. So are the people who could take advantage of a mobile solar array on a car.

Car t man | 13/04/2014

Hence. make it an option? Simple? As for the first part: Just because others already did something, doesn't mean Tesla shouldn't, even when it makes sense. Especially since the 12v system is somewhat open to issues. To keep that issue at bay, you can also get enough power in shaded and relatively dark places also. And when in direct strong sunlight, also vent the car..