Solar roof


Is it possible to have an integrated solar panel on the roof that charges the battery while in the sun?


olanmills: +1!!!

Even if the whole car were covered in magic solar paint (good luck with body work) there just isnt enough energy there shining out of Mr. Sun. Cars are too small and too heavy to move by solar power.

Now... if we invent magic super light materials that could make a safe car that weighs next to nothing (don't forget still needs seats, displays, computers, brakes, AC, motor, inverter, wire harnesses, tires, wheels.......) then it would not need so much power. Even then, the body of a modern car doesnt weigh much. For example a Subaru Outback body weighs only 700 lb and it is STEEL

I know that there isn't enough solar energy to meaningfully charge the battery for additional range. However, I would be interested in a solar roof option (say, 300w nominal) for maintaining the battery, especially to cover the drain of the on-board computers and communications electronics, interior cabin climate control, and for battery temperature maintenance (cold or hot). If you leave your car at the airport for a week, it would be nice to come back to a car that hasn't lost any charge over that period of time. If you park outside at the mall, it would nice to have climate control kick in using solar on hot days, or have the heat on in the cold. Finally, in the very cold or very hot, the car must act to protect the batteries, potentially increasing the longevity of the batteries.

Assumes a)outdoor parking in b) enough sunlight. Probably irrelevant to airports. For the $5K or so a trivial panel costs on a car, you could probably boost the battery capacity by 15-20kWh. Much better use of $$.

Solution to too little Solar irradiation: Move Earth closer to Sun. That has some tiny negative effects on life on Earth, but who cares, at least we could then drive cars powered only by Sun.

More seriously, we can get a lot more solar energy from fixed structures, even from roads and parking lots with proper tech, then use that with wireless charger to charge cars. Something like large airport parking lot and big parts of the runway could be turned to rather large solar power plants if we ignore the costs (=assume costs of manufacturing such installments goes down to feasible numbers in future).

You don't need to use solar paint for cars if you have wireless charger infrastructure with solar power plants (or any other kind of power plants) feeding those wireless chargers.

If you go to place where you don't have any charger infrastructure you are in no worse situation than with gas cars without gas stations nearby, and if there is enough Sun in that middle-of-nowhere place you could always get some large canvas solar panel folded in your trunk like large tent in future (cheap and large, not necessarily efficient panel).

Again, the issue here for me isn't about usable range out of a solar panel roof. For me, the primary risk with Tesla's cars have to do with the battery. There are all the risks wrt Tesla being a young and unproven company as well as the design and manufacturing of a new product. If Tesla was making ICE cars, that would all be there too. But the big additional risk is the very real potential for some sort of significant damage to a part of the car that costs as much or more than a full ICE replacement. The replacement costs given by Tesla Motors are after 8 years and are presumably very much subsidized. I also buy cars to keep for a very long time. So for me, the solar panel roof is about extending the potential lifespan of the battery by providing maintenance charge, reducing the effect of on-board electronics that are running when the car isn't, and maintaining the battery's temperature. The significant risk is parking the car for extended periods of time where an outlet isn't available. There should be enough solar energy falling on the roof for 200-300 watt nominal rating with actual energy produced is 70% of that for 5 hours a day. The cost of the panels should be $400-600, the additional charger and wiring is probably $500, the glass roof is already $1500, so $3500-4000 seems about right. Putting that towards the main batteries increases the weight of the car significantly.

Off the rails 3X! You're persistent, anyway.
1)subsidized? By whom, pray tell? Elon isn't fooling when he targets 30% gross margin (by getting into economies of scale, and vertical integration to "capture" the markups that normally sit between each step).
2)Extending the lifespan with trivial hard-to-integrate DC current from a tiny solar array? Dream on. The cost is $000s btw, not $00s, in the real world. All in, you'd be lucky to get much under $20/W capacity installed.
3)Significant risk? Taken only by choice, and normally in places where the sun don't shine much. Neither the problem nor the solution make sense.

Batteries are not subsidized, solar panels might be.

Cost of the solar panel depends greatly of quality of the panel. Low conversion rate panels don't cost much, but obviously require larger area to get same power. For just maintenance charge you don't need much power so low cost panel (solar paint) could be enough. IMO creating maintenance charge to prevent total battery depletion while parked is the only reasonable way to use solar panel in a car.

As option to places where Sun shines and to people that park outside. Not for everyone for sure.

The solar panel (or in the future solar paint-like surface laminate) may not be a major charging source but would be a nice auxiliary and anti-bricking device - well worth it option if it saves a $24,000 battery pack - not a simple greenwash. Worth developing as an package and some early adopters will pay for it...

No OlanMills your clearly "not getting it".
Did you even read any of my posts?
I never said that the solar paint/glass would provide enough energy to power the entire car all the time so that it could be built without a plug.
I was saying that maybe in 20-30 years solar cells/glass/paint might be being made so cheaply that it might be worth it (as an option for those who park outside/off street/ or place of work has outdoor parking)
Did you read my example?
If we had 300 kWh battery packs by then and you are only using on average 15 kWh per day and the car could generate 10 kWh of solar power for the pack when parked outside then you are only USING 5 kWh per day...carry that forward and you would only have to plug in once every two months! In this respect it might be worth it, again after 20-30 years of deveopment and as an option for people to choose if it makes sense for them in terms of where they park.

It's really not that difficult a concept.

@teddyg, your mistake is to estimate that you could get 10kWh / day from Solar. You can't. 1kWh is more like it. There just isn't enough energy coming from the Sun and car doesn't have enough surface to give you more, no matter how good tech you could get.

Just to add if the solar cells are cheap enough it might still make sense if you could only get a few kWh per day...might as well take it if you has been mentioned here it would be a great "anti-bricking" or maintainence charge.
Wouldn't it be great if you could park your Tesla at the airport and it maintained its state of charge when you got back in 2/3 weeks?
The point is at some point it may be very reasonable to put solar paint/glass on a car...but it really all depends on the price of the solar cells...I figure if the trend is anything to go by solar on cars in 20-30 years is certainly not science fiction. It may happen much sooner than that for the maintainence charge alone...people who travel a lot might really like coming back to a Tesla with the same range that they left it with and the comfort of knowing that it would be impossible to brick...I could see those people paying $3500 for that security as an option right now...let alone in 20-30 years.

Uggghhh Timo you are killing me...its about the price of the solar cells...who cares if you only got 1 or 2 kWh per day if the cells are cheap enough its worth it...and I think they just might be in 20-30 years...jeeez.
And I think if you look at the TOTAL surface area of the car (paint AND glass - see my link to solar window technology above) then I bet 5 kWh could be possible eventually...someone else actually said 20 kWh could theoretically be possible but let's say 25% of that by 2035...all depends on price though.

There is even research going on for infra-red solar technology...that could potentially create solar energy at NIGHT...again way way off but who knows what is possible.

20kWh ignoring all the realities, like the car orientation to the Sun and the fact that you don't get Sun max energy entire day including the night. About 1kWh/day is pretty close to max you could get in very sunny spot in reality. With max realistic efficiency and with entire car covered by solar paint.

Article discussing Infra-Red Solar possibilities...again before you attack me I realize this is brand new stuff and output is very low...but you have to start somewhere and it seems that the scope for improvement is there. Remember 20-30 years guys.

And solar glass Timo not just the paint...I really love how you seem to be so sure of your technology predicitions in 20-30 years some point in the future people might be laughing at those predicitons...time will tell.

Someone also mentioned breakthroughs in strong lightweight materials and lighter batteries in the future that would mean more range for less kWh's...another thing to remember in terms of miles of range that could be generated via onboard solar cells. 1 kWh generated in 2035 might mean 6-8 miles of range compared to just 3.5 miles today.

You are missing the point. There just isn't enough energy coming from the Sun. You can't get better than 100% efficient and Sun doesn't shine every direction at once so only part of the car is pointing anywhere near the Sun at any given time.

It doesn't matter how good the tech gets, you still are not getting anywhere near 10kWh / day in real world. This is not "technology prediction" it is prediction that Sun doesn't get any brighter and cars still look like cars do after 20-30 years time.

1kW/m^2 is maximum you get from Sun directly overhead facing directly at the Sun. Average is a lot less and there is no such thing as perfect conversion of energy.

teddyg won't or can't listen to reality. He's all balled up in concept so ignores the reality of energy potential and basic physics. Let him live in his little fantasy. Some of his comments are beyond laughable. For example, who would leave a car like this out in the sun for weeks at a time while on a trip as he suggests? I live in Virginia so don't leave cars at LAX often, but when I needed to leave my F-150 there for three weeks in 2011, it was parked in a covered, secure location.

I have one of the few Tesla ownership situations where I will drive 100% free most of the time - the 84 solar panels on my barn roof provide 27kw, double our current usage, so we have excess energy to burn in our car. But those panels take up an area that is about 30 feet by 70 feet... which is the practical issue - they are oriented correctly, within a few degrees of both vertical and horizontal perfection for solar collection - a function which would be impossible within the limitations of a car envelope. The panel designer/installer refused to install a couple panels where I would have even minimal shading for a few hours at the end of the day due to nearby trees, as even a short loss of sun gain would destroy the cost/benefit for those few panels.

The solar panels on my saliboat can maintain the house batteries when it is idle, but even they must be aimed for maximum efficiency to do anything. Large, flat panels on a building roof or in a field with permanent orientation and fixed installation relative to the sun will always be more effective than curved panels/paint/glass on a car, with all the vagaries of shade, orientation, etc.

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