mspohr
Well-Known Member
They also think hydrogen fueled cars are practical.
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Solar Roof Option
- Thread starter theganjaguru
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- Model 3
JRP3
Hyperactive Member
I voted yes because I like the idea of having something that can eliminate the vampire drain, I think properly done panels can look good, like the one on the Karma, and because I think it's cool to have a vehicle that is at least somewhat self sustaining. Unfortunately because of the roof design of the 3 there isn't much area available, unless they covered some of the rear window glass over the rear seats as well.
BravoSarah
Member
That would be a great idea. If someone could build a solar panel efficient enough to be effective on the roof of an EV, they'd become very wealthy.
I'd love to see it in my lifetime.
I'd love to see it in my lifetime.
physicsfita
Member
Unfortunately, solar irradiance is about 1000 W/m^2 -- Solar irradiance - Wikipedia, the free encyclopediaThat would be a great idea. If someone could build a solar panel efficient enough to be effective on the roof of an EV, they'd become very wealthy.
I'd love to see it in my lifetime.
Assuming 100% conversion (which won't happen for many reasons), and assuming you somehow have 2 m^2 of panels perfectly placed and tracking the sun (good luck!), you MIGHT get 6 mph of charging (assuming no charging losses). More realistically, you'll get maybe 1 mph at best (panels can't use the low-frequency end of the spectrum for quantum-mechanics reasons, and you can't get ideal tilt) -- for all the weight penalty and expense, plugging into a 120-V outlet will almost certainly work better for you.
JRP3
Hyperactive Member
I think they are less efficient, but an integrated conventional panel needn't weigh more than the planned glass roof. The weight penalty that some claim wouldn't really exist.
tdelta1000
Active Member
JRP3
Hyperactive Member
Not sure why you think it would be that expensive. Roof sized solar panels would be a few hundred dollars, and Elon might know a solar panel company that could make them cheaply and give him a deal...
OK, but I still think it's a gimmick. Park out in the sun all day long to get an extra 2 or 3 miles of range (at most; given the non-glass roof area of the 3 it would probably be only about 1 mile per day).
JRP3
Hyperactive Member
Sure somewhat of a gimmick, like many features in cars, though this one actually gives you some range, and, more importantly, kills the vampire drain. Remember, people spend thousands on things like rims which do nothing for the car other than look different, this actually produces something usable.
I agree.. even if its 1/2 a mile.. its 1/2 mile that someone without a panel would not have. Not practical, but it does something
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If that same bit of capital equipment were instead put where it belongs (up on the roof of a building or shade structure) along with the rest of a reasonable solar array - it can capture the sun's energy efficiently all day. Correct orientation. No shade. And it can work up there for 60+ years. And when you plug your car in at home, you'll get more than the few feet of extra range that the panel would have given you were it attached to your car.
Now you take that bit of capital equipment (no matter how small) and attach it to your car that will likely NOT last 60+ years. Where the orientation will likely never be optimal, and where you will park in the shade, in the garage, under a car cover etc.
You are correct that it is not practical. And if we want it to "do something" why not have it do more?
Now you take that bit of capital equipment (no matter how small) and attach it to your car that will likely NOT last 60+ years. Where the orientation will likely never be optimal, and where you will park in the shade, in the garage, under a car cover etc.
You are correct that it is not practical. And if we want it to "do something" why not have it do more?
JRP3
Hyperactive Member
Because all those panels on the roof are completely useless for extending range or eliminating vampire drain any time the car is not plugged into them or anything else. I do hope people realize that most vehicles spend most of the daylight hours in open parking lots, not connected to anything. The idea that if you put a panel on the car then you can't put one on your house isn't reasonable. You can do both.
I think it is very realistic to think a car with a solar roof and hood could generate 500 watts for 8 hrs a day in many places on the planet. That is 4kw/hrs, around 14 miles of range. I'd love it if my car would have 10-15 miles more range after work. I would also love it if my car gained 50 miles of range when I was parked for camping trips or at the airport for a few days.
A pano roof is expensive, an aluminum hood is expensive, you could subtract these costs from the costs of the panels likely.
A pano roof is expensive, an aluminum hood is expensive, you could subtract these costs from the costs of the panels likely.
The first problem is voltage. Solar cells are 0.5 apiece. So 30 or so will charge your 12 volt accessory battery. In order to charge the 375 volt battery pack you would either need 750 solar cells, or DC voltage step up electronics. The second is wattage, which has been addressed above. So no range increase.
If you want to negate vampire drain, put a small solar panel in the window, connected to the acc circuit. (Does the Tesla shut off the 12v outlet when the car is off?) Price: $50 at most.
Thank you kindly.
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