Solar Roof Option

[Garlan Garner]

I'm heavily involved with Solar - I even have a solar farm in Mississippi. If you want to see the progress of the solar panels on my house's roof....feel free SolarEdge

Anyway. There is no way to get enough solar cells on the roof to do anything on a Tesla. There is too much current required for a Tesla to make a solar option worth the expense.

I have 52 panels on the roof of my house and on average I produce approx. 50KWH per day.

That's approx. 1kwh per panel per day. It takes me approx. 25kwh per day to charge my MS per day. So.....I would need about 25 car roofs worth of real estate to charge my MS every day.

A solar upgrade would be Ludicrous.

Give me the full glass roof and I'll charge my car with my house panels.

 

[Booga]

Well... I can't fault your optimism. But there are only so many photons coming from the sun and physics is physics. Unless solar radiation increases by an order of magnitude, then a solar roof cannot be of much use. And if it does increase by an order of magnitude... well, we've got bigger problems!

This is exactly it. There isn't enough potential energy to capture. There are far better uses of a person's money if their goal is to generate electricity in a clean way. If the goal is range, you'll be better off putting the money into bigger batteries and/or dual motors on your car.

 

[FlatSix911]

I'm heavily involved with Solar - I even have a solar farm in Mississippi.
If you want to see the progress of the solar panels on my house's roof....feel free SolarEdge

A solar upgrade would be Ludicrous.

 

[X-Ki]

Induction might be the solution?
I had a clear moment today ;-) and though of the following... Why not lay some cables in the road and give energy by induction or so ... Wouldn't it be possible to give energy by induction on the main roads only? when driving on the main roads you don't use battery power but get energy from the "net" ... just an idea, trying to save the world ;-)... somebody can add some scientific arguments?

 

[Garlan Garner]

This idea just has too much overhead required for Tesla. They could never make money with it.

 

[EVnut]

I'd take a solar roof of it could gain me 10% increase in efficiency.

[/QUOTE]
Right. But there's no way you are going to increase the efficiency of a BEV by adding solar panels. It doesn't work that way. Best you can hope for is increased range at the cost of a bit of efficiency (having to now lug around the PV system). Now in a gasoline hybrid, when you add more electric propulsion, you can make a case for increased efficiency by generating solar energy. But that's a different situation where you are replacing ICE propulsion. With a BEV, you're merely adding more energy... not increasing efficiency.

 

[JRP3]

His point was that even with 100% efficiency, it's not worth it. .....

You missed the entire point of my post. Try this, what's the "efficiency" of buying expensive rims for your car? What's the payback from them? What's the efficiency of carbon fiber trim and accents? What's the payback from them? Pick any other option you want for a vehicle, and tell me the efficiency and payback time that makes it "worth it." It's pretty simple, a solar panel option is one of very few possible options you could get that would return anything.

 

[nwdiver]

It's pretty simple, a solar panel option is one of very few possible options you could get that would return anything.

??? There's no return if it costs more than it returns... the primary benefit of having a solar roof is 'Look, I have solar panels on my roof' At which point it's really not any different than any other accessory.

If the solar option is <$1/w then I'll bite... I'm not holding my breath... More likely it'll be cheaper to add ~5kWh of battery.... which would be far more beneficial.

 

[Garlan Garner]

You missed the entire point of my post. Try this, what's the "efficiency" of buying expensive rims for your car? What's the payback from them? What's the efficiency of carbon fiber trim and accents? What's the payback from them? Pick any other option you want for a vehicle, and tell me the efficiency and payback time that makes it "worth it." It's pretty simple, a solar panel option is one of very few possible options you could get that would return anything.

Efficiency?

Payback = Joy.
I don't mind buying joy and happiness when I can. I'm going to buy LOTS of joy with my M3. I'm going to be sitting in joy and happiness.

That's why joy and happiness is priceless.

 

[Garlan Garner]

??? There's no return if it costs more than it returns... the primary benefit of having a solar roof is 'Look, I have solar panels on my roof' At which point it's really not any different than any other accessory.

If the solar option is <$1/w then I'll bite... I'm not holding my breath... More likely it'll be cheaper to add ~5kWh of battery.... which would be far more beneficial.

Electricity is far too cheap to cover up the Full Glass Roof.

It only takes about $2.31 in electricity to fully charge my MS after 210 miles in Chicago. That's about $1 per 100 miles. An 12 hour charge from a solar panel ( about all you can fit on the top of an M3) would only yield about $0.11 worth of electricity. NO thanks.

At $.011 per day ....I wonder how many decades it will take to re-coup the price of a solar roof.

 

[Topher]

While I have no doubt my math is simplified and wrong in many places

Just a nitpick, but you missed the efficiency loss for having no tilt. Most insolation maps figure tilt at latitude (i.e 40° tilt if you live at the 40th latitude). Figure another 20% loss from having no tilt.

Thank you kindly.

 

[roblab]

And it seems that the base of this whole discussion is so that you won't have to plug in??? I actually timed myself plugging in my 90D yesterday. One second, as I passed by going to the door. One second. What is the point? Every morning my car is at 90%, or more or less as I decide. Compare this to driving down the street to get gas a block away twice a week. Would it take 5 minutes? Ten? Huh? And I have solar, have not paid an electric bill for over ten years. Supercharging is faster than getting a coffee, and also free.

And then you want me to cover up my beautiful pano roof so I can save, what? Time? Money? There is no discussion here.

 

[nwdiver]

And then you want me to cover up my beautiful pano roof so I can save, what? Time? Money? There is no discussion here.

Yup; I love solar PV. I've got ~10kW on my house and I've helped friends install another ~50kW but it doesn't belong on cars... at least not for the next 5-10 years... probably not ever... except as eco-bling

 

[Garlan Garner]

Yup; I love solar PV. I've got ~10kW on my house and I've helped friends install another ~50kW but it doesn't belong on cars... at least not for the next 5-10 years... probably not ever... except as eco-bling

Is your house panels monitored via a website? Do you have a URL for your panels?

 

[nwdiver]

Is your house panels monitored via a website? Do you have a URL for your panels?

My house isn't but a couple of my other installs are... both systems in Andrews, TX

 

[JRP3]

There's no return if it costs more than it returns

Come on NWD, you're smarter than this, it's like you're actively trying to miss my point by putting an optional solar panel into some special category. Please tell me what is the return of any other expensive option on the vehicle? Wheels, upgraded paint job, carbon fiber trim, alcantara headliner, pano roof, etc.? The fact is that unlike any other option you could spend money on, a solar panel will put some energy back into the vehicle, and will combat vampire losses when not plugged in. Compare that to an energy sapping pano roof, which decreases range when open, and increases cooling loads in the sun. I know some people love the pano roof, great, enjoy. I don't want one, for the previously mentioned reasons, along with potential leaks and mechanical issues, (which some people have in fact experienced). I don't want a hole in my roof since I spend no time looking up at the sky when I'm driving. I do want a vehicle that won't drain the battery down to nothing when parked for an extended time away from a plug.

 

[JRP3]

And it seems that the base of this whole discussion is so that you won't have to plug in???

That's not the discussion at all. Have you read any of my posts? Please at least read my most recent and see if you come to the conclusion that it's about not plugging in.

And then you want me to cover up my beautiful pano roof so I can save, what? Time? Money? There is no discussion here.

You're right about that, since you aren't addressing what is actually being discussed. I don't want to do anything to your pano roof. I do see the value in having an option to have solar panel instead of a pano roof that I don't want. Key word is "option".

 

[Garlan Garner]

Come on NWD, you're smarter than this, it's like you're actively trying to miss my point by putting an optional solar panel into some special category. Please tell me what is the return of any other expensive option on the vehicle? Wheels, upgraded paint job, carbon fiber trim, alcantara headliner, pano roof, etc.? The fact is that unlike any other option you could spend money on, a solar panel will put some energy back into the vehicle, and will combat vampire losses when not plugged in. Compare that to an energy sapping pano roof, which decreases range when open, and increases cooling loads in the sun. I know some people love the pano roof, great, enjoy. I don't want one, for the previously mentioned reasons, along with potential leaks and mechanical issues, (which some people have in fact experienced). I don't want a hole in my roof since I spend no time looking up at the sky when I'm driving. I do want a vehicle that won't drain the battery down to nothing when parked for an extended time away from a plug.

We are all getting a pano roof.

I'm going to enjoy being parked at a SC at night....looking up at the stars. That's going to be a huge instant return on investment.


Again..anyone with a solar roof is going to get a return on investment in ....lets say.....35 years. You just can't get enough solar cells on the roof of a car to make the investment worth it.
And we all know that solar cells pointed straight up to the sky are going to terribly inefficient.

 

[ecarfan]

Come on NWD, you're smarter than this, it's like you're actively trying to miss my point by putting an optional solar panel into some special category. Please tell me what is the return of any other expensive option on the vehicle? Wheels, upgraded paint job, carbon fiber trim, alcantara headliner, pano roof, etc.? The fact is that unlike any other option you could spend money on, a solar panel will put some energy back into the vehicle, and will combat vampire losses when not plugged in. Compare that to an energy sapping pano roof, which decreases range when open, and increases cooling loads in the sun. I know some people love the pano roof, great, enjoy. I don't want one, for the previously mentioned reasons, along with potential leaks and mechanical issues, (which some people have in fact experienced). I don't want a hole in my roof since I spend no time looking up at the sky when I'm driving. I do want a vehicle that won't drain the battery down to nothing when parked for an extended time away from a plug.

I'm with you when you talk about the impracticality of the pano roof -- and that most vehicle options are just for fun -- but you lose me when you grossly exaggerate vampire loss as draining "the battery down to nothing". That takes many, many weeks if not months when a Tesla is parked with a fairly high state of charge. And adding PV to the roof of a vehicle produces very small amounts of power and requires the vehicle to be parked out in full sun. How many people park in unshaded or uncovered areas for weeks or months with no access to a plug? Some yes, but in an airport parking structure you are fully covered.

I am sure that Tesla has no plans to offer an option of PV cells on the roof. They know that the potential advantages are minor in comparison to the high cost and that only a small fraction of buyers would select such an option.

 

[Booga]

Come on NWD, you're smarter than this, it's like you're actively trying to miss my point by putting an optional solar panel into some special category. Please tell me what is the return of any other expensive option on the vehicle? Wheels, upgraded paint job, carbon fiber trim, alcantara headliner, pano roof, etc.? The fact is that unlike any other option you could spend money on, a solar panel will put some energy back into the vehicle, and will combat vampire losses when not plugged in. Compare that to an energy sapping pano roof, which decreases range when open, and increases cooling loads in the sun. I know some people love the pano roof, great, enjoy. I don't want one, for the previously mentioned reasons, along with potential leaks and mechanical issues, (which some people have in fact experienced). I don't want a hole in my roof since I spend no time looking up at the sky when I'm driving. I do want a vehicle that won't drain the battery down to nothing when parked for an extended time away from a plug.

There are two issues:

1) The savings are negligible, maybe 5 cents per day, on an ideal day.
2) You're probably putting the car through more strain than normal and so you're decreasing the life of the electronics and battery. Solar power isn't as stable as the power from a proper charging outlet and so this isn't good for lithium ion batteries nor the electronics that get the power "ready" for going into the battery.

My estimation is that you're probably actually losing more money on an economic basis - it might not show up, because it's in the form of wearing out your car, so it could be years, but that's still a very real loss.