Solar Roof Option

[Garlan Garner]

Believe it. I've had cars with sunroofs, didn't spend time looking at the sky when driving, hopefully no one else does either. Have you people never seen the sky before? You enjoy driving with your necks craned back in uncomfortable positions?



I've been in an X and found the extra glass to be annoying and the sun visor inadequate because of it. Not really a fan, though I understand others may be.

L5 AP is going to eventually allow me to recline and watch the planets and stars while driving. I'm certainly going to do it.

BTW.... I love having the open sky above my head when I have my ICE sunroof open. Its not a convertible, however its the closest I can get to it right now.

 

[JRP3]

L5 AP is going to eventually allow me to recline and watch the planets and stars while driving. I'm certainly going to do it.

That's an interesting possibility, but I don't think it's going to happen with the first gen Model 3's.

 

[Garlan Garner]

That's an interesting possibility, but I don't think it's going to happen with the first gen Model 3's.

I totally disagree.

 

[ecarfan]

L5 AP is going to eventually allow me to recline and watch the planets and stars while driving. I'm certainly going to do it.

The key word being "eventually"...

 

[Topher]

According to this data, I get ~7.5 sun-hours averaged over 365 days.

That is at optimal tilt, and South facing. Unless you are planning on parking on a 40° ramp, facing South, every day, you need to use the chart for Horizontal collector. This is one of the reasons that house roofs are a better place for solar panels than car roofs.

Thank you kindly.

 

[SageBrush]

Unless you are planning on parking on a 40° ramp, facing South, every day, you need to use the chart for Horizontal collector.

And one had best plan to only drive at night, and place the ramp where there is no shading ... ever.
Other than those caveats -- no problem.

Joking aside,
How much can a solar roof attenuate interior cabin heat gain when a car is parked under a noon-ish sunny day ?

 

[Topher]

How much can a solar roof attenuate interior cabin heat gain when a car is parked under a noon-ish sunny day ?

Well, Solar cells are generally about 15% efficient, so that means they are removing 15% of the energy of the sunlight. The rest either passes through or is absorbed by the substrate, both of which probably heat the car to some extent. Think of 'passing through' as clear glass, and 'being absorbed' as either the tint in the glass or the metal in the roof (whichever you are replacing).

Thank you kindly.

 

[SageBrush]

Well, Solar cells are generally about 15% efficient, so that means they are removing 15% of the energy of the sunlight. The rest either passes through or is absorbed by the substrate, both of which probably heat the car to some extent. Think of 'passing through' as clear glass, and 'being absorbed' as either the tint in the glass or the metal in the roof (whichever you are replacing).

Yeah .. I was unsure about the part I bolded.

 

[FlatSix911]

To think that the car could potentially gain 5 Kwh from a day's solar charge is pretty huge in my opinion. My daily commute is only 3 or 4 miles to the train station. I could legitimately not need to the charge the car for a very long time as a result. If it cost $1000-$2000 I may opt for it.

How about to allow indefinite street parking with 0 vampire drain. Even that would be useful to some. This tweet reply almost confirms it. Twitter

I'll leave esthetics to Elon to figure out.

Agreed. Many Model S owners have experienced an average 3-4 mile daily vampire loss and less than 1 year 12V battery life ...
Any reason not to hook up a battery tender to the 12 volt battery ?

Aside from the nice aesthetic add to the Model 3, the roof would be best suited to handle the vampire drain and recharge the 12V battery.

 

[AudubonB]

On the question of melting snow/ice of solar roof tiles:

Assume worst case of 1" of freezing rain on the roof. That's 5 pounds of ice per square foot, which requires 144 BTUs per pound (or 688 BTUs or 200 Wh total). That represents 2 hours of full sunlight falling on that square foot (at 100% efficiency). If all the melting happened by solar power from the PV itself (presumably stored from previously), that is 13 hours worth sun energy (i.e. 3-4 days worth). Worst case.

What probably really happens is that the sun does most of the melting directly when it hits the dark surface of the tiles, melts a bit of the snow or ice, which promptly slides off the roof. Most regular solar panels around here shed their snow loads by noon on the first sunny day after the storm, so you lose a few hours of production. In the winter when production isn't great anyways.

Thank you kindly.

FROM REAL WORLD EXPERIENCE:

No! No! No!
(That's to your first straw man paragraph, which you acknowledge).

No! No! Kinda!
To your second paragraph.

Snow, hoarfrost and the like have the frustrating tendency to coat an entire surface. That leeetle top left corner that you'd want to be the solar camel's nose that will topple the whole tent....well, it can take a long time: not this morning, not until late afternoon...oops! there goes the sun; better luck tomorrow...


...and, even so, that melted corner bites back with the nefarious trick of NOT sliding off the roof, but worming its way under the frozen bit just below it and, remembering that it was only marginally above freezing when it started its journey, quickly gives up those calories, jumps back below the melt/thaw point, and snugs up to its newest bestest friends....once again as ice.

And so it goes.

But you most definitely are correct in surmising that, appropriately distributed, a little heat - directly solar or otherwise - can go a long way.

What one wants to do is to raise to melting point the entire few molecules directly adjacent to the tiles/shingles/roofing surface, so that en masse they create a near-frictionless surface and shrug off all the still-frozen layer above them.

This is the battle we fight with our many hundreds of square feet of solar panels in Alaska. And if you don't get that bottom strip melted, it really acts as the ice dam that it is in fact, and frustrates the rest of your labors.

So, from years of experience, I am all for a high-quality PV panel-cum-snow melter. There is tremendous payback for same in terms of real-world increase in efficiency.

 

[Topher]

That's to your first straw man paragraph, which you acknowledge

It wasn't a straw man. It was a worst case scenario.
Straw man - Wikipedia

This is the battle we fight with our many hundreds of square feet of solar panels in Alaska.

Is your claim that Alaska should be considered average for the rest of the US? I wasn't even trying to pretend that my experience in Maine should be considered for the rest of the US.

Thank you kindly.

 

[clp1]

Clear solar panels are a possibility...

Fully transparent solar cell could make every window in your house a power source


and


Revolutionary new solar windows could generate 50 times more power than conventional photovoltaics

 

[Garlan Garner]

The key word being "eventually"...

Absolutely.

The way I figure it...according to Elon AP2.0 is going to equal AP1.0 by December or January.

I find it difficult to believe that it's going to take Tesla 11 months to develop full Autonomy. For sure Tesla can achieve that. I'm 100% confident. The problem for me is going to be - will it be allowed to become legal by politicians. That's the only hurdle I forsee.

 

[Garlan Garner]

That is at optimal tilt, and South facing. Unless you are planning on parking on a 40° ramp, facing South, every day, you need to use the chart for Horizontal collector. This is one of the reasons that house roofs are a better place for solar panels than car roofs.

Thank you kindly.

Unless your house faces south. Like mine.

Then you put them on the east and west sides of your house. I have found that I'm out pacing south facing panels in the summer - especially with my west facing panels.

 

[Garlan Garner]

Agreed. Many Model S owners have experienced an average 3-4 mile daily vampire loss and less than 1 year 12V battery life ...
Any reason not to hook up a battery tender to the 12 volt battery ?

Aside from the nice aesthetic add to the Model 3, the roof would be best suited to handle the vampire drain and recharge the 12V battery.

First of all - I fully understand the term vampire loss, however it is accompanied by a negative connotation. Look, I want my Tesla to respond to the app that I will be using to control it. I want my Tesla to control its cabin temperature ( even if the cabin temp remains just fine ). I want my Tesla to pay attention to about 20 -25 applications as it is parked. If all of that only costs me 5 miles.....out of 250 FINE.

I lose 5 miles worth of gas on warm-up's waiting at stop lights, congestion and the like each day in Chicago's rush hour stop and go traffic.

I would volunteer to willingly give up a 5 mile daily vampire loss each day to have that Tesla Glass roof. If I'm stupid enough to plan a trip concerned about being short by 5 miles...then yes...I'm stupid.

 

[Garlan Garner]

Clear solar panels are a possibility...

Fully transparent solar cell could make every window in your house a power source


and


Revolutionary new solar windows could generate 50 times more power than conventional photovoltaics

Fantastic, however as soon as someone fits that product into a $35K car and/or making it a financially feasible option - that enough people can afford/want for the price....fine.

 

[theganjaguru]

Yeah, but Toyota also thinks fuel cells are practical too.

Well apparently Elon agrees in solar roofs for the Model 3. You're point is now null and void.

YAY! I'd definitely take a solar roof if can at least power the HVAC on a bright day and/or give me a few free daily miles. . Climate control can really have affect on range.


Tesla Model 3 will probably have a solar roof option – maybe even ‘deployable’, says CEO Elon Musk

 

[ecarfan]

I find it difficult to believe that it's going to take Tesla 11 months to develop full Autonomy. For sure Tesla can achieve that. I'm 100% confident.

In Sep 2014 Tesla started producing AP1 cars and announced the first AP software release was coming "soon".

The first AP software release came in Oct 2015. 13 months later. And all it did was keep the car in the lane on a freeway and maintain distance from the car in front of it. But not terribly well. Still, it was a big step forward.

Now you think that, as the first AP2 equipped cars are hitting the roads, in less than a year Tesla will be releasing new AP software that will provide Level 5 autonomous driving?

I disagree. Tesla is years away from Level 5 "full autonomy" on public roads (not just freeways and divided highways but suburban and city streets, parking lots, driveways, etc.).

 

[Garlan Garner]

In Sep 2014 Tesla started producing AP1 cars and announced the first AP software release was coming "soon".

The first AP software release came in Oct 2015. 13 months later. And all it did was keep the car in the lane on a freeway and maintain distance from the car in front of it. But not terribly well. Still, it was a big step forward.

Now you think that, as the first AP2 equipped cars are hitting the roads, in less than a year Tesla will be releasing new AP software that will provide Level 5 autonomous driving?

I disagree. Tesla is years away from Level 5 "full autonomy" on public roads (not just freeways and divided highways but suburban and city streets, parking lots, driveways, etc.).

Whenever Tesla does something on it's own....they do it.

For some reason vendors hamper Tesla's production. Now that AP2.0 is fully in house...I'm confident.

Mobile -Eye messed up the timeline. Now they are gone.

 

[Garlan Garner]

Well apparently Elon agrees in solar roofs for the Model 3. You're point is now null and void.

YAY! I'd definitely take a solar roof if can at least power the HVAC on a bright day and/or give me a few free daily miles. . Climate control can really have affect on range.


Tesla Model 3 will probably have a solar roof option – maybe even ‘deployable’, says CEO Elon Musk

Elon has said many things about the M3.

It will have the option of Tesla Glass <----- That's a quote
It may have the option of a solar roof <-------That's a tweet

Does anyone have solar panels here? Just because a solar panel is outside while the sun is shining does not mean that it will be producing enough for any particular purpose. It would have to be facing the correct direction at the correct angle.

The average solar panel is putting out 270watts at 13 voltsDC at the perfect angle and temperature and direction.

Here are a bunch of them you can investigate:
Buy Solar Panels - Kyocera, Mitsubishi, Sanyo, Sharp, REC Solar and More!s

A solar panel can't even power a blowdryer (1000W) or a blender (300W) or a Hedge Trimmer (450 W) and there is a desire to use it to power an Air Conditioner Compressor?
I opt not to replace my Tesla Glass for 270 watts of power when the sun is shining.

Look at my signature below and watch the panels on the roof of my house - I have 52 examples up there. You can track the progress of "each" of my panels every day. Go to the layout tab.
https://monitoringpublic.solaredge.com/solaredge-web/p/site/public?name=Garner House#/dashboard