Author Topic: Solar PV on electric cars  (Read 3935 times)

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Offline nctnico

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Re: Solar PV on electric cars
« Reply #150 on: August 03, 2019, 03:06:15 pm »
Install costs of solar on cars will always be immense as long as they are 2D curved, there's just no way to do it cheaply.
Why would the install cost be huge? They make curved roofs for cars as well. It is just a matter of feeding solar cells into a machine which sticks them on a curved substrate which then as a whole gets mounted to a case as the roof using a robot. No manual labour involved at all (well, maybe in China where labour is still cheap). The uniformity of car roofs (given the number of cars produced of each model) is what is making the installation costs per m2 go down to near zero.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Marco

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Re: Solar PV on electric cars
« Reply #151 on: August 03, 2019, 04:56:48 pm »
Curved metal roofs are pressed and powder coated.

For a solar roof with some durability you need to put a lot of flat solar panel segments into a curved mold, put curved laminated glass on top with the same manufacturing costs as a windscreen vacuum pull it to fill all the voids with resin and cure it.

Replacement costs if there is no old stock or junkyard replacement will be fun.
« Last Edit: August 03, 2019, 04:59:16 pm by Marco »
 
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Offline nctnico

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Re: Solar PV on electric cars
« Reply #152 on: August 03, 2019, 05:30:36 pm »
High replacement cost is becoming normal. Scratch the bumber of your car and check how much it costs to replace. Worse if it has sensors.
Besides that I'm quite sure the cost of a metal roof is equal to that of a glass roof. Glass in itself is a very cheap material. And don't get fooled by high replacement costs of a wind shield. The profit margins are huge.
« Last Edit: August 03, 2019, 05:48:07 pm by nctnico »
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Offline bdunham7

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Re: Solar PV on electric cars
« Reply #153 on: August 03, 2019, 09:26:34 pm »
The failure in your reasoning is that efficiency doesn't matter. Only cost versus benefit does. A large part of a solar panel setup are cost for the space itself and installation costs. Putting solar panels on roads and / or on roofs of a car reduce the space and installation costs so the financial picture may be much more favourable even though the solar panels produce less electricity per surface area.

Perhaps this is where there is a difference in our analysis, so if yours is based on any actual numbers I'd be interested in knowing them.  For me, "installation" costs including permitting were about 25% of total system cost.  The balance was materials, and the bare panels themselves were about 50% of that.  I don't know what it would be today, because material costs have plummeted.  The value of the space was inconsequential as it was just an unused roof with no other potential use.  If you just don't have roof space or you just don't want to give it up, then I suppose the equation changes--for you.  But if I were a sensible government agency looking to subsidize solar energy to reduce carbon emissions or whatever, I would just go looking for someone else to subsidize who was willing to use their roof, not pour the money into something far less efficient sorry, cost effective.

As for your other comment about the Lightyear One's tail and hypermileage, there are already cars available in showrooms with CDs of 0.22, 0.23 (Model 3) and 0.24 (Model S).  Even if the vaporware specs make it into a production car, 0.20 is not so much of an improvement as to allow the claim of "way better mileage".  Perhaps slightly better.

 

Offline Someone

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Re: Solar PV on electric cars
« Reply #154 on: August 03, 2019, 11:46:24 pm »
I'm quite sure the cost of a metal roof is equal to that of a glass roof. Glass in itself is a very cheap material.
Pressed steel panel robot welded to the rest of the frame and the painted by robot, compared to a sheet of glass with mounting hardware and the extra structure to support and transfer forces around it. Now you're off in fantasy land.

Incrementally a window on a house might be similar to the cost of a brick wall when designing, but when you try and put windows over a significant area the price skyrockets towards infinity for all the support structure. Same with the car roof, a small sunroof requires very little magic behind the scenes and can be fitted after market but a full glass roof is a complex engineering work.

More plausible is a laminated PV panel on the top of the bodywork as a single composite unit, just like solar cars have been doing for decades.
 

Offline nctnico

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Re: Solar PV on electric cars
« Reply #155 on: August 04, 2019, 12:02:14 am »
I'm quite sure the cost of a metal roof is equal to that of a glass roof. Glass in itself is a very cheap material.
Pressed steel panel robot welded to the rest of the frame and the painted by robot, compared to a sheet of glass with mounting hardware and the extra structure to support and transfer forces around it. Now you're off in fantasy land.
What mounting hardware? The glass panel will be glued in just like the windshield. Did you know that the windshield on a modern car is actually a part which gives strength to the body of a car? There is no need to have extra support to transfer forces; the glass panel handles those as well.

And it is not like cars with a glass roof don't exist:
« Last Edit: August 04, 2019, 12:07:43 am by nctnico »
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Offline Someone

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Re: Solar PV on electric cars
« Reply #156 on: August 04, 2019, 06:20:36 am »
I'm quite sure the cost of a metal roof is equal to that of a glass roof. Glass in itself is a very cheap material.
Pressed steel panel robot welded to the rest of the frame and the painted by robot, compared to a sheet of glass with mounting hardware and the extra structure to support and transfer forces around it. Now you're off in fantasy land.
What mounting hardware? The glass panel will be glued in just like the windshield. Did you know that the windshield on a modern car is actually a part which gives strength to the body of a car? There is no need to have extra support to transfer forces; the glass panel handles those as well.

And it is not like cars with a glass roof don't exist:
Thanks for talking to me like I have no idea these things exist or how they work.

If a glass roof had any advantages beyond aesthetics they would be seen in either or both of: low cost cars, or performance/racing vehicles. They aren't used in either of those (feel free to find some obscure application of them in boat racing or something). There is no way a glass roof is cheaper or similar in cost to a pressed steel panel, trying to maintain a watertight and structural seal between the dissimilar materials is not just a matter of some glue, look at the complexity of the A pillars in a windscreen to make those systems work. They add some additional rigidity compared to an old style pop in windscreen with a gasket but are in no way comparable to the rigidity and strength of a continuous solid steel panel.

Cheaper is up to you to find the evidence for, from the material properties they are close enough in strength by weight but steel sheet is around 4-10x lower cost by weight before taking on all the complexities of assembly and integration.

But why would manufacturers put such a large glass panel in place if the goal is solar cells?
https://sonomotors.com/en/faq/
They went for plastic.

Getting way off topic here...
 

Offline gmb42

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Re: Solar PV on electric cars
« Reply #157 on: August 07, 2019, 01:14:37 pm »
In the news yesterday, Hyundai are offering a Sonata Hybrid with PV roof: https://www.digitaltrends.com/cars/hyundai-sonata-hybrid-solar-roof/
 

Offline f4eru

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Re: Solar PV on electric cars
« Reply #158 on: August 08, 2019, 06:45:53 pm »
Meh. Hybrid. That's so obsolete now.
And PV on car roofs is more or less a marketing gimmick compared to realistic roof PV.
 

Offline Domagoj T

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Re: Solar PV on electric cars
« Reply #159 on: August 08, 2019, 07:46:21 pm »
Quote
Hyundai claims the solar roof can charge a car’s battery pack to 30-60% capacity, given six hours of charging per day.
But they don't say how much is that in terms of range.

Quote
Hybrids like the Sonata have smaller battery packs than all-electric cars, so a solar roof can make a bigger difference in charging.
Breaking News! Smaller batteries need less energy to charge!
 

Offline klunkerbus

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Re: Solar PV on electric cars
« Reply #160 on: August 08, 2019, 11:06:23 pm »
Here's another article on the solar Sonata that goes into some detail - https://jalopnik.com/the-hyundai-sonata-hybrids-roof-solar-panel-is-cool-but-1837039569
 
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Offline Domagoj T

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Re: Solar PV on electric cars
« Reply #161 on: August 09, 2019, 05:20:23 am »
So their 800 miles per year is extrapolated from Californian summer insolation? I will be very generous and accept this number.

Assuming the car life expectancy to be 12 years, that's 9 600 miles total. At 40 miles per gallon, that's equivalent of 240 gallons of fuel over twelve years. Average fuel price in USA being $2,7 per gallon, we're looking at total savings of $650 over ten years.
What does that option cost?
 

Offline f4eru

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Re: Solar PV on electric cars
« Reply #162 on: August 09, 2019, 07:47:21 am »
Quote
The high-voltage battery capacity of Sonata Hybrid is 1.49 kWh
Seriously, WTF Hyundai ! 1.49kWh is the battery for an electric bicycle !
A car will drive only a few kilometres with that tiny toy, and will kill it in a few tenths of cycles because of the load factor.

'Yeah. well. This whole sonata hybrid is just ridiculous greenwashing BS, even without considering the solar roof option.
« Last Edit: August 09, 2019, 07:56:16 am by f4eru »
 

Online coppice

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Re: Solar PV on electric cars
« Reply #163 on: August 09, 2019, 10:53:21 am »
Quote
The high-voltage battery capacity of Sonata Hybrid is 1.49 kWh
Seriously, WTF Hyundai ! 1.49kWh is the battery for an electric bicycle !
A car will drive only a few kilometres with that tiny toy, and will kill it in a few tenths of cycles because of the load factor.

'Yeah. well. This whole sonata hybrid is just ridiculous greenwashing BS, even without considering the solar roof option.
1.49kWh is quite big for a battery in a non-plug in hybrid. It only needs to capture and recycle braking energy, and smooth out bursts of power to keep the engine running near its sweet spot.
 
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Offline f4eru

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Re: Solar PV on electric cars
« Reply #164 on: August 09, 2019, 12:46:04 pm »
Perhaps. But HEV vehicles W/O a plug is an obsolete model from 20 Years ago.
We are now in the Year 2019, not in 1999.
Greenwashing it with a negligible drop of solar will not sell it better.
« Last Edit: August 09, 2019, 12:54:46 pm by f4eru »
 

Offline bdunham7

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Re: Solar PV on electric cars
« Reply #165 on: August 09, 2019, 03:01:08 pm »
Perhaps. But HEV vehicles W/O a plug is an obsolete model from 20 Years ago.
We are now in the Year 2019, not in 1999.
Greenwashing it with a negligible drop of solar will not sell it better.

No, HEV w/o plug-in is not obsolete at all--it is simply a more efficient gasoline powered vehicle. The PHEV and HEV are optimized for different use cases and in the case of an HEV used on long drive cycles (say as a taxi) the larger battery would actually be counter-productive.  In my view, the very-short range PHEV models are the ones that are of questionable value.
 

Online coppice

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Re: Solar PV on electric cars
« Reply #166 on: August 09, 2019, 06:43:24 pm »
Perhaps. But HEV vehicles W/O a plug is an obsolete model from 20 Years ago.
We are now in the Year 2019, not in 1999.
Greenwashing it with a negligible drop of solar will not sell it better.
Its the plug in hybrid that is obsolete. Hybrids that focus on recovering otherwise wasted energy are growing. They can be implemented for such a small price premium and weight burden compared to pure ICE cars that they becoming a no-brainer. A lot of mild hybrid models are in the product pipeline, and they might become the norm for the final generations of gasoline and diesel cars.
 

Offline nctnico

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Re: Solar PV on electric cars
« Reply #167 on: August 09, 2019, 07:09:07 pm »
Perhaps. But HEV vehicles W/O a plug is an obsolete model from 20 Years ago.
We are now in the Year 2019, not in 1999.
Greenwashing it with a negligible drop of solar will not sell it better.
Its the plug in hybrid that is obsolete. Hybrids that focus on recovering otherwise wasted energy are growing. They can be implemented for such a small price premium and weight burden compared to pure ICE cars that they becoming a no-brainer. A lot of mild hybrid models are in the product pipeline, and they might become the norm for the final generations of gasoline and diesel cars.
I agree. Electric cars are going to stay impracticle and expensive for the decades to come. Electric cars only sell in artificially created markets.

Reducing fuel consumption however gets you the best of both. Add a solar panel on the roof and you don't have to use fuel for short trips to the super market (which are the most poluting ones as well). Ofcourse the price point of the added solar panel has to be worthwhile but given the price of regular solar panels it shouldn't be a problem to achieve.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline hendorog

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Re: Solar PV on electric cars
« Reply #168 on: September 11, 2019, 01:20:02 am »
Another article, an alternative solar vehicle roof to the Panasonic one. Nicer looking, but has an efficiency hit.

https://thedriven.io/2019/09/03/invisible-solar-cells-aim-to-extend-driving-range-for-electric-cars/

 

Offline Red Squirrel

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Re: Solar PV on electric cars
« Reply #169 on: September 11, 2019, 01:56:06 am »
I think it would be a good idea, as long as the solar is not imposing any kind of drag on the car because that will actually make the efficiency worse.  I don't think the solar will be able to generate enough power to have any effect on drive distance while the car is in motion as realistically you only have room for maybe a couple 100w, however, when the car is parked, it will be able to at very least trickle charge the battery and power all the "always on" stuff like the auto start computer, or any other electronics.   Some of the power could also be used to keep the battery slightly warm.  Don't know how much of a difference it would really make though.

Now question is, is the cost of this worth it, for the small benefit it would really have.   The solar panels would be relatively flat, and be subject to the constant scraping of ice/snow every time the car is used, so it has to be very durable, and will be covered in snow half the time. Almost like solar road ways... :P
« Last Edit: September 11, 2019, 01:58:00 am by Red Squirrel »
 

Offline hendorog

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Re: Solar PV on electric cars
« Reply #170 on: September 11, 2019, 02:13:49 am »
Now question is, is the cost of this worth it, for the small benefit it would really have.   The solar panels would be relatively flat, and be subject to the constant scraping of ice/snow every time the car is used, so it has to be very durable, and will be covered in snow half the time. Almost like solar road ways... :P

I don't think these are comparable to solar roadways. Solar roadways have been shown to degrade, and unlike a car the solar still needs to be moved somewhere else before it is used.

Solar on vehicles isn't that unusual - many/most RV's have a solar panel or two on the roof. They are generally just residential panels and were never designed for being bounced around. Yet they seem to survive OK.




 


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