Solar PV on electric cars

[hendorog]

Here is a puzzle for the electric fan girls and boys to grind their teeth on.

Is putting solar panels on an EV a good idea?
Why?

Now let the games begin. 

- For the record, I think it is a great idea.

[NiHaoMike]

I recall the general consensus is that the area is too little to generate much power. The main exception being a RV, where the solar is very useful when the RV is parked.

[digsys]

This has been beaten to death on these forums and doesn't need re-starting. IF you are interested, there are a few of us here in Solar EV clubs - If you really want to know more, check out - https://www.worldsolarchallenge.org/  or https://www.facebook.com/WorldSolarChallenge/  (If you are on FB)  or https://www.facebook.com/ISFsolarcar/
(That's our last / current car :-) ) Up to 45 teams have been designing / running solar cars for over 35 yrs, and the last several years, there is a new category - Road legal capable.
In fact, the "race" is coming up in OCT 13 this year - Darwin to Adelaide. No need to start a crap shoot - ymmv

[tautech]

Just measured my 4 door sedan and there's at least 1.2 m² roof area available for panels if it was an EV.
Is that an insignificant area ? 

[hendorog]

I recall the general consensus is that the area is too little to generate much power. The main exception being a RV, where the solar is very useful when the RV is parked.

Interesting.

So solar panels don't generate much power when they are on a vehicle?

Perhaps the electrons get car sick?

[fourfathom]

I recall the general consensus is that the area is too little to generate much power. The main exception being a RV, where the solar is very useful when the RV is parked.

Interesting.

So solar panels don't generate much power when they are on a vehicle?

Perhaps the electrons get car sick?

the 1.5 square meters of available area for solar panels that Tautech mentions will receive about 1500W of sunlight at noon.  Good panels are about 20% efficient, giving about 300W peak power.  Over a day this will add up to about 1.5kWh, or perhaps a bit (or a lot) less depending on latitude and season.  Batteries, controllers and motors do have some loss, but the total efficiency might be around 80% or 1.2kWh.

1kW equals 1.3HP.  You do the math, but that's not going to get you very far in a typical electric car.

[bdunham7]

Here is a puzzle for the electric fan girls and boys to grind their teeth on.

Is putting solar panels on an EV a good idea?
Why?

Now let the games begin. 

- For the record, I think it is a great idea.

Hmmmm.  Can trolls do math? 

[hendorog]

I recall the general consensus is that the area is too little to generate much power. The main exception being a RV, where the solar is very useful when the RV is parked.

Interesting.

So solar panels don't generate much power when they are on a vehicle?

Perhaps the electrons get car sick?

the 1.5 square meters of available area for solar panels that Tautech mentions will receive about 1500W of sunlight at noon.  Good panels are about 20% efficient, giving about 300W peak power.  Over a day this will add up to about 1.5kWh, or perhaps a bit (or a lot) less depending on latitude and season.  Batteries, controllers and motors do have some loss, but the total efficiency might be around 80% or 1.2kWh.

1kW equals 1.3HP.  You do the math, but that's not going to get you very far in a typical electric car.

Correct. But that was the easy and obvious answer that everyone thinks of.

The answer I'm thinking of requires a little bit of out of the box thinking.

Edit: And, to be fair, a bit of thinking about the future.

[tautech]

Hmmmm.  Can trolls do math? 

The OP ?
Probably not but I'm not much good at it either.

However 1.2 KW into the battery daily for exactly what cost over the life of the vehicle sounds good to me.
And I haven't had to purchase it.

How much can a custom PV panel and a charge pump really cost ? 

[digsys]

Trying to stay out of this :-) just adding some REAL numbers ..
Our 10 yr old 24% "off the shelf" sunpower panels, on 6 sq mtrs of area generate 1.2KWhr
Split up into 6 sections, we got solar > battery efficiency of 98.5% (MPPTs were designed in-house and now used / sold all over the world). That efficiency is even in dawn / dusk due to a micro-groving layer on the panels.
Our wheel motor is 98+% efficient, over a wide range. Only 20KW max, but it is the first design, all back 10+ yrs ago. Also sold all over the world.
Granted, this is a pure race car, but it can get a max 900Km range on panels alone (a good day) +~ 400Km on a 5KWhr battery pack (at 20Kg). That was 10+ yrs ago
SO, a road legal car will be a lot less, due to much extra weight and poorer aero, but it is a start. Our modelling indicates, up to 250Km max per day on panels alone.
Many teams don't get that good a figure, but they only have 2 yrs to design and build, then most graduate and leave Uni, and it mostly all starts again.
The links I posted have more detailed links to all solar EV groups currently working.

[hendorog]

I recall the general consensus is that the area is too little to generate much power. The main exception being a RV, where the solar is very useful when the RV is parked.

Interesting.

So solar panels don't generate much power when they are on a vehicle?

Perhaps the electrons get car sick?

the 1.5 square meters of available area for solar panels that Tautech mentions will receive about 1500W of sunlight at noon.  Good panels are about 20% efficient, giving about 300W peak power.  Over a day this will add up to about 1.5kWh, or perhaps a bit (or a lot) less depending on latitude and season.  Batteries, controllers and motors do have some loss, but the total efficiency might be around 80% or 1.2kWh.

1kW equals 1.3HP.  You do the math, but that's not going to get you very far in a typical electric car.

Well we can work it out.

Wikipedia says that the 2016 Nissan leaf gets 19.1 kWh/100km. So 1.2kWh would get you about 6.3 km's.

[tautech]

Hmmmm.  Can trolls do math? 

I might have been quite wrong.
Apparently so. 

Well we can work it out.

Wikipedia says that the 2016 Nissan leaf gets 19.1 kWh/100km. So 1.2kWh would get you about 6.3 km's.

So that conservitavely could be 5 km free motoring/day. 
That might be 50% of someones EV running.

[f4eru]

It's not a really good idea on an everyday car, due to the added weight and disproportionnate cost.

Let's take an example of the most meaningful example we can find where it would add minimal cost/weight/aero:
A reasonnable everyday electric car : Tesla Model 3

It has 1,4m² of shaded roof glass already, ideal to replace the shading by printed on solar panels.

Printed on solar panels are crappy, but don't add weight.
You get 14% efficiency, 3.5 kWh/day of sunlight (sunny, parked with no shade) -> 0.686 kWh of electricity/sunny day

That's 4.7km of travel....

Now you get only 20% of the full sunny days in average on a year because of many factors (weather, shade, parking, etcetc...).
In average on a year, you get 1km/day.

That's nothing. With a roof solar PV panels 20m², you get 100x more, and you can cover all of your commutes, with power to spare in the summer, for a tenth of the cost/km....

'Seriously guys, the right place for solar panels in everyday use is on the roof, nowhere else.

[tautech]

Why would it be like any conventional PV panel we already know ?
Surely this is a job for a custom curved and optimized PV panel that's part of the cars structure.

Why hasn't this already been done ? 

[wraper]

Why would it be like any conventional PV panel we already know ?
Surely this is a job for a custom curved and optimized PV panel that's part of the cars structure.

Why hasn't this already been done ? 

It has been done and it's stupid. It's similar to solar roadways. It's sort of works but no way can be justified from any practical standpoint. Simply using larger battery for the same money spent makes much better car

[tautech]

Sure, but aren't we missing the use of free energy ? Stupid ? 

[wraper]

Sure, but aren't we missing the use of free energy ?

What use of that "free energy" if it will never cover the upfront costs for producing itself.

[hammy]

Is putting solar panels on an EV a good idea?

Already done: https://sonomotors.com/de/sion/
Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.
https://www.electrive.com/2019/07/04/toyota-testing-hybrid-prius-fitted-with-solar-cells/

[wraper]

FWIW unless it's nearly free to implement and maintain, it's just a gimmick.

[tautech]

Is putting solar panels on an EV a good idea?

Already done: https://sonomotors.com/de/sion/
Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.
https://www.electrive.com/2019/07/04/toyota-testing-hybrid-prius-fitted-with-solar-cells/

wraper mentioned stupid, are Toyota, Kia and Hyundai stupid or just ahead of the rest of the stupid other EV manufacturers ?

[tautech]

Sure, but aren't we missing the use of free energy ?

What use of that "free energy" if it will never cover the upfront costs for producing itself.

Could we not say the same of the carbon footprint to build an EV vs a conventional ICE car ?

[wraper]

Sure, but aren't we missing the use of free energy ?

What use of that "free energy" if it will never cover the upfront costs for producing itself.

Could we not say the same of the carbon footprint to build an EV vs a conventional ICE car ?

EVs actually pay over for themselves. Both from larger initial carbon footprint standpoint and lifetime fuel cost.

[tautech]

Sure, but aren't we missing the use of free energy ?

What use of that "free energy" if it will never cover the upfront costs for producing itself.

Could we not say the same of the carbon footprint to build an EV vs a conventional ICE car ?

EVs actually pay over for themselves. Both from larger initial carbon footprint standpoint and lifetime fuel cost.

That could be questionable IMO.
There’s another elephant in the room you may have overlooked.

[wraper]

There’s another elephant in the room you may have overlooked.

Dare to name it?

[nctnico]

EVs actually pay over for themselves. Both from larger initial carbon footprint standpoint and lifetime fuel cost.

Governments earn big bucks from tax on fuel. Do you really think they will let that milk cow go away (*)? And then there is the charging infrastructure. Nowadays largely free but at some point you'll pay dearly and you'll have no alternative (unless you have your own driveway where you can charge and never venture far away). You also have to calculate the cost of the battery into the fuel costs because batteries don't have an eternal life. Add these together and you'll see an EV is way more expensive then you are lead to believe.

Maybe putting solar panels on the roof of an EV isn't such a bad idea after all cost wise and from a point of convenience. Even if it is just to keep the batteries charged while the car is parked or have enough 'juice' to drive to a super charger nearby.

*In the Netherlands there is an ongoing study by the government about taxation of EVs. EVs are now excempt from road tax but because of their high weight EVs do more damage to the roads so that will need to be paid by the owners somehow. That is one. The other is income from fuel taxes which the EV owners don't pay; it is possible EV owners are going to pay an extra tax per distance travelled to compensate for fuel taxes. In Norway there is a similar discussion. Norway and the Netherlands are the leading countries where it comes to EV adoption so what happens in these countries is going to happen in other countries too.

[Neilm]

Governments earn big bucks from tax on fuel. Do you really think they will let that milk cow go away (*)?

Just tax sunlight.

Adding solar panels also means adding the electronics to step up the output voltage so it can charge the traction battery. That will introduce quite a lot of losses. The best idea I have heard of is car mounted solar panels charging the 12 V battery but it all does sound like solar roadways in a new guise.

[bdunham7]

Is putting solar panels on an EV a good idea?

Already done: https://sonomotors.com/de/sion/
Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.
https://www.electrive.com/2019/07/04/toyota-testing-hybrid-prius-fitted-with-solar-cells/

wraper mentioned stupid, are Toyota, Kia and Hyundai stupid or just ahead of the rest of the stupid other EV manufacturers ?

I think "not practical" would be a more diplomatic term than "stupid", but wraper doesn't mince words.  The Prius mentioned uses very expensive multi-junction cells (34% efficiency is still pretty expensive) and is a concept test car.  It isn't an economically viable solution yet.  The Sion, AFAIK, is vaporware and I haven't seen a justification for their remarkable claim of 34km/day (in Deutschland no less), so we'll wait and see. 

Meanwhile, my 30 panels on the roof have each been producing that 1.2kWh/day for the past 7 years at a cost that is probably less than 10% of what the equivalent solar panel system on a car would be.  Unless I were desperately needing another 3 or 4 miles of range on my car, it's pretty clear that car panels aren't an economically viable option yet.  They do make a nice sales gimmick for the math-challenged.

[wraper]

You also have to calculate the cost of the battery into the fuel costs because batteries don't have an eternal life.

It's basically equal with vehicle life. Unless you buy crappy Nissan leaf without battery thermal management system. What's for sure they last more than gasoline engines in average. Which is not eternal at all, especially in modern cars where they get pushed to the max while trying to make them cheap at the same time.

Governments earn big bucks from tax on fuel. Do you really think they will let that milk cow go away (*)?

When that happens, they will need to implement something for every car, not just EV. It won't be trivial to implement tax on electricity in a whole. Also by the time when that happens, EV price should go down to ICE level.

[wraper]

Is putting solar panels on an EV a good idea?

Already done: https://sonomotors.com/de/sion/
Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.
https://www.electrive.com/2019/07/04/toyota-testing-hybrid-prius-fitted-with-solar-cells/

wraper mentioned stupid, are Toyota, Kia and Hyundai stupid or just ahead of the rest of the stupid other EV manufacturers ?

Especially Toyota with their hydrogen dead end.

[hendorog]

Is putting solar panels on an EV a good idea?

Already done: https://sonomotors.com/de/sion/
Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.
https://www.electrive.com/2019/07/04/toyota-testing-hybrid-prius-fitted-with-solar-cells/

wraper mentioned stupid, are Toyota, Kia and Hyundai stupid or just ahead of the rest of the stupid other EV manufacturers ?

I think "not practical" would be a more diplomatic term than "stupid", but wraper doesn't mince words.  The Prius mentioned uses very expensive multi-junction cells (34% efficiency is still pretty expensive) and is a concept test car.  It isn't an economically viable solution yet.  The Sion, AFAIK, is vaporware and I haven't seen a justification for their remarkable claim of 34km/day (in Deutschland no less), so we'll wait and see. 

Meanwhile, my 30 panels on the roof have each been producing that 1.2kWh/day for the past 7 years at a cost that is probably less than 10% of what the equivalent solar panel system on a car would be.  Unless I were desperately needing another 3 or 4 miles of range on my car, it's pretty clear that car panels aren't an economically viable option yet.  They do make a nice sales gimmick for the math-challenged.

How do you charge your car from your solar panels? My car is not at home when the sun is shining.

[coppice]

EVs actually pay over for themselves. Both from larger initial carbon footprint standpoint and lifetime fuel cost.

The comparisons I have seen so far are highly questionable. Like comparing a RAV4 with an e-Niro, and finding the lifetime cost of the e-Niro is slightly lower. Maybe they could have tried two cars of a similar size, like an e-Niro and a non electric Niro. If that produced good lifetime costs for the electric version it might be a bit more impressive.

[bdunham7]

How do you charge your car from your solar panels? My car is not at home when the sun is shining.

My car often is home whilst the sun shines--but I charge at night.  Thanks to the Electric Grid Bank of Southern California Edison my daytime generated kWh are worth 3X what the night ones are, so on an economic basis, the roof panels are actually 3X more cost effective than even my earlier statement. 

[james_s]

Have the solar panels feed into the grid during the day when they produce excess capacity, charge your car when you get home at night pulling power from the grid during what is then off-peak.


Solar panels on cars is a fairly dumb ideal, although things are getting to the point where I would welcome virtually any car that is remotely unique amongst the sea of bland generic crossovers, fake SUVs that try to be everything and end up doing nothing well and yet they are extremely popular for reasons I will never really understand. It doesn't even really matter what you buy anymore, it's all the same car with a different logo on it.

https://medium.com/swlh/the-zombie-mobile-b03932ac971d

[hendorog]

Governments earn big bucks from tax on fuel. Do you really think they will let that milk cow go away (*)?

Just tax sunlight.

Adding solar panels also means adding the electronics to step up the output voltage so it can charge the traction battery. That will introduce quite a lot of losses. The best idea I have heard of is car mounted solar panels charging the 12 V battery but it all does sound like solar roadways in a new guise.

So in my country we convert the dam power to HV AC, transport it hundreds of km's, change it to HV DC, under a bit of sea, back to AC again, transport another few hundred kms, mix it in with other power to the biggest city.

[bdunham7]

The comparisons I have seen so far are highly questionable. Like comparing a RAV4 with an e-Niro, and finding the lifetime cost of the e-Niro is slightly lower. Maybe they could have tried two cars of a similar size, like an e-Niro and a non electric Niro. If that produced good lifetime costs for the electric version it might be a bit more impressive.

Most comparisons of electric vs gas cars, in whatever aspect, are highly questionable.  The cost of owning a Tesla (any Tesla) for example are sky-high compared to say a Honda Accord--and the Accord arguably has significant advantages for some people.  However, a premium Model S or X costs a lot less than a Ferrari or a Bentley---and also arguably has advantages over those.  So what do you compare it to and how?  The answer is different for every driver--and "cost" is not the main driving factor for most people.

[hendorog]

Have the solar panels feed into the grid during the day when they produce excess capacity, charge your car when you get home at night pulling power from the grid during what is then off-peak.

Ah so you must have a subsidised feed in tariff. Lucky you.

If everyone does what you do, will your approach still work?

Solar panels on cars is a fairly dumb ideal, although things are getting to the point where I would welcome virtually any car that is remotely unique amongst the sea of bland generic crossovers, fake SUVs that try to be everything and end up doing nothing well and yet they are extremely popular for reasons I will never really understand. It doesn't even really matter what you buy anymore, it's all the same car with a different logo on it.

https://medium.com/swlh/the-zombie-mobile-b03932ac971d

That is one reason why I drive an old car. It has more character.

[james_s]

Have the solar panels feed into the grid during the day when they produce excess capacity, charge your car when you get home at night pulling power from the grid during what is then off-peak.

Ah so you must have a subsidised feed in tariff. Lucky you.

If everyone does what you do, will your approach still work?

Solar panels on cars is a fairly dumb ideal, although things are getting to the point where I would welcome virtually any car that is remotely unique amongst the sea of bland generic crossovers, fake SUVs that try to be everything and end up doing nothing well and yet they are extremely popular for reasons I will never really understand. It doesn't even really matter what you buy anymore, it's all the same car with a different logo on it.

https://medium.com/swlh/the-zombie-mobile-b03932ac971d

That is one reason why I drive an old car. It has more character.

I don't personally have solar, but I know people who do and they get paid for energy they generate during the day.

If everyone did that then no, it probably wouldn't work out well but we are not in a situation where anywhere close to everyone is doing it so that is not a problem. If things shift to where too many people are doing it then economic realities will push them in a different direction and it will work out.

I too drive an older car, it will turn 30 next year and it is getting to where I worry something will happen to it and I won't be able to find parts. If I had space to keep them I would buy up and hoard several more, or if I could buy a brand new 80s-90s car today I would. Cars have been bland and boring for the past 15 years or so and getting worse all the time. I really don't even know what I would buy later on if I had to because looking at what is available brand new today I cannot actually think of anything out there that I would want even if it was given to me for free. Car manufactures fret that young people are not as interested in cars as older generations but it's no surprise why, cars are so boring now, there is nothing unique, no character, no individuality, nothing inspiring, why would any kid growing up today be into cars?

[nctnico]

The comparisons I have seen so far are highly questionable. Like comparing a RAV4 with an e-Niro, and finding the lifetime cost of the e-Niro is slightly lower. Maybe they could have tried two cars of a similar size, like an e-Niro and a non electric Niro. If that produced good lifetime costs for the electric version it might be a bit more impressive.

Most comparisons of electric vs gas cars, in whatever aspect, are highly questionable.  The cost of owning a Tesla (any Tesla) for example are sky-high compared to say a Honda Accord--and the Accord arguably has significant advantages for some people.  However, a premium Model S or X costs a lot less than a Ferrari or a Bentley---and also arguably has advantages over those.  So what do you compare it to and how?  The answer is different for every driver--and "cost" is not the main driving factor for most people.

I'd say cost is everything to most drivers. If you look carefully then you'll see that the market for EVs are artificially created by government incentives (even in China where it is easier to get a permit for an electric car compared to an ICE care). Take the incentive away and sales drop to zero. In the Netherlands the sales of the Tesla Model-S went from about 2000 a year until 2018 to 99 in 2019 (so far). 2018 shows a very large sales peak due to the government incentive being stopped in 2019. Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

[bdunham7]

Ah so you must have a subsidised feed in tariff. Lucky you.

If everyone does what you do, will your approach still work?

Not subsidized per se, in my case--although it is a money-loser for the utility company.  The rule is that SCE has to pay me the exact same amount that they would charge me for the electricity at the time it is provided.  So I've chosen a TOU (Time Of Use) plan that has much higher rates in the day and reasonable (not low) rates at night. My air conditioner would cost $3.00 per hour to run on this rate if I didn't have the solar system.   

Solar generally helps meet the greater daytime demand.  There is an issue called the "duck curve" that has resulted from adoption of solar,  but I think it is more due to commercial solar than private rooftops.  This has resulted in SCE pushing the peak periods later in the day in an attempt to charge me some money, as the evenings have high demand but less solar production.  The answer is that if everyone did it, there would have to be some storage involved either at the utility level or at the home level.  The products are available (Powerwall, etc) but they don't make economic sense yet. 

[wraper]

Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

Nope, they buy them exactly because they like them. And incentives help buying what they probably would have trouble to afford otherwise. If you just want to drive cheap, Model S/X is very far from something you would go for, even with incentives.

[bdunham7]

I'd say cost is everything to most drivers. If you look carefully then you'll see that the market for EVs are artificially created by government incentives (even in China where it is easier to get a permit for an electric car compared to an ICE care). Take the incentive away and sales drop to zero. In the Netherlands the sales of the Tesla Model-S went from about 2000 a year until 2018 to 99 in 2019 (so far). 2018 shows a very large sales peak due to the government incentive being stopped in 2019. Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

If cost is the main concern, then Tesla drivers must be bad at math.  As I said, it is much, much more expensive to drive a Tesla than an equivalent-sized Honda.  People may indeed respond to incentives, but that doesn't mean that the cost is actually lower.  Can you say that someone who is willing to spend $50K extra to get a $7500 tax break is "cost sensitive"--or is it something else?  Among EV owners I know, the only cost sensitivity is a form of self-delusion that was needed to talk themselves into an expensive and unnecessary purchase.

[nctnico]

Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

Nope, they buy them exactly because they like them. And incentives help buying what they probably would have trouble to afford otherwise. If you just want to drive cheap, Model S/X is very far from something you would go for, even with incentives.

Then explain to me why people stop buying them when the incentives go away. Why does that happen if people buy the cars because they like them? The incentives go away and the sales numbers go to zero. How do you explain that?

[hendorog]

Ah so you must have a subsidised feed in tariff. Lucky you.

If everyone does what you do, will your approach still work?

Not subsidized per se, in my case--although it is a money-loser for the utility company.  The rule is that SCE has to pay me the exact same amount that they would charge me for the electricity at the time it is provided.  So I've chosen a TOU (Time Of Use) plan that has much higher rates in the day and reasonable (not low) rates at night. My air conditioner would cost $3.00 per hour to run on this rate if I didn't have the solar system.   

Solar generally helps meet the greater daytime demand.  There is an issue called the "duck curve" that has resulted from adoption of solar,  but I think it is more due to commercial solar than private rooftops.  This has resulted in SCE pushing the peak periods later in the day in an attempt to charge me some money, as the evenings have high demand but less solar production.  The answer is that if everyone did it, there would have to be some storage involved either at the utility level or at the home level.  The products are available (Powerwall, etc) but they don't make economic sense yet.

You have such a biased situation with your 3X factor mentioned earlier, that you could probably make a powerwall pay - ignore the solar, just suck at night and blow during the day.

[wraper]

Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

Nope, they buy them exactly because they like them. And incentives help buying what they probably would have trouble to afford otherwise. If you just want to drive cheap, Model S/X is very far from something you would go for, even with incentives.

Then explain to me why people stop buying them when the incentives go away. Why does that happen if people buy the cars because they like them? The incentives go away and the sales numbers go to zero. How do you explain that?

Because they are luxury cars which cost an arm and a leg. Full price is way too much for most people. Aso many people who wanted EV likely have chosen to wait because of cheaper model 3 coming out.

[nctnico]

I'd say cost is everything to most drivers. If you look carefully then you'll see that the market for EVs are artificially created by government incentives (even in China where it is easier to get a permit for an electric car compared to an ICE care). Take the incentive away and sales drop to zero. In the Netherlands the sales of the Tesla Model-S went from about 2000 a year until 2018 to 99 in 2019 (so far). 2018 shows a very large sales peak due to the government incentive being stopped in 2019. Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

If cost is the main concern, then Tesla drivers must be bad at math.  As I said, it is much, much more expensive to drive a Tesla than an equivalent-sized Honda.  People may indeed respond to incentives, but that doesn't mean that the cost is actually lower.  Can you say that someone who is willing to spend $50K extra to get a $7500 tax break is "cost sensitive"--or is it something else?  Among EV owners I know, the only cost sensitivity is a form of self-delusion that was needed to talk themselves into an expensive and unnecessary purchase.

In the Netherlands EVs primarily get bought as corporate lease cars. Employers pay a monthly fee to make a car available for the employee. Depending on the position of the employee there is a certain budget. The employee gets tax added to the income which is a certain percentage of the price of the car. If the tarif is low the employee pays less compared to an ICE based car. Starting from 2019 the low tarif has been cancelled for cars over 50k euro. Next year the EV tarif is increased to 8% (was 4%) and the maximum price will be 45k euro. The low tarif costs too much money already so it had to be changed.

[hendorog]

The comparisons I have seen so far are highly questionable. Like comparing a RAV4 with an e-Niro, and finding the lifetime cost of the e-Niro is slightly lower. Maybe they could have tried two cars of a similar size, like an e-Niro and a non electric Niro. If that produced good lifetime costs for the electric version it might be a bit more impressive.

Most comparisons of electric vs gas cars, in whatever aspect, are highly questionable.  The cost of owning a Tesla (any Tesla) for example are sky-high compared to say a Honda Accord--and the Accord arguably has significant advantages for some people.  However, a premium Model S or X costs a lot less than a Ferrari or a Bentley---and also arguably has advantages over those.  So what do you compare it to and how?  The answer is different for every driver--and "cost" is not the main driving factor for most people.

I'd say cost is everything to most drivers. If you look carefully then you'll see that the market for EVs are artificially created by government incentives (even in China where it is easier to get a permit for an electric car compared to an ICE care). Take the incentive away and sales drop to zero. In the Netherlands the sales of the Tesla Model-S went from about 2000 a year until 2018 to 99 in 2019 (so far). 2018 shows a very large sales peak due to the government incentive being stopped in 2019. Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

I have to say that here we are seeing rapid growth of EV's. They are still a small proportion of the entire fleet though - about 12000 out of 3.9 million or so.

The only incentive to date has been that you pay no road user charges on EV's. In NZ that is a tax on vehicles which don't use petrol - as the petrol is already includes this tax. Diesel doesn't have this tax and so road based diesel vehicles pay an extra tax separately.

A new incentive has been added for low emission vehicles which will take effect in a couple of years. Up to $8k discount when they are sold in NZ for the first time.

[tautech]

There’s another elephant in the room you may have overlooked.

Dare to name it?

Sure.
Namely the 'big picture' reason why EV technology has even been developed, atmospheric pollution.

So the planet has come up with this wonderful solution of EV's that require charging with power from fossil fueled power stations.  And it would seem most have totally ignored the incorporation of PV. 

The result, another ~5km of EV range charge/EV is loaded onto grids and required to be generated when it could well have been harnessed from the sun free !

[wraper]

The result, another ~5km of EV range charge/EV is loaded onto grids and required to be generated when it could well have been harnessed from the sun free !

If you put PV worth the same amount of money onto roof, you would get way more electricity to charge the car and power other stuff. So I can argue that this crappy use of PV takes money away from where it actually matters and basically wastes it.

[nctnico]

That only works if you have a roof to put panels on. That is a small but significant detail.

And the more I think of it the better I like the idea of an EV which at least covers the self-discharge of the batteries by having a small solar panel on the roof. You can leave it parked with a nearly empty battery without needing to worry about the batteries getting drained completely.

[tautech]

The result, another ~5km of EV range charge/EV is loaded onto grids and required to be generated when it could well have been harnessed from the sun free !

If you put PV worth the same amount of money onto roof, you would get way more electricity to charge the car and power other stuff. So I can argue that this crappy use of PV takes money away from where it actually matters and basically wastes it.

But you presume everyone owns a roof to place PV panels on.

[tautech]

To return to wraper's stupid statement, we now have a multitude of gubbermints promoting/subsidizing the adoption of EV's in the name of protecting the planet from further pollution and yet they fail to comprehend the incorporation of PV into the roof of an EV can offer some free mile/km without any further input of fossil fuel generated power and/or reduce the full impact on the power grid if the only method to charge an EV was to plug it in.

Those that set the path we must live by and travel down are the really stupid ones for missing such an opportunity to make a further but admittedly small real difference.

[bdunham7]

I'd say cost is everything to most drivers. If you look carefully then you'll see that the market for EVs are artificially created by government incentives (even in China where it is easier to get a permit for an electric car compared to an ICE care). Take the incentive away and sales drop to zero. In the Netherlands the sales of the Tesla Model-S went from about 2000 a year until 2018 to 99 in 2019 (so far). 2018 shows a very large sales peak due to the government incentive being stopped in 2019. Other higher end EVs like the Jaguar I-pace show similar trends. People aren't buying EVs because they like them but because they want to drive around cheap due to the government incentives.

If cost is the main concern, then Tesla drivers must be bad at math.  As I said, it is much, much more expensive to drive a Tesla than an equivalent-sized Honda.  People may indeed respond to incentives, but that doesn't mean that the cost is actually lower.  Can you say that someone who is willing to spend $50K extra to get a $7500 tax break is "cost sensitive"--or is it something else?  Among EV owners I know, the only cost sensitivity is a form of self-delusion that was needed to talk themselves into an expensive and unnecessary purchase.

In the Netherlands EVs primarily get bought as corporate lease cars. Employers pay a monthly fee to make a car available for the employee. Depending on the position of the employee there is a certain budget. The employee gets tax added to the income which is a certain percentage of the price of the car. If the tarif is low the employee pays less compared to an ICE based car. Starting from 2019 the low tarif has been cancelled for cars over 50k euro. Next year the EV tarif is increased to 8% (was 4%) and the maximum price will be 45k euro. The low tarif costs too much money already so it had to be changed.

Do keep in mind that you folks living in places like the Netherlands and Belgium, and so on, are living in a different world than the US in some ways.  For example, in California fuel is expensive and we whine if it hits the equivalent of 0.80 Euro/Liter.  The tax incentive on a $100K Tesla right now, IIRC, would be $3750.  That is less than half of the sales tax that would be collected at purchase.  If these consumers are cost-sensitive, they surely aren't rational about it.   The incentives have been greatly reduced--we got a total of $10,450 on our EV--and are income-restricted in some cases, but the cars are still selling.  If the incentive were a more significant part of the cost, then of course I'd expect it to have more impact.  Our EV (Ford Focus) started with a sticker price of $41K, but due to rebates, cost reductions, tax incentives and random cash, ended up with a net cost of under $15K. Yes, that made a difference in the purchasing decision!  For Tesla though, the $3750 doesn't even offset the sales tax, let alone the much higher insurance and maintenance--yes maintenance!  The tires alone on some models would exceed many people's driving budget.

 https://insideevs.com/news/357565/ev-sales-scorecard-june-2019/

[hendorog]

That only works if you have a roof to put panels on. That is a small but significant detail.

And the more I think of it the better I like the idea of an EV which at least covers the self-discharge of the batteries by having a small solar panel on the roof. You can leave it parked with a nearly empty battery without needing to worry about the batteries getting drained completely.

That is a nice benefit.

[bdunham7]

To return to wraper's stupid statement, we now have a multitude of gubbermints promoting/subsidizing the adoption of EV's in the name of protecting the planet from further pollution and yet they fail to comprehend the incorporation of PV into the roof of an EV can offer some free mile/km without any further input of fossil fuel generated power and/or reduce the full impact on the power grid if the only method to charge an EV was to plug it in.

Those that set the path we must live by and travel down are the really stupid ones for missing such an opportunity to make a further but admittedly small real difference.

Go ahead, do the math and cost out the project.  I sort of did and quickly realized that even with 1000 free hours of my time, it was a colossal waste of money and resources.  Do some actual estimates using real measurements, data and a BOM of things that actually exist.  Keep in mind that most of the off-the-cuff approximations in this thread are wildly optimistic--even Toyota in their example using gold pressed latinum/unobtanium alloy 34% modules are only netting 860W at most (if I read that right). 

Nobody here is failing to comprehend the wonderfulness of the idea of a self-charging electric car that just has to be parked in the sun and you can drive it for free.  I'll buy it if you make it cost effective.

[james_s]

The people for whom EVs are against their religion will never be convinced, but several of my friends and family members have EVs for commuting and local driving and the #1 thing they all talk about is how great it is to not have to go to a gas station and fill up the tank. They all plug the car in when they park in their driveway, carport or garage and by the next morning it's fully charged and ready for another day just like their mobile phone. It would be a huge incentive for me too as I hate having to remember to go out of my way to fill up the tank when I'm getting low but ultimately for my own use case a conventional car is a better fit. If I were still commuting to work by car I'd seriously consider picking up a used EV commuter but I bus now so it wouldn't make sense.

There are many millions of people for whom a small EV is an excellent fit to their needs though, people who commute <50 miles round trip each day and have a driveway or garage to park in at home where they can conveniently plug in and charge and a second car in the household for the occasional longer trips.

Even so, solar panels on the car don't really make sense in terms of propulsion, but it could be nice for keeping the AC going when one is forced to park in the blazing sun. It's no fun to get into a scorching hot car and it's not good for the interior either.

[tautech]

Nobody here is failing to comprehend the wonderfulness of the idea of a self-charging electric car that just has to be parked in the sun and you can drive it for free.  I'll buy it if you make it cost effective.

Cost effective is 100+ yrs of ICE development.

[james_s]

But you presume everyone owns a roof to place PV panels on.

Of course not everyone owns a roof, but as with most things there is no one-size-fits-all solution. If you don't have a roof then obviously having your own solar installation on the roof is not going to work, but there are hundreds of millions of people who do have roofs which are potential prime locations for solar panels. There are also businesses and communal structures like apartment buildings where solar panels could be installed, not necessarily owned by the occupants.

As with many things if it doesn't work for you that doesn't mean it's not an excellent solution to someone else's situation and it doesn't mean it makes sense to try to shoehorn a concept (like solar panels) into a situation where it doesn't make sense (like trying to build them into an EV). If one has no suitable location to install their own solar panels and they wish to have an EV, then plugging it into the grid for charging is going to make the most sense. If eventually enough other people do who do have space for solar invest in it then the power generated can be distributed via the existing grid and it doesn't matter if everyone has it.

[james_s]

Cost effective is 100+ yrs of ICE development.

That depends on the bigger picture, when you factor in dwindling supplies of fossil fuels, the very real environmental costs and other factors there is no guarantee at all that ICE will always be cost effective, and the more alternatives we have meeting the needs of those who can make use of them, the more viable ICE remains going forward for those for which it is still the best or only suitable option. The more different options we have available, the better off we will all be.

[bdunham7]

Nobody here is failing to comprehend the wonderfulness of the idea of a self-charging electric car that just has to be parked in the sun and you can drive it for free.  I'll buy it if you make it cost effective.

Cost effective is 100+ yrs of ICE development.

The 100-year-old ICE was cost effective in its time or it wouldn't have survived.  But I only mean cost-effective compared to installing one more solar panel and adding a little battery to the car.  And if you don't own a roof, you can put it on someone elses!

https://www.energysage.com/solar/community-solar/community-solar-vs-rooftop-solar/

In all seriousness, I expect we'll see solar cells on car bodies someday.  We're just not there yet.

[james_s]

I don't think solar panels on car bodies will ever make sense. Even in fantasy land where a 100% efficient solar panel is possible the amount of energy required to propel a car vs the amount of solar energy falling on that car will never add up. There are always going to be more sensible places to locate the panels than on the cars themselves or in the roads, quite possibly two of the least practical locations ever devised.

[tautech]

In all seriousness, I expect we'll see solar cells on car bodies someday.  We're just not there yet.

Sure but don’t you ask yourself why not already ?

[wraper]

In all seriousness, I expect we'll see solar cells on car bodies someday.  We're just not there yet.

Sure but don’t you ask yourself why not already ?

Why don't you walk with solar cell hat already? It's very useful, for example you could charge your phone when alone in dessert.

[nctnico]

There are many millions of people for whom a small EV is an excellent fit to their needs though, people who commute <50 miles round trip each day and have a driveway or garage to park in at home where they can conveniently plug in and charge and a second car in the household for the occasional longer trips.

That depends very much on where you live. In the Netherlands 70% of the car owners don't have a driveway where they could charge an EV. In the cities this goes up to 80% to 90% (numbers from a company installing charging stations).

[hendorog]

There are always going to be more sensible places to locate the panels than on the cars themselves....

Interesting. Why is that?

[wraper]

The result, another ~5km of EV range charge/EV is loaded onto grids and required to be generated when it could well have been harnessed from the sun free !

If you put PV worth the same amount of money onto roof, you would get way more electricity to charge the car and power other stuff. So I can argue that this crappy use of PV takes money away from where it actually matters and basically wastes it.

But you presume everyone owns a roof to place PV panels on.

If you don't have a roof, it does not mean you must find a way to waste your money. Put solar panels instead of your windows, if you are so intended so stick them somewhere.

[tautech]

In all seriousness, I expect we'll see solar cells on car bodies someday.  We're just not there yet.

Sure but don’t you ask yourself why not already ?

Why don't you walk with solar cell hat already? It's very useful, for example you could charge your phone when alone in dessert.

Don’t get me wrong, I well know PV power has its place and that includes a big part of any green solution for our future.
Some years back I engaged a uni student needing a industry project to graduate to design and build a VCO based charge pump for a 6V 100mA PV panel to boost up to 150V into a 2200uF low leakage cap.
It took a little trial and error to optimise it as it’s parameters were set with passives but once right it could pump the cap full in seconds. Other than the storage cap it would easily fit into a matchbox and except for the cap cost under $5 to build.

I maintain EV manufacturers on the whole and the green legistrators have been stupid to overlook the addition of solar panels of some sort onto EV’s where one can only assume they’ve lost sight of the reason for their very existence, the reduction of pollution. 

[tautech]

I don't think solar panels on car bodies will ever make sense. Even in fantasy land where a 100% efficient solar panel is possible the amount of energy required to propel a car vs the amount of solar energy falling on that car will never add up. There are always going to be more sensible places to locate the panels than on the cars themselves or in the roads, quite possibly two of the least practical locations ever devised.

You totally miss the point.
The discussion relates to enhancing EV range and reducing charging costs.

[hendorog]

So, say I'm buying an EV in Auckland. One has solar panels and the other doesn't.

The one with solar panels states that it is on average, 25% more efficient than the other one, during the summer if it is parked in the sun. That statement is fair.

P.S. This isn't the final answer, its just something that has occurred to me as this thread has gone on.
P.P.S. General reminder that this thread is a puzzle. It says so in the first line of the OP. I want to see who is open minded enough to figure it out. Confirmation bias is the enemy in this thread.

[nctnico]

I maintain EV manufacturers on the whole and the green legistrators have been stupid to overlook the addition of solar panels of some sort onto EV’s where one can only assume they’ve lost sight of the reason for their very existence, the reduction of pollution. 

Short term it makes much more sense to ban inefficient ICE cars. In the Netherlands the purchase tax on a car is based on it's efficiency. For example: a Lada Niva which has a list price of 12k euro costs 49k euro (including tax) to buy in the Netherlands.

[nctnico]

I don't think solar panels on car bodies will ever make sense. Even in fantasy land where a 100% efficient solar panel is possible the amount of energy required to propel a car vs the amount of solar energy falling on that car will never add up. There are always going to be more sensible places to locate the panels than on the cars themselves or in the roads, quite possibly two of the least practical locations ever devised.

You totally miss the point.
The discussion relates to enhancing EV range and reducing charging costs.

And self discharge of EVs is a serious issue if you don't use the car that often. Money is evaporating into thin air if you park the car:
https://www.reddit.com/r/teslamotors/comments/5pd6fm/how_long_can_a_tesla_reasonably_hold_a_charge/

According to this posting the loss is about 10kWh per week which translates into 520kWh per year (that is as much as a big refridgerator!). I pay about .22 euro per kWh so the monetary loss is 114 euro per year. At fast charging stations the electricity price is likely double of that. If you own the car for 10 years then spending 500 euro on the solar roof to keep the battery topped up while the car is parked is well worth it.

[hendorog]

I maintain EV manufacturers on the whole and the green legistrators have been stupid to overlook the addition of solar panels of some sort onto EV’s where one can only assume they’ve lost sight of the reason for their very existence, the reduction of pollution. 

Short term it makes much more sense to ban inefficient ICE cars. In the Netherlands the purchase tax on a car is based on it's efficiency. For example: a Lada Niva which has a list price of 12k euro costs 49k euro (including tax) to buy in the Netherlands.

Wow that is spectacularly harsh! A Niva is only a small car as well.

In 2021, NZ will introduce a 3K NZD max surcharge on dirty cars, and an 8K max credit on clean ones at the border.

[tautech]

I maintain EV manufacturers on the whole and the green legistrators have been stupid to overlook the addition of solar panels of some sort onto EV’s where one can only assume they’ve lost sight of the reason for their very existence, the reduction of pollution. 

Short term it makes much more sense to ban inefficient ICE cars. In the Netherlands the purchase tax on a car is based on it's efficiency. For example: a Lada Niva which has a list price of 12k euro costs 49k euro (including tax) to buy in the Netherlands.

Sure but it’s a bigger picture that needs be better addressed.

[bdunham7]

So, say I'm buying an EV in Auckland. One has solar panels and the other doesn't.

The one with solar panels states that it is on average, 25% more efficient than the other one, during the summer if it is parked in the sun. That statement is fair.

P.S. This isn't the final answer, its just something that has occurred to me as this thread has gone on.
P.P.S. General reminder that this thread is a puzzle. It says so in the first line of the OP. I want to see who is open minded enough to figure it out. Confirmation bias is the enemy in this thread.

Your statement is not fair because it includes unstated and unjustified assumptions based on speculation and zero real world experience, as far as I can tell.

I'm sure you think yourself very clever, puzzles and all.  I'm amazed at the strength of opinions expressed here contrasted with scarcity and incorrectness of information.

I actually own a solar system that I designed and planned myself. to make my net electric bill virtually zero  I also actually own an electric car--which happened to be the most efficient (kWh/mi) one on the market when purchased.  I've sat down and figured out (roughly) how to implement solar panels on two different vehicles--the Focus and the old Ford Ranger Electric (pickup truck).  The Focus is impossible and the old Ranger maybe might have worked a little bit because it would have been a lot easier--it could essentially use two regular 60-cell panels cut up and reconfigured.  I ended up not pursuing the Ranger because they are scarce, old, not cheap, and I didn't need more projects (it would have required redesigning the battery as well).

My point is not that I'm smarter than you or that I know everything.  It is that this subject has been considered by many and actually implemented in few cases.  As of yet, nobody has shown me a system that has any meaningful technical advantage at anything remotely close to a viable price.  If a 5% (or less) increase in range or reduction in electricity costs is worth $5000 to you, great.  Please note that even Tesla, who are able to sell very expensive cars with expensive options, haven't offered anything like this, despite clearly having the technical capability--if anyone does--to implement car solar charging.

[bdunham7]

And self discharge of EVs is a serious issue if you don't use the car that often. Money is evaporating into thin air if you park the car:
https://www.reddit.com/r/teslamotors/comments/5pd6fm/how_long_can_a_tesla_reasonably_hold_a_charge/

According to this posting the loss is about 10kWh per week which translates into 520kWh per year (that is as much as a big refridgerator!). I pay about .22 euro per kWh so the monetary loss is 114 euro per year. At fast charging stations the electricity price is likely double of that. If you own the car for 10 years then spending 500 euro on the solar roof to keep the battery topped up while the car is parked is well worth it.

You guys are making these wild conclusions with pretty skimpy evidence.  One Reddit post?  Here's the facts:

1.  Li-Ion batteries of the kind in cars generally don't self-discharge very much.  Rather they are discharged by the car using power to do things when parked.  As stated right in the response you are cherry-picking, this is very simple to change--it's just a setting.  Sort of like shutting your computer down as opposed to putting it to sleep.

2.  I don't own a Tesla, but my car doesn't lose ANY significant power from the main battery when parked, even if I leave for a month.  In fact, I generally try to leave it partially discharged if it will be parked because it is less stress on the batteries if it gets warm out.  This is a design feature where the main batteries are completely disconnected when the car is not running and all power is drawn from the accessory battery.  Some cars actually have a small panel to keep the accessory battery charged, which is a gimmick but one I do like.

3.  That solar roof is going to cost you 5000 Euro, not 500, if you want even so much as a peak kilowatt out of it.  And for that you'll need a large car to boot.  You might do a bit better if you could park the car on an elevated ramp facing south with an inclination equal to your latitude, but I'm sure you'll agree that is not a generally practical solution.

Seriously, I'd love a solar roof for an EV.  I"m not some diesel-loving anti-EV fanatic. I looked into it.  Many other people with a lot more knowledge and capital than I have done so as well. Right now it is somewhere between 8K television and supersonic commercial air travel--yes it can be done, but it isn't economical or practical. I'd be happy to be proven wrong--make one! 

[wraper]

Wow that is spectacularly harsh! A Niva is only a small car as well.

Yet eats fuel like a tank.

[hendorog]

So, say I'm buying an EV in Auckland. One has solar panels and the other doesn't.

The one with solar panels states that it is on average, 25% more efficient than the other one, during the summer if it is parked in the sun. That statement is fair.

P.S. This isn't the final answer, its just something that has occurred to me as this thread has gone on.
P.P.S. General reminder that this thread is a puzzle. It says so in the first line of the OP. I want to see who is open minded enough to figure it out. Confirmation bias is the enemy in this thread.

Your statement is not fair because it includes unstated and unjustified assumptions based on speculation and zero real world experience, as far as I can tell.

I'm sure you think yourself very clever, puzzles and all.  I'm amazed at the strength of opinions expressed here contrasted with scarcity and incorrectness of information.

I actually own a solar system that I designed and planned myself. to make my net electric bill virtually zero  I also actually own an electric car--which happened to be the most efficient (kWh/mi) one on the market when purchased.  I've sat down and figured out (roughly) how to implement solar panels on two different vehicles--the Focus and the old Ford Ranger Electric (pickup truck).  The Focus is impossible and the old Ranger maybe might have worked a little bit because it would have been a lot easier--it could essentially use two regular 60-cell panels cut up and reconfigured.  I ended up not pursuing the Ranger because they are scarce, old, not cheap, and I didn't need more projects (it would have required redesigning the battery as well).

My point is not that I'm smarter than you or that I know everything.  It is that this subject has been considered by many and actually implemented in few cases.  As of yet, nobody has shown me a system that has any meaningful technical advantage at anything remotely close to a viable price.  If a 5% (or less) increase in range or reduction in electricity costs is worth $5000 to you, great.  Please note that even Tesla, who are able to sell very expensive cars with expensive options, haven't offered anything like this, despite clearly having the technical capability--if anyone does--to implement car solar charging.

It is not about who is smarter. I also thought it was a stupid idea. So did tautech initially.
But then was simply a random thought that occurred to me and I thought would stick my neck out and challenge the general 'common wisdom'. What has come to light is that there are even more benefits than I originally realised. Clear proof that I'm not that smart

And yes, this is pretty abstract. It's all a bit loosey goosey.

And I agree, that 5% increase in range is not that important. But the PV benefit is per day, and you don't need a full charge every day. How far is the average daily commute? Work out that as a percentage.
What could you do to your EV to get that sort of gain? You said you got the most efficient one on the market, so it was something you valued. I would too. But the solar one will eat its lunch all day long and twice on Sundays.

Tautech sent me this link, which has already been mentioned in the thread.
These bleeding edge multi junction cells might cost $5k at volume to slap on the car if/when they ever get to production. I have no idea what these cost, but I'm sure they are very expensive at 34% efficiency. Does anyone know what the state of play is with multi-junction cells getting to production?

But the point is, this thing gets a range of more than 40kms on solar alone. That $5k-ish and my sunny car park would get me to work and back at zero fuel cost.
https://techxplore.com/news/2019-07-toyota-solar-panels-electric-cars.html

Yet at the bottom the editor still felt the need to say:
"As we always like to point out with these solar car efforts, a car's roof is not the most ideal place to install solar cells. They would most likely be more efficient installed on the rooftop of a home and then, you can use the power to charge your vehicle."

Really?! They have just seen a working (albeit experimental) example of a commuter car which for most people potentially would very rarely if ever need to be filled up or charged, and yet they still think putting solar panels on the car is the wrong thing to do. I'll try very hard not to be judgmental on that one.

And that wasn't even the benefit I was thinking of when I started the thread actually. I had no idea that they were getting that sort of range out of solar on a road car. I had something else entirely in mind.

But anyway, if you don't want to participate, then don't.

[tautech]

It is that this subject has been considered by many and actually implemented in few cases.  As of yet, nobody has shown me a system that has any meaningful technical advantage at anything remotely close to a viable price.  If a 5% (or less) increase in range or reduction in electricity costs is worth $5000 to you, great.  Please note that even Tesla, who are able to sell very expensive cars with expensive options, haven't offered anything like this, despite clearly having the technical capability--if anyone does--to implement car solar charging.

You assume viable based on your own metric and that's fine however I ask why you've gone solar to the degree to reach zero cost ?
Surely the investment required means the cost is indeed not zero so you must have done it as your contribution to reducing pollution, correct or is there another reason ?
If the presumption that it's your contribution to the environment and obviously at some cost to you would you not agree that the cost of adding PV to EV is also a contribution to the environment and also not without some cost.
It would seem wrt EV PV's you can't see also the benefits of less generation requirement that might seem insignificant for a single EV it's not for a country full of them.

Sure, those that use EV's are doing their bit along with some substantial purchase incentives of which could well reduce any additional cost of a PV equipped EV for further benefit of the environment.

[David Hess]

Is solar PV worth it on cars?  What is the opportunity cost?

The solar PV adds a couple kilometers to the range per day, assuming good conditions.  But the same cost placed into larger battery capacity adds even more range under any conditions.  So solar PV is not worth it.

[tautech]

Is solar PV worth it on cars?  What is the opportunity cost?

The solar PV adds a couple kilometers to the range per day, assuming good conditions.  But the same cost placed into larger battery capacity adds even more range under any conditions.  So solar PV is not worth it.

David, that's a very short sighted and selfish view.
There is a very much bigger picture to consider here.

[David Hess]

Is solar PV worth it on cars?  What is the opportunity cost?

The solar PV adds a couple kilometers to the range per day, assuming good conditions.  But the same cost placed into larger battery capacity adds even more range under any conditions.  So solar PV is not worth it.

David, that's a very short sighted and selfish view.
There is a very much bigger picture to consider here.

What bigger picture?

It is a waste of money which is better spent on either larger battery capacity or a fixed solar installation.

The exception is if you expect to park your car for long periods in the sun without using it like if you were camping out.  After a few days, you might have enough energy stored to get to a charger.

[bdunham7]

So, say I'm buying an EV in Auckland. One has solar panels and the other doesn't.

The one with solar panels states that it is on average, 25% more efficient than the other one, during the summer if it is parked in the sun. That statement is fair.

P.S. This isn't the final answer, its just something that has occurred to me as this thread has gone on.
P.P.S. General reminder that this thread is a puzzle. It says so in the first line of the OP. I want to see who is open minded enough to figure it out. Confirmation bias is the enemy in this thread.

Your statement is not fair because it includes unstated and unjustified assumptions based on speculation and zero real world experience, as far as I can tell.

I'm sure you think yourself very clever, puzzles and all.  I'm amazed at the strength of opinions expressed here contrasted with scarcity and incorrectness of information.

I actually own a solar system that I designed and planned myself. to make my net electric bill virtually zero  I also actually own an electric car--which happened to be the most efficient (kWh/mi) one on the market when purchased.  I've sat down and figured out (roughly) how to implement solar panels on two different vehicles--the Focus and the old Ford Ranger Electric (pickup truck).  The Focus is impossible and the old Ranger maybe might have worked a little bit because it would have been a lot easier--it could essentially use two regular 60-cell panels cut up and reconfigured.  I ended up not pursuing the Ranger because they are scarce, old, not cheap, and I didn't need more projects (it would have required redesigning the battery as well).

My point is not that I'm smarter than you or that I know everything.  It is that this subject has been considered by many and actually implemented in few cases.  As of yet, nobody has shown me a system that has any meaningful technical advantage at anything remotely close to a viable price.  If a 5% (or less) increase in range or reduction in electricity costs is worth $5000 to you, great.  Please note that even Tesla, who are able to sell very expensive cars with expensive options, haven't offered anything like this, despite clearly having the technical capability--if anyone does--to implement car solar charging.

It is not about who is smarter. I also thought it was a stupid idea. So did tautech initially.
But then was simply a random thought that occurred to me and I thought would stick my neck out and challenge the general 'common wisdom'. What has come to light is that there are even more benefits than I originally realised. Clear proof that I'm not that smart

And yes, this is pretty abstract. It's all a bit loosey goosey.

And I agree, that 5% increase in range is not that important. But the PV benefit is per day, and you don't need a full charge every day. How far is the average daily commute? Work out that as a percentage.
What could you do to your EV to get that sort of gain? You said you got the most efficient one on the market, so it was something you valued. I would too. But the solar one will eat its lunch all day long and twice on Sundays.

Tautech sent me this link, which has already been mentioned in the thread.
These bleeding edge multi junction cells might cost $5k at volume to slap on the car if/when they ever get to production. I have no idea what these cost, but I'm sure they are very expensive at 34% efficiency. Does anyone know what the state of play is with multi-junction cells getting to production?

But the point is, this thing gets a range of more than 40kms on solar alone. That $5k-ish and my sunny car park would get me to work and back at zero fuel cost.
https://techxplore.com/news/2019-07-toyota-solar-panels-electric-cars.html

Yet at the bottom the editor still felt the need to say:
"As we always like to point out with these solar car efforts, a car's roof is not the most ideal place to install solar cells. They would most likely be more efficient installed on the rooftop of a home and then, you can use the power to charge your vehicle."

Really?! They have just seen a working (albeit experimental) example of a commuter car which for most people potentially would very rarely if ever need to be filled up or charged, and yet they still think putting solar panels on the car is the wrong thing to do. I'll try very hard not to be judgmental on that one.

And that wasn't even the benefit I was thinking of when I started the thread actually. I had no idea that they were getting that sort of range out of solar on a road car. I had something else entirely in mind.

But anyway, if you don't want to participate, then don't.

You sound like a slick salesman--or someone who has been sold by one.

I didn't say efficiency was important to me, it just happened that way.  Range is much more important, as well as cost, reliability and ease of use--my wife drives it to work.

You are assuming the assertion that the car can gain 27 miles per day is supportable in a realistic use scenario.  If that's true, then that is a big step forward--even if the cost is astronomical.  So I figured I could put about 0.9 m^2 of panels on the roof of the Focus.  1.2 or so if I used the hood.  I see they've covered the back window as well, so let's assume they have somehow put on 1.5 m^2 of panels.  Or, provide your own estimate and justify it.  So my panels are about 1.5 m^2 each, they're about half as efficient as the VERY EXPENSIVE cells on the Toyota and they produce 1.2 to 1.3 kWh in the summer here in one of the highest insolation areas in the inhabited world, installed on a roof facing south and tilted at an angle that nearly maximizes annual production.  So if you parked your car on the south-facing elevated ramp that I posited earlier, perhaps you could get 2.5kWh per day.  For my car, that's 10 miles.  That is certainly something.  It certainly isn't 27 miles and I'd like to see their math--something's got to give.

Now, lets have a realistic look at costs and realistic output scenarios. Am I mistaken that this is a forum of engineers?  Is this math and economics not relevant?  So I'd like to compare your "free" energy with the more traditional concept of adding rooftop solar power and a bit of battery.  If you don't have a roof, then you'll have to do your model using purchased electricity. 

The first issue is that the car cannot and will not produce as much electricity as a the ideal model would indicate.  The panels will at times be shaded, not at an ideal angle--since they are at different angles, they simply cannot all be at the ideal angle at the same time and most places don't have as much sun as we do here--of course this last one applies to roof panels as well.  The car may be inside or shaded at times, a truck may be driving next to it, etc.  I think you'd be doing really really well to get 2.0 kWh on average and I'd like to see evidence to the contrary.

The second issue is that sometimes the car will be fully charged, especially shorter range models.  So figure out how often a fully charged EV sits in the sun (mine does quite often) and put that power in the wasted energy column.

So, as I said, my panels produce about 1.2-1.3kWh/day, and since they are half as efficient as the triple-junction ones here, it makes sense that it would take two of them to be somewhat equivalent.  My NET COST per panel of an installed system was about $500/panel and I contracted out most of the labor.  I actually have room (theoretically) to add 6 more panels and I could do it for the same price or less.  So $1000 (and I can actually do it MUCH cheaper, but I'm trying to be evenhanded).  To be fair, I have to cost in the additional battery capacity, so perhaps another $1000?  At this point, I'll have the rough equivalent of your solar roof. They each have some advantages and disadvantages, but I think they're close enough to compare. 

A very similar debate arose over the Tesla solar roofing product for homes--and it appears to be a complete failure in the market place. So how much for the solar roof? 

[bdunham7]

It is that this subject has been considered by many and actually implemented in few cases.  As of yet, nobody has shown me a system that has any meaningful technical advantage at anything remotely close to a viable price.  If a 5% (or less) increase in range or reduction in electricity costs is worth $5000 to you, great.  Please note that even Tesla, who are able to sell very expensive cars with expensive options, haven't offered anything like this, despite clearly having the technical capability--if anyone does--to implement car solar charging.

You assume viable based on your own metric and that's fine however I ask why you've gone solar to the degree to reach zero cost ?
Surely the investment required means the cost is indeed not zero so you must have done it as your contribution to reducing pollution, correct or is there another reason ?
If the presumption that it's your contribution to the environment and obviously at some cost to you would you not agree that the cost of adding PV to EV is also a contribution to the environment and also not without some cost.
It would seem wrt EV PV's you can't see also the benefits of less generation requirement that might seem insignificant for a single EV it's not for a country full of them.

Sure, those that use EV's are doing their bit along with some substantial purchase incentives of which could well reduce any additional cost of a PV equipped EV for further benefit of the environment.

Buying into bleeding edge  "green" technology at greater cost to "save the environment" generally is both expensive....and doesn't help the environment.  I went solar because electricity is expensive here and we have a lot of sun.  I did the math and once costs came down enough--they're even lower today--I bought in.  The system I have has more than paid for itself and I'll have recouped double my investment in about another two years.  Many people that bought in too early got vastly more expensive systems with not-fully-developed technology that had high failure rates.  So their systems have either been scrapped or are sitting on their roofs not doing anything.  That wastes money and doesn't help the environment. 

Everything you do has a cost--both environmental and economic.  According to some economic theories, the two are actually closely related--the more something costs to make, the more impact it has on the environment.  So you have to balance the costs--both types--of producing your solar auto roof with the benefits of it.  And then you have to compare those costs with the alternatives.  The last time I looked at it the idea was not viable.  Eventually this may change, but I don't think it has yet.

If anyone wants to call and price out those triple-junction modules, here's the manufacturer.  If you have any experience with procurement, you'll know not to guess at the price.

https://www.spectrolab.com/photovoltaics.html

[hendorog]

Is solar PV worth it on cars?  What is the opportunity cost?

The solar PV adds a couple kilometers to the range per day, assuming good conditions.  But the same cost placed into larger battery capacity adds even more range under any conditions.  So solar PV is not worth it.

Adding to the range is not much help for a commuter car, and most EV's are - at least in this country. Putting the same cost into the battery gives you more range, but what use is that when you are only doing 20km's a day? The average daily commute by car in Auckland is around that figure.

But that extra power is power you don't need to pay for. So it makes the car more efficient by 25% if the solar gives you 5kms per day and your commute is 20kms. That is worth having instead of extra battery you are just lugging around for the lifetime of the vehicle. Could you do anything else to an EV that would get an efficiency boost like that?

As tautech alluded to, that power you don't need to put into the car is power that doesn't need to be generated. That is particularly relevant if it is generated from fossil fuels. 18% of the power in this country is generated from fossil fuels.
It is also power that doesn't need to be moved from the generator to the load. It is already there.

[tautech]

It is that this subject has been considered by many and actually implemented in few cases.  As of yet, nobody has shown me a system that has any meaningful technical advantage at anything remotely close to a viable price.  If a 5% (or less) increase in range or reduction in electricity costs is worth $5000 to you, great.  Please note that even Tesla, who are able to sell very expensive cars with expensive options, haven't offered anything like this, despite clearly having the technical capability--if anyone does--to implement car solar charging.

You assume viable based on your own metric and that's fine however I ask why you've gone solar to the degree to reach zero cost ?
Surely the investment required means the cost is indeed not zero so you must have done it as your contribution to reducing pollution, correct or is there another reason ?
If the presumption that it's your contribution to the environment and obviously at some cost to you would you not agree that the cost of adding PV to EV is also a contribution to the environment and also not without some cost.
It would seem wrt EV PV's you can't see also the benefits of less generation requirement that might seem insignificant for a single EV it's not for a country full of them.

Sure, those that use EV's are doing their bit along with some substantial purchase incentives of which could well reduce any additional cost of a PV equipped EV for further benefit of the environment.

Buying into bleeding edge  "green" technology at greater cost to "save the environment" generally is both expensive....and doesn't help the environment.  I went solar because electricity is expensive here and we have a lot of sun.  I did the math and once costs came down enough--they're even lower today--I bought in.  The system I have has more than paid for itself and I'll have recouped double my investment in about another two years.  Many people that bought in too early got vastly more expensive systems with not-fully-developed technology that had high failure rates.  So their systems have either been scrapped or are sitting on their roofs not doing anything.  That wastes money and doesn't help the environment. 

Everything you do has a cost--both environmental and economic.  According to some economic theories, the two are actually closely related--the more something costs to make, the more impact it has on the environment.  So you have to balance the costs--both types--of producing your solar auto roof with the benefits of it.  And then you have to compare those costs with the alternatives.  The last time I looked at it the idea was not viable.  Eventually this may change, but I don't think it has yet.

Yep, right with you up until the last bit when big picture thinking that seems absent in this thread should be a important part of the cost viability.
Let's for a moment think we we are heading with the subsidisation of EV's to enhance their uptake that btw has been rightly pointed out might be nearer to zero if it wasn't for EV buying incentives.

So those that have the power to have implemented this artificial EV uptake in some attempt to meet their countries Paris accord commitments have totally missed a double barrel opportunity to insist PV's are a mandatory part of EV technology and production in order have a further positive impact on their electrical grid charging demands that can only grow in the future, notwithstanding the lesser environmental cost of burning fossil fuels to charge EV's.
So who might pay for this, an arguably nonviable mandatory PV on a EV, pretty simple, it's those that are already paying for the artificial uptake of EV's.......the taxpayer.
A few hundred $/EV, no big deal when spread over all the taxpayers/country and at the the current uptake of EV's might amount to bugger all in the big picture.

In my thoughts of our leaders and forward thinking planners......the words dumb and dumber come instantly to mind !

[nctnico]

And self discharge of EVs is a serious issue if you don't use the car that often. Money is evaporating into thin air if you park the car:
https://www.reddit.com/r/teslamotors/comments/5pd6fm/how_long_can_a_tesla_reasonably_hold_a_charge/

According to this posting the loss is about 10kWh per week which translates into 520kWh per year (that is as much as a big refridgerator!). I pay about .22 euro per kWh so the monetary loss is 114 euro per year. At fast charging stations the electricity price is likely double of that. If you own the car for 10 years then spending 500 euro on the solar roof to keep the battery topped up while the car is parked is well worth it.

You guys are making these wild conclusions with pretty skimpy evidence.  One Reddit post?  Here's the facts:

1.  Li-Ion batteries of the kind in cars generally don't self-discharge very much.  Rather they are discharged by the car using power to do things when parked.  As stated right in the response you are cherry-picking, this is very simple to change--it's just a setting.  Sort of like shutting your computer down as opposed to putting it to sleep.

2.  I don't own a Tesla, but my car doesn't lose ANY significant power from the main battery when parked, even if I leave for a month.  In fact, I generally try to leave it partially discharged if it will be parked because it is less stress on the batteries if it gets warm out.  This is a design feature where the main batteries are completely disconnected when the car is not running and all power is drawn from the accessory battery.  Some cars actually have a small panel to keep the accessory battery charged, which is a gimmick but one I do like.

3.  That solar roof is going to cost you 5000 Euro, not 500, if you want even so much as a peak kilowatt out of it.  And for that you'll need a large car to boot.  You might do a bit better if you could park the car on an elevated ramp facing south with an inclination equal to your latitude, but I'm sure you'll agree that is not a generally practical solution.

That solar roof costs 5k if you are using experimental stage solar cells. That is not relevant for a commercial product. Based on commercially available solar cells a solar roof for a car can be made for 500 euro. And perhaps the Tesla is a poor example but having to put a car in deep sleep (and likely disabling stuff like remote monitoring / software updates) before parking it for a longer period is something I'd typically forget / don't care about so for me it would be nice to have a feature which just makes the car easier to use. Especially since I can't keep an EV plugged in at home.

[wraper]

A very similar debate arose over the Tesla solar roofing product for homes--and it appears to be a complete failure in the market place. So how much for the solar roof?

It's not a failure in market. It just was never really released to wide public until now as it just starts ramping up.

[james_s]

There are always going to be more sensible places to locate the panels than on the cars themselves....

Interesting. Why is that?

Because math.

Calculate the area available on a typical car body and work out the maximum typical power you'd get by covering the entire thing with the most efficient solar panels available. Now compare that to the amount of energy required to propel a car and you'll find that even under ideal circumstances the contribution is going to be underwhelming and most of the time we do not have ideal circumstances. Once you factor in the additional weight, cost, maintenance and repair challenges, etc I think you'll find it cannot possibly be cost effective. A stationary installation is cheaper, lasts longer, is not married to one specific car for life, the panels can be optimally placed and using them does not require you always to park your car outside under the scorching sun which damages the interior and degrades plastics like lamp lenses and trim.


I really don't understand why a few people latch on to these silly ideas like solar panels in roads or on cars when there are SO many superior as of yet untapped options.

[klunkerbus]

As a Bolt EV owner, the thread is interesting to follow.  I wouldn't have wanted to pay anything extra for a solar rooftop, because
 
a) I haven't measured it, but the Bolt rooftop seems pretty small and cells would be flat to the ground - not angled towards the sun for optimal efficiency.  On the Bolt, the hood is really small, so very little to be gained by PV there.  Optimizing the orientation and even tracking the sun can be a benefit of building-rooftop or freestanding solar that our Bolt couldn't achieve. 
b) For us, achieving a few extra miles or km range on a daily basis is insignificant. If that was a substantial portion of our daily driving, I'd have likely bought an e-bike instead.
c) We garage our Bolt every chance we can to reduce exposure to what seems like daily summer hail storms here, and when it isn't raining the sun at our higher elevation can be a killer on plastics and vinyl.  Besides, if we were to park the car in the sun instead of the garage, how much gain from PV would we then lose in then having to cool or heat the vehicle when we got in to drive somewhere? 

Also, as I recall, Elon Musk has said he had Tesla engineers study vehicle rooftop PV, and their conclusion is that it just doesn't make sense.  The way I look at it, if Musk can't find a creative way to hype it, odds are no one can. Well, perhaps except for certain, limited scope use cases. 

[hendorog]

There are always going to be more sensible places to locate the panels than on the cars themselves....

Interesting. Why is that?

Because math.

Calculate the area available on a typical car body and work out the maximum typical power you'd get by covering the entire thing with the most efficient solar panels available. Now compare that to the amount of energy required to propel a car and you'll find that even under ideal circumstances the contribution is going to be underwhelming and most of the time we do not have ideal circumstances. Once you factor in the additional weight, cost, maintenance and repair challenges, etc I think you'll find it cannot possibly be cost effective. A stationary installation is cheaper, lasts longer, is not married to one specific car for life, the panels can be optimally placed and using them does not require you always to park your car outside under the scorching sun which damages the interior and degrades plastics like lamp lenses and trim.


I really don't understand why a few people latch on to these silly ideas like solar panels in roads or on cars when there are SO many superior as of yet untapped options.

So, on the car:

No need to buy a battery
No need to buy an inverter
No fees to pay to setup feed into the grid.
No electrician to pay
No certification required
No installer to pay - assuming the panel is purchased already integrated with a part of the car such as the moon roof.
One panel system is viable.
No need to transport power. It is produced directly on the load
Mass produced, every system is the same
Nothing to arrange. It just comes with the car. Your granny can do it.
Design is one time cost.
No need to seek additional funding. It is included with the car
Makes the car more efficient
Allows the battery to be maintained while disconnected

The house install can be larger. It will be more expensive per kW for the simple reason that the non-generating one off costs are significant.
Cost breakdown of a typical professional quote I have is very roughly 33% Panels, 33% Inverter/Charger and Hardware, 33% install and misc.
That is a system without a battery. A battery is hugely beneficial, but it makes the costing much worse. Big win for the car.

On the house:

Design simpler, but is required each time - every system is different.
Inverter/inverters/inverter charger
Battery - depends on power company terms whether you need it. Eventually if enough solar is installed it will be essential.
Installation - every installation is different. Its expensive to get people onto your roof.
Grid tie setup costs
Certification costs
Funding costs/opportunity costs - nobody (professionally) installs a tiny PV system. Average size (based on my observations and quotes) I estimate somewhere around $5-10K

I think the panel on the car will win the cost effective argument every time.

Rooftop solar is less likely to be shaded and will be better aligned, so on average the same panel will generate more power. However that power is used up paying back the one off install and hardware costs.

Rooftop solar does have the ability to scale up, by adding a couple more panels to a roof.

However consider there are thousands of EV cars coming off production lines every week. That scales up pretty good.

If each one had a PV panel then that is a significant capacity being installed every year.
This is a virtual power station that requires zero infrastructure, zero management. It just quietly offsets other generation.

[Nauris]

If you think typical city bus, like a MB Citaro 12 meters long, 2.5 wide that is 30 m2 quite flat roof you can put maybe 6 kW solar array there. It provides about 5 MWh electricity annually in central Europe enough for about 4000 km city driving that is like two or three weeks maybe. Quite small help but might actually make economic sense as electricity from battery is expensive and panels are cheap.

[nctnico]

Rooftop solar does have the ability to scale up, by adding a couple more panels to a roof.

However consider there are thousands of EV cars coming off production lines every week. That scales up pretty good.

If each one had a PV panel then that is a significant capacity being installed every year.
This is a virtual power station that requires zero infrastructure, zero management. It just quietly offsets other generation.

I think this pretty much sums up the 'problems' with solar panels on roofs. Roof top solar just doesn't scale because every home owner has different priorities (and may not even want to use the roof for solar panels).

[David Hess]

But that extra power is power you don't need to pay for. So it makes the car more efficient by 25% if the solar gives you 5kms per day and your commute is 20kms. That is worth having instead of extra battery you are just lugging around for the lifetime of the vehicle. Could you do anything else to an EV that would get an efficiency boost like that?

As tautech alluded to, that power you don't need to put into the car is power that doesn't need to be generated. That is particularly relevant if it is generated from fossil fuels. 18% of the power in this country is generated from fossil fuels.
It is also power that doesn't need to be moved from the generator to the load. It is already there.

And the same cost put into a fixed solar installation delivers even more energy and lasts longer as well.

There are some unusual use cases where solar on a vehicle makes sense but energy economy and range are not them.

[hendorog]

But that extra power is power you don't need to pay for. So it makes the car more efficient by 25% if the solar gives you 5kms per day and your commute is 20kms. That is worth having instead of extra battery you are just lugging around for the lifetime of the vehicle. Could you do anything else to an EV that would get an efficiency boost like that?

As tautech alluded to, that power you don't need to put into the car is power that doesn't need to be generated. That is particularly relevant if it is generated from fossil fuels. 18% of the power in this country is generated from fossil fuels.
It is also power that doesn't need to be moved from the generator to the load. It is already there.

And the same cost put into a fixed solar installation delivers even more energy and lasts longer as well.

There are some unusual use cases where solar on a vehicle makes sense but energy economy and range are not them.

The same cost put into fixed solar will get you nothing - unless of course you happen to already have a fixed solar installation handy that you can add a panel to, or you DIY something and you account your time as very cheap or free. The DIY approach is great, but it doesn't scale up like PV cars would.

Now if there was a solar farm that existed somewhere you could just buy a panel and add to their infrastructure then it gets more interesting.

However if you attempt to get that power from the solar farm to your car, in my country at least, it loses about 2/3 of its value.
The retail cost of power here is very roughly 3 times the wholesale power price. About 1/3 is the wholesale price the generator gets, 1/3 is transmission, 1/3 is margins, fees and taxes.
So when you feed power into the grid, you get paid the wholesale price. When you pull it out you pay the retail price.

I know this won't be the same for everyone. Some people will be able to get a special deal, and that's great, good for them. But a great deal in California isn't much use here.

The point there is, the panel on the car is right on top of the battery and the load. So no need to move the power and so no extra cost.

[wraper]

The same cost put into fixed solar will get you nothing - unless of course you happen to already have a fixed solar installation handy that you can add a panel to, or you DIY something and you account your time as very cheap or free. The DIY approach is great, but it doesn't scale up like PV cars would.

Your point only works if one is idiot who doesn't plan anything beforehand. And just "needs" to put (additional) solar panels the day car is bought. Also you don't necessarily need to buy any solar panels to begin with. There are thousands of ways ways how to spend your money more efficiently, rather than buying barely working technology. It's not like you are obliged to blow the largest amount of money possible when buying a car.

[hendorog]

The same cost put into fixed solar will get you nothing - unless of course you happen to already have a fixed solar installation handy that you can add a panel to, or you DIY something and you account your time as very cheap or free. The DIY approach is great, but it doesn't scale up like PV cars would.

Your point only works if one is idiot who doesn't plan anything beforehand. And just "needs" to put additional panels the day car is bought. Also you don't necessarily need to buy any solar panels to begin with. There are thousands of ways ways how to spend your money more efficiently, rather than buying barely working technology.

Huh? It is the same solar tech that goes on the roof.
How is that barely working tech?

Of course perhaps a big car company with buying power can certainly do better on price, efficiency or both, than the ordinary panels we mere mortals can afford.

Everyone is talking about rooftop solar like you can just spend a few hundred bucks and make it happen and it will be better than on a car. I've looked into it and that is not the case. Certainly not the case for the same money as are talking about on the car.

You have to pay much more, get a bigger system before it starts to work out on a roof. _Or_ you have to DIY it.

[wraper]

Huh? It is the same solar tech that goes on the roof.
How is that barely working tech?

If it somewhat adds at least noticeable range 5% of the time when you parked your car on sunny spot during a middle of a day, it's barely working.

[ahbushnell]

But that extra power is power you don't need to pay for. So it makes the car more efficient by 25% if the solar gives you 5kms per day and your commute is 20kms. That is worth having instead of extra battery you are just lugging around for the lifetime of the vehicle. Could you do anything else to an EV that would get an efficiency boost like that?

As tautech alluded to, that power you don't need to put into the car is power that doesn't need to be generated. That is particularly relevant if it is generated from fossil fuels. 18% of the power in this country is generated from fossil fuels.
It is also power that doesn't need to be moved from the generator to the load. It is already there.

And the same cost put into a fixed solar installation delivers even more energy and lasts longer as well.

There are some unusual use cases where solar on a vehicle makes sense but energy economy and range are not them.

On Mars

[schmitt trigger]

All this discussion matters depending on your geographical location. In other words, how much YEARLY sunshine on receives on average, not only in the summer.

Case in point: I was in Budapest a few weeks ago. It was hot and very sunny. I saw the many trams in the city, and suggested to my Hungarian engineer friend that they should put solar panels to power the trams.
He replied: you haven't seen a bleak Budapest winter.

[nctnico]

Huh? It is the same solar tech that goes on the roof.
How is that barely working tech?

If it somewhat adds at least noticeable range 5% of the time when you parked your car on sunny spot during a middle of a day, it's barely working.

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

[wraper]

Huh? It is the same solar tech that goes on the roof.
How is that barely working tech?

If it somewhat adds at least noticeable range 5% of the time when you parked your car on sunny spot during a middle of a day, it's barely working.

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

And then sit under shade most of the time. If thing somewhat works when you are lucky, it's basically not working. It has the major problem of regular solar panels squared.

don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

The issue is it still needs both of those. And practically to the same extent as regular EV.

[hendorog]

All this discussion matters depending on your geographical location. In other words, how much YEARLY sunshine on receives on average, not only in the summer.

Case in point: I was in Budapest a few weeks ago. It was hot and very sunny. I saw the many trams in the city, and suggested to my Hungarian engineer friend that they should put solar panels to power the trams.
He replied: you haven't seen a bleak Budapest winter.

Quite. One of the things which is not being grasped by some is that these cars go all over the world.
So at any point in time, some will be good, some will be bad, some will be average.

But as a collective fleet of cars the power becomes significant.

[nctnico]

Huh? It is the same solar tech that goes on the roof.
How is that barely working tech?

If it somewhat adds at least noticeable range 5% of the time when you parked your car on sunny spot during a middle of a day, it's barely working.

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

And then sit under shade most of the time. If thing somewhat works when you are lucky, it's basically not working. It has the major problem of regular solar panels squared.

I was hoping for a better argument. Solar panels on roofs are at a fixed angle / position so they don't catch all of the sunlight during the day as well.

[hendorog]

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

The issue is it still needs both of those. And practically to the same extent as regular EV.

You have totally missed his point.

The point is, solar panels need storage and infrastructure (and management) if you put the solar panels _anywhere else_

[wraper]

I was hoping for a better argument. Solar panels on roofs are at a fixed angle / position so they don't catch all of the sunlight during the day as well.

On the roof they are still usually placed in best possible (fixed) position. Yet car always will be in suboptimal (horizontal) position and usually in shade on top of that. Frankly I thought you could at least use math to understand it will work poor regardless of how good technology gets because area is simply too small. Even when put in nearly perfect conditions.

[wraper]

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

The issue is it still needs both of those. And practically to the same extent as regular EV.

You have totally missed his point.

The point is, solar panels need storage and infrastructure (and management) if you put the solar panels _anywhere else_

Nope, you completely missed the point. Solar panels will barely charge battery existing in the car = provide only a small portion of energy needed. So you still need all of infrastructure regular EV needs.
Actually you could put 5 times smaller solar panel on a roof and most likely still get more energy from it in total. Given you use it as a normal car, not portable solar battery which you leave in rural empty space unobstructed by any buildings or trees.

[nctnico]

I was hoping for a better argument. Solar panels on roofs are at a fixed angle / position so they don't catch all of the sunlight during the day as well.

On the roof they are still usually placed in best possible (fixed) position. Yet car always will be in suboptimal (horizontal) position and usually in shade on top of that. Frankly I thought you could at least use math to understand it will work poor regardless of how good technology gets because area is simply too small. Even when put in nearly perfect conditions.

Without doing a cost versus benefit calculation this statement doesn't say anything. In the end it is all about ROI and efficiency is just a small part of that. Also: from where comesthe assumption that a car is always in the shade?

[hendorog]

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

The issue is it still needs both of those. And practically to the same extent as regular EV.

You have totally missed his point.

The point is, solar panels need storage and infrastructure (and management) if you put the solar panels _anywhere else_

Nope, you completely missed the point. Solar panels will barely charge battery existing in the car = provide only a small portion of energy needed. So you still need all of infrastructure regular EV needs.
Actually you could put 5 times smaller solar panel on a roof and most likely still get more energy from it in total.

I understood your point already. Nobody said you can remove the battery from the car and no longer charge it. You came up with that all by yourself.

And then there you go again ignoring the additional costs of storage and everything else when you put a solar panels on a roof.

You have one argument that has merit and that is shading. That counter argument to that is that if you view the group of EV's as a collective then the numbers will be so large that significant energy is still generated. These things are being produced in huge numbers already. The growth curve looks exponential.

You may well be right about shading, maybe it does require 5 times as much power. So lets just wait an hour. Another 20 EV's just got made. And that is only counting the Teslas.

I think that covers the shading issue.

[wraper]

That counter argument to that is that if you view the group of EV's as a collective then the numbers will be so large that significant energy is still generated. These things are being produced in huge numbers already. The growth curve looks exponential.

How that's an argument? You can say the same thing about houses. If you spent all that money on solar roofs and powerwalls... woohoo, we would have tons of electricity. It does not matter what total quantity there is unless it can make big contribution for powering individual car.
EDIT: To rephrase it. Making tons of inefficient crap does not make it gold because of huge quantity present.

[hendorog]

That counter argument to that is that if you view the group of EV's as a collective then the numbers will be so large that significant energy is still generated. These things are being produced in huge numbers already. The growth curve looks exponential.

How that's an argument? You can say the same thing about houses. If you spent all that money on solar roofs and powerwalls... woohoo, we would have tons of electricity. It does not matter what total quantity there is unless it can make big contribution for powering individual car.

Sweet, go do that then. You haven't read the comments above about why not, so you won't start now.

Your first problem might be convincing everyone who buys an EV to give you $500. But you clearly have thought this through.

You will be kept so busy putting up solar panels trying to keep up with the EV solar fleet that you won't have time to post much.

[bdunham7]

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

The issue is it still needs both of those. And practically to the same extent as regular EV.

You have totally missed his point.

The point is, solar panels need storage and infrastructure (and management) if you put the solar panels _anywhere else_

Nope, you completely missed the point. Solar panels will barely charge battery existing in the car = provide only a small portion of energy needed. So you still need all of infrastructure regular EV needs.
Actually you could put 5 times smaller solar panel on a roof and most likely still get more energy from it in total.

I understood your point already. Nobody said you can remove the battery from the car and no longer charge it. You came up with that all by yourself.

And then there you go again ignoring the additional costs of storage and everything else when you put a solar panels on a roof.

You have one argument that has merit and that is shading. That counter argument to that is that if you view the group of EV's as a collective then the numbers will be so large that significant energy is still generated. These things are being produced in huge numbers already. The growth curve looks exponential.

You may well be right about shading, maybe it does require 5 times as much power. So lets just wait an hour. Another 20 EV's just got made. And that is only counting the Teslas.

I think that covers the shading issue.

Y'all are scaring me!    You ignore the assessment of people skilled in the art and those like me who have looked at this closely, you bandy about numbers and concepts without any actual application and then you want to MANDATE (if I'm reading you correctly) a technology that every entitity capable of making has declared either not practical or not practical yet.  Somebody (not you!) will pay for all this so the cost doesn't matter and it's all OK because it will do some good (of course it will...if you don't care how much)   You say "I think that covers the shading issue".  Really?  You wouldn't bother to study the issue a bit more?  Just a flippant "lets just wait an hour". 

So show us how it is done.  I'm all for it if it works and doesn't cost too much proportional to the benefit.  Apparently in addition to dodging any and all actual math and engineering, you want to avoid the perils of the marketplace as well.  This type of thinking has given us solar roadways, bullet trains to nowhere (hopefully now mostly cancelled here in CA) and the Elio. 

[hendorog]

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

The issue is it still needs both of those. And practically to the same extent as regular EV.

You have totally missed his point.

The point is, solar panels need storage and infrastructure (and management) if you put the solar panels _anywhere else_

Nope, you completely missed the point. Solar panels will barely charge battery existing in the car = provide only a small portion of energy needed. So you still need all of infrastructure regular EV needs.
Actually you could put 5 times smaller solar panel on a roof and most likely still get more energy from it in total.

I understood your point already. Nobody said you can remove the battery from the car and no longer charge it. You came up with that all by yourself.

And then there you go again ignoring the additional costs of storage and everything else when you put a solar panels on a roof.

You have one argument that has merit and that is shading. That counter argument to that is that if you view the group of EV's as a collective then the numbers will be so large that significant energy is still generated. These things are being produced in huge numbers already. The growth curve looks exponential.

You may well be right about shading, maybe it does require 5 times as much power. So lets just wait an hour. Another 20 EV's just got made. And that is only counting the Teslas.

I think that covers the shading issue.

Y'all are scaring me!    You ignore the assessment of people skilled in the art and those like me who have looked at this closely, you bandy about numbers and concepts without any actual application and then you want to MANDATE (if I'm reading you correctly) a technology that every entitity capable of making has declared either not practical or not practical yet.  Somebody (not you!) will pay for all this so the cost doesn't matter and it's all OK because it will do some good (of course it will...if you don't care how much)   You say "I think that covers the shading issue".  Really?  You wouldn't bother to study the issue a bit more?  Just a flippant "lets just wait an hour". 

So show us how it is done.  I'm all for it if it works and doesn't cost too much proportional to the benefit.  Apparently in addition to dodging any and all actual math and engineering, you want to avoid the perils of the marketplace as well.  This type of thinking has given us solar roadways, bullet trains to nowhere (hopefully now mostly cancelled here in CA) and the Elio.

Ignore? If anything I have responded with counter points mostly to you and wraper - who have been the most prolific critics.

Lets just start with one thing.

..every entitity capable of making has declared either not practical or not practical yet...

Yet this...

Is putting solar panels on an EV a good idea?

Already done: https://sonomotors.com/de/sion/
Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.
https://www.electrive.com/2019/07/04/toyota-testing-hybrid-prius-fitted-with-solar-cells/

Do you accept that what you said is no longer accurate?

[bdunham7]

Do you accept that what you said is no longer accurate?

Um, no.  I can read and I can smell BS.  We discussed this earlier.  The SION is vaporware and I don't yet include Sono as "and entity capable..."  If they ever show up, we'll have to see what they actually produce from solar. 

The Toyota is a prototype, which implies pretty clearly that it isn't ready yet.

Obviously the basic concept can be implemented.  I can duct tape a solar panel on my roof and do some bodge wiring, for that matter.  None of that--claims, prototypes or home experiments--make this anywhere near ready for production or useful and cost effective enough to sell. 

[hendorog]

Do you accept that what you said is no longer accurate?

Um, no.  I can read and I can smell BS.  We discussed this earlier.  The SION is vaporware and I don't yet include Sono as "and entity capable..."  If they ever show up, we'll have to see what they actually produce from solar. 

The Toyota is a prototype, which implies pretty clearly that it isn't ready yet.

Obviously the basic concept can be implemented.  I can duct tape a solar panel on my roof and do some bodge wiring, for that matter.  None of that--claims, prototypes or home experiments--make this anywhere near ready for production or useful and cost effective enough to sell.

Hrm, yes I could have made that clearer. The two links hammy posted are not the key part.

The real message is this statement:

Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.

Given how far ahead the car industry operates, it is pretty clear that they have already accepted solar has some merit.

And apparently Toyota already have one on the market in Japan.
https://cleantechnica.com/2018/11/06/hyundai-kia-to-begin-offering-solar-sun-roofs-after-2019/

And it at least gives us our first price: $2,500

Which is higher than I expected, but well it is the first one on the market I assume, so not surprising.

[bdunham7]

Do you accept that what you said is no longer accurate?

Um, no.  I can read and I can smell BS.  We discussed this earlier.  The SION is vaporware and I don't yet include Sono as "and entity capable..."  If they ever show up, we'll have to see what they actually produce from solar. 

The Toyota is a prototype, which implies pretty clearly that it isn't ready yet.

Obviously the basic concept can be implemented.  I can duct tape a solar panel on my roof and do some bodge wiring, for that matter.  None of that--claims, prototypes or home experiments--make this anywhere near ready for production or useful and cost effective enough to sell.

Hrm, yes I could have made that clearer. The two links hammy posted are not the key part.

The real message is this statement:

Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.

Given how far ahead the car industry operates, it is pretty clear that they have already accepted solar has some merit.

And apparently Toyota already have one on the market in Japan.
https://cleantechnica.com/2018/11/06/hyundai-kia-to-begin-offering-solar-sun-roofs-after-2019/

And it at least gives us our first price: $2,500

Which is higher than I expected, but well it is the first one on the market I assume, so not surprising.

So read the links and look at the numbers, even if you don't do any math.  They simply disprove every point you are trying to make.  The Toyota example is $2500 and it is puny--less than half the roof is covered and if you understand how fuel economy is measured in Japan, you'll know that the "theoretical maximum" of 3.7 miles probably equates to 0.6kWh or so.  Ludicrously minimal performance at a high cost.  And it is not offered in the US because it the glass on the panels cannot pass the NHTSA crash/rollover requirements.  I said $5000, 1.2kWh at best and not ready yet.  Here you have an exactly what I said, but at half scale.

As for the Hyundai, well "ideally" it will charge 60% of a 1.56kWh battery (do a little math there) for some unknown cost that we'll find out later.

I know you are expecting performance to increase dramatically and prices to fall even more, but not all technology does that.  There are plateaus.  Cars and electric motors are mature technology.  I wouldn't bank on any dramatic improvements in solar cells, although cost will continue to fall.  Batteries are where most of the gains are to be had, IMO.

[klunkerbus]

I think another significant area for gains is with regenerative braking.  Now there's an effective way to add miles/kms back into the battery without plugging in.  How well have the regen systems been optimized?  I've really grown to like the capability for one-pedal driving with our BoltEV, which as I understand not all EV can do.  What a waste. 

[bdunham7]

I think another significant area for gains is with regenerative braking.  Now there's an effective way to add miles/kms back into the battery without plugging in.  How well have the regen systems been optimized?  I've really grown to like the capability for one-pedal driving with our BoltEV, which as I understand not all EV can do.  What a waste.

When you say "one-pedal driving" do you mean you can pull up to stop sign and stop without using the brake pedal?  The car won't 'creep' like a regular automatic?

The Ford Focus EV was specifically designed to drive exactly like a regular gas Focus, using blended braking and normal coast down if you have it in drive.  It's actually pretty efficient, but I drive it in "L" all the time--but I still use the brake pedal, although the friction brakes don't kick in until 7 MPH or so if I do it right.  I don't know how much improvement is possible in this area--since regen adds to range and EVs are all about range, I'm sure everyone has put quite a bit of effort into it already.

[hendorog]

Do you accept that what you said is no longer accurate?

Um, no.  I can read and I can smell BS.  We discussed this earlier.  The SION is vaporware and I don't yet include Sono as "and entity capable..."  If they ever show up, we'll have to see what they actually produce from solar. 

The Toyota is a prototype, which implies pretty clearly that it isn't ready yet.

Obviously the basic concept can be implemented.  I can duct tape a solar panel on my roof and do some bodge wiring, for that matter.  None of that--claims, prototypes or home experiments--make this anywhere near ready for production or useful and cost effective enough to sell.

Hrm, yes I could have made that clearer. The two links hammy posted are not the key part.

The real message is this statement:

Toyota, Kia and Hyundai use solar panels for the next generation of BEV and PHEV.

Given how far ahead the car industry operates, it is pretty clear that they have already accepted solar has some merit.

And apparently Toyota already have one on the market in Japan.
https://cleantechnica.com/2018/11/06/hyundai-kia-to-begin-offering-solar-sun-roofs-after-2019/

And it at least gives us our first price: $2,500

Which is higher than I expected, but well it is the first one on the market I assume, so not surprising.

So read the links and look at the numbers, even if you don't do any math.  They simply disprove every point you are trying to make.  The Toyota example is $2500 and it is puny--less than half the roof is covered and if you understand how fuel economy is measured in Japan, you'll know that the "theoretical maximum" of 3.7 miles probably equates to 0.6kWh or so.  Ludicrously minimal performance at a high cost.  And it is not offered in the US because it the glass on the panels cannot pass the NHTSA crash/rollover requirements.  I said $5000, 1.2kWh at best and not ready yet.  Here you have an exactly what I said, but at half scale.

As for the Hyundai, well "ideally" it will charge 60% of a 1.56kWh battery (do a little math there) for some unknown cost that we'll find out later.

I know you are expecting performance to increase dramatically and prices to fall even more, but not all technology does that.  There are plateaus.  Cars and electric motors are mature technology.  I wouldn't bank on any dramatic improvements in solar cells, although cost will continue to fall.  Batteries are where most of the gains are to be had, IMO.

Yes fair point, you have called that price. I think it is a reasonable assumption that price is an early adopter price and it will decrease. Toyota presumably think they can sell them at that price.

Taking your 0.6kW and observing that they have covered only the roof then they would have to be using high efficiency cells to make it fit. Which could also explain the high price.
https://europe.autonews.com/article/20160616/COPY/306169846/new-toyota-prius-has-solar-roof-for-europe-japan

OTOH if Toyota have put 250W in that space and used 4 hours of sunlight in the calcs (1kWh) then that is close enough match using the EPA figure for the Prius Prime from Wikipedia. That might just about be possible with ordinary cells. Which then makes it highly likely the price will reduce from $2500 once the engineering is sorted out.

I don't know how what is special about fuel economy measurement in Japan though so please explain that.

Solar on cars is obviously not mature. I certainly would not bet against solar efficiency improving, and I wouldn't bet against the price dropping.

You are making an assumption that I expect solar performance to increase dramatically.  Great if it does, but I am not banking on that for this idea to work.

[klunkerbus]

I think another significant area for gains is with regenerative braking.  Now there's an effective way to add miles/kms back into the battery without plugging in.  How well have the regen systems been optimized?  I've really grown to like the capability for one-pedal driving with our BoltEV, which as I understand not all EV can do.  What a waste.

When you say "one-pedal driving" do you mean you can pull up to stop sign and stop without using the brake pedal?  The car won't 'creep' like a regular automatic?

The Ford Focus EV was specifically designed to drive exactly like a regular gas Focus, using blended braking and normal coast down if you have it in drive.  It's actually pretty efficient, but I drive it in "L" all the time--but I still use the brake pedal, although the friction brakes don't kick in until 7 MPH or so if I do it right.  I don't know how much improvement is possible in this area--since regen adds to range and EVs are all about range, I'm sure everyone has put quite a bit of effort into it already.

The BoltEV has a couple of approaches to regenerative braking. The mode we typically use (driving in L) will yes, bring the EV to a stop and hold it by simply letting up on the accelerator and without having to touch the brake pedal.  Pedal touch and timing can be a bit of a trick, but I found it only took a couple of stops to figure it out.  On the Bolt, a bit more regenerative braking can be brought to bear using a finger paddle on the steering wheel, even in L mode. When at a full stop, we do typically apply the brake out of habit more than anything, plus doing that keeps the brake lights on. Otherwise the brake lights shut off after the Bolt comes to a stop. 

[bdunham7]

Yes fair point, you have called that price. I think it is a reasonable assumption that price is an early adopter price and it will decrease. Toyota presumably think they can sell them at that price.

Taking your 0.6kW and observing that they have covered only the roof then they would have to be using high efficiency cells to make it fit. Which could also explain the high price.
https://europe.autonews.com/article/20160616/COPY/306169846/new-toyota-prius-has-solar-roof-for-europe-japan

OTOH if Toyota have put 250W in that space and used 4 hours of sunlight in the calcs (1kWh) then that is close enough match using the EPA figure for the Prius Prime from Wikipedia. That might just about be possible with ordinary cells. Which then makes it highly likely the price will reduce from $2500 once the engineering is sorted out.

I don't know how what is special about fuel economy measurement in Japan though so please explain that.

Solar on cars is obviously not mature. I certainly would not bet against solar efficiency improving, and I wouldn't bet against the price dropping.

You are making an assumption that I expect solar performance to increase dramatically.  Great if it does, but I am not banking on that for this idea to work.

Pricing and early adopter theory aside, Prius customers are in their own category, at least here in the US.  The price would have to drop a LOT.

If you calculate 6 sun/hrs (6000 watts per square meter per day) x 1/3 m^2 and 24% efficiency, you get 480Wh.  The Japanese fuel economy test cycle is much gentler than the US model and involves slower driving and a top speed of 50 MPH.  So they could make their estimate work if ideal conditions means California sun and 135 Wh/mile.

They aren't using triple-junction cells.  Nobody has priced them out here ( I provided a link to a manufacturer) but I believe using them to get 600-700Wh out of the same area would cost $10,000 to $20,000 just for the cells alone.  Somebody correct me if they know better.

You can dream, but if they are selling it, the engineering is sorted--except for passing the required safety test for their largest market.  Only large demand, volume and competition is going to drive the price down.  I'm sorry to tell you, but that's a pipe dream.  A crack pipe dream at that!

[tautech]

If you calculate 6 sun/hrs (6000 watts per square meter per day) x 1/3 m^2 and 24% efficiency, you get 480Wh.

What vehicle has just 0.3m² roof area ? A rickshaw ?

My sedan has 1.2m²+ roof area.
So with your ~500W * 4x the roof area we get to 2kWh which is somewhat higher than anything previously put forward here.
Of course the true Wh figure lies somewhere between.

[bdunham7]

If you calculate 6 sun/hrs (6000 watts per square meter per day) x 1/3 m^2 and 24% efficiency, you get 480Wh.

What vehicle has just 0.3m² roof area ? A rickshaw ?

My sedan has 1.2m²+ roof area.
So with your ~500W * 4x the roof area we get to 2kWh which is somewhat higher than anything previously put forward here.
Of course the true Wh figure lies somewhere between.

I read the link and looked at the photo of the specific car in question and guessed how big the actual panels on that car were.  I didn't see your car there, sorry!  Have a look yourself, see if you agree or have a different estimate.

I was merely surmising how Toyota may have come up with their assertion that under ideal conditions the solar roof could add 3.7 miles per day.  I'm not claiming that any of their numbers are realistic--even they don't claim that!

[hendorog]

Yes fair point, you have called that price. I think it is a reasonable assumption that price is an early adopter price and it will decrease. Toyota presumably think they can sell them at that price.

Taking your 0.6kW and observing that they have covered only the roof then they would have to be using high efficiency cells to make it fit. Which could also explain the high price.
https://europe.autonews.com/article/20160616/COPY/306169846/new-toyota-prius-has-solar-roof-for-europe-japan

OTOH if Toyota have put 250W in that space and used 4 hours of sunlight in the calcs (1kWh) then that is close enough match using the EPA figure for the Prius Prime from Wikipedia. That might just about be possible with ordinary cells. Which then makes it highly likely the price will reduce from $2500 once the engineering is sorted out.

I don't know how what is special about fuel economy measurement in Japan though so please explain that.

Solar on cars is obviously not mature. I certainly would not bet against solar efficiency improving, and I wouldn't bet against the price dropping.

You are making an assumption that I expect solar performance to increase dramatically.  Great if it does, but I am not banking on that for this idea to work.

Pricing and early adopter theory aside, Prius customers are in their own category, at least here in the US.  The price would have to drop a LOT.

If you calculate 6 sun/hrs (6000 watts per square meter per day) x 1/3 m^2 and 24% efficiency, you get 480Wh.  The Japanese fuel economy test cycle is much gentler than the US model and involves slower driving and a top speed of 50 MPH.  So they could make their estimate work if ideal conditions means California sun and 135 Wh/mile.

They aren't using triple-junction cells.  Nobody has priced them out here ( I provided a link to a manufacturer) but I believe using them to get 600-700Wh out of the same area would cost $10,000 to $20,000 just for the cells alone.  Somebody correct me if they know better.

You can dream, but if they are selling it, the engineering is sorted--except for passing the required safety test for their largest market.  Only large demand, volume and competition is going to drive the price down.  I'm sorry to tell you, but that's a pipe dream.  A crack pipe dream at that!

At least we agree on our dislike of Prius's. But they are a convenient example to use so lets not get carried away.

The solar on the Prius Prime is actually only 180W. That is where the 3.7 mile/5.9 km comes from.
There was no way your estimated 0.6kW could fit on that roof, which is the only reason I suggested they might be using high efficiency cells. Edit: Misread by me.

And sorry, there is no way that the price is locked in at $2500 for only 180W using bog standard solar cells. Competition will fix that, and it will take time.

And the engineering point was about the solar roof failing the rollover test in the US. That part is clearly not sorted.

It is obvious it needs to be mass produced. The price will drop and then the collective power of all of the solar together becomes significant.

[tautech]

If you calculate 6 sun/hrs (6000 watts per square meter per day) x 1/3 m^2 and 24% efficiency, you get 480Wh.

What vehicle has just 0.3m² roof area ? A rickshaw ?

My sedan has 1.2m²+ roof area.
So with your ~500W * 4x the roof area we get to 2kWh which is somewhat higher than anything previously put forward here.
Of course the true Wh figure lies somewhere between.

I read the link and looked at the photo of the specific car in question and guessed how big the actual panels on that car were.  I didn't see your car there, sorry!  Have a look yourself, see if you agree or have a different estimate.

I was merely surmising how Toyota may have come up with their assertion that under ideal conditions the solar roof could add 3.7 miles per day.  I'm not claiming that any of their numbers are realistic--even they don't claim that!

Ah, OK a Prius.  Thanks for pointing that out. So we have PV tacked onto an existing body shell without any mods to fully utilize the full roof area available whereas a manufacturer could/should implement PV on an EV as an integral part of the roof structure not some afterthought tack on.

However Toymota do say: They improve the car’s efficiency by up to 10 percent.
Something that shouldn't be overlooked IMO.

[hendorog]

If you calculate 6 sun/hrs (6000 watts per square meter per day) x 1/3 m^2 and 24% efficiency, you get 480Wh.

What vehicle has just 0.3m² roof area ? A rickshaw ?

My sedan has 1.2m²+ roof area.
So with your ~500W * 4x the roof area we get to 2kWh which is somewhat higher than anything previously put forward here.
Of course the true Wh figure lies somewhere between.

I read the link and looked at the photo of the specific car in question and guessed how big the actual panels on that car were.  I didn't see your car there, sorry!  Have a look yourself, see if you agree or have a different estimate.

I was merely surmising how Toyota may have come up with their assertion that under ideal conditions the solar roof could add 3.7 miles per day.  I'm not claiming that any of their numbers are realistic--even they don't claim that!

Ah, OK a Prius.  Thanks for pointing that out. So we have PV tacked onto an existing body shell without any mods to fully utilize the full roof area available whereas a manufacturer could/should implement PV on an EV as an integral part of the roof structure not some afterthought tack on.

However Toymota do say: They improve the car’s efficiency by up to 10 percent.
Something that shouldn't be overlooked IMO.

You are right, it is way bigger than 0.3 sqm. I missed that in bdunham7's post.
It looks very close to 1 sqm to me.

Which makes sense as they are getting nearly 200W out of that area.

[wraper]

However Toymota do say: They improve the car’s efficiency by up to 10 percent.
Something that shouldn't be overlooked IMO.

1% is also 'up to 10%'.

[bdunham7]

At least we agree on our dislike of Prius's. But they are a convenient example to use so lets not get carried away.

The solar on the Prius Prime is actually only 180W. That is where the 3.7 mile/5.9 km comes from.
There was no way your estimated 0.6kW could fit on that roof, which is the only reason I suggested they might be using high efficiency cells. Edit: Misread by me.

And sorry, there is no way that the price is locked in at $2500 for only 180W using bog standard solar cells. Competition will fix that, and it will take time.

And the engineering point was about the solar roof failing the rollover test in the US. That part is clearly not sorted.

It is obvious it needs to be mass produced. The price will drop and then the collective power of all of the solar together becomes significant.

I don't dislike Prii per se, I just know the drivers.  I don't know where you got 0.6kW from, I had previously referred to 0.6kWh/day.  Everything else is just rough guesses.  But I have to ask--when you say significant, significant to whom and compared to what? 

[ahbushnell]

It is a big numbers game. Take 16 million cars and you have 4 to 6 km^2 worth of solar panels which are mass produced in a shape which fits their environment precisely, can be mounted using robots, don't need any extra space, don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

don't need any infrastructure for connection and/or storage (storage is going to make solar and wind energy really expensive) and are right at the load.

The issue is it still needs both of those. And practically to the same extent as regular EV.

You have totally missed his point.

The point is, solar panels need storage and infrastructure (and management) if you put the solar panels _anywhere else_

Nope, you completely missed the point. Solar panels will barely charge battery existing in the car = provide only a small portion of energy needed. So you still need all of infrastructure regular EV needs.
Actually you could put 5 times smaller solar panel on a roof and most likely still get more energy from it in total. Given you use it as a normal car, not portable solar battery which you leave in rural empty space unobstructed by any buildings or trees.

Plus the weight of the panels and the associated power electronics will increase energy usage of the car. 

[bdunham7]

Well, everybody, I guess I was wrong.  Here you go....

https://lightyear.one/

[tautech]

Plus the weight of the panels and the associated power electronics will increase energy usage of the car.

Yep panels a little but the only electronics required is a charge pump, probably 50% of the size and weight of a car radio......nutthing.

Well, everybody, I guess I was wrong.  Here you go....

https://lightyear.one/

We're all wrong. hendorog alluded to this earlier when he mentioned the rate of change to these sorts of technologies and the possible efficiencies in price from mass production and improvements to PV's.

Do I see PV's on EV's as the bee's knees, NO, however if you're to have administrations subsidizing the adoption of EV's just to get to sell them make that subsidization a truly worthwhile investment of your nations taxpayers funds by saving some grid generation capacity while you're at it.

[wraper]

Well, everybody, I guess I was wrong.  Here you go....

https://lightyear.one/

Only $170k, what a steal!

[bdunham7]

Well, everybody, I guess I was wrong.  Here you go....

https://lightyear.one/

Only $170k, what a steal!

I think the 'steal' happens when you put your 120K euro deposit on vaporware...

[tautech]

Yeah well, it's only 75k NZ to just reserve a Roadster ! 
Full price: NZD$365,000     

Doesn't even come with a PV roof ! 

[wraper]

Yeah well, it's only 75k to just reserve a Roadster ! 
Full price: $365,000     

Doesn't even come with a PV roof ! 

First roadster more than a decade ago was cheaper than $170k. New one is expected to be almost 2x less than nonsense number you claim. Not to say you compare apples vs oranges, performance is simply incomparable. Fastest production car, with 1.9s 0-60 mph acceleration and 1000 km (620 mi) range on single charge (200 kWh battery). Why don't you compare it with say McLaren pricing? Also lighthyear one has only 60kWh battery. As big as cheapest Tesla model 3 has. There is one issue though, it has <$40k base price.

[Domagoj T]

If that lightyear one ever sells and achieves the claimed range from solar roof, I'll eat my porridge.
PVs on cars will always be sub-optimal solution. If you have a roof available, put the panels there, if you don't because you live in an urban environment, then your car will spend a lot of time in shadows anyway, so why bother?
That being said, solar bicycles and tricycles are viable, especially if they have an attached trailer. It simply boils down to much lower energy requirements.
https://solarbikeproject.com

[tautech]

Yeah well, it's only 75k to just reserve a Roadster ! 
Full price: $365,000     

Doesn't even come with a PV roof ! 

First roadster more than a decade ago was cheaper than $170k. New one is expected to be almost 2x less than nonsense number you claim.

Sorry, NZD. Will edit post.

[hendorog]

At least we agree on our dislike of Prius's. But they are a convenient example to use so lets not get carried away.

The solar on the Prius Prime is actually only 180W. That is where the 3.7 mile/5.9 km comes from.
There was no way your estimated 0.6kW could fit on that roof, which is the only reason I suggested they might be using high efficiency cells. Edit: Misread by me.

And sorry, there is no way that the price is locked in at $2500 for only 180W using bog standard solar cells. Competition will fix that, and it will take time.

And the engineering point was about the solar roof failing the rollover test in the US. That part is clearly not sorted.

It is obvious it needs to be mass produced. The price will drop and then the collective power of all of the solar together becomes significant.

I don't dislike Prii per se, I just know the drivers.  I don't know where you got 0.6kW from, I had previously referred to 0.6kWh/day.  Everything else is just rough guesses.  But I have to ask--when you say significant, significant to whom and compared to what?

Yes I read your comment too quickly and thought you had proposed 0.6kW as the panel capacity of the prius instead of the kWh generated by the panels per day. Took me a while to realise my mistake. My bad.

It has been well documented here that one small solar panel on an EV generates a rather insignificant amount of energy every day.

Now consider the number of EV's being produced per annum. Even the small amount of solar generation on each adds up to a significant total amount. That was what I meant by significant.

As to who would be interested, well that is above my pay grade, but logically I would think it would be of interest to governments and the electricity authority responsible for planning.

[nctnico]

If that lightyear one ever sells and achieves the claimed range from solar roof, I'll eat my porridge.

Ofcourse it achieves the claimed range from solar. It just take time to charge the battery while parked outside.  And the lightyear is extremely light and has optimised aerodynamics so it doesn't need as much energy as a regular car (be it EV or ICE). The improved aerodynamic shape isn't new at all and well known amongst hypermilers.

[wraper]

If that lightyear one ever sells and achieves the claimed range from solar roof, I'll eat my porridge.

Ofcourse it achieves the claimed range from solar. It just take time to charge the battery while parked outside.  And the lightyear is extremely light and has optimised aerodynamics so it doesn't need as much energy as a regular car (be it EV or ICE). The improved aerodynamic shape isn't new at all and well known amongst hypermilers.

Tesla model 3 is already most aerodynamic mass production car ever made.
EDIT: And sure it won't be light because it has substantial size battery.

[wraper]

Now consider the number of EV's being produced per annum. Even the small amount of solar generation on each adds up to a significant total amount. That was what I meant by significant.

I'll repeat it again. Multiplying bad doesn't not make it good. It's just waste of money and materials on large scale.
Here is analogy: If you make a lot of solar roadways, do they suddenly become a good thing?

[nctnico]

If that lightyear one ever sells and achieves the claimed range from solar roof, I'll eat my porridge.

Ofcourse it achieves the claimed range from solar. It just take time to charge the battery while parked outside.  And the lightyear is extremely light and has optimised aerodynamics so it doesn't need as much energy as a regular car (be it EV or ICE). The improved aerodynamic shape isn't new at all and well known amongst hypermilers.

Tesla model 3 is already most aerodynamic mass production car ever made.

Once they start producing the lightyear one not any more. Not by a long shot. Next time do more research before posting. Hint: the tail of the lightyear has a huge impact on the aerodynamics of a car because it minimizes drag.

[hendorog]

Now consider the number of EV's being produced per annum. Even the small amount of solar generation on each adds up to a significant total amount. That was what I meant by significant.

I'll repeat it again. Multiplying bad doesn't not make it good. It's just waste of money and materials on large scale.
Here is analogy: If you make a lot of solar roadways, dko they sudidenly become a good thing?

Your analagy sucks balls. The solar part in solar roadways falls to bits. The solar part on a car does not fall to bits.

Keep trying though. But please stop slapping yourself in the face. I didn't feel a thing.

[wraper]

Now consider the number of EV's being produced per annum. Even the small amount of solar generation on each adds up to a significant total amount. That was what I meant by significant.

I'll repeat it again. Multiplying bad doesn't not make it good. It's just waste of money and materials on large scale.
Here is analogy: If you make a lot of solar roadways, dko they sudidenly become a good thing?

Your analagy sucks balls. The solar part in solar roadways falls to bits. The solar part on a car does not fall to bits.

Keep trying though. But please stop slapping yourself in the face. I didn't feel a thing.

They are common in a way that both use solar panels in inefficient way. Not only reducing their efficiency but also vastly increasing cost of implementation. If Lightyear one gets even in a small crash, repair costs will be huge due to damaged parts including solar panels. Also you cant just paint it if some scratches appear. Not to say solar panel life will be limited to car life, so often you will be throwing them away prematurely.

[nctnico]

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.

[wraper]

For the cost of Lightyear one you could buy Tesla model 3 and cover your house with solar panels and powerwalls from top to bottom.

[nctnico]

For the cost of Lightyear one you could buy Tesla model 3 and cover your house with solar panels and powerwalls from top to bottom.

Ofcourse because it is a novelty item. But if it catches on it will pave the way to have similar tails on other cars and make them way more efficient. You really should google 'hyper miling' and look at how people modify their cars to get significantly better mileage.

[wraper]

You really should google 'hyper miling' and look at how people modify their cars to get significantly better mileage.

That's not something any normal driver will ever do. You can hypermile on of the shelf tesla just fine as well. It's just trading off convenience for mileage.
https://www.teslarati.com/tesla-model-s-model-3-hypermile-world-records/

[NiHaoMike]

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.

Put them on buildings instead, that's one of the best places to build solar. Get back to me once almost all usable roof area has been used for solar.

[nctnico]

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.

Put them on buildings instead, that's one of the best places to build solar. Get back to me once almost all usable roof area has been used for solar.

Not true at all. Putting solar panels on my roof is a bad investment. I get a much better ROI if I install a dorm (roof extension) due to the extra space and therefore an increase of the value of my home.

[coppice]

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.

Put them on buildings instead, that's one of the best places to build solar. Get back to me once almost all usable roof area has been used for solar.

Not true at all. Putting solar panels on my roof is a bad investment. I get a much better ROI if I install a dorm (roof extension) due to the extra space and thus increase in value of my home.

These two things are not mutually exclusive. The windows for the roof space rooms somewhat reduce the quantity of PV panels you can fit, but there are many many homes in the UK combining PV panels with roof space rooms.

[Marco]

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.

[nctnico]

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.

[Marco]

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.

[nctnico]

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.

[bdunham7]

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.

[Someone]

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.

[nctnico]

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:

[Someone]

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...

[gmb42]

In the news yesterday, Hyundai are offering a Sonata Hybrid with PV roof: https://www.digitaltrends.com/cars/hyundai-sonata-hybrid-solar-roof/

[f4eru]

Meh. Hybrid. That's so obsolete now.
And PV on car roofs is more or less a marketing gimmick compared to realistic roof PV.

[Domagoj T]

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.

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!

[klunkerbus]

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

[Domagoj T]

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?

[f4eru]

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.

[coppice]

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.

[f4eru]

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.

[bdunham7]

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.

[coppice]

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.

[nctnico]

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.

[hendorog]

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/

[Red Squirrel]

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...

[hendorog]

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...

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.