Self-charging electric cars

[starcanuck64]

I was just wondering with the development of new solar power technology from companies like Nanosolar where they use roll to print to produce solar cells and panels, would it be practical to build electric cars entirely clad in solar panels?

And how efficient would the panels have to be to recharge the electric vehicles?

[quotation]

I was looking for info on the largest solar farm the other day to compare it to small modular reactors (SMR). One that came up immediately via google was a 100 acre site being built for Apple. It produces a whopping 20 MWe. Compare that to a SMR that can be housed in roughly the size of a double-wide mobile home and produces 200 MWe and I think you'd need a pretty big car to hold all the photovoltaic panels, but someday maybe.

[starcanuck64]

I was just thinking of all the energy that goes to waste as cars sit out parked in the sun all day. Even if they only gave a partial charge, at some point covering electrical vehicles in solar panels becomes economical, I was just wondering how to figure out where that point is.

The new roll-to-print panels are more flexible in terms of production and shaping, but less efficient than older traditional cells.

[Van Rijn]

I was just wondering with the development of new solar power technology from companies like Nanosolar where they use roll to print to produce solar cells and panels, would it be practical to build electric cars entirely clad in solar panels?

No, not unless you don't drive the car much, and unless you're happy with a super lightweight car design. Forget crash protection, air conditioning, heating . . .

Even with 100% efficient panels, the amount of energy would be pretty limited. It's the same basic reason why plants don't tend to move under their own power (with very limited exceptions). If solar is to be used in a practical way, it would have to be through charging up from power produced by fixed panels somewhere.

[starcanuck64]

So much for that idea, thanks

[NEOWatcher]

I decided to look for some numbers to ballpark it with today's technology.

I saw references to the Leaf of 34kw/100Miles.
Let's say at a reasonable driving speed, that works out to about 15kw per hour.

Now; the numbers I see for solar panels are about 150 w/m^2. (0.15kw/m^2).
So, you would only need about 100 square meters for your Leaf.
Or, with the width limit of 8 feet and assuming no trailer weight or rolling resistance.... 3-45 foot trailers. Basically, an Australian road train.

Looking at it the other way around. How much would a 2mx2m solar roof give you in one hour of recharging. 1000 feet of driving.

[Swift]

I believe there have been some very limited uses along these lines. I think the newest Priuses have a small solar powered ventilation system to keep the car cool when parked. I think there are similar after-market devices for other cars. There have been some custom made "solar race cars" built (college student contests) that are solar powered, but these are extremely light weight and non-practical cars.

It might be practical to put a solar array on the roof of your house, to plug your rechargable electric car into.

[Van Rijn]

I believe there have been some very limited uses along these lines. I think the newest Priuses have a small solar powered ventilation system to keep the car cool when parked.

That was one thing I thought of after my last post. That can reduce fuel/energy requirements (less air conditioning) and increase comfort, so some limited use can make sense.

[starcanuck64]

I decided to look for some numbers to ballpark it with today's technology.

I saw references to the Leaf of 34kw/100Miles.
Let's say at a reasonable driving speed, that works out to about 15kw per hour.

Now; the numbers I see for solar panels are about 150 w/m^2. (0.15kw/m^2).
So, you would only need about 100 square meters for your Leaf.
Or, with the width limit of 8 feet and assuming no trailer weight or rolling resistance.... 3-45 foot trailers. Basically, an Australian road train.

Looking at it the other way around. How much would a 2mx2m solar roof give you in one hour of recharging. 1000 feet of driving.

Not very practical then.

Unless you had the electric car towing it's own solar array on a trailer or balloon this one is a non-starter I guess. And doing that would have it's own issues, it would make the morning and evening commutes more interesting though.

[JCoyote]

I wouldn't say it's completely hopeless, it's most a matter of if the cells can be light enough and cheap enough. Let's assume the cells are the aforementioned Leaf and have the same efficiency referenced. They are paint-on cells so therefore are part of the paint job of the care. Even 1000 feet of travel per hours adds up. That's 8 to 9 thousand feet per day while you work. If the cells are cheap enough the offset could be worth it if you lived close enough to work. (However if you live within 2 miles of work most days you should ride a bike...)

[Ivan Viehoff]

Unless you had the electric car towing it's own solar array on a trailer

The above calculations are on the assumption that it doesn't cost any extra power to tow the trailers. In reality, this is not a good approximation.

[profloater]

I had a boss who persuaded a major car company that a solar cell on the roof of a car would enable the car to be charged parked in its garage with the light on. Obviously there is a huge power mismatch there but they swallowed it for a while. Of course with the right frequency range, not light, and powerful equipment, such wireless charging is possible.

[joevega]

An inventor from the Philippines has demonstrated a bare bones electric vehicle with an 11-kW DC motor running on just one 12-volt battery, which is kept charged via an antenna circuitry that draws electrostatic or radio wave energy from the surroundings. He's also developed a super-efficient repelling force that he wants to engineer into an engine.

[Swift]

... which is kept charged via an antenna circuitry that draws electrostatic or radio wave energy from the surroundings. He's also developed a super-efficient repelling force that he wants to engineer into an engine.

First, welcome to BAUT joevega.

Second, I really doubt the two things I quoted, they both sound like nonsense. Do you have a reference to these?

[JustAFriend]

So, you would only need about 100 square meters for your Leaf.
Or, with the width limit of 8 feet and assuming no trailer weight or rolling resistance.... 3-45 foot trailers. Basically, an Australian road train.

Yup, the limitation is NOT the efficiency of solar cells, its the limitation of how much
sunlight power is actually falling on each square yard or meter of the Earth.

There is no magic and you can't get more power out than is coming in.

[starcanuck64]

The above calculations are on the assumption that it doesn't cost any extra power to tow the trailers. In reality, this is not a good approximation.

It was more an attempt at humor than a practical suggestion.

To be practical you couldn't alter the dimensions of the vehicle significantly and it's been made clear why that would prevent adequate power to be produced from solar cells.

[HenrikOlsen]

But, if the solar panels are cheap enough that the electricity produced by them is cheaper than that of the power company, having them is still a net win. Even if they don't cover the entire energy requirement they'll still reduce the cost of driving.

[Trebuchet]

But, if the solar panels are cheap enough that the electricity produced by them is cheaper than that of the power company, having them is still a net win. Even if they don't cover the entire energy requirement they'll still reduce the cost of driving.

Right! If the panels are sufficiently inexpensive, they provide a source of supplemental power at no ongoing cost.

[Ara Pacis]

But, if the solar panels are cheap enough that the electricity produced by them is cheaper than that of the power company, having them is still a net win. Even if they don't cover the entire energy requirement they'll still reduce the cost of driving.

Assuming no externalities such as trailer insurance, parking space fees or restrictions, annoyance by other drivers and government regulation addressing the preceding.

[NEOWatcher]

It was more an attempt at humor than a practical suggestion.

Actually, It was an attempt at putting it into perspective lightly presented.

Yup, the limitation is NOT the efficiency of solar cells, its the limitation of how much
sunlight power is actually falling on each square yard or meter of the Earth.

Ultimately, yes. If we could magically get to 100% efficiency we get 1 kW/m^2. Of course, we have clouds, changing angles, driving under trees and bridges, etc, etc.

But, if the solar panels are cheap enough that the electricity produced by them is cheaper than that of the power company, having them is still a net win. Even if they don't cover the entire energy requirement they'll still reduce the cost of driving.

You can't really say "cheaper than the power company" until a payback is computed.
If you can get that theoretical 8 thousand feet per day... then let's see what that works out to.
Assuming an ideal of being able to capture the sun 100% of the time every day for a year, we get a "free" 553 miles per year.
Nissan is claiming 3.5 cents per mile in electricity.
That works out to a savings of less than $20 per year. Those solar cells are going to have to be basically "free".

[starcanuck64]

Actually, It was an attempt at putting it into perspective lightly presented.

Yes.

One alternative could be to clad buildings with solar panels, there's a huge amount of surface area that's now glass or stone that could be used to produce electricity from sunlight. Instead of your car charging itself maybe your place of work could provide a meaningful boost to your vehicles charge as you pass your day. You'd probably need to design buildings and entire blocks from the ground up to take full advantage of this, but as time goes on solar cells should become cheaper, more durable and efficient.

[Swift]

Yes.

One alternative could be to clad buildings with solar panels, there's a huge amount of surface area that's now glass or stone that could be used to produce electricity from sunlight. Instead of your car charging itself maybe your place of work could provide a meaningful boost to your vehicles charge as you pass your day. You'd probably need to design buildings and entire blocks from the ground up to take full advantage of this, but as time goes on solar cells should become cheaper, more durable and efficient.

ToSeeked

It might be practical to put a solar array on the roof of your house, to plug your rechargable electric car into.

We can share the patent.

[starcanuck64]

We can share the patent.

I always wanted to be rich.

[NEOWatcher]

One alternative could be to clad buildings with solar panels, there's a huge amount of surface area that's now glass or stone that could be used to produce electricity from sunlight.

I consider that to be independent of any issues with electric vehicles. And; effectively, you can only talk about the building's footprint and not the entire surface area. During peak hours, those sides are getting the sun at a very shallow angle.

An employee perk of plugging in is happening in places now with or without solar panels.

[starcanuck64]

I consider that to be independent of any issues with electric vehicles. And; effectively, you can only talk about the building's footprint and not the entire surface area. During peak hours, those sides are getting the sun at a very shallow angle.

It is.

You'd have to come up with some creative design features to take full advantage of the surface area, possibly variable geometry buildings that mimic plants that follow the sun.

[Ara Pacis]

It is.

You'd have to come up with some creative design features to take full advantage of the surface area, possibly variable geometry buildings that mimic plants that follow the sun.

I prefer that my buildings not move, thank you.

[Swift]

I prefer that my buildings not move, thank you.

The solution to that is to mount your solar panels on sun-tracking platforms that move, instead of the whole building moving.

I've seen some analysis as to whether sun-tracking is worth it or not. The added energy you get is countered by the adding complexity and cost. As best as I can tell, it is generally a toss-up. Most of the roof-top solar installations I've seen do not do sun-tracking, but I haven't made a detailed study.

[Ara Pacis]

The solution to that is to mount your solar panels on sun-tracking platforms that move, instead of the whole building moving.

I've seen some analysis as to whether sun-tracking is worth it or not. The added energy you get is countered by the adding complexity and cost. As best as I can tell, it is generally a toss-up. Most of the roof-top solar installations I've seen do not do sun-tracking, but I haven't made a detailed study.

I wonder if a lenticular screen would help. Alternately, some sort of reflector might work for different angles, and perhaps these might be made to move more cheaply.

[whimsyfree]

I decided to look for some numbers to ballpark it with today's technology.

I saw references to the Leaf of 34kw/100Miles.
Let's say at a reasonable driving speed, that works out to about 15kw per hour.

That makes no sense at all. A watt is a unit of power, not energy.

[NEOWatcher]

That makes no sense at all. A watt is a unit of power, not energy.

I'm just using numbers in units that the industry is providing. Whether they make total sense or not, doesn't mean that it's the most logical choice of "ballparking". Only that it's the best that I can find.

I would be glad to see things stated in real units (and related to kwh, which is what we pay for).