### Author Topic: Solar Roadways need Solar Cars, duh!  (Read 1480 times)

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#### Fid

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##### Solar Roadways need Solar Cars, duh!
« on: March 30, 2018, 11:29:59 pm »
Hey Dave, interested in some more solar panel calculations?

https://futurism.com/fully-solar-powered-car-hitting-road-2019/
https://www.lightyear.one

I love how they'll be glad to take your preorder (from 4000€ to the full 120.000€), but won't show you real pictures of the car, nor real-life data.

This seems quite misleading to me

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Effortless Energy
Lightyear One is charged by solar power. This unique quality allows it to drive for months without charging. You are sure to have peace of mind, knowing your electric car can always drive. The battery ensures that you can drive anywhere, even at night.

Drive for months without charging... after not driving for months waiting for a charge?
In the preorder FAQ, they do vaguely state that

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How many kilometers can be harvested/collected from the sun?
This depends on the climate of your country. Here are some estimates for the Lightyear One:
Amsterdam: 10.000 km
Paris: 11.000 km
Madrid: 17.000 km
Los Angeles: 19.000 km
Chicago: 14.000 km
Houston:16.000 km
New York: 14.000 km
Washington: 15.000 km
Honolulu: 20.000 km
U.S. Virgin Islands: 21.000 km

If a Tesla P100 consumes 15kWh per 100km, they're stating that I can charge 1650kWh/year from solar alone, or 4.5kWh/day on average. And let's pretend there are no buildings in Paris to block the sun from my car.
If I'm not mistaken, I'd need four 260W rooftop panels to achieve this (under ideal conditions), or 6.8m2 of cells... on a car. That's not to say you can't find 6.8m2 of free space on a car, but given the complex design of today's cars, what would they use? I've seen those flexible panels, but if I remember correctly, the efficiency was really bad.

So is this just another attempt at pulling money out of people's pockets or is it just a gimmick that will barely have any use unless driven out to the Sahara? (I'm aware it also has traditional charging capability, but why try to make solar its main selling point?)
« Last Edit: March 30, 2018, 11:51:47 pm by Fid »

#### digsys

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##### Re: Solar Roadways need Solar Cars, duh!
« Reply #1 on: March 31, 2018, 12:02:51 am »
Solar electric cars have been around for over 30 yrs, The first "crude" one crossed Australia, non-stop, 35 yrs ago by Hans Tholstrup.
https://www.dasolar.com/solar-energy/solar-powered-cars
https://www.worldsolarchallenge.org/dashboard/galleries
https://www.facebook.com/ISFsolarcar/
Our solar team has been building them for over 30 yrs, and our last effort can do around 1,000Km in a single day, with full battery.
As per links above, these are not really road useable, but it PROVES a point. In the last 3 events, we included a "road legal capable" class.
Min specs - 250Km+ solar, 250Km + battery
Again, not at the same build / options level as today's mass produced ICEs, but getting there pretty fast. There's a hell of a lot of research and
prototyping going on around the world. The points you make are correct (surface area for panels etc etc), and that is stuff out team, and ALL the
other teams are working on now.
Yeah, they make some stupid claims, but a lot is the way they worded it, but that's advertising for you.
It WILL happen .. or it IS happening. google is your friend :-)
Hello <tap> <tap> .. is this thing on?

#### Fid

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##### Re: Solar Roadways need Solar Cars, duh!
« Reply #2 on: March 31, 2018, 04:05:46 am »
I have been following some of the solar car challenges, but those cars (the ones I've seen or the ones linked) are very far from being "typical" passenger cars as presented here. I don't want to say that the technology can never become feasible, since cells are getting more efficient every year, but with today's available technology, I fail to see how a passenger car meant to be sold in 2019 (that would mean it is basically production-ready now) could benefit from solar due to the available surface area and shape. Simple logic tells me that I'd be better off parking in the shade and using less A/C than purposely trying to park in the most sunlight and having to cool the car down (from the gathered energy). Wouldn't it just make more sense to build car parks with solar roofs for "free" shade and energy?
« Last Edit: March 31, 2018, 04:14:57 am by Fid »

#### IanMacdonald

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##### Re: Solar Roadways need Solar Cars, duh!
« Reply #3 on: April 01, 2018, 01:15:05 pm »
"Yeah, they make some stupid claims, but a lot is the way they worded it, but that's advertising for you."
Ever heard of the Advertising Standards Authority? Other firms get busted for telling porkies in adverts.

"It WILL happen .. or it IS happening. google is your friend :-)"
Or, it's just that a team of volunteers from NGOs has flooded the searchengines with disinformation. Seen that one before.

Decibelocracy - where he who shouts loudest gets to make the rules.

#### SgtTech

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##### Re: Solar Roadways need Solar Cars, duh!
« Reply #4 on: April 19, 2018, 10:19:52 pm »
I had a chat with my 15 year old daughter the other day and mentioned something about solar roadways, it took her about 10-15 seconds to list all the practical reasons why it would not work and suggested roofing would be a better place? Makes me wonder how they got funding?? Skinning a car with solar patches is not as daft an idea although this is not new, endurance vehicles space age one man prototypes have been playing with this stuff for a very long time. The cost benefit analysis with current technologies does not look good for England where Sun is an infrequent luxury.
Back to my daughter, having scoffed at the solar roadways she thought you could have something under the tarmac of current roads that could convert some kinetic energy from passing vehicles into electricity. Also you could some how harness the air turbulence from passing vehicles on high speed motorways. Both of these ideas are better than solar roadways although probably still highly impractical.

#### Brumby

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##### Re: Solar Roadways need Solar Cars, duh!
« Reply #5 on: April 20, 2018, 09:06:36 am »
Back to my daughter, having scoffed at the solar roadways she thought you could have something under the tarmac of current roads that could convert some kinetic energy from passing vehicles into electricity.

Full marks for her insight into solar roadways - and for thinking about alternatives.  This is to be encouraged.  Unfortunately, the kinetic energy harvesting idea has one significant problem.  Taking energy out of a moving vehicle means that the total energy of the moving vehicle system must fall and, as a result, the engine will have to work harder to put that energy back into the system to maintain speed.  An exercise for her might be to work out why.

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Also you could some how harness the air turbulence from passing vehicles on high speed motorways. Both of these ideas are better than solar roadways although probably still highly impractical.
It's still great to encourage this sort of thinking - with the ability to be objective and realistic.

Smf