On 26 Sep 2014 at 18:08, Cor van de Water via EV wrote:

> BTW, which car has a flat 90 sqft straight roof surface and is
> aerodynamic?

This is what Lawrence is talking about :

http://www.evdl.org/archive/index.html#nabble-td4671714


http://www.greenoptimistic.com/2014/09/24/stella-500-mile-solar-powered-
electric-vehicle/

http://tinyurl.com/qh2f6ox

http://www.dailymail.co.uk/sciencetech/article-2385976/Stella-solar-powered-
family-car-travels-420-miles-sunny-energy-positive.html

http://tinyurl.com/lyq3n6o

Estimating from the size of a person's hand near the PV panels in one photo, 
I'd estimate that the car has somewhat less than 90 sq ft of PV.  I'd guess 
closer to 60, but I could be wrong.  In any case, the ENTIRE top of the 
vehicle is covered, literally nose to tail.  This PV array is claimed to 
produce either 1.2kW or 1.5kW, depending on the source.  Presumably that's 
under ideal conditions - fine if you're driving in San Diego, maybe not so 
fine here in cloudy Ohio.

Supposedly they got the car to run on 50 watts (!).  I haven't found that 
claim elsewhere, but that's what Lawrence says the "day time running system 
including lights" uses.  

I find this impossible to believe.  My e-bike cruses at 15mph, typically 
using between 150 and 250 watts (depending on terrain and how much I pedal). 
My bike weighs 50lb.  Their car weighs around 900lb.  You do the math, and 
tell me how they manage 50 watts.

All that aside, the principle here reminds me of the solar racers, highly 
optimized engineering-challenge vehicles where cost is no object.  Most 
solar racers are developed in academic settings with hundreds of thousands 
of dollars in (largely donated) components and materials.  Tens of thousands 
of labor hours go into them, made possible in part by teams of students who 
volunteer their time.  The tools and workshops are provided by the 
university, or are donated.

The result is a super-efficient vehicle suited only to one purpose, winning 
the prize in a solar race.  Solar racers by and large are not practical for 
everyday use.  They're notoriously uncomfortable, and frankly most of them 
would be pulverized in a low speed road accident.   

The folks who built Stella, from a university in The Netherlands, claim 
they've made their solar racer more practical and comfortable.  Unlike the 
other racers it does indeed carry more than one person.  It does not seem to 
have doors, however.  (No word on the safety issues.)  

The builders claim the PV cost them only UKP 2600 (about US$4200), but I'm 
skeptical.  (Of course $4200 also buys a fair amount of batteries.)

The drive system for an EV like this would have to be highly optimized.  
Every compromise you make so that it's buildable in your garage instead of a 
university machine shop is going to cost efficiency.  If the typical home EV 
converter built an EV like this, he might end up with something interesting. 
 Would it manage to be, as these students claim, a "car you never have to 
plug in" (100% self-solar powered)?  That I'm not so sure about.  

The other problem I see with this is that you're building a high-precision 
complex machine from scratch.  Look at how many kit cars never get finished, 
and this would be even more work than those!  You'd have to be really, 
really serious about building it, truly dedicated.

If that's you, my hat's off to you.  Personally, I wouldn't try building 
something like this because (1) I don't want to devote all my time to it; 
and (2) I'd be afraid that I wouldn't have it done in time to drive it 
before I was too old (or dead).  But hey, I'm kinda old already.  ;-)

I think this would be a great project for someone who's dedicated to the EV 
cause, and fairly wealthy.  Duplicating this prototype could work, if you 
could afford to hire out most or all of the labor and fabrication (sort of 
like what Neil Young did with his LincVolt).  I can see someone like Ed 
Begley Jr commissioning something like this, for example.

David Roden - Akron, Ohio, USA
EVDL Administrator

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