# Re: [EVDL] Solar trailer calculation

```On 28 Dec 2017 at 5:05, ROBERT via EV wrote:

> I do not know who does your math.  The email states "Leaf gets 4.5 miles per
> kw at 55mph more or less depending on wind."  Therefore, 1000 W / 4.5 miles =
> 222 W per mile.   This appears to be a little low to me.  However, if it is
> accurate, you would need 222 W to go one mile.```
```
First of alll, that should be kilowatt hours (KWH) and watt-hours, not just
watts.  Watts per mile is a meaningless unit.  Saying your EV uses 222 watts
per mile is like saying your ICEV uses 120 horsepower per mile.

Second, I don't see anything wrong with the math in the message you're
replying to.  My only quibble would be with "you would need a minimum input
of 12,220 watts."  I would say that he needs a minimum AVERAGE input of

Others have posted the amount of square PV area needed, so I won't rehash
that.  I'll just remind you that the sun doesn't shine 24 hours a day, and
that insolation is lower on cloudy days and in the winter.  Even if you can
design a trailer to keep your EV going 55 at noon on a clear summer day,
what will you do at other times?

Putting PVs on a vehicle (or its trailer)  probably isn't the most efficient
use of your PV dollars.  Is it really worth it?  Your call.

David Roden - Akron, Ohio, USA

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