What? To maintain a small car like a Leaf at 55 MPH only requires about 10 - 12 
HP.  This is only 7.5 KW (10HP) - 8.9 KW (12HP).  The battery in the Leaf is 
rated at 30 KW-Hr.  At 55 MPH it does not require all the power in the battery 
(30KW-Hr).  It only requires 7.5KW-Hr - 8.9 KW-Hr to maintain 55 MPH.  A solar 
panel system that could replenish this energy plus conversion losses would keep 
the car going and the battery level at a its current level of charge because 
the solar panel system would run the car.

From: EV <ev-boun...@lists.evdl.org> on behalf of Marc de Piolenc via EV 
Sent: Thursday, December 28, 2017 9:39 PM
To: ev@lists.evdl.org
Cc: Marc de Piolenc
Subject: Re: [EVDL] Solar trailer

You're getting power and energy mixed up.
Your Leaf has a POWER rating of 30 kW, which means that (at full power)
it consumes 30 kW-hours of energy per hour.
It does not get 4.5 miles per kW because a kilowatt is a unit of power,
not energy - maybe 4.5 miles per kWh which is roughly consonant with its
power rating and speed.
To support that speed without dipping into batteries, you need a solar
array that constantly produces 30 kW, which at 20% efficiency, receiving
100 watts per square meter, will require 300/.20 square meters of solar
photovoltaic panels, or 1500 square meters. Not easy to tote around.

It is safe to say that you cannot generate enough juice to recharge
while driving.

On the other hand, having a much smaller array can still allow your car
to recharge while it is parked in the open, and that might be
worthwhile, depending on your application. This would work if you have a
short commute, followed by the car being idle for nine hours or so in
broad daylight in a sunny climate.

Marc de Piolenc

On 12/28/2017 11:52 PM, ev-requ...@lists.evdl.org wrote:
> My math is good enough to figure out I get about my 30kw Leaf gets 4.5 miles 
> per kw at 55mph more or less depending on wind.? What I'd like to know is 
> what size solar panel would be needed to support that speed.? Now don't tell 
> me it can't be done.? I just want to know the formula for figuring it out.? 
> My puny brain exploded when I thought of all the variables.? I do know that a 
> 3000 watt system would charge my car in 10 hours.? I would just like to know 
> the numbers of what would be needed for continuous power at speed.? I 
> guesstimated it would be about 10000 watts.? I'd just like the exact number.? 
> Thanks,? Lawrence Rhodes...the point is to build a teardrop solar range 
> extender/RV that could charge while driving.

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