Re: (ET) Fwd: [EVDL] The Case for the Electric Tractor

["harry landis" <hlandis hotmail com>]

Sunpower sells 19.7% efficient modules using 22% efficient cells:

http://investors.sunpowercorp.com/releasedetail.cfm?ReleaseID=238439

The world record for a single cell is about 42%. But the most important 
number is watts/$, not watts/area. First solar claims a manufacturing cost 
of $1.40/watt for their thin film CdTe panels.

Harry Landis


From: Christopher Zach <cz alembic crystel com>
CC: Elec-trak cosmos phy tufts edu
Subject: Re: (ET) Fwd: [EVDL] The Case for the Electric Tractor
Date: Fri, 24 Aug 2007 18:50:42 -0400

David Roden wrote:
> On 24 Aug 2007 at 15:11, Darryl McMahon wrote:
>
>> solar panels are the most efficient way of converting
>> radiant sunlight energy into electricity (approaching 20% vs 1% or
>> much less for plants).
>
> Where do they get this number?  I think I've read that mass-produced PV 
is
> around 10% efficient at normal operating temperatures.

It depends. Thin film is about 7% efficient, polycrystaline is around
14%, single-crystal about 18%.

I have 1.8kw of single crystal Shell 75 watt panels on the house and
about 800 watts of Solarex polycrystaline on the shed. The Solarex 80
watt panel is *much* heaver and larger than the Siemens 75, and the one
thin film panel is bigger than both and only 43 watts.

> I may have missed it, but they also don't seem to have figured battery
> amortization into the operating costs.  For road EVs, this is the largest
> contribution to per-mile expense, and I'd bet that this will also be true
> for an electric tractor in daily service.

Mmmm. Maybe. If you get 8 years out of a set of T105's, that's not
unusual for an Elec-trak with a stupid charger. How long does the
average B&S engine last these days (seems to be about 6-8 years)

Chris


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