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Reworking the equation (was: Solar sham) - Page 3

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Posted by Anthony Matonak on February 15, 2008, 4:11 am
 
J. Clarke wrote:

My understanding is that the heating processes used to refine
silicon require very precise control of the heating over long
durations. I don't believe direct solar heating would be able
to do this very well.

Evergreen solar uses a ribbon pulling method.
http://www.evergreensolar.com/app/en/technology/item/48

Anthony

Posted by Morris Dovey on February 15, 2008, 4:16 am
 
Anthony Matonak wrote:

IBM also experimented with pulling ribbons in the early 70's -
but abandoned the process because the ribbon surface wasn't good
for a darned thing except solar cells - and the company wasn't
interested in that market.

Both the cylinders and the ribbons are "pulled". The primary
difference is that the ribbon is pulled from a narrow opening,
rather than an open surface. The diameter of the pulled cylinder
is determined in large part by the pull rate. Either way, the
starting point was a suspended seed crystal touched to the molten
surface.

John, they're just different terms for the same process. The
roughly cone-shaped tops of the cylinder (which showed the growth
from the seed crystal to the full diameter) were sawed off and at
least some few became treasured paper weights in a number of EF
lab offices - just as some of the folks in other labs have full
(usually spoiled) wafers for "show-off" display. At Philips I had
a wafer of MIPS cable modem SOC's that I passed on to someone
else when my time there ended. It's probably proof of incurable
geekhood, but I always thought it beautiful. :-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto

Posted by J. Clarke on February 15, 2008, 12:56 pm
 Anthony Matonak wrote:

When I think of "pulling" I think of processse like wire drawing in
which the material is deformed into the new shape, not lifted in
molten form by a process so gentle that it doesn't break surface
tension.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)



Posted by Bill Ward on February 16, 2008, 7:52 am
 On Thu, 14 Feb 2008 17:27:33 -0500, Morris Dovey wrote:


Wouldn't "free" solar DC electricity be a perfect match, then?  Yet no one
seems to use it for aluminum electrolysis...



Posted by Anthony Matonak on February 16, 2008, 9:36 am
 Bill Ward wrote:

Free electricity would be a perfect match but there ain't no such thing.
Solar PV electricity today costs more than other sources of electricity.
Solar PV tomorrow, who knows? It's likely to be cheaper but is it going
to be cheaper than any other source of electricity anywhere? Probably
not for a long time.

Anthony

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