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Posted by R. H. Allen on January 30, 2004, 6:21 pm
On Thu, 29 Jan 2004 19:58:41 GMT, Ecnerwal

I think a big part of the problem is that efficiencies are not as high
as they anticipated. Their newly opened plant was scheduled to open
"next year" for 5-6 years, and I believe a significant part of the delay
was getting production efficiencies that came anywhere near their
laboratory efficiencies. Then again, it probably wasn't wise for them to
promote 15% efficiency when that was their record-high laboratory
efficiency (I sure hope they weren't basing their cost calculations on

Posted by Maurie Daly on January 31, 2004, 4:04 am
On Fri, 30 Jan 2004 13:21:58 -0500, R. H. Allen

Its unclear to me why there seems to be such an obsession with solar
cell efficiency.
I couldnt care less if solar cells are only 5% efficient as long as
they are cheap (1$ per watt or less.).
Lets face it, space with sun shining on it isnt something that is in
short supply


Posted by Henry on January 31, 2004, 7:07 am
  mauried@tpg.com.au (Maurie Daly) wrote:

Most people live in cities.  Real-estate is expensive there.  Roof-space
is at a premium.  Line-of-sight is often obstructed.  Efficience _does_

Nonetheless, the price _is_ vastly more important in the big scheme of


Posted by H. E. Taylor on February 1, 2004, 2:53 am
    This whole either/or opposition is a sham, IMNSHO.
    What matters is the cross product of the two.  How much
    energy can you get from a given PV cell?  Cost and size
    are both relevant.

"The universe is full of magical things patiently waiting for
 our wits to grow sharper." -Eden Phillpotts

PV FAQ: http://www.autobahn.mb.ca/~het/energy/pv_faq.html
H.E. Taylor  http://www.autobahn.mb.ca/~het/

Posted by R. H. Allen on February 1, 2004, 7:34 pm
 On Sat, 31 Jan 2004 04:04:45 GMT, mauried@tpg.com.au (Maurie Daly)

Consider a solar panel that costs $00. Suppose it produces 100 peak
watts at 8% efficiency -- a cost of $/peak watt. Now suppose you could
raise the efficiency to 12%. That same module now produces 150 peak
watts -- a cost of $.33/peak watt. Big difference.

That is the situation that, AFAICT, Unisolar is facing with the
aforementioned solar cell design. They expected higher efficiency from
the design they're producing. If they actually *got* higher efficiency,
their design would be cheaper on a cost per peak watt basis than
crystalline silicon. Since they're having trouble getting high
efficiency, it took them five years to develop a process that could
compete with crystalline silicon, blowing their original plan to
undercut crystalline silicon in under a year.

I agree with you completely. But the price of glass doesn't fall just
because your cells have low efficiency. Low efficiency is expensive.
Consider the raw materials for assembling a module -- glass, EVA
pottant, the frame, the junction box, etc. These cost roughly $0/square
meter for a crystalline silicon module (it may be slightly cheaper for
an amorphous module, but the glass, frame, and junction box are about
60% of this cost). Just for the sake of argument, let's assume that all
other materials, silicon and solar cell processing, labor, and
production equipment are free. To get a MANUFACTURING cost of $/watt,
then, the module must have an efficiency of at least 6% (which means the
cells in the module must have an efficiency of 7-8%). Retail price would
then be $.50-2.00/watt, so the module efficiency would then have to be
9-12% to get a RETAIL cost of $/watt. Factor in the real costs of
silicon and other raw materials, processing, and labor, and the
efficiencies required to get $/watt are much higher.

This is why efficiency is important. It's still not the only thing, but
with current commercial technologies, low cost cannot be achieved
without higher efficiency using ANY technology. Modules at $/watt will
be achieved first by increasing efficiency, reducing consumption of raw
materials, and reduced material prices through economies of scale. One
or two of these won't do it; it will require all three.

Is 5% efficiency at $/watt impossible? I don't think so. But it will
happen with a non-silicon technology that is still a LONG way from
coming out of the laboratory, or it will happen long after $/watt is
reached through high efficiency and reduced materials costs. Either way,
it will not happen at all for a very long time.

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