Why not photovoltaic trough?

Ed Ferris

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Jul 20, 2008, 9:30:53 PM7/20/08

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This may be a dumb question, but: Why not use parabolic mirror troughs, as
in solar thermal systems, with a narrow strip of photovoltaic cell at the
focus? Seems it would be a lot cheaper.

Ralph

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Jul 21, 2008, 6:25:45 AM7/21/08

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they don't like heat.
- and it's not a dumb question.

"Ed Ferris" <none> wrote in message
news:Xns9AE1DADC...@216.168.3.44...

coj

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Jul 21, 2008, 7:08:52 AM7/21/08

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There are some solar pv concentrating troughs in existence, one such was
the Euclides project

http://www.pvresources.com/en/euclides.php
http://www.inspira.es/newsroom/981130.html

Solar concentration from this sort of arrangement could be 20-30x but as
Ralph mentioned the heat build up meant that heat sinks had to be
used. Plus you had to add the cost of the solar tracker and support.

Most ordinary cell and module designs aren't good at high concentration
due to the higher temperatures and the I^2R loss from high currents,
these cells used laser grooved buried contacts (narrower than screen
printed lines) for the ability to have more fingers with low shading loss.

--
coj

Roland Mösl

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Jul 21, 2008, 7:16:11 AM7/21/08

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"Ed Ferris" <none> schrieb im Newsbeitrag
news:Xns9AE1DADC...@216.168.3.44...

Silicon based photovoltaic looses 0,48% efficiency at
ever degree Celsius more warm.

Concentrators are tested, here from Sharp
http://live.pege.org/2006-intersolar/sharp-concentrating-cell.htm

They are more for very sunny areas.

I live for example in Austria.
In winter, 60% of irradiation is diffuse,
diffuse light can not be concentrated.

New cheap thin film technics make concentration obsolete
http://live.pege.org/2008-intersolar/photovoltaic-factories.htm

--
Roland Mösl
http://car.pege.org cars and traffic
http://live.pege.org building and live
http://www.pege.org

mike

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Jul 27, 2008, 7:19:32 AM7/27/08

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Roland Mösl wrote:
> "Ed Ferris" <none> schrieb im Newsbeitrag
> news:Xns9AE1DADC...@216.168.3.44...
>> This may be a dumb question, but: Why not use parabolic mirror
>> troughs, as
>> in solar thermal systems, with a narrow strip of photovoltaic cell at the
>> focus? Seems it would be a lot cheaper.
>
> Silicon based photovoltaic looses 0,48% efficiency at
> ever degree Celsius more warm.
>
> Concentrators are tested, here from Sharp
> http://live.pege.org/2006-intersolar/sharp-concentrating-cell.htm
>
> They are more for very sunny areas.
>
> I live for example in Austria.
> In winter, 60% of irradiation is diffuse,
> diffuse light can not be concentrated.

This is counter-intuitive. Thought experiments with
arbitrarily large parabolic reflectors and arbitrarily small
solar cells suggests that there should be non-zero improvement????

ohar...@mindspring.com

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Aug 1, 2008, 8:36:08 PM8/1/08

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A: Diffuse light CAN be concentrated but not with a parabola. You
have to use either a "Compound Parabolic Concentrator" or "Compound
Elliptical Concentrator". You can even calculate the degree of
concentration.

B. Trough style "compound parabolic concentrators" work very well and
do not require tracking. They are mostly used for heating fluid for
indirect solar-electric.