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<div class="moz-cite-prefix">On 6/3/2013 3:23 PM, RT wrote:<br>
</div>
<blockquote cite="mid:op.wx4astdv0ciq73@rt-acernb" type="cite">On
Mon, 03 Jun 2013 12:51:27 -0400, Topher
<a class="moz-txt-link-rfc2396E" href="mailto:topher@greenfret.com"><topher@greenfret.com></a> wrote:
<br>
<br>
<blockquote type="cite">
<blockquote type="cite">Also, I'm pretty sure that I remember my
neighbour saying that CPV
<br>
systems are typically designed as tracking systems,
<br>
</blockquote>
</blockquote>
<br>
<blockquote type="cite">tracking is /already/ more expensive than
just
<br>
adding more panels.
<br>
</blockquote>
<br>
Is this true ?
<br>
<br>
You may recall that about a year ago I posted some messages to
this list about the output from one of my neighbours' 10 kW
single-axis tracking array.
<br>
<br>
He was regularly getting up to 40% higher production than an
identically-sized fixed array in the same neighbourhood. (I had
posted a link to a site that provided real-time monitoring data
for the fixed array).
<br>
</blockquote>
Details always matter in this business. So, perhaps it works out
better for him, but not around here. Also, panels have halved in
price over the last 1.5 years or so. What was true then may no
longer be. No installers around here even consider tracking
anymore.<br>
<br>
Here is a solar tracker for $1893 USD holds 64ft^2 of panels.<br>
<a class="moz-txt-link-freetext" href="http://www.altestore.com/store/Solar-Panel-Mounts-Trackers/Passive-Solar-Panel-Trackers/Zomeworks-UTRF-072-Universal-Solar-Tracker/p10390/?source=shopzilla">http://www.altestore.com/store/Solar-Panel-Mounts-Trackers/Passive-Solar-Panel-Trackers/Zomeworks-UTRF-072-Universal-Solar-Tracker/p10390/?source=shopzilla</a><br>
The same store will sell me 5 panels to go on it for $275 each
(250W) <br>
<a class="moz-txt-link-freetext" href="http://www.altestore.com/store/Solar-Panels/SolarWorld-Sunmodule-SW250-Poly-250W-20V-Solar-Panel-V25-Frame/p10149/">http://www.altestore.com/store/Solar-Panels/SolarWorld-Sunmodule-SW250-Poly-250W-20V-Solar-Panel-V25-Frame/p10149/</a><br>
Total cost: $3268.<br>
<br>
Or I could just buy panels with that amount and get about 12 of
them. For 230% better performance.<br>
<br>
Note: I just picked the first one that came up in Google, to remain
impartial. YMWV.<br>
<blockquote cite="mid:op.wx4astdv0ciq73@rt-acernb" type="cite">
<blockquote type="cite">The problem is not just the cost of the
lenses. In order to get the
<br>
same output as a 20 meter^2 PV panel array, you need 20 meter^2
of
<br>
Fresnel lenses; and some means of holding it very steady in the
wind, a
<br>
precise distance away from the collector; plus be able to move
the whole
<br>
unit (including the cooling system), very precisely throughout
the day,
<br>
every day.
<br>
</blockquote>
<br>
I suspect that the above is not much of a challenge for the PV
cowboys/gals these days judging by the number of 10 KW tracking
arrays one sees mounted atop a single mast when out for a morning
bike ride around this neighbourhood.
<br>
</blockquote>
<br>
Perhaps I should back up and get a description of what the 1 square
inch solar cell you are talking about is going to produce. If we
are talking about replacing an average sized home PV array, then we
need roughly the same sized Fresnel lens, and that needs to be
focused on a 1" collector, with an appropriate focal distance
(presumably many feet). That is a very tough problem. If we are
only talking about the 300x concentrators (like the ones Sanjay
pointed out), than a 1" cell needs a Fresnel lens 17" on a side.
Much more feasible, but that is only about 186 Watts (<i>total</i>
before efficiency losses), nothing like a whole house system.<br>
<br>
Some pertinent quotes for Sanjay's link:<br>
* "Despite having been researched since the 1970s, it has only now
entered the solar electricity sector as a viable alternative."<br>
* "<strong>Active Cooling:</strong> Typically, liquid metal is used
as a cooling fluid, capable of cooling from 1,700°C to 100°C."<br>
[required for high concentration systems i.e. > 100x]<br>
*"Thus, it is less dependant on the immature silicon supply chain.
Moreover, optics are less expensive than cells."<br>
<br>
This last I think is debatable at this point. Silicon supply is
pretty mature at this point. Optics are<i> very</i> mature. Anyone
into expensive cameras will tell you that cameras keep getting
better and cheaper, and lenses get better only by getting more
expensive. Cameras are a good analogy to solar PV systems because
they both do NOT take advantage of Moore's law when it comes to the
Silicon. Bigger is better.<br>
In forty years that concentrator technology has been known, it has
not taken off, in the mean time, prices for solar cells have dropped
by 250x. If it could have taken off, 1970's was the time for it to
do so.<br>
<br>
Moving the other direction, I could get thin film flexible panels
and just glue them to my standing seam roof. Drastically reduced
infrastructure. No racks, no module frames, No aluminum at all.
Probably worth the 50% drop in efficiency, once the sales volume
drops the price commensurate with typical panels.<br>
<br>
<br>
Thank You Kindly,<br>
<br>
Corwyn<br>
<br>
<pre class="moz-signature" cols="72">--
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
<a class="moz-txt-link-freetext" href="http://www.GreenFret.com/">http://www.GreenFret.com/</a>
<a class="moz-txt-link-abbreviated" href="mailto:topher@greenfret.com">topher@greenfret.com</a>
</pre>
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