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Carl,<br>
<br>
As you posed your question, with the array fixed at the angle
optimized for annual energy production, you've forced a solution
that cannot meet the goal of harvesting the maximum energy from the
site.<br>
<br>
To get the most energy from any site, the array will be horizontal
with no spacing between rows. The intuitive way to see this is to
consider the question: how do you get every photon that hits the
site to land on a PV module? Horizontal is not a very practical
solution. To wash clean with rainfall, the modules need to have some
slope; 10° to 15° is usually considered minimum. If someone is to
clean the modules by hand, or inspect the modules, there must be
access space between the rows. <br>
<br>
Also, the horizontal solution isn't the most cost effective
solution, except perhaps near the equator. To get the most energy
per money unit (insert your choice: dollar, yen, ...), more
information needs to be considered. If the value of the land or roof
surface is ignored, the lowest cost per kWh will probably occur when
the modules are spaced far enough apart that there is virtually
never any shading from the rows in front and the optimum angle is a
little less than the latitude. This solution produces much less
energy the maximum possible. And, of course, ignoring the value of
the land or roof space isn't practical either.<br>
<br>
Ultimately, you have to look at what limits apply to the problem and
work from there.<br>
<br>
<pre class="moz-signature" cols="72">Kent Osterberg
Blue Mountain Solar, Inc.
<a class="moz-txt-link-abbreviated" href="http://www.bluemountainsolar.com">www.bluemountainsolar.com</a>
</pre>
On 4/15/2012 4:44 PM, Michael Welch wrote:
<blockquote cite="mid:20120415234948.B9EEAFE8C@che.dreamhost.com"
type="cite">
Carl is having sending issues, so I am posting this on his behalf.
He
will be able to receive your responses on the list, though.<br>
<br>
<font face="Tahoma" size="2"><b>From:</b> Carl Emerson
<a class="moz-txt-link-rfc2396E" href="mailto:Carl@solarking.net.nz"><Carl@solarking.net.nz></a><br>
<b>Sent:</b> 15 April 2012 10:16 p.m.<br>
<b>Subject:</b> Array Spacing for optimum performance.<br>
</font> <br>
<font color="#0000FF"> Hi there,<br>
<br>
Can I raise a design issue with large grid-tied arrays.<br>
<br>
Using William’s spreadsheet for array spacing leaves me with
several
questions unanswered.<br>
<br>
Assuming the array is inclined for max year round performance,
one could
then space the array for no shading for a certain sun Elevation
and
Azimuth.<br>
<br>
The question I have is what is the sweet spot when compromising
shading
for array spacing in large arrays.<br>
<br>
Narrower spacing means more panels in the array and better
output in
summer.<br>
<br>
Wider spacing means better winter performance with less panels
and less
annual power production.<br>
<br>
Is there a guideline available to optimise these factors…<br>
<br>
Thanks for your help.<br>
<br>
Carl Emerson<br>
Freepower Co.<br>
Auckland N.Z.<br>
</font>
<br>
</blockquote>
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