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<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>In principle, two strings with different
orientations should not be wired in parallel into the same inverter. However,
when the mismatch is minor (15 degrees in pitch or 15 degrees in azimuth) there
is practically no degradation. Fronius circulated a white paper for a while
that argued that their inverters did maximum power point tracking on the string
with the greatest irradiance and therefore did an optimum mppt job on the
string with the greatest “available power”. This part of the
argument makes sense. What I have never been clear about is how close to “optimum”
this arrangement is (optimum being two separate monitors one for each string).</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Fronius appears to be backing away from
this white paper, as I was told about six months ago from a member of their
tech support staff that they recommended two separate inverters.</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<div>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>- Peter</span></font></p>
<p><font size=2 color=navy face=Arial><span style='font-size:10.0pt'> </span></font></p>
<p class=MsoNormal><img width=67 height=80
src="cid:image002.gif@01CA32C0.C15EDE10" align=left hspace=12><font size=1
color=navy><span style='font-size:9.0pt;color:navy'>Peter T. Parrish, Ph.D.,
President<br>
California Solar Engineering, Inc.<br>
820 Cynthia Ave., Los Angeles, CA 90065<br>
CA Lic. 854779, NABCEP Cert. 031806-26<br>
<a href="mailto:peter.parrish@calsolareng.com">peter.parrish@calsolareng.com</a>
<br>
Ph 323-258-8883, Mobile 323-839-6108, Fax
323-258-8885
</span></font></p>
<p><font size=2 color=navy face=Arial><span style='font-size:10.0pt'> </span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Nick Vida<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, September 09,
2009 6:38 PM<br>
<b><span style='font-weight:bold'>To:</span></b> wrenches<br>
<b><span style='font-weight:bold'>Subject:</span></b> [RE-wrenches] losses to
competing angles in single strings</span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<div>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>hello wrenches.<br>
<br>
I was wondering if any of you have any data on what the losses would be if you
had your string split with 2 different angles, but at the same azimuth. For
instance, string of 11 with 8 facing 180 south at 30 degrees, and 3 facing
south 180 at 45 degrees. I have heard that the voltages and currents would
differ and the IV curve would be inefficient as a string, but I don’t
know how much of a loss would be expected.<br>
<br>
thanks in advance, and hopefully I didn’t miss anything in the archives.<br>
<br>
thanks,<br>
<br>
nick<br>
<br>
</span></font></p>
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