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<DIV><SPAN class=765552802-20022011><FONT face=Arial>At least that's the
conclusion of Gottfried Wilhelm Leibniz. </FONT></SPAN></DIV>
<DIV><SPAN class=765552802-20022011>"The largest difference of the
[PV] plant yield was less than 6% for tilt angles between 0° and
70°."</SPAN></DIV>
<DIV><SPAN class=765552802-20022011><FONT face=Arial>This begs the question,
where did the notion that tilt to latitude is critical come from. Surely
NREL or someone else has tested this concept before. </FONT></SPAN><SPAN
class=765552802-20022011><FONT face=Arial>Anyway if N-S angle energy
production loss is only 6% to +/-35° then E-W should be too,
right? But it's not. </FONT></SPAN></DIV>
<DIV><SPAN class=765552802-20022011><FONT face=Arial>Here's why. If you measured
irradiance at 10°-70° only at noon over 12 months, the air mass would at
its minimum during the entire test and so irradiance
deviation would be too. AM would not be constant at +/- 35° E-W which has
been verified by NREL and others for a long time, AM increases the further from
solar noon the sun gets. </FONT></SPAN></DIV>
<DIV><SPAN class=765552802-20022011><FONT face=Arial>But if the Earths tilt is
23.5 degrees and Gottfried measured to 35 degrees, the difference is 11.5
degrees at summer and winter solstice. And if your array angle is +/- 11.5
deg from true south, rule of thumb is that irradiance losses are minimal. Maybe
only 6% or so. </FONT></SPAN></DIV>
<DIV><SPAN class=765552802-20022011><FONT face=Arial>This puts the significance
of array tilt in a whole new light. Pun intended... </FONT></SPAN></DIV>
<DIV><SPAN class=765552802-20022011><FONT face=Arial><SPAN
class=765552802-20022011>Of course there is a fee to download the entire
document but the abstract is here </SPAN></DIV></FONT></SPAN>
<DIV><SPAN
class=765552802-20022011></SPAN><STRONG>http://tinyurl.com/4zf2syk</STRONG></DIV>
<DIV><FONT face=Arial><A
href="http://www.scopus.com/record/display.url?eid=2-s2.0-78951495350&origin=inward&txGid=kX6CkwoH_w_VL01NbmaciIC%3a2">http://www.scopus.com/record/display.url?eid=2-s2.0-78951495350&origin=inward&txGid=kX6CkwoH_w_VL01NbmaciIC%3a2</A></FONT></DIV>
<DIV><STRONG><FONT face=Arial size=2></FONT></STRONG><FONT size=2><FONT
face=Arial><STRONG></STRONG></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT face=Arial><STRONG></STRONG></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT face=Arial><STRONG>Jim
Duncan</STRONG></FONT></FONT></DIV>
<DIV><FONT face=Arial size=2><STRONG>North Texas Renewable
Energy</STRONG></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff
size=2><STRONG><U></U></STRONG></FONT> </DIV>
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