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<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>Ray,
<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>The
$ could be making power I agree on a large scale project. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>The
point here is where is the cutoff point?<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>Let’s
take a very small cabin system:<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>410
watts or 13 amps [inc.1.25%]@ 44VOC, over a 90’ one-way run.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>Utilizing
and Electro-calc with 2008 NEC installed<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>2.6%VD
– 1.1vd requires a pair #6 Thhn @ $0.66/ft = $118 for 180’wire @ whole sale
price.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>1.6%VD
– 0.7vd requires a pair #4 Thhn @ $0.78/ft = $140 for 180’wire @ whole sale.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>0.4%VD
– 0.4vd requires a pair #1 Thhn @ $1.55/ft = $279for 180’ wire @ whole sale.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>I
grant you the cost savings up front, and MPPT covers a lot errors these days,
but where do we say what is better?<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>So
my question is-<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>In
MPPT what is .3volt drop worth VS 0.7vd VS 1.1vd worth in MPPT charge
capabilities over the life of the system? <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'>Weather
it is a utility scale project or a small cabin.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>Thanks,
Dana Orzel<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>Great
Solar Works, Inc<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>E -
dana@solarwork.com<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>V -
970.626.5253<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>F -
970.626.4140<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>C -
970.209.4076<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>web
- www.solarwork.com<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif"'>"Responsible
Technologies for Responsible People since 1988"</span><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif"'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal style='margin-left:.5in'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>R Ray
Walters<br>
<b>Sent:</b> Thursday, July 22, 2010 3:30 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] calculating DC voltage drop<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p>
<p class=MsoNormal style='margin-left:.5in'>Hi Dana;<o:p></o:p></p>
<div>
<p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'>I'd say that's a bit overkill for
today's market. That money could be making more power, not just preventing
losses. <o:p></o:p></p>
<div>
<div>
<p class=MsoNormal style='margin-left:.5in'>Definitely a law of diminishing
returns on wire sizing. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'>If you allocated 50% of the budget
to wire, and 50% to PV, your losses would be very low, (immeasurable but
unfortunately still there) but your total system production vs. the money spent
would be terrible.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'>I'm only using this ridiculous
example to show, that at some point, we all spend money on more PV, not bigger
wire. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'>I pick that point based on sound
economic analysis, not some over applied rule of thumb. As copper costs rise,
and PV gets cheaper, that point moves up. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'>If copper was still at 20th century
prices, and PV were $10/ watt, your 1% might very well be the right answer.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'>( this is also the point where
Bob-O starts hammering me, so I'd better run. ??)<o:p></o:p></p>
</div>
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<p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p>
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<div>
<p class=MsoNormal style='margin-left:.5in'><span style='font-size:9.0pt;
font-family:"Helvetica","sans-serif";color:black'>R. Walters<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><span style='font-size:9.0pt;
font-family:"Helvetica","sans-serif";color:black'><a
href="mailto:ray@solarray.com">ray@solarray.com</a><o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><span style='font-size:9.0pt;
font-family:"Helvetica","sans-serif";color:black'>Solar Engineer<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><span style='font-size:9.0pt;
font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p>
</div>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:9.0pt;
font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:9.0pt;
font-family:"Helvetica","sans-serif";color:black'><br>
<br>
</span><o:p></o:p></p>
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