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<DIV><FONT size=2 face=Calibri>I would never design such a system. That is what
MPPT controllers are for. 10 years ago we did not have that choice, but now we
do, so there is no reason at all to design a 40 amp 12 volt array
circuit.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV>..................................................................................................<BR>Northern
Arizona Wind & Sun - Electricity From The Sun Since 1979<BR>Solar Discussion
Forum: <A
href="http://www.wind-sun.com/ForumVB/">http://www.wind-sun.com/ForumVB/</A><BR>..................................................................................................</DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=kent@coveoregon.com href="mailto:kent@coveoregon.com">Kent
Osterberg</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=re-wrenches@lists.re-wrenches.org
href="mailto:re-wrenches@lists.re-wrenches.org">Wrenches</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, April 10, 2010 9:22
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [RE-wrenches] DC wire
sizing</DIV>
<DIV><BR></DIV>Here's my challenge to all of you that want to design for 1% or
1.5% voltage drop all the time:<BR>Take a 50-ft circuit carrying 40 amps at 12
volts, going to a C40 charge controller, select your wire size for 1% or 1.5%
loss. You know that's not a practical solution. I know that it makes
more sense to replace the charge controller and run the PV circuit at a higher
voltage.<BR><BR><B>At % loss did it become impractical?</B> Ray's answer
and my answer is "when there is a cheaper alternative -- lower cost per watt
out or lower cost per kWh over the project life." And that answer works
even when you are considering a 400-kW PV array that is 1000 feet
away.<BR><BR>Kent Osterberg<BR>Blue Mountain Solar, Inc.<BR><BR>
<P>
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