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<DIV><FONT size=2 face=Calibri>Yes, it is a poor design. though you may not
have any problems there with the heat de-rating of the panels. If the panel
temperature gets under about 40C you may blow out the input. As long as you have
a load on the output of the contgroller, it will keep the voltage down, but if
the output is disconnected the input could go up to full voltage.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>Who designed such a system?</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV>..................................................................................................<BR>Northern
Arizona Wind & Sun - Electricity From The Sun Since 1979<BR>Online Store: <A
href="http://store.solar-electric.com/">http://store.solar-electric.com/</A><BR>Solar
Discussion Forum: <A
href="http://www.wind-sun.com/ForumVB/">http://www.wind-sun.com/ForumVB/</A><BR>..................................................................................................</DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=wratterman@sunenergypower.com
href="mailto:wratterman@sunenergypower.com">Walt Ratterman</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">'RE-wrenches'</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, June 26, 2009 3:22 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [RE-wrenches] Solar Boost
Controller in Senegal</DIV>
<DIV><BR></DIV>
<DIV class=Section1>
<P class=MsoNormal>Hello,<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>I am in a very remote part of Senegal, (near the
Guinea and Mali borders…) and I have come across some prefabricated
“plug and play” American made systems installed for educational
institutions.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>The systems use two Sharp panels that are 220Watts, 33.6
Voc, 29.2 Vmp, wired in series, using #10AWG home run wire from the panels
back to the charge controller.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Charge Controller is a Solar Boost 50.
<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Batteries are Dekka AGM – two strings of 250AH, 12V
batteries. (four batteries total).<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>My specific question is about the controller. This is
a 24V in / 24V out charge controller with MPPT. I have not used this
before, so I am not familiar with the details of operation.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>The data sheet that I downloaded says that the maximum open
circuit voltage is 57 VDC. But, this system is hitting the charge
controller with two panels of 33.6 VDC wired in series for 73.2VDC. So,
why is the controller not fried, or what am I seeing wrong here. I
suppose with the panel temperature being elevated maybe 35 degrees above 25
degrees and a resulting 17.5% loss, coupled with some voltage drop, the system
may actually be seeing less than the 57 volts. <o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>But…..isnt this a dangerous way to design a system?
(it will get cooler here ….)<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Or am I missing something? <o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>What would be the appropriate application
here….<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Sorry, I cant do a lot of internet research from here –
limited download capability on the satellite….<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Thanks!!<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Walt<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">Walt
Ratterman<o:p></o:p></SPAN></B></P>
<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">SunEnergy Power
International</SPAN></B><B><SPAN
style="FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt"><o:p></o:p></SPAN></B></P>
<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt"><o:p> </o:p></SPAN></B></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 8pt">11 Laurel Lane
South Washougal, WA
98671<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 8pt">(360)-837-3680
▪ fax (360)-837-1315 ▪ Skype
Walt-Mobile<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 8pt"><A
href="mailto:wratterman@SunEPI.org">wratterman@SunEPI.org</A>
</SPAN><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt"> </SPAN><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 8pt">▪ <A
href="http://www.sunepi.org/">www.SunEPI.org</A><o:p></o:p></SPAN></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><o:p> </o:p></P></DIV><BR><BR>__________ Information
from ESET NOD32 Antivirus, version of virus signature database 4193 (20090626)
__________<BR><BR>The message was checked by ESET NOD32 Antivirus.<BR><BR><A
href="http://www.eset.com">http://www.eset.com</A><BR>
<P>
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