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<TITLE>Re: [RE-wrenches] AC wiring loss on micro-inverters</TITLE>
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<FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Maybe Marv can help out here. I’ve talked with tech support at Enphase and am under the impression that you can center tap their branch circuits to reduce voltage drop. This technique was used on a project that we profiled in SolarPro:<BR>
<BR>
<a href="http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1&search=">http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1&search=</a><BR>
<BR>
David Brearley, Senior Technical Editor<BR>
<I>SolarPro</I> magazine <BR>
<BR>
<BR>
On 6/11/10 2:50 PM, "Nick Soleil" <<a href="nicksoleilsolar@yahoo.com">nicksoleilsolar@yahoo.com</a>> wrote:<BR>
<BR>
</SPAN></FONT><BLOCKQUOTE><FONT FACE="Arial"><SPAN STYLE='font-size:12pt'>Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8%<BR>
<BR>
Nick Soleil<BR>
Project Manager<BR>
Advanced Alternative Energy Solutions, LLC<BR>
PO Box 657<BR>
Petaluma, CA 94953<BR>
Cell: 707-321-2937<BR>
Office: 707-789-9537<BR>
Fax: 707-769-9037<BR>
<BR>
<BR>
</SPAN></FONT><FONT FACE="Tahoma, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'><HR ALIGN=CENTER SIZE="1" WIDTH="100%"><B>From:</B></SPAN><FONT SIZE="2"><SPAN STYLE='font-size:10pt'> "<a href="markf@berkeleysolar.com">markf@berkeleysolar.com</a>" <<a href="markf@berkeleysolar.com">markf@berkeleysolar.com</a>><BR>
<B>To:</B> RE-wrenches <<a href="re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><BR>
<B>Sent:</B> Fri, June 11, 2010 7:02:00 AM<BR>
<B>Subject:</B> Re: [RE-wrenches] AC wiring loss on micro-inverters<BR>
</SPAN></FONT></FONT><FONT SIZE="2"><SPAN STYLE='font-size:10pt'><FONT FACE="Arial"><BR>
Nick,<BR>
<BR>
Good to see other wrenches looking at this issue. However, remember that<BR>
in the interconnect cable between the last and the second to last Enphase,<BR>
the current is small. If you really want to see how the loss is adding up<BR>
you need a more detailed analysis that averages the voltage drop for the<BR>
entire system of interconnect cables.<BR>
<BR>
Mark Frye<BR>
Berkeley solar Electric Systems<BR>
<BR>
> Hello wrenches and Marv:<BR>
> How many Enphase inverters do you put on a single parallel string?<BR>
> The Enphase manual allows for up to 15, but I have found that a single<BR>
> string of 15 can have very high voltage rise on the AC wiring. Up to<BR>
> 1.5% loss just on the Enphase cables, and that does not take into<BR>
> account resistance at the plug connectors or any home-run wiring.<BR>
> 15 inverters x 190 watts = 2850 watts<BR>
> 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the<BR>
> string it is 0 Amps)<BR>
> Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps<BR>
> length of contacts + internal wiring = ~6'<BR>
> Total Enphase cabling length (6' x 15 inverters) = ~90'<BR>
> 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss<BR>
> It is pretty hard to design for 1.5% voltage drop if you have to size for<BR>
> 0% loss on your wiring! I hope Enphase will increase the size of the wire<BR>
> in their cables soon. Have you experienced issues with micro-inverters<BR>
> shutting off due to high AC voltages?<BR>
><BR>
> Nick Soleil<BR>
> Project Manager<BR>
> Advanced Alternative Energy Solutions, LLC<BR>
> PO Box 657<BR>
> Petaluma, CA 94953<BR>
> Cell: 707-321-2937<BR>
> Office: 707-789-9537<BR>
> Fax: 707-769-9037<BR>
><BR>
><BR>
><BR>
><BR>
> ________________________________<BR>
> From: i2p <<a href="i2p@aol.com">i2p@aol.com</a>><BR>
> To: RE-wrenches <<a href="re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><BR>
> Sent: Thu, June 10, 2010 4:50:47 PM<BR>
> Subject: Re: [RE-wrenches] Real world PV production<BR>
><BR>
><BR>
><BR>
> On Jun 10, 2010, at 7:57:53 AM, "Kelly Keilwitz, Whidbey Sun & Wind"<BR>
> <<a href="kelly@whidbeysunwind.com">kelly@whidbeysunwind.com</a>> wrote:<BR>
><BR>
> PV Watts VASTLY underestimate PV production<BR>
>> in our area.<BR>
> PV Watts underestimates in Central Ca too.<BR>
><BR>
> Don<BR>
><BR>
><BR>
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