<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial,helvetica,sans-serif;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><div> </div>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<div><br></div><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt;"><br><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> "markf@berkeleysolar.com" <markf@berkeleysolar.com><br><b><span style="font-weight: bold;">To:</span></b> RE-wrenches
<re-wrenches@lists.re-wrenches.org><br><b><span style="font-weight: bold;">Sent:</span></b> Fri, June 11, 2010 7:02:00 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [RE-wrenches] AC wiring loss on micro-inverters<br></font><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 ymailto="mailto:i2p@aol.com" href="mailto:i2p@aol.com">i2p@aol.com</a>><br>> To: RE-wrenches <<a ymailto="mailto:re-wrenches@lists.re-wrenches.org" href="mailto: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 ymailto="mailto:kelly@whidbeysunwind.com" href="mailto: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>> _______________________________________________<br>>
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