Hi Nick, You bring up a good point that Enphase should address more clearly. However, I think the math should be done section by section to accurately account for the wire loss and not the total combined amps for the entire length. If the loss's are too high then reducing the number in each string to an acceptable wire loss would be my recommendation.
On Jun 11, 2010, at 12:14 AM, Nick Soleil wrote: > Hello wrenches and Marv: > How many Enphase inverters do you put on a single parallel string? The > Enphase manual allows for up to 15, but I have found that a single string of > 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on > the Enphase cables, and that does not take into account resistance at the > plug connectors or any home-run wiring. > 15 inverters x 190 watts = 2850 watts > 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the > string it is 0 Amps) > Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps > length of contacts + internal wiring = ~6' > Total Enphase cabling length (6' x 15 inverters) = ~90' > 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss > It is pretty hard to design for 1.5% voltage drop if you have to size for 0% > loss on your wiring! I hope Enphase will increase the size of the wire in > their cables soon. Have you experienced issues with micro-inverters shutting > off due to high AC voltages? > > Nick Soleil > Project Manager > Advanced Alternative Energy Solutions, LLC > PO Box 657 > Petaluma, CA 94953 > Cell: 707-321-2937 > Office: 707-789-9537 > Fax: 707-769-9037 > > > From: i2p <i...@aol.com> > To: RE-wrenches <re-wrenches@lists.re-wrenches.org> > Sent: Thu, June 10, 2010 4:50:47 PM > Subject: Re: [RE-wrenches] Real world PV production > > > On Jun 10, 2010, at 7:57:53 AM, "Kelly Keilwitz, Whidbey Sun & Wind" > <ke...@whidbeysunwind.com> wrote: > > PV Watts VASTLY underestimate PV production in our area. > PV Watts underestimates in Central Ca too. > > Don > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
_______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
