[RE-wrenches] AC wiring loss on micro-inverters

[Nick Soleil]

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 <i2p at aol.com>
To: RE-wrenches <re-wrenches at 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" <kelly at whidbeysunwind.com> wrote:

PV Watts VASTLY underestimate PV production
>  in our area.
PV Watts underestimates in Central Ca too.

Don


      
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