[RE-wrenches] Can I handle the voltage drop?

[Nick Soleil]

Hi Mark:
    I wouldn't feel comfortable with that scenario, either.  Many inverters do 
shut off at 254V-255V, but most of them can be adjusted if you have the software 
and laptop for the job.  Enphase generally shuts off when the AC voltage reaches 
258V-259V.  Keep in mind that just the Enphase cabling can add an additional 
1.75% to the rise.  I break my Enphase circuits into two sub-circuits of half 
length.
    Enphase is defintitely more tolerant of voltage issues than other 
inverters.  Xantrex is the worst, but can be adjusted.

 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: Mark Frye <markf at berkeleysolar.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Mon, February 14, 2011 7:42:11 PM
Subject: [RE-wrenches] Can I handle the voltage drop?

Can I handle the voltage drop? 
Folks, 
I am working on a proposal. It's a ground mount 300+ feet from the meter. There 
is an existing, near by run of #2 copper I can tap into. The desired system is 
relatively large, 64 amps AC max. I have modeled the yield using PV watts hourly 
data, applying a power loss based on the voltage drop at the varying current. 
This model shows a 3% loss in annual yield with the #2 copper. Because of the 
economics of the system, we can absorb this loss.
My concern however is that I do not want the inverters to shut down when 
operating at higher currents. I do not want a high AC line voltage fault due to 
the voltage drop on the line. At the 64 amps max, the drop  would be about 4%. 
Of course all the manufactures I talk with recommend keeping the drop on the AC 
below 1.5%.
I am looking at using Enphase inverters which spec an AC voltage range up to 
264V, or 10% above 240V nominal. 

What experience have folks had out there? How far can one realistically push the 
1.5% limit and still avoid AC voltage faults when there is high voltage drop on 
the line?
My guess is that everything would work out fine, but I stand to loss a huge 
amount of energy if the inverters are spending all their time faulting and 
resetting during daily peaks.
  
Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
www.berkeleysolar.com  


      
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