Acvoor In Only A Few Microinverters; When Only A Few Microinverters Are Impacted - enphase M250 Troubleshooting Manual

ACVOOR in only a few microinverters

1. If the condition alternates among microinverters, incorrect cabling may be in use. The following
array in Enlighten shows the result of using 208 Volt cabling at a site with 240 Volt service. Only
every third unit is productive.
2. If only one unit experiences an ACVOOR, and the condition persists with consistent, out of spec
readings, the problem is likely with the microinverter. The microinverter may need to be replaced.
3. If multiple units consistently experience ACVOOR events, there was probably an installation or
wiring error during installation.

If the affected units are contiguous or if an entire branch is affected, there might be:
An On/Off switch
o
A homemade AC combiner
o
An incompatible AC disconnect between the circuit breaker and the AC pigtail of the
o
PCU branch circuit.
Faulty wiring, terminations, or circuit breakers only for those affected Enphase branch
o
circuits. Something as simple as a wire terminated on a circuit breaker that is not
screwed down tightly can cause ACVOOR on a given branch circuit.
 An AC pigtail is defective, or its AC connector (or one of the microinverters on the branch's
AC connector) is damaged or defective. If, for example, on a branch circuit the first three
units are fine, but the remaining 8 or 9 units on the branch are in a state of ACVOOR, there is
something wrong either at location #3 or #4 in the branch circuit affecting the AC Voltage
from that point and downstream on the branch circuit.

If the ACVOOR is not an installation or wiring defect, and there are multiple units impacted on
an intermittent basis, utility service on site may be too high. One of the following may be
causing this on the utility side:
The utility transformer bringing service to the site is damaged or defective.
o
The utility is purposely pushing the higher AC voltage into some areas during times of
o
peak demand.
The homerun conductors from the Enphase branch circuits to their respective circuit
o
breakers are undersized. Refer to the Calculating Voltage Rise Technical Brief at
enphase.com/support.
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 2014 Enphase Energy Inc.
Troubleshooting an Enphase System
August 2014