enphase M250 Troubleshooting Guide

Troubleshooting an Enphase System
 2014 Enphase Energy Inc. August 2014
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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:
o An On/Off switch
o A homemade AC combiner
o An incompatible AC disconnect between the circuit breaker and the AC pigtail of the
PCU branch circuit.
o Faulty wiring, terminations, or circuit breakers only for those affected Enphase branch
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:
o 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
peak demand.
o The homerun conductors from the Enphase branch circuits to their respective circuit
breakers are undersized. Refer to the Calculating Voltage Rise Technical Brief at
enphase.com/support.

enphase M250 Specifications

General

Model	M250
Manufacturer	Enphase Energy
Efficiency	96.5%
Output Voltage	240 V
Operating Temperature Range	-40°C to +65°C
Maximum Output Current	1.04 A
CEC Efficiency	96.0%
Start-up Voltage	22 V
Output Frequency	60 Hz
Enclosure Rating	IP67
Weight	1.6 kg