Dc Too Low - enphase M250 Troubleshooting Manual

4. Click Send Command.

DC Too Low

A DC Too Low condition occurs when the microinverter detects that DC input voltage from the PV
module is too low. This is normal in the morning and in the evening. If this condition triggers during
daylight hours, any of the following conditions may trigger this event:

There is an extended period of low solar irradiance (for example, a period that includes the night
hours plus a few hours of low sunlight after sunrise).

There is a bad or missing DC connection to the microinverter. Enphase recommends that a
qualified electrician inspect the DC connection between the module and the microinverter. The
connection may need to be tightened or may require replacement.

The microinverter may have been paired with an incompatible PV module. Is the PV module on
the Enphase Compatibility list? An incompatible PV module may work sometimes, but will not
work consistently or effectively. Some incompatible PV modules do not produce enough DC to
start up the microinverter. To check DC input measurements to a microinverter, see "Check DC
measurements" under "One unit shows 0W of production but adjacent units are productive" on
page 29.

The polarity is reversed. If the unit shows zero production, does the site use adaptors (or
jumpers) between the PV module and the microinverter? Verify by measuring the PV modules
VOC (Open Circuit Voltage) and inspect the positive and negative markings on the PV module
and microinverter.

To determine if the problem is with the microinverter or with the PV module, swap the DC leads
from the suspect unit and an adjacent unit. Check Enlighten periodically (this may take up to 30
minutes), and if the problem moves to the adjacent module, then the PV module is not functioning
correctly. If the problem stays in place, then the problem is with the microinverter. Contact
Enphase Customer Support for help in reading the microinverter data and for help in obtaining a
replacement microinverter if needed.

The PV module may be damaged or defective. Although PV modules have a very long service-life
expectation, they are somewhat fragile and directly exposed to the elements. The glass on the
surface of the PV module can become cracked, lowering the PV module output or causing a
Ground Fault (GFI) to trip.
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 2014 Enphase Energy Inc.
Troubleshooting an Enphase System
August 2014