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Lightning and Surge Suppression
Enphase Microinverters have integral surge protection, greater than most traditional inverters. However, if
the surge has sufficient energy, the protection built into the microinverter can be exceeded, and the
equipment can be damaged. For this reason, Enphase recommends that you protect your system with
lightning and/or surge suppression devices. In addition to having some level of surge suppression, it is
also important to have insurance that protects against lightning and electrical surges.
NOTE: Protection against lightning and resulting voltage surge must be in accordance
with local standards.
Pre-installation Tasks
Install supporting structures, home-run wiring, load centers, revenue grade meter, and any other
equipment required for your installation. Install this equipment per manufacturer instructions.
•
Verify DC polarity between the PV module and the microinverter by temporarily connecting a
PV module to a microinverter with no grid connection. The microinverter LED lights solid
green for a few seconds to indicate compatibility. After two minutes the LED will flash red to
indicate that no grid is present. This is normal.
•
Install an auto-transformer or isolation transformer so that the voltage presented to the
microinverter is limited to no more than 248V, line to neutral.
•
Auto-transformer: An auto-transformer is more affordable, smaller, lighter and more
efficient than an isolation transformer. You can use one to generate the operating voltage
for C250 from a 480Y/277V grid. The primary disadvantages of auto-transformers are
that they do not provide isolation and do not derive a neutral from a delta configured
system. Used in boost mode (as viewed from the PV side), these transformers usually
have taps for adjustments to the PV side voltage.
•
Isolation Transformer: Isolation transformers with a WYE configured winding on the PV
side can derive a neutral conductor when the grid side is delta configured, filter electrical
noise and communication signals, and provide isolation of communication domains.
These transformers usually have taps for adjustments to the PV side voltage.
•
Install a phase coupler to couple the Enphase power line communication signal between the
three phases. You need a phase coupler with each Envoy-C in a C250 system to allow
communication with the microinverters on all three phases.
•
Install Enphase Line Filters (model LCF-250-PC), if needed. If you have more than one
communication domain and multiple Envoy-Cs that are tied to a common service panel or off
of a single transformer, you need filters to prevent cross-talk between the communication
domains. You can accomplish this with power line filters or with a single isolation transformer
feeding a single communication domain, such as when a medium voltage transformer is
provided for each sub-array. You must also physically separate the racking, conduits and
wires of one communication domain from another communication domain by at least 12
inches.
•
Install surge protection. An inline surge protective device provides the greatest level of
protection, but is usually more expensive than a surge protective device that sits in parallel to
the microinverter panel board. If using an inline surge protective device, locate the Envoy-C
and C250s together on the load side of this device.
Refer to the C250 Commercial Design Guide at http://www.enphase.com/support for details on tested
transformers and other devices.
12
2015 Enphase Energy Inc. All rights reserved.
C250 System Installation and Operation
141-00025 Rev 03
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