Design Considerations For Reliable Plc Communications; Design Considerations For Sites With Power Export Limit Requirements - enphase IQ8D-72-E-US Design Manual

Design considerations for reliable PLC communications

Enphase IQ Microinverter systems use power line
communications (PLC) to communicate module level
data between the Microinverters and the Gateway.
The PLC signal is at 110kHz in an IQ8D System. In a
commercial-scale system, the IQ8D Commercial Gateway
is continuously polling the Microinverters for their recent
power production, temperature, voltage, amperage, and
frequency data.
01 Do not exceed 165 IQ8D micros per Gateway.
02 Install the Gateway as close as possible to the
Microinverters. Consult Enphase if you need
to exceed 75 meters (246 feet) conductor
length between the Gateway and the last IQ8D
Microinverter in the circuit.
03 Install a line communication filter to isolate Gateway
communications domains. Filtering is mandatory
when multiple Gateways are installed in order to
separate communication domains.

Design Considerations for Sites with Power Export Limit requirements

The Enphase Power Export Limit (PEL) function can be configured to operate at different power export limits to meet the
site requirements, as is required by the local utility service. The value for power export limit is defined within a specific
Enphase grid profile. Installer needs to use different grid profiles for different PEL values.
Primary Protection
An Enphase IQ8D system can support Power Export
limit by using a PEL Grid profile and an IQ8D Commercial
Gateway with Production CTs installed at solar PV sub
panel & Consumption CTs installed at/near the utility
service location. When configured for Power export limit,
the Enphase system still automatically limits the PV
generation so that energy is exported to grid is Zero/as per
set power export limit within grid profile. This functionality
is set through the grid profile and called Soft Export Limit.
© 2022 Enphase Energy Inc. All rights reserved.
Hence it is critical to maintain good communication
between devices with minimal interference on the
PLC signal. Enphase recommends following design
considerations for maintaining reliable PLC communication
between Microinverters and IQ8D Commercial Gateway
Designs for reliable PLC require the following:
04 For sites with multiple Gateways, the conductors
and conduits of each Gateway communication
domain must be kept physically separated from the
conductors and wiring of other communications
domains by at least 12 inches using properly
grounded metal conduits. Coupling of the signals
can occur between the conductors and conduits
when run together, especially on long conduit and
wire runs.
Secondary Protection
The IQ8D Commercial Gateway also has a secondary level
of protection called a hard PEL. The hard PEL operates
a voltage free contact in the IQ8D Commercial Gateway
that can be wired to an external contactor to physically
disconnect the IQ8D Microinverters from the grid if the
power export limit target is not reached in the configurable
time frame. Refer to Figure 16 to check for relay contacts
on the IQ8D Commercial Gateway.
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