IQ system Controller 2 Installation
G) PCS Export Limiting via Enphase Installer App
PCS that ensures the Import Only mode for ESS is always running in the
system and the import only mode is not changeable. Energy storage
never exports to grid and therefore never backfeeds the main panel in a
partial backup scenario if consumption/PCS CTs are placed as outlined
in section 6.
This section outlines how to congure current export limiting to limit PV
current when PV current exceeds the allowed backfeed/export.
The MPU avoidance use case of PCS can be enabled via Enphase
Installer App during installation at Step 2 b) Site Conguration as shown
in the gure below:
NOTE: The MPU avoidance use case requires conguration using the
Enphase Installer App version v3.0.8 or higher and IQ Gateway software
version 6.1.32 or higher.
In the site conguration menu, the user can see 2 options:
• Select Backup Type
• PCS Export Limiting
As the MPU avoidance conguration can only be enabled in the partial
home backup mode, the installer has to rst select the ‘Partial Home
Backup’ conguration under ‘Select Backup Type’.
Then, in the ‘PCS Export Limiting’ section, the installer is required to
enter the type of micro-inverters(IQ8, IQ7, IQ6) & the number of micro-in-
verters of each type. Along with this, the installer adds information on
the rating of the main load panel busbar, the main service breaker rating
& can also set the PCS Controlled Export Current Limit. If this value is
not set, the system auto-calculates the export current limit based on the
2017 NEC.
Auxiliary Contact Connections
IQ System Controller 2 has three I/O ports and one Rapid Shutdown Switch
(RSD) port.
- I/O-1, I/O-2 are for load and excess PV control:
- I/O-1 has two normally open auxiliary contacts (NO1, NO2), and each
auxiliary contact has two terminals
I/O-2 has two normally close auxiliary contacts (NC1, NC2), and each auxil-
iary contact has two terminals
The RSD port is for connecting with a remote RSD switch. It has two normal-
ly close auxiliary contacts (NC3, NC4), and each auxiliary contact has two
terminals.
Gen-I/O has one normally open auxiliary contact (NO3) for generator control,
and this contact has three terminals.
All the auxiliary contact relays are rated for pilot duty at 24Vac/Vdc (nomi-
nal) and 1 Amp.
A. Auxiliary Contact connections for shedding excess PV and load
For making the connections you would need the following components: a
denite purpose contactor, control transformer, and fuse.
For recommendations please refer the tech brief
https://support.enphase.com/s/article/Load-and-Solar-Circuit-Control-using-Enpower-Auxiliary-Contacts
Steps for connecting auxiliary contact for shedding excess PV or load:
1. Use wires sized per local code requirements taking into consideration
the voltage drop/rise and upstream breaker or fuse.
2. Connect one of the primaries of the control transformer to 120V
breaker, and the other wire to the neutral bus in the backup load panel
via an OCPD such as an inline fuse.
3. Connect one wire of the secondary of the control transformer to one of
the terminals of either NO/NC auxiliary contact from I/O-1 or I/O-2 on
IQ System Controller 2.
4. Connect the other terminal of the auxiliary contact to the 24Vac coil
terminal (usually named A1) of the denite purpose contactor.
5. Connect the other terminal of the contactor coil (usually named A2) to
the other wire of the secondary of the control transformer.
6. For shedding excess load:
a. Connect the L1 (and L2 if 240V) terminal of the denite purpose
contactor to the backup load panel protected by a breaker.
b. Connect the T1 (and T2 if 240V) terminal of the contactor to the
excess load circuit that needs to be shed.
7. For shedding excess PV:
a. Connect the L1 and L2 terminals of the denite purpose contactor to
the OCPD (e.g., breaker in the AC combiner) protecting the inverter
output circuit of the excess PV to be shed.
b. Connect the T1 and T2 terminals of the denite purpose contactor to
the inverter output circuit of excess PV that needs to be shed.
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