Cable Configurations For Qd Cabling Skus; Phase Balancing For Iq8 Commercial Microinverter System - enphase IQ8 Design Manual

9.1.2 Cable configurations for QD Cabling SKUs

The QD Cable includes a center-tapping connector after every six connectors, as shown in the
following figure. The center-tapping connector follows a similar pattern of sequence throughout the
QD Cable QD-12-42-63 (15.1 ft QD Cable SKU). Utilizing the center-tapping connectors for the AC
branch connection shall ensure a <1% voltage rise in the QD Cable. Therefore, center feeding is
recommended for all installations with QD-12-42-63 (15.1 ft QD Cable SKU).
For details on voltage rise calculations and installation guidelines for center tapping of branch circuit
with QD-12-42-63 cable installations, see the
IQ8 Commercial Microinverter with QD

9.1.3 Phase balancing for IQ8 Commercial Microinverter system

This section explains how phase balancing can be achieved in IQ8 Commercial Microinverter
system with different system configurations. If the site layout does not allow the installer to
meet all required design considerations, then calculate the expected phase power imbalance
due to the additional number of microinverters on each phase. Refer to local AHJ rules for
acceptable phase imbalance across the system.
•
If the number of microinverters in the IQ8 Commercial Microinverter system is in
multiples of 3 with individual branch circuits of any size (max. 12 microinverters of
IQ8P-3P and 15 microinverters of IQ8H-3P), then IQ8 Commercial System shall have
balanced configuration across all three phases if no connectors in QD Cable are
skipped during installation.
•
If the number of microinverters in the IQ8 Commercial Microinverter system is not in
multiples of 3, then the number of microinverters across each phase (L1-L2, L2-L3 &
L3-L1) may differ by a maximum of 1 microinverter per phase if no connectors in QD
Cable are skipped during installation. Refer to local AHJ rules on acceptable phase
imbalance across the system.
•
When connectors in QD Cable are left unused in a three-phase system, it creates a
phase imbalance for the system, with each phase (L1-L2, L2-L3, L3-L1) having a
different number of microinverters. If multiple connectors in QD Cable are skipped
over multiple branch circuits, the imbalance shall multiply.
o
Minimize the number of unused QD Cable connectors: You can avoid skipping
the QD Cable connectors with the use of three-phase Field Wireable QD
Connectors (QD-CONN-10F and QD-CONN-10M) along with Raw QD Cable to
extend the cable drop length.
o
If the installation requires a few connectors to be skipped during installations, it
is recommended to ensure an equal number of microinverters connected to
C1(L1-L2), C2(L2-L3), and C3(L3-L1) type connectors.
67
Technical Brief on Calculating AC line voltage rise for
Cable.
Figure 46: QD Cable configuration for QD-12-42-63 (15.1 ft)
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IQ8 Commercial Microinverter grid-tied PV system
November 2023
USG-00026-1.0