Advantages Of Center Feeding Qd Cable Ac Branch Circuit - enphase IQ8 Design Manual

The following table lists the different scenarios based on the starting point of the circuit using QD
Cables and the possible number of microinverters, which could be on either side of the center tap.
IQ8P-3P
Start
Circuit size
from
connector
1 12
2 12
3 12
4 12
5 12
6 12
1 9
2 9
3 9
4 9
5 9
6 9
Though we recommend a maximum of nine connectors on either side of the center tap, there are two
instances with IQ8H-3P where the QD Center Taps have ten on either side, especially when the installer
starts from connectors 2 and 3. This is acceptable as per the VRise table (refer to Table 13).

2.3.4 Advantages of center feeding QD Cable AC branch circuit

Enphase recommends that the total percentage of voltage rise in the AC wiring be a maximum of 2%,
with (an inclusive) less than 1% voltage rise in the QD Cable. A fully populated IQ8 Commercial branch
circuit has 12 microinverters with IQ8P-3P and 15 microinverters with IQ8H-3P on the AC Branch circuit.
As voltage rise is exponential, reducing the number of microinverters in the branch circuit greatly
reduces the voltage measured at the farthest microinverter in the branch. One way to minimize this
voltage rise is to center feed the branch, that is, divide the circuit into two subbranch circuits protected
by a single OCPD. Therefore, for all installations with IQ8 Commercial Microinverters, center feeding of
three-phase AC supply is recommended.
All three QD Cable SKUs include center-tapping connectors after every 6 AC male QD connectors in
the QD Cable spool. The center tap connectors are sealed with a sealing cap, and the sealing cap
should be removed only when the connector is used for feeding the AC supply to the branch.
22
Table 14: QD Cable variants
Center tap
connector
6,6
5,7
4,8
3,9
8,4
7,5
NA
NA
NA
NA
NA
NA
© 2023 Enphase Energy Inc. All rights reserved.
IQ8 Commercial Microinverter grid-tied PV system
IQ8H-3P
Circuit
Start from
size
1 15
2 15
3 15
4 15
5 15
6 15
1 12
2 12
3 12
4 12
5 12
6 12
1 9
2 9
3 9
4 9
5 9
6 9
Center tap
6,9
5,10
10,5
9,6
8,7
7,8
6,6
5,7
4,8
3,9
8,4
7,5
NA
NA
NA
NA
NA
NA
November 2023
USG-00026-1.0