Center Tap Connection Scenarios - enphase IQ8 Design Manual

Portrait PV module orientation – 1.7 m (5.6 ft) pitch
Table 11: Internal QD Cable VRise (IQ8H-3P – 208 V / Portrait cable, QD-12-13-120)
IQ8H
-
3P-72-
1 2
E- US
VRise (V) 0.041 0.093
VRise (%)
0.02 0.04%
%
Portrait PV module landscape – 2.4 m (7.9 ft) pitch
Table 12: Internal QD Cable VRise (IQ8H-3P – 208 V / Portrait cable, QD-12-20-120)
IQ8H-
3P-72-
1 2
E-US
VRise (V) 0.058 0.132
VRise (%) 0.03% 0.06% 0.10% 0.17% 0.25% 0.33% 0.44% 0.56% 0.69% 0.84% 1.00% 1.16% 1.36% 1.56% 1.77%
Portrait PV module landscape – 2.9 m (9.5 ft) pitch
Table 13: Internal QD Cable VRise (IQ8H-3P – 208 V/Portrait cable, QD-12-25-108)
IQ8H-3P-
72-E-US
1 2
VRise (V) 0.07 0.159 0.263 0.436 0.629 0.837
VRise (%) 0.03 0.08
% %
As the voltage rise is non-linear, 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 sub-branch circuits
protected by a single OCPD.

2.3.3 Center tap connection scenarios

All the QD Cable variants come with a center tapping connector provision positioned after every six
QD connectors for microinverter connection. Select the center tap connector such that a maximum of
nine IQ8 Commercial Microinverters are installed on either side of the center tap connector to limit
voltage rise <1% in the QD Cable. In case the circuit length itself is less than nine microinverters, the
circuit shall be end-terminated, leaving the QD Center Tap connectors unused.
NOTE: Do not connect microinverters to the QD Center Tap connector provision.
In sites, there could be scenarios where the starting point for a circuit is not the first connector in a
circuit.
21
IQ8P-3P Microinverters per branch (208 VAC three-phase system)
3 4 5 6
0.154 0.256 0.369 0.491
0.07 0.12% 0.18% 0.24% 0.31%
%
IQ8P-3P Microinverters per branch (208 VAC three-phase system)
3 4 5 6
0.217 0.361 0.521 0.693 0.923
IQ8P-3P Microinverters per branch (208 VAC three-phase system)
3 4 5 6
0.13% 0.21% 0.30 0.40
% %
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IQ8 Commercial Microinverter grid-tied PV system
7 8 9 10
0.654 0.828 1.011 1.235
0.40 0.49% 0.59
% %
7 8 9 10
1.169 1.428 1.744
7 8 9 10
1.115 1.412 1.725 2.10
7
0.54% 0.68 0.83 1.01
% % %
11 12 13 14
1.47 1.715 2 2.297 2.602
0.71 0.82% 0.96 1.10%
% %
11 12 13 14
2.076 2.421 2.824 3.242 3.674
11 12 13 14
2.50 2.92 3.413 3.918 4.44
8 6
1.21% 1.41% 1.64 1.88% 2.13
%
November 2023
USG-00026-1.0
15
1.25%
15
15
%