Wiring the Sunny Boy
SMA America, LLC
46
SB20_25_30HFUS-eng-IUS113711
Installation Guide
6.4 Connection of PV strings without optional string fuses
DC connection of the Sunny Boy with a negatively grounded PV array
If your PV plant requires negative grounding, connect the cables of the PV strings and the DC cable
of the Sunny Boy to the terminal block in the following way:
Connecting the Sunny Boy on the DC side
1. Connect the negative inverter wire (black wire) of
the Sunny Boy to the terminal (B).
2. Connect the positive inverter wire (red wire) of the
Sunny Boy to the terminal (C).
Connecting the PV strings
3. Connect the negative DC wires of the PV strings
with a cross-sectional area of of AWG 10 up to but
not including AWG 8 (10 mm²) to the terminal (A).
4. If a negative DC wire of the PV strings has a cross-
sectional area of AWG 8 (10 mm²) to maximum
AWG 2 (35 mm²):
– Completely loosen the screw of the screw clamp
(F) (turn the screw counterclockwise).
– Feed in the DC wire from below into the screw
clamp.
– Tighten the screw of the screw clamp (turn the
screw clockwise).
5. Connect the positive DC wires of the PV strings with
a cross-sectional area of AWG 10 up to but not
including AWG 8 (10 mm²) to the terminal (D).
6. If a positive DC wire of the PV strings has a cross-
sectional area of AWG 8 (10 mm²) to maximum
AWG 2 (35 mm²):
– Completely loosen the screw of the screw clamp
(E) (turn the screw counterclockwise).
– Feed in the DC wire from below into the screw clamp.
– Tighten the screw of the screw terminal clockwise.
Using DC-Terminal blocks
Connect the wires to the DC-terminal block as described in section 12.7.1 ”Connect wires
to DC terminal block” (page 100).
