Wiring the Sunny Boy
SMA America, LLC
48
SB20_25_30HFUS-eng-IUS113711
Installation Guide
DC connection with a positively grounded PV plant
If your PV plant requires positive 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 positive inverter wire (red wire) of the
Sunny Boy to the terminal (B).
2. Connect the negative inverter wire (black wire) of
the Sunny Boy to the terminal (C).
Connecting the PV strings
3. Connect the positive DC wires of the PV strings with
a cross-sectional area of up to AWG 8 (10 mm²) to
the terminal (A).
4. If a positive DC wire of a PV string 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 negative DC wires of the PV strings
with a cross-sectional area of up to AWG 8 (10
mm²) to the terminal (D).
6. If a negative DC wire of a PV string 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 clamp (turn the screw 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).
