Wiring the Sunny Boy
SMA America, LLC
50
SB20_25_30HFUS-eng-IUS113711
Installation Guide
6.5 Connection of PV strings with optional fuses
By using optional fuses for the connection of the PV strings, you can connect up to three PV strings to
the Sunny Boy. For this you must install fuse holders to the top-hat rail next to the terminal block.
Requirements for installing optional fuses
• Only use the fuse holders and fuses specified in section 14 "Accessories" on page 108.
• Use 3 wires with a length of 10 in. (254 mm) and a size of AWG 8 (10 mm²).
These wires are not included in the delivery.
DC connection with a negatively grounded PV plant
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. Remove the screwless end block from the top-hat-
rail (left of the DC-terminal block).
4. Mount three fuse holders to the top-hat rail.
5. Install fuses in the fuse holders.
The fuses must be functional and of the correct size.
Refer to section 14 ”Accessories” (page 108) for a
specification of suitable fuses.
6. Put the sticker delivered with the fuse holder plainly
visible near by the fuse holder.
7. Loosen the screws of the lower terminals of the fuses
(G) in a counterclockwise direction.
8. For each positive DC wire of the PV strings:
– Feed in the wire from below into the terminal of
a fuse (G).
– Tighten the terminal screw in a clockwise
direction.
9. Strip the ends of the additional wires on one side in
accordance with the specifications of the fuse
holder manufacturer.
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).
