User's Manual

SMA Technologie AG Electrical Connection
Installation Guide SMC50A_60A-IEN073320 Page 45
Rating of the Circuit Breakers
We assume a PV system with 9 Sunny Mini Central inverters with three inverters per
phase.
Required technical data of the Sunny Mini Central SMC 5000A / SMC 6000A
• Maximum output current = 26 A / 26 A
• Maximum permissible fuse protection for the Sunny Mini Central = 40 A
The choice of cable together with the way it is routed, ambient temperatures and
other underlying conditions limit the maximum fuse protection for the cable.
• In our example we assume that the chosen cable (6 mm²) is ideally routed and
can take a nominal current of 32.2 A.
Selecting the line circuit breakers:
• The maximum possible nominal current for the cable used and the maximum
possible fuse protection for the Sunny Mini Central limit the maximum possible
nominal current for the line circuit breaker.
• In our example, 32 A is possible (SMC 6000A)
• Additionally, check the thermal suitability of the line circuit breakers!
Example for the thermal rating for a line circuit breaker in a photovoltaic power-
generating system operated in parallel with the low voltage grid.