What typically protects PV module source circuits in combiner boxes?

The typical protection for photovoltaic (PV) module source circuits in combiner boxes is provided by fuses rated at 15A or 20A. These fuses serve an essential role in safeguarding the system by limiting the current flowing through the source circuits. In the event of a fault or overload condition, the fuses will blow, effectively disconnecting the affected circuit and preventing potential damage to the PV modules, wiring, and other components of the system.

Using fuses rated at 15A or 20A is common practice because they suitably match the output characteristics of most PV modules in residential and small commercial applications. This ensures that the protective devices are efficient in maintaining circuit integrity and overall system reliability while preventing nuisance trips and unnecessary downtime.

Other options may reference different current ratings or types of protection, which may not align with the standard practices for PV systems or may exceed the requirements for the specific size and rating of the source circuits in question. The selection of appropriate fuses is based on the module specifications and the design of the electrical system to ensure both safety and efficiency.