Master the Sunshine: NABCEP PV Installation Pro Test 2025 – Shine Bright in Solar!

The minimum size busbars required in a subpanel that incorporates both inverter and utility breakers must be capable of handling the maximum current that these devices might introduce into the panel. When evaluating the size of busbars, it is crucial to consider the combined output of the inverters along with any additional loads that will be present during peak usage periods.

In this context, a 125A busbar is the appropriate choice because it is designed to accommodate the total current flowing through the panel without risk of overheating or failure. This size allows for some margin for error and future expansion, which is essential for ensuring the safety and longevity of the system.

Using a busbar smaller than 125A could result in inadequate current handling, leading to overheating or circuit failure, particularly during peak solar production periods when inverters may push their output close to their maximum rating. Thus, selecting busbars that are appropriately sized is critical to meeting the NEC (National Electrical Code) requirements as well as ensuring safe and reliable operation of the electrical system.