What safety feature must PV system circuits installed on buildings include to reduce shock hazard for firefighters?

The inclusion of a rapid shutdown function in photovoltaic (PV) system circuits installed on buildings is essential for enhancing safety, particularly for firefighters responding to emergencies. This feature allows for the quick deactivation of PV system circuits, significantly reducing the risk of electric shock in the vicinity of the building during firefighting operations.

In the event of a fire, firefighters need to ensure their safety while accessing the roof or areas near the PV system. The rapid shutdown function enables them to quickly isolate the electrical supply from the solar panels, which prevents the flow of electricity into the system's electrical circuits. This capability is crucial because photovoltaic systems can continue generating electricity even in compromised situations, increasing the potential hazards for emergency responders.

While other options like emergency lighting, one-way access control, and outdoor circuit isolation may have their own safety benefits, they do not specifically address the need to quickly deactivate the electrical hazards posed by active PV circuits in an emergency scenario as comprehensively as a rapid shutdown function does. Therefore, implementing a rapid shutdown function is a critical safety measure in promoting firefighter safety while ensuring effective response to situations involving PV systems.