Auxiliary electrodes for ground and pole mounted DC photovoltaic arrays must be connected directly to what?

The correct choice is connecting auxiliary electrodes for ground and pole mounted DC photovoltaic arrays directly to the array frame or structure. This practice is grounded in safety and functionality when dealing with photovoltaic systems.

By connecting auxiliary electrodes to the array frame or structure, you ensure that any fault currents or lightning strikes have a direct path to ground. This helps to protect the entire system from electrical surges, which can cause damage to the photovoltaic panels and associated equipment.

When the auxiliary electrodes are connected to the array frame, there is a consistent reference point for grounding, which minimizes the risk of electrical potential differences that can occur in different parts of a system. This enhances overall safety for maintenance personnel and anyone interacting with the photovoltaic system.

The other options may not provide the same level of safety or effectiveness in grounding. Connecting to the building might create a less safe situation by introducing additional grounding paths. Similarly, connecting to the circuit breaker or the grounding grid might not be as effective as directly connecting to the array frame, as these points could have varying resistance or response in fault conditions. Therefore, ensuring a solid and immediate ground connection to the array frame or structure is essential for optimal safety and performance in DC photovoltaic systems.