Photovoltaic DC systems that are solidly grounded must connect to a grounding electrode system in accordance with which section?

The correct choice is Section 250.166, which addresses the grounding of photovoltaic (PV) systems. This section outlines the requirements for connecting PV systems to a grounding electrode system, ensuring a safe and effective grounding method that protects both the system and personnel.

In the context of solidly grounded DC systems, effective grounding is crucial to minimize the risk of electrical shock and to ensure the system's proper operation under fault conditions. Section 250.166 provides specific criteria for how these connections should be made, reflecting the importance of grounding to maintain safety standards.

Understanding how photovoltaic systems integrate into overall electrical systems is vital, as they often operate in unique conditions compared to other types of electrical installations. Thus, recognizing the specific grounding requirements for these systems aids in compliance with regulations and enhances the overall effectiveness of the electrical installation.