Quick Answer
Yes, there are guidelines for bonding AC and DC systems in solar, primarily dictated by the National Electric Code (NEC) and the International Electrotechnical Commission (IEC).
NEC and IEC Bonding Requirements
The National Electric Code (NEC) and the International Electrotechnical Commission (IEC) provide guidelines for bonding AC and DC systems in solar installations. According to NEC 250.30(A)(1), PV arrays and their associated equipment must be bonded to the neutral of the AC system. IEC 60364-5-56 requires DC systems to be bonded to a common point, such as the negative DC bus.
Grounding and Bonding Methods
To achieve safe and compliant bonding, installers can use various methods, including direct bonding (NEC 250.30(A)(1)), bonding via a neutral conductor (NEC 250.94), and bonding through a grounding electrode conductor (NEC 250.30(A)(1)). For example, a direct bonding method involves connecting the PV array’s grounding terminal to the AC system’s neutral conductor. This method meets the NEC and IEC requirements.
Common Bonding Points
A common bonding point is essential for ensuring safe and efficient operation of AC and DC systems. Typically, this point is the negative DC bus, but it can also be a grounding electrode conductor or a neutral conductor. It’s crucial to select a suitable bonding point that minimizes voltage differences between the AC and DC systems. For instance, if the negative DC bus is chosen as the common bonding point, ensure that all PV arrays and their associated equipment are bonded to it.
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