Are There Specific Regulations for Lightning Protection?

Lightning Protection Systems (LPS) Requirements

Lightning protection systems must be designed and installed according to specific guidelines to prevent damage from lightning strikes. For off-grid solar systems with a combiner box, a surge arrester is typically installed to protect the electrical equipment from power surges caused by lightning strikes. The surge arrester should be rated for a minimum of 10/350 μs, which means it can withstand a 10 kA current surge for 350 μs.

NFPA 780 Compliance

NFPA 780, the standard for lightning protection systems, requires that all electrical equipment, including solar combiner boxes, be protected by a listed surge arrester or a lightning arrestor. This standard also specifies the minimum requirements for the installation of surge arresters, including the mounting height and the distance between the arrester and the protected equipment. For a solar combiner box, the surge arrester should be installed within 10 feet of the equipment and at a height of at least 10 feet above the surrounding terrain.

Surge Arrester Selection

When selecting a surge arrester for a solar combiner box, several factors must be considered, including the rated voltage and current, the type of surge protection, and the certification to international standards such as IEC 61643. The surge arrester should also be compatible with the combiner box and the solar inverter. It’s essential to consult with a qualified electrical engineer or a certified lightning protection specialist to ensure that the surge arrester is properly selected and installed to protect the solar system from lightning strikes.