John Wiles retired in April 2013 as a Senior Research Engineer at the Southwest Technology Development Institute at New Mexico State University. However, he works part time as 25% employee and continues to assist the PV industry, electrical contractors, electrical inspectors, and purchasing agencies in understanding the PV requirements of the National Electrical Code (NEC). He is an active member on six UL Standards Technical Panels. John served as Secretary for the PV Industry Forum involved with Article 690 of the NEC. Over 30 submissions were accepted for the 2011 NEC and 55 proposals were submitted for the 2014 Code. He drafted the text for Article 690 in the 2005 NEC Handbook and 2008 NEC Handbook. Fieldwork involves balance of systems design for PV systems, inspections and acceptance testing of PV systems, test and evaluation of PV components, and the design and installation of data acquisition systems. He bought his first codebook in 1960 and installed his first PV system in 1984. He lived in an off-grid, PV/wind-powered home (permitted and inspected, of course) with his wife Patti, two dogs, and a cat for more than 16 years. His retirement home currently has a 8.5 kW utility-interactive PV system will full-house battery backup and now has three dogs and two cats. He writes the “Perspectives on PV” series of articles for the International Association of Electrical Inspectors in their IAEI News magazine and has published an IAEI book on PV and the NEC for inspectors and plan reviewers. He has a Master of Science Degree in Electrical Engineering.
Numerous Code requirements apply to the PV array and other equipment located in the vicinity of the array. These include conductors, DC combiners, arc-fault protection equipment, and rapid shut down equipment. This article addresses some of these requirements as they are found in the 2020 National Electrical Code (NEC).
A PV system is relatively simple in concept, but after the NEC requirements are added for safety, the execution of the system requires considerable attention to detail. There are also significant numbers of electrical inspectors that are new to the field of inspecting PV systems.
Although changes to the 2020 National Electrical Code for PV systems have been covered in previous issues, this article compares the 2017 requirements with the 2020 requirements and determines how clarifications have been made.
Nearly every week, I get calls and e-mails from inspectors, plan reviewers, photovoltaic (PV) professionals, engineers, and electricians asking about areas of PV system installation that are not clearly addressed in the National Electrical Code (NEC).
Continuing education is critical. It will be mandatory to use all available communication devices and advanced tools at our disposal to effectively plan, review, and inspect the current and next generation of PV systems.
Codes, standards, equipment, and the organizations certifying that equipment meets a particular standard are continually changing. The harmonization of U.S. standards with international standards—while potentially reducing costs in the international arena—may complicate the application of these standards as they are adopted.
Before we get into the details of conductors, currents, and circuit protection on the AC side of the PV system, let’s step back and try to get a bigger picture of where are some of the dangers or hazards that need to be considered.