Codes & Standards


The material contained on this web site is provided for informational use only; it is not intended to replace or supplant any codes or standards. There are no warranties associated with the use of this information.  This material, published over many years, is/was believed to be accurate at the time of publication, but may no longer be accurate, current, or comply with existing codes and standards.  Neither the authors, SWTDI, NMSU, or any other organization mentioned on this web site is accountable for the use or misuse of information obtained herein.

For access to the material listed on this page, you will be required to agree to this disclaimer.  By agreeing to this disclaimer, you acknowledge that you have read and understand the inherent warnings and will not hold the authors or other organizations accountable for any issues that arise from having read the material on the subsequent pages.

Welcome to the source for cutting edge information on PV balance of systems design and installation. Material in this web site is continually updated with the latest Code requirements and with information on the latest installation techniques that are being used by the top installers and systems integrators throughout the country.

This site will not tell you how to size a system, but after the sizing is accomplished, it should provide valuable information on how to connect and install the selected components into a safe system.

A thorough knowledge of the National Electrical Code® (NEC) is required to competently install any electrical power system, including PV systems, in the United States. While there is a specific section (Article 690) of the NEC that is dedicated to PV systems, more than 80% of the remainder of the NEC is directly applicable to PV systems. Anyone using the material in this site should have a copy of the NEC or the NEC Handbook. The NEC Handbook contains the text of the entire NEC plus additional explanatory information and diagrams.

The material in this site is based on the requirements of the National Electrical Code (ANSI/NFPA 70). State, regional, and local codes may impose differing or additional requirements. The local electrical inspector (Authority Having Jurisdiction (AHJ)) has the final say on what is and what is not acceptable.

The information presented in this web site is based on SWTDI interpretations of the National Electrical Code ®, the National Electrical Code Handbook ®, various Institute of Electrical and Electronics Engineers (IEEE) Standards, Underwriters Laboratories Standards, and material from the International Association of Electrical Inspectors (IAEI). Good engineering practices have also been applied.

Some of the material and suggestions are not covered in current codes or standards, but may appear in future editions of the existing documents or in new codes and standards. The material presented is thought to be technically correct. However, the reader is cautioned to use it at his or her own risk. Neither the author, John Wiles, the Southwest Technology Development Institute, New Mexico State University, Sandia National Laboratories, U.S. Department of Energy, or the U.S. Government make any claims to the accuracy of the material included and are not liable for damages or injury incurred from any use of this material.

NEC and NEC Handbook are registered trademarks of the National Fire Protection Association (NFPA). Both documents are available from the NFPA.

Articles, Publications, & Resources

“Perspectives on PV” articles in the IAEI News
by John Wiles

The White Paper Series
by John Wiles
A Critical Look at PV Module Grounding
by Thomas Bowes

Archived “Code Corner” articles in Home Power Magazine
by John Wiles

Presentations Schedule

PV Power Systems & The National Electrical Code
John C. Wiles, Instructor
Solar PV Systems and the National Electrical Code Workshop


March 6, Dulles, VA   March 7, New Castle , DE   March 8 Laurel, MD 

Register on the web site below and get more information.

Website with additional information Here:

Future PV/NEC Presentations

Watch this page for details, which will be posted as they become available.