Standards & Codes

Federal, State and Local agencies require all PV systems to comply with NEC (National Electric Code) specifications as well as other local requirements. In 1984, Article 690 Solar Photovoltaic Systems, which addresses safety requirements for the installation of Photovoltaic (PV) power systems, was added to the code. The section covers the different aspects of safety when installing a PV system and other NEC codes for wiring etc also apply when not specifically covered by article 690. All PV installations must be permitted and inspected as required by local inspection authority similar to other electrical systems. NEC code requires all components used for the PV system be UL listed or recognized.

UL or Underwriters Laboratory is a not-for-profit safety testing and certification authority and has two classes of rating - UL Listed and UL Recognized.

A product achieves the UL Listed certification after UL has evaluated representative samples of the product and certified that it meets all required UL safety criteria. UL also checks the products at the manufacturing site periodically to make sure they continue to meet UL requirements.

A product that is a component part of a larger product or system that has been evaluated by UL to meet all safety requirements is granted the UL recognized certificate. UL may or may not have certified the main product or system of which the component part has been used in.

UL also sometimes evaluates a product in the field, for large and/or one-off products and systems and when they meet all safety criteria are awarded the UL Field listed certificate.

UL certificate UL 1741 is conferred on Inverters, Charge Controllers and Utility Interconnect systems and UL 1703 for PV panels and modules.

NEC Code requires all components used in a PV system are UL certified. IEEE, the Institute of Electrical and Electronic Engineers also have specifications written and recommended practices for safe PV installations. IEEE 929-2000 has recommended practices for Utility interface or residential and intermediate Photovoltaic systems. IEEE 937-2000 has recommended practices for installation and maintenance of lead-acid batteries for PV Systems. IEEE 1262-1995 has recommended practices for qualification of PV Modules and finally IEEE 1374-1998 is a guide for PV Power system safety.

More information on IEEE can be found at their website: http://www.ieee.org/portal/site

Some key 'messages' from the NEC article 690 are listed below:

• All Voltages in domestic PV systems need to be less than 600 volts
• The PV Panel, inverter and battery circuits need to have over-current protection
• All junction boxes need to be accessible
• A single ground point needs to be made and all exposed metal components grounded
• If the system interacts with the power grid, the Inverter must have islanding capability
• All components and system specifications such as maximum current, voltage etc must be marked and clearly visible

The NEC Code is published and updated every three years by the National Fire Protection Association (NFPA), Batterymarch Park, Quincy, Massachusetts. The National electric code and the term NEC are registered trademarks of the National Fire Protection Association and may not be used without their permission. Copies of the current edition of the NEC code and handbook are available from NFPA at: www.nfpacatalog.org