IEEE 929-2000

This recommended practice applies to utility-interconnected PV power systems operating in parallel with the utility and utilizing static (solid-state) inverters for the conversion of direct current (dc) to alternating current (ac). (This recommended practice does not apply to systems utilizing rotating inverters.) This recommended practice describes specific recommendations for “small” systems, rated at 10 kW or less, such as may be utilized on individual residences. These recommendations will provide greater standardization for these smaller systems, thereby reducing the engineering and design burden on both the PV system installer and the interconnecting utility. “Intermediate” applications, ranging from over 10 kW up to 500 kW, follow the same general guidelines as small systems. Options to have adjustable setpoints or other custom features may be required by the inter-connecting utility, depending on the impact of the PV system on the portion of the utility system to which it is interconnected. “Large” systems, greater than 500 kW, may combine various standardized features as well as custom requirements, depending on the impact of the PV system on the portion of the utility system to which it is interconnected. A greater degree of custom engineering of the utility interface is to be expected as the size of the PV system grows in relation to utility system capacity

This recommended practice will provide value to a wide spectrum of personnel involved with utility interconnected PV systems, including utility engineers, PV system designers and installers, and PV system owners. The standardized interconnection recommendations included in this recommended practice will minimize custom engineering of many aspects of the interconnection. This document is focused on providing recommended practice for utility interconnection of PV systems in a manner that will allow the PV systems to perform as expected and be installed at a reasonable cost while not compromising safety or operational issues. Small utility-interconnected PV systems should use standardized, listed inverters (listed to test standards, such as UL 1741-19991, which include the testing requirements described in Annex A). The listing process assures that the inverter incorporates fixed voltage and frequency trip settings and incorporates an integral anti-islanding scheme. It is the intent of this recommended practice that small systems designed and installed in accordance with this document and other applicable standards, such as the National Electrical Code® (NEC®) (NFPA 70-1999), will require no additional protection equipment.

Revision Standard - Inactive-Withdrawn. This recommended practice contains guidance regarding equipment and functions necessary to ensure compatible operation of photovoltaic (PV) systems that are connected in parallel with the electric utility. This includes factors relating to personnel safety, equipment protection, power quality, and utility system operation. This recommended practice also contains information regarding islanding of PV systems when the utility is not connected to control voltage and frequency, as well as techniques to avoid islanding of distributed resources.