The safety of everyone involved with solar electric systems is of great importance, which is why, every three years, the National Electrical Code (NEC) is reviewed and often expanded. After examining over 4,000 public inputs (PIs) during the last Code cycle, acting on them, and reviewing over 1,500 public remarks made on the accepted changes, the NFPA Code Making Panels has released the latest edition of the NEC 2017.
The following are four important new articles of the Code, focus on the generation, distribution, and storage of electrical power. They include:
Article 691: Large-scale Photovoltaic Electric Supply Stations
This article covers the installation of large-scale photovoltaic (PV) electric supply stations operated for the sole purpose of providing electric supply to the utility transmission or distribution system with an output power rating of no less than 5,000 kilowatts (kW). These stations are at times referred to as solar farms, especially when located in agricultural areas.
Electric supply stations hold the generating stations and substations, as well as their associated generator, storage battery, transformer and switchgear areas. Facilities covered by this article have specific design and safety features unique to large-scale PV facilities. The rapid increase in the number of large-scale PV electric supply stations presents new dilemmas to authorities having jurisdiction (AHJs). Due to the intricacy of these systems, it is unlikely that the AHJ will have expertise in the design and construction of multi-megawatt PV power plants.
Article 706: Energy Storage Systems
This article covers all permanently installed energy storage systems (ESSs) which may be stand-alone or interactive with other electric power production sources. An energy storage system is identified as a device, or more than one device assembled together, capable of storing energy for future use. ESS(s) include but are not limited to electrochemical storage devices (such as batteries), flow batteries, capacitors, and kinetic energy devices (for example flywheels and compressed air). These systems can operate at over 50V AC or 60V DC output for consumption and can include inverters and converters to transform stored energy into electrical energy.
Article 710—Stand-alone Systems
This article covers requirements for electric-power-production sources operating in the stand-alone mode. A significant stipulation in this new article expresses that—even though the system may not be connected to a serving utility—the system must be sufficient to meet NEC requirements as if it were supplied by a feeder or service. All equipment established for these systems must be listed or labeled.
Article 712: Direct-current microgrids
A direct-current microgrid (dc microgrid) is described as a power-distribution system containing one or more interconnected DC power sources, DC–to–DC converters, DC loads, and AC loads powered by DC–AC inverters. A DC microgrid is normally not directly connected to an AC primary source of electricity, but some DC microgrids interconnect via one or more DC–AC bi-directional converters or DC–AC inverters.
Written by Vania Silva, an electrical safety advocate.