NEC Solar and Storage Regulations Explained

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    NEC Solar and Storage Regulations Including NEC 690, 705, 706, and 710

    Innovative and brand new solar markets have changed the photovoltaic (PV) systems across the country in recent decades. Technological advancements and fire protection objectives have impacted this industry. The National Electrical Code (NEC) is updated to align with these changes. 

    New NEC regulations come out every three years in a book format. Advancements in lithium-ion energy storage systems have also revolutionized some of the requirements of NEC. Photovoltaic system designers must begin learning how these changes and new conditions will impact the systems. 

    Due to these changes, solar industry professionals are constantly attempting to relearn new requirements. They often have trouble keeping up. As such, it is essential to describe new NEC requirements, such as NEC 690, 705, 706, 710, and 712, for solar industry specialists to stick to these regulations.

    NEC Article 690 for Solar Photovoltaic Systems

    If photovoltaic processes fuel an energy storage system, then you must follow the NEC 690. The eighth part of Article 690 accounts for storage batteries. The eighth part covers charge control, battery storage replacement, disconnects, and overcurrent security.

    Today, NEC Article 690 is about decreasing electrical risks after installing and employing a solar photovoltaic system so that it is safe to use.

    NEC 690 has eight parts to it. The first part applies to charge controllers, inverters, PV electrical energy systems, and array circuits. NEC electric and solar requirements under Article 690 relate to correctly install a PV system. Designers will need to pay attention to these regulations, especially regarding how their systems employ energy storage.

    Under NEC Article 690, solar photovoltaic systems must align with the correct PV output polarity to link with energy storage systems and rules for a rapid shutdown.

    Since energy storage systems bring backup power when a grid goes down, designers will need to keep a close eye on NEC 690. This requirement describes how the PV power needs to flow to charge the batteries during an outage issue. Designers will need to ensure the rapid shutdown tool is on the PV part of the overall system.

    NEC 705 on Electric Power Interconnections

    One of the most important aspects of NEC 705 is keeping the sum of the ampere ratings in overcurrent tools supplying power to a busbar or conductor through circuits from rising above 120% of the busbar or conductor’s rating.

    Article 705 is important when the energy storage system is interconnected to the main power source, which may be the utility power. The requirement describes how to interconnect to the main power source. Power is automatically disconnected from the grid upon the disappearance of this primary power source. 

    To follow the NEC 705 regulations, first find the inverter output circuit current. In most interconnection processes, 125% of the inverter output circuit current is applied when calculating the ampacity. 

    The inverter output circuit current is found on the nameplate of the inverter. You can also locate this current by dividing the wattage of the inverter by the applied voltage. Article 705 can also define a micro-grid system and identify the sources of power. 

    NEC 706 for Energy Storage Systems

    Article 706 relates to platforms that use energy storage systems as their everyday operating conditions. The requirement refers to ways to disconnect currents, DC voltage limits, circuit sizing, overcurrent prevention, and installation guidelines. The guidelines are also relevant for one-family and two-family households. 

    The Direct Current (DC) Task Group in charge of developing NEC Article 706 received input from many organizations. Some organizations included equipment manufacturers, the National Electrical Manufacturers Association, the IEEE Battery Group, and the Article 690 Task Group. This article delves into 12 standards and uses information about energy storage from other resources. 

    Furthermore, Article NEC 706 is meant for all inalterably installed energy storage platforms. This aligns with all systems that operate above 50 volts AC or 60 volts DC. Some typical energy storage systems include kinetic energy devices, capacitors, and batteries. 

    Several key requirements under NEC 706 include appropriate overcurrent protection for energy storage circuits, maximum voltage between conductors, and flow battery energy storage system guidelines. Some final NEC solar requirements involve NEC 710 and 712.

    NEC 710 for Stand-Alone Systems

    In 2017, some significant changes occurred due to feedback from authorities, investors, designers, and other stakeholders. Due to these comments and feedback, NEC Article 710 was developed. This article focuses on electric power sources in stand-alone systems.

    Essentially, NEC Article 710 is associated with energy storage systems that operate independently in a stand-alone format. This includes systems that operate off the grid and those providing backup power. 

    The general requirements outlined in Article 710 include inverter input circuit current, supply output guidelines, and output circuit sizing. Furthermore, the NEC solar and storage requirements allow a smaller supply capacity than the cumulative load previously calculated. However, it needs to be equal to or larger than the biggest single load.

    Lastly, NEC Article 712, focusing on direct-current microgrids, is addressed.

    NEC Article 712 for Direct-Current (DC) Microgrids

    NEC Article 712 offers invaluable information on properly installing DC microgrids and the requirements for this installation. DC microgrids can remove the need for power conversion, which leads to more productive use of renewable energy origins. DC power sources include the following systems:

    • Fuel cells
    • Photovoltaic systems
    • Wind generators
    • AC-DC converters
    • Bidirectional DC-AC inverters/converters

    DC microgrids are aligned with the immediate use of power from DC systems to direct-current loads, which include computers and servers, LED lighting, HVAC devices, and communications platforms.

    By learning more about the latest NEC 2017 solar requirements, designers and others working in the solar energy storage industry is prepared to develop safe and effective system

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