NEC Article 705 addresses the requirements for the installation, operation, and maintenance of interconnected electric power production sources. These systems operate in parallel with the primary source(s) of electricity, such as the utility grid, and are essential for integrating renewable energy sources like solar photovoltaics (PV) into electrical systems. Here is a detailed overview of the key sections within this article:

705.1 Scope

This section covers installations of one or more electric power production sources operating in parallel with a primary source of electricity. Examples include utility supplies or on-site generators.

705.2 Definitions

Defines essential terms related to interconnected power production sources, ensuring clarity in application.

705.5 Parallel Operation

Specifies requirements for the parallel operation of interconnected power sources, including output compatibility and synchronous generator requirements. It refers to standards like IEEE 1547 and UL 1741 for detailed guidelines.

705.6 Equipment Approval

Requires that all equipment used in interconnected power production systems be listed or labeled for the intended use, ensuring it meets safety standards.

705.10 Identification of Power Sources

Mandates the installation of permanent plaques or directories that denote all power sources on the premises. This ensures that anyone servicing the system can easily identify and locate all interconnected power sources.

705.11 Supply-Side Source Connections

Provides detailed guidelines for making supply-side connections, including:

• 705.11(C) Connections: Specifies that service-entrance spliced and tapped conductors, such as power distribution blocks and pressure connectors, can be utilized within proper code restrictions.
• 705.11(E) Ground Fault Protection: Requires ground fault protection for supply-side connections rated 1000A or more.
• 705.11(F) Overcurrent Protection: Stipulates that overcurrent protection must comply with Article 230 requirements.

705.12 Load-Side Source Connections

Details the requirements for making load-side connections, including:

• 705.12(B) Point of Connection: Provides six methods for sizing busbars and making connections, including the commonly used 120% rule and alternatives for different installation scenarios.
• 705.12(E) Disconnecting Means: Requires each source interconnection to have a dedicated circuit breaker or fusible disconnecting means.

705.13 Power Control Systems (PCS)

Outlines requirements for PCS used to manage and limit the amount of current flowing through the busbar, ensuring that the current does not exceed the conductor or busbar rating.

705.20 Power Production Source Disconnect

Specifies the requirements for disconnecting means to isolate the power production source from the rest of the electrical system during maintenance or emergencies.

705.25 Wiring Methods

Allows for the use of all applicable Chapter 3 wiring methods, provided that the specific requirements for each wiring method are followed.

705.50 Microgrid Systems

Describes the requirements for microgrid systems, including the ability to disconnect from interconnected sources and operate in island mode. This section ensures that microgrids can safely and effectively manage their power production and consumption independently when necessary.

For more detailed information and specific requirements, consulting the NEC Handbook and additional resources provided by the NFPA is highly recommended. Further insights can be found on resources like IAEI Magazine and Codebook City.