National Electric Safety Microgrid

What is a microgrid and how does it work?

A microgrid is a group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid.2 A microgrid can operate in either grid-connected or in island mode, including entirely of-grid applications. Figure 1 shows one example of a microgrid.

Does article 702 apply to microgrid systems?

As a result, Article 702 of the National Electrical Code does not apply to Microgrid systems. A microgrid, on the other hand, is a localized group of electricity sources and loads that can operate independently from the main grid (islanded mode) or in conjunction with it (grid-connected mode).

What happens if a microgrid is grid-connected?

If the microgrid is grid-connected (i.e., connected to the main electric grid), then the community can draw power from the main electric grid to supplement its own generation as needed or sell power back to the main electric grid when it is generating excess power.

What happens when a microgrid loses power?

When the main electric grid loses power, the microgrid goes into island mode (i.e., operates independently of the main electric grid) and serves its own customers with the generation and other DERs (i.e., batteries or vehicle-to-grid electric vehicles) operating within the microgrid.