How is a Microgrid defined?
I recently wrote an article about how a minigrid is defined. It sparked a great discussion on LinkedIN. Understandingly, the comments are related to the size of such a grid, rather than it’s purpose. Especially as many brought up the term microgrid. The big question thus is: what is the difference between them? To understand, I have looked up the definition of a microgrid by the U.S. Department of Energy Microgrid Exchange Group. They state that 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. A microgrid can connect and disconnect from the grid to enable it to operate in
both grid-connected or island-mode. “
I don’t entirely disagree with the definition. But it does not fully clarify the term. Especially when also comparing it to the term of minigrids.
So, again, I wanted to take a look from the feature perspective, rather than look at size and found that the following criteria are true for microgrids:
Typical microgrid features
- Microgrids consist out of areas that are already electrified, with existing infrastructure
- They include generation assets
- A distribution grid is part of it
- Microgrids include a metering & payment infrastructure, that can be provided by an outside vendor
- They supply energy 24/7
- The purpose of technology integration is to increase security of supply
- The grids use renewable energy sources to reduce energy cost
- They are technology open, e.g. not necessarily are AC based
- Microgrids can have storage technologies, but not necessarily have them
- These grids are already connected to the main grid, but can be disconnected and operated autonomously.
My microgrid definition
Based on the criteria, I came up with a definition, that I believe is most accurately, while keeping it flexible on the size matter.
A Microgrid is the result of upgrading an existing grid-connected power system, built up in either AC or DC technology, with technology to increase the security of supply and reduce the operational energy cost, for which locally distributed non-renewable and renewable energy sources may be used, possibly together with energy storage solutions that also enable a standalone operation.
Microgrid vs. Minigrid
The key distinguishing factors between a minigrid and microgrid are thus:
- A minigrid provides energy access to a former non-electrified area
- A microgrid provides advanced features for grid stability and resilience while often utilizing distributed renewable energy sources to reduce energy costs and reduce dependency from the main grid.
Looking at the features of the two, we can change the terms in the daily use. Donor agencies, development organisations and rural energy authorities could use a term without the “mini” in it, and industries, the military and commercial and industrial players could use a term without the “micro” in it. This avoiding the confusion about size to distinguish the two. My ideas:
- Rename minigrids in “standalone rural electrification grids”
- Rephrase microgrids in “advanced feature local grids”
I am sure the industry will keep on using the established terms, which is okay, as long as everyone knows what is behind the terms, which I do hope my articles helped with.