The electric grid has been called the greatest invention of the 20th Century. The big electric grid, that web of power generation, transmission and distribution.

Micro-grids may be a big feature of the 21st Century. They are really just like they sound. Smaller electric grids. Really small.

Micro-grids have local power sources and their own controls so they can operate on their own. Independent of the big grid. A micro-grid can serve part of a city, an industrial park, or a facility of some sort.

Depending on how they were designed they can go indefinitely on their own, outside the big grid. There is a connection to the larger grid, though, to add flexibility to both systems.

The appeal to microgrids can be the “make it locally and use it locally” idea. The users of the microgrid may decide to go with solar and energy storage, for instance, to add a strong renewable angle to their energy.

This image of one kind of microgrid may be more than you want, but provides the basic idea … make and use power locally.

So, when someone talks about be “off the grid” does that mean a microgrid is on or off the grid? There is probably debate about that, but it seems that for the intent of the phrase, a microgrid is off the main grid, independent.

Here’s a story that is a neat example, image below, of a microgrid built to serve an Alaskan island. It is from ABB. By the way, ABB has offices in the North Carolina Triangle. (Image: ABB)