A reality based independent journal of observation & analysis, serving the Flathead Valley & Montana since 2006. © James Conner.
That’s a trick question. There isn’t an official definition, let alone a precise definition. “Distributed generation” is one of those terms that sounds important, has a precise definition for each person who uses it, and almost as many precise, and thus precisely differing, definitions as the number of persons using it. But unofficially, it’s shorthand for net-metered photovoltaic, and perhaps wind, generation.
It’s not synonymous with rooftop solar, or net-metered photovoltaics, or net-metering. Rooftop solar includes thermal collectors (for heating water or heating a structure) as well as photovoltaics. Net-metered photovoltaics can be pole or ground mounted arrays as well as rooftop mounted arrays. Net-metering includes electricity generated by wind, microhydro, fossil and fiber fueled generators, hamsters running in a cage; every method of generating juice.
The definition of distributed generation is distributed all over the political and economic landscape. Electric utilities consider it shorthand for net-metered generation, which they consider an evil akin to communism; regulators, shorthand for regulatory headaches; renewable energy advocates, shorthand for something as pure as motherhood, apple pie, and the flag; most everyone else, shorthand for obfuscation.
And that’s just one set of problems with the phrase.
Another is that virtually no one distinguishes independently distributed generation from non-independently distributed generation. Independently distributed generation makes the electric grid more robust: if one generating plant goes down, the rest pick up the slack and the grid stays up. But the current state of net-metering is such that if the grid goes down, so do all of the net-metered generating facilities. Indeed, there’s an argument that net-metering weakens the grid by introducing additional failure points.
Many of the comments and analyses of net-metering published by the Montana Legislature’s interim committee on energy and telecommunications use the term distributed generation; none provides a precise, useful, definition for it. The authors simply assume that everyone knows what it means. That’s a false assumption that will be revealed as such once the committee starts writing definitions for draft legislation (if the committee ever gets that far). Agreeing on a precise, useful, definition of distributed generation should be on the agenda for the committee’s meeting this month.