...because this hasn't gone in enough different directions already...
Would you include data-logging with the subject of Microcontrollers? That would be the way I got into them, personally, and I used a PicAxe. Others data-log with a HOBO that they bought and wired up. Where does that go?
What seems to be coming about as a rough definition of "Controls" vs "Microcontrols" is this:
Controls:
Power regulation systems for managing or optimizing the energy produced by RE (such as battery charge controllers, but not limited to just electricity because it can also mean thermostats and valves in thermal systems). Another way of thinking about it "ANALOG". Also: commercial technology bought by the user for their RE system.
DIY Electronic Controls and Microcontrollers:
Systems to monitor, manage, or optimize the energy produced or consumed by RE (primarily electrical/electronic in nature, employing computer programming and/or producing data files and logs for the user to interpret). This implies that it is "DIGITAL". Also note that these projects are built from raw electronics and/or open-source computer/controllers by the user.
Overlap in these subjects will be INEVITABLE. Don't go punishing people for posting about the MuController-based charge controller in the Controls section, if you don't have to.
The only benefit in this division IMHO is that the site will be more visible to Google bots, hence easier to find in searches, and maybe attract more users. But as long as you're doing it, please make sure there's a Sticky to explain what the division is, and also tidy up some of the Stickies that are now in Controls, but contribute more to Microcontrols now.