Step 13: A Brief Explanation
The benefit of doing it this way is that we can jam in some more coils than we would if we just did a simpler version that produced a simple AC wave. Also, this method allows us to get about 1.7 times more voltage out of the generator than the coil groups would produce on their own. That's the magic of this "Y" configuration: it gets us more voltage for low RPM generators, which is definitely what we have here.
There is another configuration worth mentioning (and it's the reason my "B" looked out of order in the photos). The "Delta" configuration gives us the same voltage as the individual coil groups but about 1.7 times the current. So, if you really needed more current, and you could get the turbine spinning fast enough to take care of your voltage needs, that might be the way to go. It wasn't for me, but feel free to research it for your own stuff and let me know how it works for you.