*sigh* if only I could add working tentacles to my station so they can grab and crush any pesky pirates that show up to ruin my day. But I guess I'll just have to settle for swarmer turrets instead...
I checked out how power cubes are built and they're not what I had in mind. Mine are more like THIS...
It's not complete. When it's done the entire thing will be filled AND encased in capacitors.
Yeah, that's about as efficient as a power cube gets. Power cubes were challenges to get the most amount of power generation out of the smallest space (the typical challenge size was 5^3.) Such as a fighter's or dropship's "engine room", for lack of a better term. The key to the challenge was "smallest space", so actual power generation is secondary in these challenges.
The "tower" behind that power cube is considered a better design, because it can go as far (high) as you need it to, and you can have power sticks veering out the side as far as you want them to go.
Personally, I wish that power "bottles" (hollow cubes with mostly-solid walls) of power generators were an efficient design, so that you can create a "reactor pod" as a more conventional power generator, without being too terribly punished. Sure, you can build a RP reactor pod now, but the power generation is not very efficient at all, hence the "RP" part of the description.