What I took from this episode is that it's definitely a matter of tactics and pilots. The HRL Lt Colonel at least had a better idea about fighting Setsuna than Graham did. Why fight what is clearly an air superiority mech (shown from how many plane/mobile suits Exia annihilated in eps 1?) when you can try to handicap.
Granted, it didn't pan out too well, but at least Setsuna got serious and pissed off.
If not for the overwhelmingly superior Gundam, Setsuna could have been in a bit of trouble. I'm guessing that the white-haired girl is the HRL's ace, like Graham is to the Union. Perhaps things won't go so smoothly next time.
It could have just been Nyoro~n's translation, but I thought that the Gundams ran off the solar energy collected by the Ptolemaios, not the other way around. That's why the others were complaining about having to return to space occasionally.