A good way I found to complete this mission (took 3 attempts) was to attack the weapons platforms first by getting in close and underneath them, and whenever Nomad fighters appear engage and destroy them (they drop plenty of batteries) and this way I could always recharge shields etc - once the fighters were clear, head back and blow up the platforms, then the generator at leisure - usually took about 3 or 4 waves of fighters to kill before I could finish off a generator. One thing I noticed in the game is that wingmen seem to be invincible, so never worry if they get hit or not. Very addictive game, yet annoying how you HAD to follow the plot in order to progress and explore being couped up in only a few systems at a time. Gonna have to try the multiplayer angle now 
