Armor & Shields On Units...

[Raging Deadstar]

Q said:
Using the combat simulator PPB and shard cannon against fighters, it seems that neither shields nor armor are skipped. Both weapons have to make the full damage including armor and shield points before the fighter is destroyed. However shield depleters seem to function on fighters.

From my Expirience in game:

Shield Depleters Work on Fighters, Drones and Satellites
Shield Depleters Don't Seem to work on Weapons Platforms and Troops.

Though i rarely use Shield Depleters on troops, Usually i pile them high with Ground Cannons or DUC. Less Protected yes, but the return volley the enemy finds impressive, for the brief few moments it survives.