There are currently two types of generators available, one that increases Speed, and the other type increases Shield, Speed generators and Shield generators. These can be equipped to any ship in the generator slot.
Shield generators can also be equipped on drones and your P.E.T. 10 with varying results. Generators equipped on drones provide shield bonuses to your ship, while those equipped on your P.E.T. 10 give shield bonuses to itself.