If you have any interest in doing space missions at all, an essential upgrade to get for your ship is a power converter module. It costs 30 commendations and is available for use at Level 25. The power conversion module allows you to either switch between more firepower (and slower shield generation) or faster shield generation (and less firepower) for your ship.
This upgrade has saved my ship numerous times from destruction. If I’m flying into a barrage of enemies, I hit number 2 on my keypad, stop firing, and watch my shield reach full strength in just a few seconds. Once I’m fully charged, I hit number 1 and continue blasting enemy ships.
Power converter FTW!