I don't think there's a way to mass-edit in StarSector. Depending on your fleet doctrine, there might be a time-saving shortcut that will reduce the tedium, but there's no way to completely eliminate it. If you have several of the same kinds of each ship (multiple Atlases for cargo, multiple Eradicators for a battle line, whatever) you can create two custom loadouts for each class of ship, one with your Solar Shielding build and one with your normal build. You still have to individually click on each ship, but selecting a custom loadout is way quicker than actually moving the hullmods around manually.