Best method for me: Just rip the fleets in space apart,don’t bother looking for the cargo pods withe the modules. Destroy everything,so the freighters as well. Easy targets and they give you great loot(s-class freighter upgrades+dumbloads of bulkhead storage modules which you need to expand the storage and tech slots on your freighter)as well. Just have enough sodium to recharge your shields. You can do that with 3-4 fleets in every system before they stop spawning. Then just jump to the next system and repeat.

Note: Try to go to rich systems. I don’t know if you get s-class upgrades in poorer systems as well. Always keep an eye on the race of the system(Gek,Korvax,Vykeen). Stick with one race,cause after all you gonna destroy your own reputation pretty quickly. So loose it on one and not all three of them.

End of the song: Keep expanding your freighter slots with the bulkhead storage modules(you can choose if you wanna use them for tech or storage,just click on a tech slot and it will be used for that), soon you will have more bulkhead storage modules and freighter upgrades than you need so you can sell them for nanites at the space station. Meanwhile your ‘salvaged frigate modules’ keep filling up. Still gonna take time but you gonna kill a LOT of bird’s with one stone.

Cheeeers