How many commerce centers should i use?

[hyme]

How many commerce should i use for space ports and other bases?

[Tcby]

A single commerce center. There are no benefits for additional copies.

[hyme]

Thank you. It really should say it doesn't stack. Are there other things that don't stack as well?

[Tcby]

Yes there are. The others are the medical center, recreation center, command center, targeting/countermeasures components, damage control components, and hyper drives.

Edit: and hyper deny.

Edit2: aaaand technically you could say that you gain a very limited benefit from additional weapons/energy/high tech plants, because each one provides massive production capability as is. Unless this was changed in universe.

[fenrislokison]

For repairing damage control component, it may be a good idea to add 2, since an single unlucky strike could destroy the repairing ability of a ship with only one.
And the component is cheap enough so it doesn't impact the design of the ship.

[Aeson]

Yes there are. The others are the medical center, recreation center, command center, targeting/countermeasures components, damage control components, and hyper drives.

It's not entirely true that hyperdrives don't stack. Adding multiple copies of the same hyperdrive does nothing for you, it's true. However, when you have include one hyperdrive of kind A and one hyperdrive of kind B, the following is true:

1. Jump Initiation Time is equal to the fastest Jump Initiation Time of all the hyperdrives carried
2. Maximum Hyper Speed is equal to the highest hyper speed of all the hyperdrives carried
3. Energy Usage while Warping is equal to the highest energy required of all the hyperdrives carried

So there is an advantage to including multiple hyperdrives, if you have access to multiple hyperdrives which have different advantages. There's also a redundancy advantage, as a ship which carries two or more hyperdrives is less likely to be stranded by damage out in the middle of nowhere or prevented from jumping to safety due to the loss of a hyperdrive. Whether or not these advantages are worth the cost is a different question.

[Locarnus]

Resource extractors only stack to a certain limit (which imho is defined by the tech level, the higher the tech level, the less extractors are needed to reach the cap, since each one is better).

You should orient yourself at the ai designs in this regard, to not have an "unfair" advantage over the ai, although technically i think 3 extractors for gas and mining was useful.

[Unforeseen]

Depending on the actual purpose of the station certain non stacking modules are definitely worth having two of for the reason stated above that it could be destroyed. Having a second one ensures continued operation despite losing the first in battle.