Space Yard Expansions:

Dark Nova v4.23 added something new to DN4: Space Yard Expansion capability.

Research into Resupply will eventually grant Advanced Resupply System, which basicly adds repair ability to resupply bases but also has another aspect. Advanced Resupply Systems can also enhance Space Yard construction rates! 

Similar to other mods, what you will need to do to take advantage of these is to build a lower tech version of the Resupply facilities (Resupply Depot or Resupply Base), then upgrade them to an Advanced Supply System and it will provide the addition to your existing Space Yards. 

Two things to note: 
	First, you MUST have a Space Yard already built before you upgrade.
	Second, you must remember to build a lower tech version first. As long as you keep building lower tech version, you can keep doing upgrades and further improve your build rate on that planet in exchange for facility slots.