So your right, Solar Modules are DC, connected in Series (TYPICALLY!) higher voltage systems like 1500vdc systems have both a series and parallel string wiring.I thought all panels are basically connected with +/- terminal to a controller. Wouldn't the problem with re-powering setting up the wiring, controller, and battery storage to match the new panels' capacity? Also, won't the panels be sold as used assuming they can still produce power?
Think of the problem this way. Your New house electrical panel is a 200amp service. The conductor used to feed the 200amp service from the distribution line is sized according to that 200amp spec (3/0 or 250mcm... ). Now one day you decide you want a 400amp panel... to do that you need to replace your existing feed conductors to say 500MCM or larger (This is just an example).
Now imagine that the distribution line is maxed out or the bucket transformer on the pole can not handle the additional current draw; now all that needs to be upgraded.
Same thing happens on a Solar Farm. Everything is built to meet the spec of whats being installed, not to an oversized spec in the future.