If launch costs are assumed to be $0/kg, how does that solve the waste heat problem? Add more mass? What about the maintenance of failing hardware?
I'm genuinely curious, I thought basically heat radiation was a hard physical boundary, regardless of launch cost.
Arbitrarily large radiators can dispose of arbitrarily large amounts of heat. In practice the radiators don't even need to be as large as the solar panels.
If launch cost was truly $0 you could also do maintenance in space but I think it's more likely that you'd work to push up reliability instead. That's what SpaceX did with Starlink.