Adjust the wire size of feeders and branch circuits based on derating. This calculation needs to account for Ambient Temperature Correction Factors, Adjustment Factors and conduits on a roof (even though NEC 2017 eliminated this one). For example, there is an option in DME RT feeder sizing that asks about a double neutral. If we are acknowledging we need a double neutral, it should be understood the neutral is a current carrying conductor and should adjust the wire size and conduit size per the NEC.