TEP has upgraded their distribution system and as of December 7, 2021 the following no longer applies.  Remaining posted for historical reasons.

TEP customers intending to install a new PV system now need to check that their system can be safely installed and connected to TEP’s grid.

TEP now has service areas that are saturated with PV systems where new PV systems are subject to additional review and requirements under Arizona’s Distributed Generation Interconnection Rules. TEP has prepared DG Saturation Maps showing these areas.

This further described at https://www.tep.com/get-started-with-solar/

This requirement stems from the recent Distributed Generation Interconnection Rules issued by the Arizona Corporation Commission.

Further information is available at:Interconnection of Distributed Generation Facilities

Update: See the related article on tucson.com: New state rules limit rooftop solar systems in some Tucson neighborhoods