The City of Phoenix is now (January 2020) requiring a special permit from the Fire Department for most solar systems and batteries. The fees and required plans varies with size and content. See this link for an application and details:
This is in addition to a building permit from the Planning & Development Department and must be separately obtained at a different address (150 South 12th Street) or on-line via the above link. Also noted is that residential PV permits are no longer over the counter and as of March 2020 are estimated to take 29 working days to process. Separate inspections are required.
The code requirements are contained in Phoenix-Chapter 12 BESS R-3-1.pdf
Related: PV Rapid Shutdown Signage- Phoenix