Solar in Arizona has no shortage of sun, and that is not the same thing as a roof that is ready. Tile, foam, and flat built-up surfaces each take attachments differently, and a tired underlayment should be faced before an array covers it up. High country roofs add snow, pitch, and a shorter clear season. Shade from a neighbor parapet, a mesquite, or a mountain slope matters as much as the brochure sky. Start with the roof you have, in the town you are in.
Ask for a look at the roof in person. An image from above has not seen the deck, the flashing, or the soft spot at a cooler curb. Ask how old the covering is and what happens if the roof needs work before any module is set. Ask what attachment and flashing details are specified on tile versus a composition roof versus a foam roof. Ask whose obligation covers a leak at a penetration. Ask how the array comes off later if the roof has to be replaced.
The electrical service is the next constraint. Many desert houses already carry a large cooling load, a pool, and an electric range, and the panel may not have room. Say what you know about the panel, and expect someone to open it rather than guess. Ask for the module and the inverter to be named in the writing, and ask whether the inverter is a string unit or electronics at each module. Ask who can see production and who you call when a section goes quiet.
Permits and utility interconnection are part of the work, not a courtesy. Ask who pulls the permit and who files to connect. Ask whether the system is allowed to operate before the utility says so. Ask what is excluded if the utility or the building department requires a change. Ask whether you will own the equipment. Dust will settle on the glass, and monsoon wind will test the attachments, so ask how those facts are handled in the scope.
Bring the town, the roof surface, and the age of that roof. Skip any pitch about a bill. Call the number on this page.