Ask what the savings figure assumes
Traditional one-to-one net metering has been replaced in Arizona by net billing export rate riders at the major utilities, so exported solar is credited below the retail rate. A quote that values all production at your retail rate is describing an arrangement Arizona no longer has, and it will overstate your return.
So ask three questions of any savings figure. Which utility and which rate or plan does it assume. What export rate does it apply, and where did that number come from. What share of production does it assume you consume yourself rather than export.
That third number is the one that quietly does most of the work. A model assuming you use most of your production at home will produce a much better result than one that does not, and whether it is realistic depends on your household rather than on the equipment.
Ask for the same system modelled on a more conservative self-consumption assumption. The gap between the two tells you how much of the promised return depends on behaviour you have not yet committed to.
What belongs in the contract
Get the equipment specified by manufacturer and model number rather than by description. Panel and inverter model numbers are what make a warranty enforceable years later, and they are also what let you compare two quotes on the same basis rather than on adjectives.
Establish who honours each warranty and for how long. Panels, inverter and workmanship are commonly covered by three different parties on three different terms, and a company that has left the market cannot support a workmanship warranty however well it is written.
Ask what the workmanship warranty covers on roof penetrations specifically. Leaks around mounting hardware are the most common physical failure in residential solar and they typically appear a few years in, well after the installation has been forgotten about.
Get the production estimate in the contract, along with what happens if actual production falls materially short. An estimate that appears only in a sales presentation is not a commitment, and knowing whether anyone stands behind the number changes how much weight it deserves.
Permits, interconnection and the timeline that matters
Agree in writing who files the permit and who submits the interconnection application, and ask for the expected date of permission to operate rather than the installation date. Those are different milestones and only the second one earns you anything.
That matters more than usual in Arizona because of how export arrangements are set. An APS customer locks an initial Resource Comparison Proxy purchase rate for ten years, and the rate is the one in effect at interconnection, so the date carries a decade of consequence.
Ask what happens if the timeline slips past a rate change: does the quote get re-modelled, and who carries the difference. An installer who has thought about the Arizona market will have an answer, and one who has not has just told you something useful.
Confirm which utility serves your address as the first step, since boundaries in this part of the Valley change block by block. Verify by entering your address on the utility websites rather than assuming from your city.
The state credit you claim yourself, and the federal one that ended
Arizona still has a state income tax credit of its own, claimed on Arizona Form 310, Credit for Solar Energy Devices. It is calculated by multiplying the cost of a solar energy device by 25 percent, capped at $1,000, and the form provides for tracking credit carryover across multiple years.
Ask a tax advisor how the cap and the carryover apply to your situation before you rely on a figure in a quote. A credit is only worth what you can actually use against tax owed, and an installer is not the right party to advise you on that.
Arizona also exempts solar equipment from state sales tax and excludes it from property tax, so the improvement does not raise your property tax bill the way a renovation of similar cost would. Neither arrives as a cheque, which is exactly why they get left out of people's own arithmetic.
The federal position has changed and much published material has not caught up. The 30 percent Residential Clean Energy Credit under Section 25D expired for property placed in service after December 31, 2025, so a cash or loan purchase now does not receive it. Section 48E survives at 30 percent for third-party owners under leases and power purchase agreements, so such a provider may claim it and reflect part of the value in the rate offered. Ask what they claim and what actually reaches you, and confirm with a tax advisor.