Answer the utility question by address, not by city
SRP serves much of the Phoenix metropolitan area, including parts of Phoenix itself along with parts of Mesa, Scottsdale, Tempe, Chandler and Gilbert. Service territory boundaries can change block by block, so verify your provider by entering your address on the utility websites rather than assuming based on your city.
This is not a technicality. APS credits exported solar under a Resource Comparison Proxy rate rider, metering export energy on an instantaneous basis and providing monthly bill credits, with the initial purchase rate locked in for ten years. SRP puts solar customers on demand and export based price plans, where a per-kilowatt demand charge is based on 30-minute intervals during on-peak hours.
Those are different products requiring different decisions. Under one, the timing of your interconnection sets a rate for a decade. Under the other, the shape of your household's peak usage drives a charge that solar alone does not reduce.
So the first thing to establish, before any quote, is the name on your bill. A neighbour two streets over may genuinely be on a different utility with different economics, which is why solar advice travels so badly across this metro area.
If APS bills you, the interconnection date is a ten-year decision
The APS Resource Comparison Proxy is a rate rider available to partial requirements residential customers with qualified on-site solar generation. Customers lock in an initial RCP purchase rate for ten years.
That lock is the part worth planning around. The rate is set through the Arizona Corporation Commission process and reviewed annually, and the rate you get is the one in effect when you interconnect. A project that lands either side of an annual change is locked to a different number for a decade.
So ask APS directly what the current RCP purchase rate is, when the next change takes effect, and what rate a system interconnecting on your expected date would lock. Ask for it in writing. That answer is worth more to your return than any equipment upgrade an installer will offer you.
One further condition matters if you might expand later. A material increase in capacity ends eligibility for the initial RCP purchase rate locked in for ten years. If you are considering adding panels for an electric vehicle or an addition, ask what counts as a material increase before you size the first system, not after.
What you use is worth more than what you send out
Traditional one-to-one net metering has been replaced in Arizona by net billing export rate riders at the major utilities. Exported solar is credited below the retail rate, which means electricity you consume as it is generated is worth more to you than electricity you export.
That inverts the old sizing instinct. Rather than building generously to cover annual consumption and letting the grid balance the seasons, you want a system matched more closely to what your household actually uses during daylight, with the surplus valued honestly at the export rate rather than at retail.
Ask your installer to model the self-consumed share of production explicitly and to value the remainder at the actual export rate you will be on. A projection that treats every kilowatt hour as equally valuable is describing net metering, which Arizona no longer has.
It also makes batteries a more serious question here than in a net-metered state, because storing production for evening use converts a low-value export into an avoided retail purchase. Ask for the arithmetic with and without storage rather than accepting a general recommendation either way.
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.