Snow, pitch and how the array sheds
Snow on panels stops production, and how quickly an array clears depends on pitch, orientation and how the modules are mounted. A steeper south-facing plane sheds sooner than a shallow one, which matters more here than anywhere else in the state.
Ask your installer how the proposed layout behaves under snow: how quickly it is expected to clear, whether snow guards or other roof features would trap it against the array, and what the mounting is rated to carry as a load.
Ask about access as well. If snow does sit, what is the safe way to clear it, and is that something you would be doing or someone else. An answer that assumes you will climb onto a snowy roof is not a good answer.
Then ask for a production estimate that reflects winter losses honestly rather than an annual figure derived from statewide averages. A model built on Phoenix irradiance and no snow days will overstate what a Flagstaff roof delivers.
What altitude gives back
Cold is good for photovoltaic output. Panel efficiency falls as cell temperature rises, which is why the hottest afternoons in the desert are not the highest-producing ones, and Flagstaff simply does not have that problem to the same degree.
Altitude and clear air help too. A cold bright winter day at 7,000 feet can be a genuinely productive one, and the seasonal shape of production here is different from the low desert rather than uniformly worse.
So ask what temperature assumptions sit behind your production estimate, and whether the model has been run for your actual location rather than a regional average. The answer separates an installer doing engineering from one filling in a template.
Winter heating load is the other half of the picture. If your home heats with electricity, your consumption peaks in the season when production is lowest and snow is most likely, and a quote should show you monthly figures rather than an annual average that hides the mismatch.
The roof underneath, and what exports are worth
Check the roof covering before anything is ordered. Panels outlast most coverings, so one within a few years of replacement should be replaced first rather than paying later to remove and reinstall the array. Freeze and thaw cycling is harder on a roof than steady desert sun, so ask for a condition assessment rather than an age estimate.
Ask how the mounting penetrations are flashed and sealed, and what the workmanship warranty covers on them and for how long. Leaks around mounting hardware are the most common physical failure in residential solar, and a climate with snow melt and refreeze is an unforgiving place to discover one.
On the utility side, 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 and electricity you consume as it is generated is worth more.
Confirm which utility serves your address and what its export arrangement is, then ask your installer to model the self-consumed share explicitly and value the remainder at that export rate. A projection valuing all production at retail is describing net metering, which Arizona no longer has.
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.