Short answer: Yes. Extreme heat trims a panel's output by roughly 0.3% to 0.4% per degree Celsius above its 25C rating, but Arizona's world-class sun and sun-hours more than make up for it. Arizona is consistently among the top US states for solar production per panel.
The honest part: heat does trim output
Solar panels are rated at a cell temperature of 25 degrees Celsius, about 77 Fahrenheit. As the cells heat up past that, their output slips. For the crystalline-silicon panels on most homes, the loss is roughly a third to four-tenths of a percent of output for every degree Celsius above the rating. On a 115-degree Phoenix afternoon, a panel sitting in full sun runs much hotter than the air around it, so on the worst summer days you genuinely lose a slice of production compared to a mild day.
That is the part some installers gloss over. We would rather you hear it up front, because it is also a small effect next to the thing that actually decides solar in Arizona: how much sun hits your roof in the first place.
Why Arizona still wins, by a lot
Arizona gets some of the highest solar irradiance and the most sun-hours of any state. That abundance swamps the heat derate. The same panel that loses a few percent on a scorching afternoon is still soaking up far more total sunlight across the year than it would in a cooler, cloudier state. It is why Arizona is consistently near the top of US states for solar production per panel installed.
Put plainly: the heat costs you a little; the sun gives you a lot. The net is strongly positive, which is exactly why so many Arizona roofs pencil out.
What a good install does about the heat
- Proper roof standoff for airflow, so the panels run cooler than if they were pinned flat to a hot roof.
- Panels and inverters rated for desert operating conditions, not a mild climate.
- A system right-sized around your actual summer load, not a generic template.
- Clean wiring and workmanship, since heat is hard on sloppy connections and a tidy install protects your output for the long haul.
The bottom line for an Arizona homeowner
Heat is a real but minor factor, and a competent installer designs around it. The reason to go solar in Arizona has not changed: you have world-class sun and a utility bill that keeps climbing. If you want to see how those two forces play out on your home, read whether solar is worth it in Arizona, check the rising APS and SRP rates you are up against, or run your bill through the savings calculator.
Output figures here describe typical crystalline-silicon panel behavior and Arizona's well-documented solar resource; your system's real numbers depend on your specific equipment, roof, and usage.