What the company makes, and why desert projects want it
If you have panels on a roof in Phoenix, or you drive the Maricopa road out past Gila Bend and pass a field of them tilted at the sun, there is a fair chance the company that designed those modules sits about fifteen miles from your meter, in Tempe. That company is First Solar, one of the few large panel makers headquartered in the United States rather than overseas.
First Solar does not build the silicon panels you see on most houses. It builds cadmium telluride thin-film modules, meaning a thin coating of cadmium telluride (a compound that converts sunlight into electricity) is laid onto sheets of glass instead of sliced silicon wafers. In desert heat that chemistry tends to hold its output a little better than ordinary silicon, which is part of why you find these panels on big Arizona solar farms. The company reports its output in gigawatts of nameplate capacity (the maximum a plant is rated to produce under ideal conditions), on the order of twenty gigawatts a year and climbing at last public report, per its own filings.
What 'built here' means on a project's paperwork
The phrase carries weight because of a federal rule. Projects that use enough American-made steel, iron, and manufactured parts can claim a domestic content bonus, an extra slice of federal tax credit on top of the base clean-energy credit. For a utility-scale desert project in APS or SRP territory, that adder can change whether a solar farm pencils out, so developers care a great deal about where the panels were actually built.
Here the Arizona story gets honest. Most of First Solar's high-volume lines run in Ohio, where it has operated for years, with newer plants added in Alabama and Louisiana, again per its own reporting. Arizona's piece is the headquarters in Tempe and the research that goes with it, which matters but is not the same as a stamping line turning out panels by the truckload. The state did have a factory once: the company built one in Mesa around 2011 and 2012, idled it during a solar downturn before it ran at scale, and the building was later sold (Apple bought it in the middle of that decade). A headquarters address and a factory address are two different facts.
How to check any of this yourself
You do not have to take a company's word, or ours. First Solar is publicly traded, so its annual report (the 10-K it files with the Securities and Exchange Commission) lists where its factories sit and roughly how much they can produce. Those filings are free to read, and they are the plainest record of which states actually hold the manufacturing.
For the Arizona side, the U.S. Energy Information Administration publishes a state energy profile showing how much of the state's power now comes from solar, and the Arizona Commerce Authority posts economic-development announcements when a company pledges jobs or takes an incentive. Treat pledged jobs as pledges, not as a current headcount. The two often differ, schedules slip, and an announcement is a plan rather than a line that is running.
Worth watching this month
1. First Solar's next quarterly earnings report, due in the normal cadence of a public company, should restate its factory locations and capacity, and is the plainest place to see whether any new Arizona line is actually planned.
2. The EIA Arizona state profile updates on a rolling basis, worth a glance to see if the state's solar share has moved; this is routine, not dramatic.
3. Any Arizona Commerce Authority announcement tying First Solar or a supplier to a new in-state facility would be the real signal, so watch for one rather than assuming it.
4. Federal domestic content guidance from the Treasury and the IRS can shift what counts as American-made, which changes how much a Tempe-designed, out-of-state-built panel helps a project's credit.
5. SRP and APS procurement for new solar and storage is where you would first see the large orders a domestic manufacturer might fill.