Thermal Drone Inspection for Utility-Scale Solar in Cochise County

Cochise County has quietly become a solar county. AEPCO's Solar II project is 234 MW. Tucson Electric Power's Babacomari installation carries more than 350,000 panels on the Fort Huachuca to Tucson transmission corridor. A 300 MW farm near Willcox was approved in 2023, Sulphur Springs Valley Electric Cooperative has a 20 MW array north of Willcox, and BrightNight's Three Sisters project is in the mix.

That is a great deal of glass sitting in one of the harshest operating environments in the country — and every one of those arrays is degrading right now in ways nobody can see from a truck.

Why thermal, and why from the air

A photovoltaic cell that is not converting light into electricity converts it into heat instead. That is the whole principle. A failed bypass diode, a cracked cell, a corroded interconnect, a shaded or soiled module, a disconnected string — each has a thermal signature, and each is invisible in ordinary light.

The alternative is walking the array with a handheld imager. On a 234 MW site that is not an inspection strategy, it is a career. An aerial scan covers in a morning what a ground crew covers in weeks, at a consistent standoff distance and angle, with every frame geotagged so a finding maps back to a specific module.

What a scan actually finds

The reporting matters as much as the imagery. A useful deliverable is a site orthomosaic with every anomaly located and classified, a severity ranking, and a table an O&M team can work from — not four hundred thermal frames in a folder.

The conditions that make a scan valid, and the ones that waste your money

This is where a lot of aerial thermal work goes wrong, and it is worth knowing before you commission any.

The international standard for outdoor PV thermography, IEC 62446-3, sets conditions for a reason. In practice:

• Irradiance needs to be high and steady — generally at least 600 W/m², and ideally above 700. Panels need to be working hard for a fault to show a thermal difference.
• Clear sky. Broken cloud moving across an array during a scan produces thermal variation that looks exactly like faults and is not.
• Low wind. Wind convectively cools the modules and washes out the very temperature differences you are looking for.
• The array must be operating under load. A curtailed or offline array shows nothing, because nothing is converting.
• Angle discipline. Glass is reflective in the infrared. Shoot too obliquely and you are imaging the sky, not the panel.

Being straight about what we are and are not

We sell this as thermal anomaly screening. We are not certified thermographers, and we will not describe a deliverable as a certified thermographic inspection.

The distinction is real and the people buying this know it. A Level 1 or Level 2 thermographer's report carries a certification behind the interpretation. Screening identifies and locates anomalies, classifies them by signature, and hands your O&M team or your consultant a prioritised list to act on. For most operational monitoring that is exactly the right product. For a warranty claim, an acceptance test or an insurance dispute where interpretation will be contested, you want a certified thermographer, and we will say so rather than take the job.

An operator who blurs that line once will lose the account, and deserves to.

The airspace question on a solar site

Most utility-scale solar in this county sits on the valley floor in Class G airspace, which means no LAANC authorization and no waiting. That is a genuine scheduling advantage — a scan can often happen the week you decide you want one.

Two local exceptions to check. Arrays on the transmission corridor toward Fort Huachuca may sit under or near R-2303 or the Libby Army Airfield Class D, which changes the planning. And an array within fifteen miles of the international border sits inside the band where Arizona law gives peace officers immunity to disable an unmanned aircraft on reasonable suspicion — so that work is done with advance coordination rather than turning up.

What it costs

Panel inspection is priced from our commercial inspection line rather than per megawatt, because scan time is driven by array footprint and row geometry rather than nameplate capacity. Commercial inspection starts at $895 per building-scale asset; a utility-scale array is quoted on footprint, and there is no travel charge inside the Sulphur Springs Valley.

For an operating asset the sensible structure is not a one-off. It is an annual or semi-annual scan with the same flight parameters each time, so you are comparing like with like and tracking degradation rather than taking a snapshot. That is a retainer conversation, and it is a better product for you than a single visit.

Full rate card and travel zones.

Who this is for

O&M contractors managing arrays they did not build. Asset owners who want an independent read on performance. EPC firms documenting an installation at commissioning, which is worth far more than people expect — a commissioning scan is the baseline that makes every later scan meaningful, and almost nobody does one.

And anyone who has noticed production drifting down and cannot find the cause from the inverter data, which is the call we get most often.

If you have an array in Cochise County or the Tucson metro, tell us the site and the nameplate and we will tell you what a scan involves.