Drone thermal inspection for solar arrays in Puerto Rico.

1. We fly when the array is hot enough to tell you anything.

   A thermal image of a solar array is a picture of heat, and heat only separates a working module from a failing one while the array is working hard. Fly it under a thin overcast, or an hour after a cloud crossed the field, and every module reads the same lukewarm grey. The flight is cheap to repeat and the wasted one costs you the whole day, so the window is the first thing we agree on and the first thing we abandon a day for.

2. We hand back a record, not a verdict.

   The international specification for this work, IEC TS 62446-3, describes a procedure. It does not decide anything: it sets out equipment, conditions, method and reporting, and it carries no pass/fail criteria for the modules being looked at. The same specification points at ISO 9712 Level 2 as the orientation for whoever interprets the images. So the split is not our caution, it is how the field is built — we fly the capture and hand over an indexed set of radiometric frames; your O&M contractor, or a thermographer qualified for it, calls the fault and signs the finding.

3. We plan the flight against Puerto Rico airspace, not the mainland’s.

   The airspace over an array here does not behave the way a mainland checklist assumes. San Juan is Class C. Ponce and Mayagüez are not Class D at all — they carry Class E surface areas that are part-time, so the same field with the same aircraft gets a different answer depending on the hour. Ceiba took on Class D in July 2026 and is not in LAANC, which turns a 72-hour request into a 60-day one. We read the class at the point of flight and get the authorization before the date, not on the morning.

4. We get written permission before we record the property.

   Puerto Rico has its own statute on this, and it is not a formality: Law 68-2021 makes it a misdemeanour to record a specific private property without the owner’s consent, and it gives anyone harmed a separate civil action with attorney’s fees. An array sits on somebody’s land, often somebody else’s land than the one who hired the scan. The signed consent letter is the first document in the campaign folder.

5. You get the same record as every other campaign we fly.

   One indexed PDF per campaign: every frame with its date and its position, the radiometric files alongside it, and the hash sheet at the back so that a file pulled out of it in three years can be checked against the day it was captured. When something has to be corrected we put the correction on top and keep both layers. The files are yours, and we log every export.

We tell you the conditions before we quote the day.

• Irradiance. Above 600 W/m² in the plane of the modules. Below that the temperature difference a fault produces is too small to separate from noise.
• Sky. Clear. Cloud both cuts the irradiance and reflects off the glass, and a reflection reads as a hot spot that is not there.
• Wind. Low and steady. Wind cools unevenly across an array and lays a temperature pattern over the one you are looking for.
• Settling time. A module needs roughly 5 to 15 minutes to settle after the light, the temperature or the wind changes. A pass flown inside that window is a pass flown on stale heat.
• What we need from you. The array layout, the string configuration and the module datasheet. Without them a warm rectangle is a warm rectangle; with them it is a string.

Where those numbers come from.

The specification itself is a paid document, so we quote the free review that the IEA Photovoltaic Power Systems Programme published alongside it, and we say which page each sentence is on. Read them against the source before you take our word for anything.

It is recommended to take IR images at high solar irradiance (> 600 W/m²) and constant ambient conditions, i.e. no clouds, low wind speeds, stable ambient temperatures.

Typically, a PV module takes 5 to 15 minutes to thermally stabilize for new environmental conditions such as change of global irradiation intensity, temperature, or wind speed.

having an instructional purpose, and is not intended to have pass/fail criteria for the PV modules being investigated.

The analysis of the IR images should be done by qualified personnel using special IR analysis software. As orientation for personal qualification, the ISO 9712 Level 2 can be named, as also described in IEC 62446-3 TS Ed.1 – Part 3.

The specification itself is IEC TS 62446-3:2017, Photovoltaic (PV) systems — Requirements for testing, documentation and maintenance — Part 3: Photovoltaic modules and plants — Outdoor infrared thermography.

The rules behind the flight are in the field guide, free.

• Do I need FAA permission to fly over my Puerto Rico job site?Which airports here carry a surface area, where LAANC applies, and the long route where it does not.
• Can I legally fly a drone over my job site in Puerto Rico?The nine checks, and the two that come from Law 68-2021.
• What should I require before anyone flies over my site?What to ask a vendor for before the aircraft leaves the ground.

Tell us where the array is and when the window opens. Tell us what you need →