You're not hiring a flyover. You're hiring a radiometric pass over an array so a site lead can point at a string, a combiner, or a dirty block and send a crew to the right row.
A ladder walk tells you what a tech can reach. A thermal drone pass tells you how the array is behaving — string and combiner faults, soiling, inverter-adjacent heat — without putting someone on a wet roof or a tracker they don't need to climb.
I fly commercially out of Springdale, Arkansas. Eight years of this work has a simple split: the useful solar jobs are the ones where the thermal file and the RGB overlay become a punch list.
What thermal solar inspection actually is
A useful thermal inspection uses a radiometric camera. Each pixel carries a temperature, not just a color. A palette-only "hot look" from a consumer camera is not the same product. If you cannot export temperatures, you cannot brief an electrician on a threshold.
Utility-scale and rooftop are the same physics and different logistics. A ground-mount or tracker field is about acres, row access, and not clipping a module on landing. A rooftop array is about fall protection you no longer need for the scan, HVAC units that confuse a lazy palette, and a launch plan that does not surprise the building next door.
Fly when the modules have been under the sun long enough to show a real thermal difference. Overcast, early morning, or wet glass will hide the faults you hired for. Ask for the irradiance and weather abort rule in writing. A common field practice is clear or high-thin sky, array producing, abort if the glass is wet or the wind is above the aircraft limit.
What you actually get
String and combiner faults
A dead or underperforming string often shows as a run of modules that are cooler or warmer than their neighbors. A combiner or a dirty fuse can light up a whole homerun. You are looking for pattern, not a single bright pixel.
The drone does not replace a clamp meter or an IV-curve trace. It tells the electrician where to walk first. On a large field, that is a morning of targeted work instead of a day of random row walking.
Soiling
Dust, pollen, bird mess, and agricultural film do not always look dramatic from the gate. Under load they show as patterned heat. A thermal pass plus same-day RGB lets you separate soiling from a diode or a cracked cell. Soiling is often a wash decision. A fault is a parts decision. Mixing those two wastes a truck roll.
Inverter-adjacent heat
Inverters and transformers run warm by design. A thermal pass can still flag a cabinet that is out of family, a lug hotter than its neighbors, or pallets against the fence. Treat that as a "look here" list for the electrical lead, not a diagnosis. You still need a qualified person at the disconnect.
A punch list, not a movie
Ask for pin locations on the as-built or tracker map, an annotated PDF, and the raw R-JPEG for the person who will open it. Date, site name, and camera on the packet.
Why a Part 107 thermal pilot beats a ladder walk
A walk is incomplete by design. You see the modules a person can stand next to. You miss the middle of a rooftop array, the far tracker, and the pattern that only shows when the whole block is in one frame.
A walk also puts someone on a roof, a ballasted rack, or a wet slope. The drone does not remove the repair crew. It removes the need to walk the whole array just to find the repair.
Part 107 is the commercial license in the U.S. Solar inspection for pay is commercial work. Ask for the certificate number and who is the remote PIC on site. A hobbyist with a "thermal" camera is not a substitute.
What this is not
Don't hire thermal solar if what you want is a marketing flyover, a full electrical acceptance test, or a stamped engineering report unless you scoped a PE. Thermal flags anomalies. It does not by itself prove a warranty claim.
Don't treat a single hot module as a death sentence. Bypass diodes, reflection, metal flashing, and a bird can fool a rushed palette. A good operator will say when a signature is ambiguous.
How to hire
Write the scope like a field inspection, not a photo shoot.
Operator checklist
- Current FAA Part 107 Remote Pilot Certificate. Ask for the number.
- Certificate of insurance. Many owners and GCs ask for $1 million commercial general liability, additional insureds, and aviation / unmanned aircraft coverage. Use your risk team's minimums.
- A radiometric payload. Ask for the camera model and whether files are radiometric.
- A written method: time of day, sky, abort for wet glass or low irradiance, and how they keep the aircraft off the modules.
- Airspace plan. Rooftop jobs near a towered airport need a LAANC or ATC path before launch. Confirm they will file. Need the law on LAANC? dronelaws.us.
- A report, not just a memory card.
Deliverable checklist
- Radiometric stills plus RGB of the same blocks.
- An annotated PDF punch list with locations a crew can find.
- Date, site name, camera, and the weather/irradiance note.
- Turnaround in writing. A few business days for a report is common.
Rain, wet glass, fog, and high wind cancel the useful flight. Write the slip rule: next flyable slot, not a silent skip. You still need site access, a launch spot that is not on a module, and a contact who can speak to lockout.
What to put in the RFP
- Site address, array type (rooftop, fixed tilt, tracker), and approximate MW or module count.
- What you want found: strings, combiners, soiling, inverter pad — or full-array scan.
- Deliverables: radiometric files, RGB, annotated PDF, optional mosaic.
- Any as-built, row map, or combiner list you can share.
- Date window and the weather/irradiance abort rule.
- Part 107 proof, COI with additional insureds, and who files airspace.
- Where to drop files and who gets the punch list.
If you don't have a pilot yet, search the directory by state or post that RFP on findadronepilot.com. You hire the operator directly. There's no broker in the middle and no commission on the job.
Hire the scan, then send the crew
Your techs should spend their time on the string that is actually down, not on a ladder tour of modules that are fine. Hire a Part 107 thermal pilot for coverage, a radiometric file, and a punch list a superintendent can act on.
Search Part 107 pilots by state, or post the RFP, at findadronepilot.com.