Why timing matters for thermal inspection
An infrared camera records surface temperature. A solar module that is working normally under load has a fairly uniform temperature. A module with a fault often shows a hotter region, because a failed cell, a bypass diode, a bad connection or mismatched current causes energy to dissipate as heat. A thermal scan is therefore a way of seeing electrical behavior, but it only works while that behavior is happening. An idle array at night has nothing to show.
Conditions that make a scan useful
- The array is producing. Current flowing through the modules is what reveals faults. A scan during low output tells you little. Industry practice and standards for field infrared work, such as IEC TS 62446-3, call for strong irradiance, and the inspection provider should state the conditions they apply.
- Stable sunlight. Passing clouds change the load on the array and the temperature of the modules, which can produce misleading patterns.
- Light wind. Strong wind cools the modules and can hide mild hotspots. It also affects the drone.
- Clean modules, or known soiling. Dirt can create its own patterns. Record it so it is not mistaken for a defect.
- Good geometry. The camera angle relative to the module surface affects reflections and readings. A planned flight keeps this consistent.
Good reasons to fly
Commissioning and handover
A baseline scan after construction records the condition of a new array and catches installation problems such as bad connections or damaged modules before warranties and responsibilities become unclear.
A production drop
If monitoring data shows an array or a string underperforming, a thermal scan helps locate where the loss sits. It turns "something is wrong" into a list of locations.
After an event
Hail, high wind, a storm, a fire nearby or a grid disturbance can all leave damage. A scan afterward identifies affected areas, and a visual pass can pair with it.
Periodic checks
A scheduled scan builds a history. The follow-up note on how often a commercial array should get an infrared inspection covers how to choose the interval.
Before a sale or warranty claim
Buyers, lenders and manufacturers often want an independent condition record. A documented scan with located findings supports that conversation.
What a drone thermal scan will miss
It is just as important to understand the limits, because an all-clear from a thermal scan is not a certificate of health.
- Defects that do not heat up. Many microcracks and inactive cell regions do not produce a visible thermal signature under normal load. These are better revealed by electroluminescence imaging, discussed in thermal scan versus EL test.
- Faults that only appear under other conditions. A problem that shows at high load may not show on a partly cloudy day.
- Problems behind the module. Wiring, connectors and rack issues that are not on the front surface may be hard to see from above.
- Electrical problems away from the modules. Inverter and combiner faults need their own inspection.
- Surface condition. Soiling, coating wear and physical damage are better recorded by visual imagery.
Pair the scan with the right records
A good deliverable ties each finding to a module location on the as-built layout, with a thermal image and a visible image together, and states the conditions of the flight. Monitoring data for the same period helps rank findings by their effect on output.
Planning the flight
Choose a weather window with steady sun, confirm site access and airspace permissions, and tell the facility team when you will be flying. Provide the as-built drawings so findings can be located. Ask the provider what they will do if conditions turn: a good one reschedules instead of flying a scan that will not stand up.
What to ask the provider before booking
- What irradiance and weather conditions do you require, and what happens if they are not met?
- Will findings be located against our as-built layout?
- Do you pair each thermal image with a visible image?
- Who classifies findings, and how are they ranked?
- Is airspace authorization and site coordination included?
Where Solar Survey AI fits
Our drone thermal inspection service uses radiometric infrared capture across every module and delivers findings located against the array. Tell us why you want the scan, whether it is commissioning, underperformance or a periodic check, and we will scope the flight to the question.