Open Sky Photography · Drone survey guides
Solar panel hot spots: what thermal drone images can tell you
A bright patch in a thermal image of a solar panel is a reason to investigate, rather than a diagnosis on its own. For owners of rooftop and ground-mounted arrays, the useful question is what the pattern means in context and what information a maintenance contractor needs to check it.
This guide explains how to brief a thermal and visual drone inspection, and how to use the results without confusing an image with a confirmed electrical fault.
Start with the performance concern
Explain why you want the inspection. Perhaps output has changed, monitoring shows an alert, visible debris has accumulated or you need a condition record. Provide the site location, approximate array size, layout and any available generation history. A single low-output day is not enough context to identify a problem: season, shading, weather and system operation also matter.
If your maintenance contractor has already identified a suspect area, share its location. Ask how thermal observations will be related to the physical panels so the contractor can find them again.
Why thermal and normal photographs belong together
Thermal imagery records surface-temperature patterns. Visual photographs add context, such as visible soiling, debris, shading or damage large enough to resolve from the camera position. Comparing both views helps distinguish an observation that merits follow-up from a conclusion that the imagery cannot support.
DJI describes the use of drones to view temperature anomalies and inspect arrays during operation in its energy inspection overview. The relevant output for the owner is a traceable set of observations, rather than simply a colourful picture.
Conditions affect what the image shows
The system’s operating state and environmental conditions influence thermal contrast. Reflections, moisture and changing sunlight can complicate interpretation. An inspection plan therefore needs suitable timing and a record of relevant conditions, rather than an assumption that every available flight slot will produce comparable thermal evidence.
FLIR’s guidance on limitations of thermal imaging for PV inspections explains why conditions and operating status matter. Agree with the operator how an unsuitable day will be handled.
What to request in the handover
- An overview showing the agreed inspection area and any coverage gaps.
- Thermal and visual images of the relevant locations.
- A clear way to locate each observation on the array.
- The scope and limitations of the inspection.
- A written report or annotated panel plan if included in your quotation.
For illustration, “unusual thermal pattern in the third row beside the rooflight, matched to image 12” is more useful for follow-up than “several hot panels”. This is an example of a reporting brief, not a finding from your site.
What happens after a hot spot is identified?
Use the image record to direct an appropriate on-site check. Thermal imagery alone does not confirm the cause, quantify lost generation or prove that replacing a module is necessary. Electrical testing and specialist diagnosis may be needed. Cleaning, repairs and testing are separate from the aerial capture unless expressly included.
Keep the original report and any subsequent findings together. If you commission a repeat inspection, explain what has changed since the first visit so the comparison has a clear purpose.
Arrange a solar inspection in Scotland
Open Sky Photography combines infrared and high-definition visual capture for solar inspections across Edinburgh, East Lothian and Scotland. See our thermal image gallery and deliverables guide, then send your site location, array size and reason for the inspection.
