Why Aerial Thermography (Done Properly) Is a Game Changer for Solar Asset Health

As a thermographer and drone pilot, I’m often asked why aerial thermography paired with standard RGB imagery has become the go-to method for solar farm inspections across Australia. Simple: it’s fast, repeatable, and it reveals performance issues you can’t reliably see from the ground. But here’s the kicker—not all thermal images are created equal. If the work isn’t done to the right standard, you risk false positives, missed defects, and weak evidence for warranty claims.

Start with the right standard: IEC 62446
For photovoltaic (PV) systems, the benchmark is IEC 62446: “Grid-connected photovoltaic systems – Minimum requirements for system documentation, commissioning tests and inspection.” Working to this standard ensures the inspection delivers defensible data—fit for asset documentation, performance analysis, and warranty support.

A licensed thermographer who understands IEC 62446 will:

Select the correct sensor and lens to achieve the manufacturer-required ground sampling distance (GSD) and thermal resolution.
Capture repeatable datasets for year-on-year comparisons.
Document test conditions (irradiance, wind, ambient and module temperature, time of day) so results are meaningful and comparable.
The big error trap: conditions and technique
Thermal cameras don’t diagnose faults by magic—they measure emitted radiation. Technique and conditions matter.

Common pitfalls we see from inexperienced operators:

Reflections: Shiny glass modules can reflect the sky, pilot, or surroundings, faking hot spots. Proper viewing angles and flight paths reduce this.
Poor irradiance: If the sun isn’t doing its job (low irradiance), anomalies won’t stand out. Plan flights to meet minimum irradiance guidelines for reliable contrast.
Bad geometry: Flying too oblique or too high/low alters apparent temperatures and can smear cell-level detail. Maintain the right altitude and nadir angle to meet resolution requirements.
Inconsistent baselines: Without local reference cells or modules captured under the same conditions, temperature differences are meaningless.
Delta T (ΔT): what the numbers actually mean
Thermal anomalies are all about temperature difference—the ΔT between overheated cells/modules and nearby, normally performing ones under the same conditions. That local comparison is your baseline.

Manufacturers set their own criteria, but a commonly used threshold in practice is around ΔT ≥ 20 °C between hotter-than-normal cells and healthy neighbours. The key is context: a 12 °C delta on a mild, breezy morning may be more telling than a 20 °C delta on a scorching, still afternoon. That’s why we record irradiance, ambient, wind, and module temperatures and show our working in the report.

Modern thermography tools let us:

Measure spot and area temps on-image (with proper emissivity, reflected temperature, and atmospheric corrections),
Overlay RGB and thermal so you can see exactly which module/string is affected, and
Export annotated imagery that stands up in a warranty conversation.
What “good” looks like: our aerial workflow
Pre-flight planning

Confirm site layout, commissioning status, and any known issues.
Check weather and irradiance windows; select altitude and overlaps to hit required GSD and thermal resolution.
On-site setup

Calibrate sensors; set correct emissivity and reflected apparent temperature.
Log environmental conditions (irradiance, wind, ambient).
Acquisition

Fly nadir for uniform coverage; adjust headings to minimise reflection.
Capture radiometric thermal plus high-res RGB for context and asset ID.
Quality control

Verify focus, contrast, and coverage on site; re-fly gaps immediately.
Analysis

Identify anomalies at cell, module, and string level; compute local ΔT against nearby references.
Classify likely issues (e.g., cracked cells, solder/junction problems, bypass diode behaviour, soiling, shading, PID signatures).
Reporting

Provide a clear register: location, image tiles, ΔT, severity, probable cause, and recommended next steps.
Include IEC-aligned documentation suitable for warranty and O&M workflows.
Why pair thermal with RGB?
RGB images anchor every hotspot to a specific module and position, help rule out soiling or shading, and support rapid rectification. When you’re coordinating crews across a big site, precise visual context saves hours.

Choosing a thermography provider: a quick checklist
Licensed thermographer with flight approvals and solar experience.
Radiometric thermal camera capable of cell-level inspection at your array’s altitude.
Demonstrated IEC 62446-aligned workflow and sample reports.
Transparent environmental logging (irradiance, wind, temps) and on-image annotations.
Ability to calculate and justify ΔT using local baselines.
Clear QA process and repeatable survey plans for trend analysis.
The bottom line
Aerial thermography—done to standard and under the right conditions—does more than find “hot spots.” It builds a defensible record of asset health, speeds up maintenance, and strengthens warranty claims. If you’re investing in solar performance, insist on IEC-compliant methods, proper ΔT analysis, and reporting that your O&M team can act on straight away.

Want your next inspection to be both audit-ready and actionable? Bring in a licensed thermographer with the right kit and a repeatable plan, and you’ll see the difference on your bottom line.