Drone Thermography for Solar Farms: Process, Technology & Costs
A 5 MWp solar farm comprises over 12,000 modules. Manually inspecting each one would take days and would not be economically justifiable. Drone thermography has fundamentally changed the inspection of large PV systems: 100% module coverage, geo-referenced, while the system continues undisturbed. This article explains how the technology works, what equipment is used and what a professional drone inspection costs.
Why drones for PV thermography?
Before the drone era solar farms were inspected by hand thermography – a thermographer walked through the site with the camera checking module by module. For a 500 kWp system this meant considerable effort. The result: high costs, low coverage, widely varying results depending on the thoroughness of the inspector.
Drones with integrated infrared cameras solve this problem. They fly automatisierte, GPS-gestützte Routen at a constant speed and constant distance from the module surface and capture IR and RGB images simultaneously. The result is a gap-free, geo-referenced thermogram of the entire site – without quality loss from human fatigue.
This makes drone thermography not only more efficient but also more comparable: every subsequent inspection flies exactly the same route, the results are directly comparable with previous year's inspections. For operators with multiple sites this enables a standardised condition comparison across the entire portfolio.
The technology: drones and infrared cameras
Not every drone with a thermal imaging camera is suitable for professional PV inspections. The requirements of IEC TS 62446-3 for measuring instruments and image quality exclude many consumer solutions. The following platforms have established themselves in professional use:
Mindestanforderung IEC TS 62446-3: For standards-compliant reports the IR camera must have a thermal sensitivity of ≤0.1 K (NETD) and a spatial resolution that permits unambiguous identification of individual cells. Consumer drones with simple thermal imaging cameras (160×120 pixels) do not meet these requirements.
Messbedingungen: Was stimmen muss
Drone thermography only delivers usable results when the atmospheric conditions are right. IEC TS 62446-3 sets clear minimum requirements that apply to all camera types – including drones:
In practice the biggest challenge is not the technology but the weather window. Good thermography days – cloud-free, low wind, sun high enough for 500 W/m² – are not available every day even in the main season. An experienced provider plans flexibly and communicates appointment cancellations early.
Ablauf einer Drohnen-Inspektion
Based on the system data (area, module layout, orientation) the optimal flight route is calculated. Flight speed, height and the overlap of images are chosen such that every module is captured at least once in full. Obstacles such as trees, poles and buildings are incorporated into the route planning.
Before the start, irradiance (pyranometer), wind and cloud cover are measured and logged. This evidence is part of the IEC report and proves the standards-compliance of the measurement. The survey only begins when all parameters are correct.
The drone flies the pre-calculated route fully automatically. IR and RGB images are captured simultaneously and stored geo-referenced. For larger systems multiple batteries are used; the route continues seamlessly. An experienced pilot monitors the flight manually at all times.
In parallel with or following the drone survey all inverters, junction boxes, string boxes, DC main cables and fuses are inspected with the IR hand camera. These components are not accessible to the drone – and are frequently the source of critical defects.
The geo-referenced thermograms are analysed with software support. All anomalies are classified, provided with temperature differences and assigned a priority level. The complete IEC-compliant report contains the site plan, thermograms, RGB comparisons and recommended actions.
Drone vs. IR hand camera: when each makes sense
The drone is not a complete replacement for hand thermography – they are complementary tools for different tasks:
| Aufgabe | Drohne | IR-Handkamera |
|---|---|---|
| Modulinspektion (Fläche) | ✓ Ideal – 100 % Abdeckung, schnell | Possible, but slow and incomplete |
| Wechselrichter | ✗ Nicht möglich | ✓ Unverzichtbar |
| Anschlusskästen | ✗ Nicht möglich | ✓ Unverzichtbar |
| Kabel & Verbinder | ✗ Nicht möglich | ✓ Geeignet |
| Detailaufnahme Einzelmodul | Eingeschränkt (Abstand) | ✓ Sehr detailliert |
| Georeferenzierung | ✓ Automatisch (GPS/RTK) | Manuell, aufwendig |
| Geschwindigkeit | ✓ ~10 Min./MWp | ~2–5 Std./MWp |
| Windbedingungen | Abhängig (max. 4 Bft.) | Unabhängig |
For a complete, IEC-compliant inspection immer beide Methoden nötig. The drone handles the area capture, the IR hand camera the in-depth inspection of the electrical components. Providers offering only drone thermography without BOS inspection do not deliver a complete picture of the system.
Costs of drone thermography for solar farms
The costs for drone thermography of ground-mounted systems are generally calculated by installed capacity (€/kWp) or by area (€/ha). Market guide values for professional inspections incl. BOS thermography and IEC report:
Preisanfrage: The costs for drone thermography depend on farm size, location and desired report scope. Contact us with your system details – we will prepare you an individual quote.
For systems from 750 kWp our transparent price calculation applies via the calculator on the homepage. Based on the findings you can decide whether an in-depth investigation or direct remediation measures make sense.
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The guide value is approx. . Additionally preparation, hand thermography of BOS components and weather breaks where necessary.
Professional inspections use drones such as the DJI Matrice 4T (1280×1024 IR) or DJI Mavic 3T (640×512 IR) with simultaneous RGB capture and GPS geo-referencing. Consumer drones with low-resolution IR cameras do not meet IEC TS 62446-3.
For drones below 25 kg up to 120 m height outside exclusion zones no separate permit is generally required. The pilot needs an EU drone licence. Near airports or in exclusion zones permits are required – we handle this.
The drone detects all thermally visible module defects (hotspots, bypass diodes, PID, substring failures) at 100%. BOS components such as inverters and junction boxes are only accessible via hand thermography – a complete inspection always combines both methods.
Conclusion
Drone thermography has revolutionised the inspection of solar farms. What previously took days is now efficiently completed – fully, geo-referenced and clearly documented. Decisive for professional results are the right equipment (at least 640×512 pixels IR), standards-compliant measurement conditions per IEC TS 62446-3 and the combination with hand thermography for all BOS components.
Anyone who wants to learn more about the basic workings of thermography will find it in the vollständigen Leitfaden all the details. Information on costs can be found in the article What does PV thermography cost?. For solar farms from 750 kWp our no-obligation enquiry form is available.