Thermal Inspection of a 30.54 MW Ground-Mounted Solar Plant

Drone-based RGB and thermal inspection of the solar plant in Borgdorf-Seedorf, Germany, covering 47,448 photovoltaic modules to identify and assess suspected thermal anomalies requiring maintenance attention.

Utility-scale30.54 MWpThermal + RGBIEC 62446-3 Compliant Thermographic InspectionBorgdorf-Seedorf, Germany2026-08

Hakan Yaralı · Technical Manager

Aerial view of solar panel rows separated by green vegetation

Project at a Glance

Plant capacity: 30.54 MWp
Modules inspected: 47,448
Inspection area: ~20.830 ha
Data captured: Thermal + RGB
Inspection duration: 1 day
Suspected anomalies: 9,551
Location: Borgdorf-Seedorf, Germany
Inspection date: 2026-08
Inspection standard: IEC 62446-3 Compliant Thermographic Inspection

Project Context

The solar plant in Borgdorf-Seedorf, Germany operates where vegetation growth has become an increasingly important factor in plant performance and site management. Over time, unmanaged vegetation around and between the module rows has contributed to more frequent shading, while also increasing the potential fire risk across parts of the site. The plant has an installed capacity of 30.54 MWp DC.

Inspection Scope

What was inspected

Thermal and RGB imagery of all covered module rows
12,288 LONGi LR7-72HYD-640M bifacial modules
35,160 LONGi LR7-72HYD-645M bifacial modules
A total of 47,448 photovoltaic modules were included in the inspection scope
AI-assisted anomaly screening at module level
Detection and classification of module and string-level thermal anomalies
Technical review of identified findings
Prioritization based on estimated operational impact

Methodology

1
Pre-flight planning
Flight altitude was defined to achieve a 3 cm/pixel GSD in accordance with IEC 62446-3 requirements, while overlap and flight route were planned according to the plant layout.
2
RGB and thermal data acquisition
Thermal and RGB imagery was captured across the inspected photovoltaic array.
3
Image quality control and alignment
Coverage and thermal image integrity were checked and imagery was georeferenced for analysis.
4
AI-assisted anomaly screening
Thermal patterns were detected, grouped and mapped to individual photovoltaic modules.
5
Technical review
Detected findings were reviewed and classified according to their thermal characteristics.
6
Reporting and verification plan
Prioritized findings were delivered to the client together with efficiency and loss-impact assessments to support subsequent maintenance activities.

Findings

Finding	Detected pattern	Possible cause	Verification	Status
Open Circuit String	Electrical continuity is interrupted, causing the entire string to become inactive.	Blown fuse, damaged or disconnected cable, faulty connector, or another interruption within the string circuit.	Thermal measurement and visual inspection: reported; further field verification may be required.	Pending
Hotspot	A localized area reaches an abnormally high temperature compared with its surroundings.	Cell damage, microcracks, physical defects, shading, contamination, or other conditions that cause abnormal localized heating.	Thermal measurement and visual inspection: reported; further field verification may be required.	Pending
Cell Fault	A PV cell loses normal function, causing localized heating and reduced performance.	Manufacturing defects, microcracks, physical damage, or deterioration of the affected cell.	Thermal measurement and visual inspection: reported; further field verification may be required.	Pending

Thermal Evidence

Grayscale thermal view of solar panel rows with bright areas near vegetation — Thermal and RGB views of module rows at Borgdorf-Seedorf. Vegetation is visible along module edges; thermal patterns indicate areas requiring further investigation.

Actions and Outcome

Vegetation was found to be concentrated along the lower edges of several PV strings and around module edges, creating localized shading and additional thermal stress in the most affected areas.
Modules exposed to heavier vegetation showed a higher occurrence of cell and multicell anomalies, particularly along the affected edges, indicating areas where vegetation management and module-level maintenance should be prioritized.
The additional efficiency loss and estimated financial impact associated with these affected modules were assessed to help the O&M team identify where corrective action could provide the greatest operational benefit.
An unusually high number of open circuit string anomalies was detected across the plant. Further assessment of their distribution indicated that 20 inverters were non-operational during the inspection.
All findings were prioritized according to their estimated impact on plant efficiency, energy production, and financial loss, providing the client with a clear basis for maintenance planning and field intervention.

Limitations

Thermal imagery can identify temperature patterns requiring investigation, but it does not independently confirm every electrical or mechanical root cause. Irradiance, wind, reflections, shading, soiling, flight conditions and equipment configuration may affect interpretation.