Thermografie Photovoltaik:
The complete guide
Photovoltaic systems work silently. No noise warns of an overheating module, no fault message appears when a bypass diode fails. Thermographic inspection is the only method that checks the entire system for defects quickly, without contact and during live operation. This guide explains how it works, what it costs, which defects it finds – and when it is worthwhile.
Basics: what is thermography for photovoltaics?
Thermografie an Photovoltaikanlagen is a non-destructive testing method based on infrared measurement technology. Every object with a temperature above absolute zero emits heat in the form of infrared radiation. A thermography camera captures this radiation and converts it into a colour-coded image – the so-called thermogram.
During operation under solar irradiance intact solar modules produce an even temperature distribution. Where defects are present increased electrical resistance develops: electrical energy is not conducted as current but converted into heat. These local temperature increases – Hotspots – are visible in the thermogram as bright spots and can be precisely assigned to a module, a cell string or an individual component.
The method has a decisive advantage over all other inspection methods: The system neither needs to be shut down nor dismantled. An inspection during normal operation is not only possible but necessary – only under load are the thermal anomalies pronounced enough to be reliably detected.
Measurement conditions per IEC TS 62446-3: At least 500 W/m² solar irradiance, maximum cloud cover 2/8, wind below 4 Beaufort, thermal equilibrium of the modules. These conditions are reliably achievable in Germany from March to September.
Drone or IR hand camera – technology overview
Professionelle PV-Thermografie setzt heute auf zwei sich ergänzende Aufnahmemethoden:
Drohnen-Thermografie: Vollflächige Befliegung
For rooftop systems from approximately 50 kWp and all ground-mounted systems drone survey is the standard. A drone with an integrated infrared camera flies automated, GPS-guided routes over the system and captures IR and RGB images simultaneously. The images are stored geo-referenced so every module can be precisely located on a map.
Current drone platforms such as the DJI Matrice 4T with a 1280×1024 pixel IR sensor enable complete 100% coverage of large systems in a few hours. Analysis can subsequently be carried out software-assisted or AI-assisted.
IR hand camera: detailed inspection and BOS components
Inverters, junction boxes, fuses and cable connections – the so-called BOS-Komponenten (balance of system) – are not accessible to a drone. Hand thermography is indispensable here. With a high-performance IR hand camera such as the FLIR T series individual components can be inspected at close range and even the smallest temperature differences of less than 0.1 K can be captured.
A complete inspection always combines both methods: the drone for the area survey, the IR hand camera for the in-depth and component diagnosis.
| Kriterium | Drone thermography | IR-Handkamera |
|---|---|---|
| Abdeckung | 100 % aller Module, flächig | Selektiv, punktuell |
| Geschwindigkeit | ~10 Min. pro MWp | Depending on level of detail |
| Georeferenzierung | GPS-gestützt, automatisch | Manuell |
| BOS inspection | Nicht möglich | Unverzichtbar |
| Auflösung (IR) | 640×512 bis 1280×1024 px | Bis 1024×768 px |
| Einsatz ab | Ca. 50 kWp | Jede Anlagengröße |
Detectable defects: what does thermography see?
Thermography detects all defects that manifest through altered heat emission. The following anomalies are the most common findings in PV inspection:
Hotspot
Local overheating of individual cells from increased resistance. Most common fire cause in PV systems. From ΔT >30 K immediate action is required.
Bypass-Diode defekt
Uniformly heated cell strip across 1/3 or 1/4 of the module. Identifiable by the characteristic strip pattern in the thermogram.
PID-Degradation
Potential-induced degradation: elevated edge temperatures as the first sign. Reversible when detected early – irreversible with prolonged progression.
Substring-Ausfall
Complete failure of a cell string from a line break or connection fault. Means 33% power loss per affected module.
Anschlusskasten-Defekt
Overheated connectors, corroded contacts or faulty seals – the main cause of system failures and electrical fires.
Delamination
Detachment of the encapsulation film allows moisture ingress. Common in systems from 8–10 years of age. Visible in the thermogram as an irregular heat pattern.
Mikrorisse (teilweise)
Advanced microcracks with cell failure are thermographically detectable. Early, inactive cracks additionally require an EL measurement.
Verschmutzung & Verschattung
Bird droppings, leaves and moss create characteristic temperature patterns. The most cost-effective measure: cleaning increases yield immediately and measurably.
Standards and certifications
Professional PV thermography is normatively regulated. The following standards are decisive for insurance-compliant, court-admissible and warranty-relevant reports:
Ablauf einer professionellen PV-Thermografie
Inquiry and planning
Recording of system data (location, kWp, system type, orientation). Planning the measurement window based on the weather forecast – at least 500 W/m² irradiance and calm wind are prerequisites.
Vor-Ort-Inspektion
Drone survey with simultaneous IR and RGB capture of all modules (100% coverage). Subsequently hand thermography of all BOS components: inverters, junction boxes, cable trays, fuses.
Analysis and classification
All thermograms are analysed to IEC TS 62446-3. Anomalies are classified: fault type, temperature difference, affected area and action priority (critical / medium / low).
Berichterstellung
Structured inspection report with geo-referenced thermograms, comparison of RGB and IR images, temperature tables, yield-loss calculation and prioritised recommended actions. Insurance-compliant to VdS 2858.
Instandsetzung (optional)
On request we carry out the complete repair – module and component replacement, final control thermography and documentation of the repaired condition. Full service from a single source.
What does PV thermography cost?
The cost of PV thermography depends on system size, location and desired scope of service. The following market ranges serve as guidance:
Preisanfrage: The cost of PV thermography depends on system size, location and desired report scope. We will prepare an individual quote on request.
Für PV systems of all sizes we prepare a transparent quote by system size and location. Contact us – we will clarify together which scope of service (Basic, Complete or Premium) makes sense for your system.
Wirtschaftlichkeit: Undetected defects cause annual yield losses that add up considerably over the lifetime of a system. In most cases an inspection pays for itself quickly – provided defects found are also remedied.
We come to you, survey the system completely and provide an initial assessment – without a fee. Individual quote on request.
Analyse anfragen →Häufig gestellte Fragen
Thermography for photovoltaics is a non-contact inspection method in which infrared cameras measure the heat emission from solar modules during operation. Defective cells generate more heat than functioning ones – these temperature differences are visible in the thermogram as hotspots.
The governing standard is IEC TS 62446-3, which defines measurement conditions, equipment requirements, inspection procedures and report contents. Additionally VdS 2858 applies for insurance-compliant expert reports and DIN EN ISO 9712 for the certification of inspection personnel.
For small rooftop systems up to 30 kWp market prices are available on request. For commercial systems from 750 kWp we offer a no-obligation enquiry – available on request. For the complete IEC report we prepare an individual quote.
Drones are suited to the full-coverage inspection of large systems with 100% coverage and geo-referencing. IR hand cameras are indispensable for BOS components such as inverters and junction boxes. Professional inspections always combine both methods.
Conclusion
Die Thermografie an Photovoltaikanlagen is the most efficient and least invasive method for assessing the condition of a PV system. It delivers a complete picture of all actively effective defects quickly – without touching the system or interrupting its operation.
Decisive for usable results are the correct measurement conditions and compliance with IEC TS 62446-3. A standards-compliant report is not only technically more valuable – it is also a prerequisite for usability with insurers, warranty claims and court expert reports.
Wenn Sie wissen möchten, when the right time for thermography is, or what an inspection specifically costs, you will find more information in our knowledge base. For systems from 750 kWp we are happy to prepare a free initial assessment.