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Technical Due Diligence Field Testing
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Electroluminescence (EL) Testing
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Infrared Thermography
Understand hidden PV asset risk before acquisition, refinancing, or portfolio review
When you are buying, refinancing, or reviewing an operating solar PV asset, you need evidence that is practical, repeatable, and explainable.
In many operating plants, you do not have a perfect baseline. Factory records may be incomplete. Past inspections may have used different methods. Site conditions may have changed over time. At the same time, stakeholders still need to understand whether hidden module damage, thermal anomalies, or recurring patterns could affect performance, safety, warranty position, or long-term asset value.
Technical due diligence field testing helps you assess an operating PV asset with a scope that can scale across a site or portfolio, without turning every review into a full high-resolution inspection of every module.
When this inspection helps
You are buying, refinancing, or reviewing an operating solar PV asset.
You need evidence that can be explained to investors, lenders, owners, or technical advisors.
You want to identify hidden issues before acquisition or refinancing.
You need a repeatable inspection approach across one site or a portfolio.
You need full-site screening, but also enough detail to understand higher-risk areas.
You want a defined sampling method rather than an open-ended inspection.
You need findings mapped clearly by string, inverter block, site grid, GPS, or plant conventions.
Technical due diligence field testing needs to be broad enough to screen the asset, but structured enough to remain feasible at scale. Intertek CEA may use full-site IR screening, AQL-based EL sampling at string level, and targeted follow-up where screening indicates higher-risk areas or patterns.
| Method / approach | What it helps identify | When it is useful |
|---|---|---|
| 100% IR screening / thermography | Thermal anomalies, hotspots, affected modules or strings, and plant-wide patterns that may need closer review. | Useful for full-site coverage and broad anomaly mapping during technical due diligence. |
| AQL-based EL sampling at string level | Hidden module damage, cell-level anomalies, and recurring defect patterns in a defined sample of strings. | Useful when diligence needs a repeatable sampling approach that is feasible at site or portfolio scale. |
| Targeted follow-up | Higher-risk areas or patterns identified during screening or sampling. | Useful when initial findings show areas that need closer review before the diligence conclusion is finalized. |
The exact scope depends on the diligence objective, asset size, risk appetite, site constraints, and how findings need to be reported for investment or ownership decisions.
How we decide the right scope
The final inspection plan depends on the asset, the transaction context, and how the results will be used.
What decision needs to be supported?
Due diligence may support acquisition, refinancing, portfolio review, or internal asset risk assessment. Each use case may require a different level of documentation, sampling, and reporting.
What level of site coverage is needed?
For technical due diligence, full-site thermal screening can provide broad coverage across the asset. This helps identify thermal anomalies and areas that may require more detailed review.
How should EL sampling be defined?
EL sampling should be planned before fieldwork starts. For diligence-style inspections, the sampling basis can be defined at string level using AQL inspection levels, rather than treating every module as the sampling population.
What triggers targeted follow-up?
The inspection plan should define what happens if screening or sampling shows higher-risk areas, repeating patterns, or unexpected findings. Those triggers help avoid ad hoc decisions during the inspection.
How should findings be mapped?
A diligence report needs to be usable by technical and commercial stakeholders. Before fieldwork starts, it helps to agree how findings will be reported: by string ID, inverter block, site grid, GPS location, or the asset’s existing naming conventions.
What you get
The report should give your team a clear view of:
Which site areas, strings, or samples were inspected
What thermal anomalies or EL findings were observed
Whether findings appear isolated or repeated across the asset
Which areas may require targeted follow-up
How sampling was defined and tracked
How findings are mapped by string, inverter block, site grid, GPS, or plant convention
Whether the findings affect the technical due diligence view of the asset
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