Automated Screening for Decommissioned PV Modules

A research group in Australia has developed an automated screening method to qualify decommissioned PV modules for second-life applications. The method comprises two main current-voltage (I-V)-based screening steps: quality-control pre-filtering and quantitative module health assessment.

The key novelty of this method is its scale and breadth of analysis. The researchers applied a quantitative I-V screening framework to several thousand decommissioned modules, estimated their residual useful life, and compared the results with electroluminescence (EL) imaging and wet leakage insulation-resistance testing.

The framework was demonstrated using a prototype implementation of portable Rapid-Triage screening equipment developed by Commonwealth Scientific and Industrial Research Organization (CSIRO) Energy. Testing was carried out by Australian circular PV solutions provider Second Life Solar.

The measurement campaign was conducted over 18 testing days between December 2024 and June 2025. The final dataset comprised 3,749 modules with associated I-V datasets suitable for detailed analysis, of which 3,679 also had matching EL data. The modules came from more than 100 manufacturers and had rated power outputs ranging from 160 W to 370 W.

The modules originated from a range of decommissioning pathways, including end-of-life replacement and early replacement for various reasons, such as system upgrades, weather damage, and building works.

### Screening Process

The screening process consists of two stages. In stage 1, the system acts as a quality-control pre-filter, rejecting modules with clearly abnormal I-V characteristics, including substring mismatches, non-diode-like behavior, early current collapse, steep low-voltage slopes, and low Vmp/Voc ratios.

Modules that pass the first stage proceed to stage 2, where their condition is assessed quantitatively using key I-V parameters, including fill factor (FF), series resistance (Rs), shunt resistance (Rsh), and estimated power degradation.

### Results

In the main analysis, modules were rejected if their fill factor was below 60% or their estimated degradation exceeded 25%. The resulting automated pass/fail classifications were then compared with manual screening based on I-V and EL data and, separately, with IEC 61215 wet-leakage testing.

The quantitative I-V screening of the dataset found 58.1% of the analyzed modules acceptable based on the selected performance criteria. The median estimated residual useful life for modules that passed I-V screening was around 12 years.

However, the researchers highlighted that around 14% of modules that passed the combined I-V and EL screening failed wet-leakage testing.

“This shows that a module can appear suitable from a performance perspective, yet still have insulation-related issues that require additional testing,” said corresponding author Marco Ernst.

### Implications

The results of this study demonstrate that a module that still performs well is not necessarily safe to reuse. Poor insulation can create electrical safety risks and can also cause operational problems, such as triggering inverter ground-fault protection.

For second-life PV to gain wider uptake, industry and consumers need confidence in both the performance and safety of reused modules. The study's results show that these are different aspects of module condition, and that a more comprehensive screening process is needed to ensure the safe and efficient reuse of decommissioned PV modules.