Overview
IEC TS 63342:2022 - "C‑Si photovoltaic (PV) modules - Light and elevated temperature induced degradation (LETID) test - Detection" specifies a reproducible laboratory procedure to detect sensitivity of crystalline‑silicon (C‑Si) PV modules to LETID using a current injection approach. The Technical Specification defines sample preparation, apparatus, measurement accuracy and a test sequence that reveals LETID‑related performance loss at elevated temperatures (>50 °C). It emphasizes detection (sensitivity) rather than providing an exact prediction of field degradation.
Key topics and requirements
- Test focus: Detection of LETID activated by excess carriers at elevated temperature via electrical current injection (not light‑only stress).
- Scope limits: B‑O (Boron‑Oxygen) and Fe‑B (Iron‑Boron) degradation phenomena are excluded from the test objective; procedures attempt to separate their effects but separation may be imperfect. The method does not quantify field‑observable degradation magnitude or timing.
- Samples: Three modules - one control and two test samples - stored in the dark (≤35 °C) and produced under normal manufacturing controls.
- Apparatus essentials:
- Climatic chamber capable up to (75 ± 3) °C with air circulation and condensation control.
- Temperature sensors and instruments (accuracy ±2.0 °C, repeatability ±0.5 °C).
- Current source able to apply the specified continuous injection current (accuracy 1 % or better).
- Voltage/current monitoring with resolution ≥5 min and accuracy ±0.2 %.
- Measurements and sequence: visual inspection, electroluminescence (EL) imaging (forward bias at ISC and optionally 0.1·ISC), initial performance at STC, B‑O preconditioning via current injection (CID), LETID stress sequence, dark voltage monitoring, and defined stop criteria based on temperature‑corrected dark voltage evolution.
- Data handling: temperature correction, filtering, averaging and explicit stop criteria for the LETID sequence are specified to ensure reproducibility.
Applications and users
- Who benefits: PV module manufacturers, test laboratories, R&D teams, quality assurance engineers and reliability specialists concerned with PV module degradation mechanisms.
- Practical uses:
- Screening module designs and production lots for LETID sensitivity.
- Comparative lab evaluation of cell/module processes and materials.
- Supporting root‑cause analysis using EL and dark‑voltage diagnostics.
- Limitations: Use for detection and comparison; not a direct replacement for long‑term field monitoring or full quantification of site‑specific degradation.
Related standards
- IEC 61215‑1 / IEC 61215‑2 (PV module qualification tests)
- IEC TS 60904‑13 (Electroluminescence of PV modules)
- IEC TS 63202‑4 (cell LETID test methods - differing injection levels)
Keywords: IEC TS 63342:2022, LETID detection, C‑Si PV modules, current injection, EL imaging, dark voltage, B‑O, Fe‑B, climatic chamber, STC performance.