Daylight defect detection in PV modules using narrow bandpass filters
Publisher
SPIE
Date Issued
2026-10-12
Author(s)
Benkö, Lukas J.
Kern, Martin
Grasel, Bernhard
Wolfgang, Matthias
Fleischhacker, Heinz
Abstract
Daylight electroluminescence (dEL) and photoluminescence (dPL) imaging enable outdoor inspection of photovoltaic (PV) module defects, but their performance is limited by the intense solar background. The current study investigates the influence of narrow optical bandpass filters on SWIR-based dEL and dPL imaging of silicon PV modules. Three narrow bandpass filter configurations near the silicon luminescence peak and the corresponding atmospheric water vapor absorption band, with different bandwidths ranging from 10 nm to 50 nm, were selected to systematically vary the balance between EL signal transmission and solar irradiance suppression. The filters were spectrally characterized and evaluated for solar background suppression, luminescence signal transmission, and defect visibility under outdoor illumination. Outdoor measurements up to ~590 W/m² showed that a narrow bandpass filter near the atmospheric water vapor absorption maximum effectively balances solar background suppression and luminescence signal transmission, enabling reliable defect visibility in both dEL and dPL without lock-in amplification. While dEL is most effective for resolving fine defect structures, dPL provides strong contrast for extended inactive cell areas, indicating that the combined use of both methods offers the most comprehensive defect assessment. These findings highlight the importance of optical filter selection for robust daylight luminescence imaging of PV modules.
Type
Konferenzbeitrag