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Photovoltaic Module Characterization using Electroluminescence. J.L. Crozier, E.E. van Dyk , F.J. Vorster. Energy Postgraduate Conference 2013. Outline:. Introduction to Electroluminescence (EL) imaging EL spectrum and intensity Voltage dependence of EL intensity Conclusions.
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Photovoltaic Module Characterization using Electroluminescence J.L. Crozier,E.E. van Dyk, F.J. Vorster Energy Postgraduate Conference 2013
Outline: • Introduction to Electroluminescence (EL) imaging • EL spectrum and intensity • Voltage dependence of EL intensity • Conclusions
EL Image of a Solar Cell • Cell Defects • Micro Cracks • Finger Defects • Poor Solder/Contacts • Material Variations • Multi-crystalline Silicon- Grains • Edge-defined Film-fed Growth (EFG) Silicon- Striations • Material Properties (Quantitative Analysis) • Voltage Dependant features Series and Shunt Resistance • Wavelength Dependant features Minority carrier diffusion length/ lifetime
Electrical Input Electrical Output EL Emission Spectrum Solar Cell LED • The intensity of the emitted photons is related to • recombination mechanisms • material properties • optical properties • junction voltage. • The junction voltage varies across the surface of the cell but is not wavelength dependant so can be determined from a spatial EL intensity image. Emission Spectrum Incoming Spectrum (Kirchartz et al., 2009).
Electroluminescence Detection (Fuyuki et. al.2009) • EL Signal: 950 nm – 1300nm, Peak: 1150 nm • Si CCD Camera: 300 nm - 1100 nm
Electroluminescence (EL) • EL image highlights the following defects: • Areas of delamination • Micro cracks • Variations in cell material
EFG Module: EL of Cell Defects Back Contacts Busbar Micro Cracks Micro Crack EFG Material Growth Property
Electroluminescence (EL) • EL image highlights the following defects: • Short-circuited cells • Broken Fingers • Cracks
Electroluminescence Quickly detects micro cracks and other cell defects Material Properties (Quantitative Analysis) Voltage Dependant features Series and Shunt Resistance Wavelength Dependant features Minority carrier diffusion length/ lifetime Application of Electroluminescence Defect Identification in Photovoltaic Modules Conclusions
Acknowledgements CSIR National Laser Centre, Rental Pool Programme