Tutorial 4

Tutorial 4
Power losses in solar cells: Analytical toolbox

Tutorial Overview

Solar cells must efficiently absorb sunlight and convert the photons into electrons and holes.  It is important to routinely quantify the optical losses and recombination losses that exist throughout the cell to identify areas to improve. In particular for multicrystalline cells we should know how strong certain defect regions degrade the efficiency of a cell. By combining commonly available solar cell characterization methods with easy-to-prepare test structures and partially processed rear-passivated solar cells from the production line, we show that various cell loss mechanisms can be quantified in exquisite detail to generate process-related diagnostics.  Examples in p-type monocrystalline silicon localized back surface field (LBSF) solar cell and n-type bifacial silicon solar cell are examined using a systematic routine that breaks down the factors limiting open-circuit voltage, short-circuit current and fill factor, to identify the cell structures’ headroom for improvement.

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Overview of all the PVSEC-26 Tutorials


Tutorial conductors:  
Dr Otwin BREITENSTEIN, Max Planck Institute of Microstructure Physics & Dr Johnson WONG, SERIS

Dr Otwin Breitenstein received his Ph.D. in physics from University of Leipzig (Germany) in 1980 with a work on Deep Level Transient Spectroscopy (DLTS). Since 1992 he is with Max Planck Institute of Microstructure Physics, Halle, Germany, where he investigates defects in semiconductors. Since 1999, he has been using lock-in thermography, optical imaging methods, and electron microscopy for characterizing crystalline solar cells. His in mainly interested in detecting internal shunts and generally evaluating the local efficiency of inhomogeneous silicon solar cells. He is Assistant Professor at University of Halle, Germany, giving lectures on the physics of solar cells and on advanced characterization techniques. He is author of several hundred publications in journals and at conferences and author of a book on "Lock-in Thermography" (Springer 2003, second edition 2010).

Johnson Wong is the head of PV characterisation at the Solar Energy Research Institute of Singapore (SERIS). He completed his PhD in photovoltaic engineering at UNSW in the area of thin-film silicon on glass solar cells. Since then he joined SERIS as a scientist, engaging in various research topics such as screen-printed and evaporated-metal all-back-contact solar cells, and a-Si:H/uc-Si:H c-Si heterojunction solar cells. His current work includes the development of photoluminescence and electroluminescence detection and analysis methods, application of solar cell reciprocity relations, and the study of the impacts of solar cell lateral non-uniformity and distributed resistances on device performance.  Johnson is the inventor of Griddler, a computer program that applies full area, two-dimensional finite element analysis (FEA) to solar cells with arbitrary metallisation geometries.