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The existence of cracks in silicon solar cells can drastically reduce the electrical performance of an individual cell and even of an entire photovoltaic module. An in-depth understanding of the influence of cracks on solar cells enables therefore calculations of the crack impact and other following effects on module level. This paper shows a detailed analysis of the electrical influence of cracks with two different spatially resolved methods including global and local current-voltage characteristics. The main influence of cracks is an increased recombination current density in the depletion region, which is clearly shown by spatially resolved dark lock-in thermography measurements with local current-voltage investigation. This increased recombination current density affects further cell parameters such as the efficiency, which is confirmed also by the global current-voltage characteristics. The additionally used ratio image technique based on electroluminescence measurements is in comparison with the local current-voltage method, the more reliable and faster method for the crack detection itself, and allows on cell-level and module-level a continuous inspection of cracks. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT An algorithm to calculate the current in the two-diode equivalent circuit of a solar cell is described and characterized in detail. It enables fitting measured current-voltage characteristics with hundreds of voltage points and six fit parameters at practically instantaneous speeds and can handle thousands of voltage points within a few seconds, without simplifications of the two-diode model. This performance enables routine two-diode model parameter extraction at in-line speeds, which may help to enhance cell characterization for module integration. The source code is publicly available. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, we demonstrate single-sided screen-printed emitters in thin monocrystalline Czochralski silicon (Cz-Si) wafers with an improved gettering of iron compared with conventional double-sided POCl3 emitters. The phosphorus dopant pastes used have to be chosen carefully to provide a sufficiently low emitter sheet resistance and to avoid iron contamination. The iron concentration is determined in a non-destructive way from the minority carrier lifetime obtained by quasi-steady-state photoconductance measurements, down to levels not yet demonstrated for screen-printed emitters. In addition, the well-known metastable boron-oxygen complexes in Cz-Si have been transferred into a stable state by light-induced degradation prior to these measurements. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]