Local efficiency analysis of solar cells based on lock-in thermography

Abstract By evaluating four lock-in thermography images of a solar cell taken at four different biases and an independently measured series resistance image, images of all local two-diode parameters are obtained. Assuming the local validity of the two-diode model, this information enables the construction of local and global dark and illuminated characteristics and of realistic images of local solar cell parameters like efficiency, fill factor, and open circuit voltage with a good spatial resolution. Within this procedure, an injection-dependent lifetime may be regarded by assuming an ideality factor larger than unity for the diffusion current. The possibilities and limitations of this approach are discussed and selected results on a typical industrial multicrystalline cell are introduced. The proposed procedure is a valuable tool for judging which local defects are especially harmful for degrading the fill factor or the open circuit voltage, respectively, and extrapolating the properties of a cell where certain types of defects are excluded. A general limitation of this approach is that it assumes an individual but constant series resistance to each pixel, which neglects the distributed character of the series resistance.

[1]  Thorsten Trupke,et al.  Spatially resolved series resistance of silicon solar cells obtained from luminescence imaging , 2007 .

[2]  Eicke R. Weber,et al.  Fast series resistance imaging for silicon solar cells using electroluminescence , 2009 .

[3]  O. Breitenstein,et al.  Can Luminescence Imaging Replace Lock-in Thermography on Solar Cells? , 2011, IEEE Journal of Photovoltaics.

[4]  Andreas Schenk,et al.  Explanation of commonly observed shunt currents in c-Si solar cells by means of recombination statistics beyond the Shockley-Read-Hall approximation , 2011 .

[5]  O. Breitenstein,et al.  Measurement of the Peltier coefficient of semiconductors by lock-in thermography , 2009 .

[6]  Wilhelm Warta,et al.  Lock-in Thermography: Basics and Use for Evaluating Electronic Devices and Materials , 2003 .

[7]  M. Green,et al.  Departures from the principle of superposition in silicon solar cells , 1994 .

[8]  Martin A. Green,et al.  Spatially resolved photoluminescence imaging of essential silicon solar cell parameters , 2012, PVSC 2012.

[9]  Otwin Breitenstein,et al.  Quantitative evaluation of electroluminescence images of solar cells , 2010 .

[10]  O. Breitenstein,et al.  Imaging the local forward current density of solar cells by dynamical precision contact thermography , 1994, Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC).

[11]  Otwin Breitenstein,et al.  Evaluation of Local Electrical Parameters of Solar Cells by Dynamic (Lock-In) Thermography , 1997 .

[12]  Otwin Breitenstein,et al.  Electrothermal simulation of a defect in a solar cell , 2005 .

[13]  D. Macdonald,et al.  Reduced fill factors in multicrystalline silicon solar cells due to injection‐level dependent bulk recombination lifetimes , 2000 .

[14]  K. Bothe,et al.  Correlation between spatially resolved solar cell efficiency and carrier lifetime of multicrystalline silicon , 2008 .

[15]  Wilhelm Warta,et al.  Efficiency limiting bulk recombination in multicrystalline silicon solar cells , 2012 .

[16]  G. L. Araújo,et al.  The effect of distributed series resistance on the dark and illuminated current—Voltage characteristics of solar cells , 1986, IEEE Transactions on Electron Devices.

[17]  Ronald A. Sinton,et al.  A quasi-steady-state open-circuit voltage method for solar cell characterization , 2000 .

[18]  K. Ng,et al.  The Physics of Semiconductor Devices , 2019, Springer Proceedings in Physics.

[19]  Otwin Breitenstein.  Nondestructive local analysis of current-voltage characteristics of solar cells by lock-in thermography , 2011, PVSC 2011.

[20]  David Hinken,et al.  Recombination current and series resistance imaging of solar cells by combined luminescence and lock-in thermography , 2007 .