The breakdown behaviour of multicrystalline silicon solar cells under -5 to -15 V reverse bias is an important reliability issue for solar modules. Different physical processes may be acting in different breakdown sites. Lock-in thermography (LIT) allows to image local breakdown current densities quantitatively. By performing LIT investigations under different conditions and appropriately combining the results, the temperature coefficient of breakdown sites (in % current change per K) and their slope (in % current change per V) can be imaged quantitatively. By performing special LIT measurements under pulsed illumination, also the local avalanche carrier multiplication factor can be imaged quantitatively.

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