Snail trails and micro cracks

Snail trails (snail tracks) are a product of the formation of silver carbonate nanoparticles which discolor the silver grid. Micro-cracks are instead due to thermo-mechanical stress.

In the first activity (August 2013) and second activity (Summer 2015) the performances of modules affected by "snail trails" and/or "micro-cracks" phenomena are measured and compared to the expected production in order to determine the efficiency and incidental degradation phenomena. Measurement of PV modules' I-V and P-V characteristics under actual environmental conditions, thermal analysis and power output analysis have been performed.

After completing the experimental measurements on affected PV modules we observed that daily energy production can be decreased by 30% when this phenomenon occurs.

Picture, thermal image, and Measured I–V and P–V curves of one PV modules affected by the snail trail phenomena in comparison with datasheet curve.

Maximum power point of some PV modules affected by snail trails or micro-cracks measured at STC in comparison with datasheet value (100%).