Title:	Performance Analysis of Pre-Cracked PV-Modules at Realistic Loading Conditions
Author(s):	C. Buerhop-Lutz, T. Winkler, F.W. Fecher, A. Bemm, J. Hauch, C. Camus, C.J. Brabec
Keywords:	Degradation, Performance, Module, Cracks, EL Imaging
Topic:	Performance, Reliability and Sustainability of Photovoltaic Modules and Balance of System Components
Subtopic:	PV Module Performance and Reliability
Event:	33rd European Photovoltaic Solar Energy Conference and Exhibition
Session:	5CO.8.2
Pages:	1451 - 1456
ISBN:	3-936338-47-7
Paper DOI:	10.4229/EUPVSEC20172017-5CO.8.2
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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Damaged modules, especially with existing cell cracks, are observed quite often in PV-installations. Little knowledge exists about the stability of such pre-cracked modules under real operating conditions. Previous investigations and existing standards focus on the degradation of new, defect-free modules. This work highlights a twofold approach for performance study of pre-cracked modules: 1) artificial stressing of 20 representative pre-cracked modules with a novel load test set-up simulating snow and wind loads, 2) simulating IV-curves of cracked cells. The experimental results are discussed with respect to field exposure data. EL-images of stressed PV-modules indicate that new cracks are only initiated once a certain threshold is exceeded. Below this threshold formerly unseen cracks open, as can be seen by small changes in the EL-intensity. Power measurements yield a strong power reduction at the loaded state. Due to the solar cell being under tension the cracks open and the separated areas lose their electrical contact. Considering a break resistance in the IVcurve, simulations lead to good agreement with the observed experimental results. It is highlighted that the electric contact after unloading for the previously unloaded module recovers visibly in the ELimage as well as in the power output. Simulating real weather (operating) conditions by moderate static loading tests reveals no measurable changes in the EL-images affecting the power output.