title: Fatigue degradation and electric recovery in Silicon solar cells embedded in photovoltaic modules.
abstract: Cracking in Silicon solar cells is an important factor for the electrical power-loss of photovoltaic modules. Simple geometrical criteria identifying the amount of inactive cell areas depending on the position of cracks with respect to the main electric conductors have been proposed in the literature to predict worst case scenarios. Here we present an experimental study based on the electroluminescence (EL) technique showing that crack propagation in monocrystalline Silicon cells embedded in photovoltaic (PV) modules is a much more complex phenomenon. In spite of the very brittle nature of Silicon, due to the action of the encapsulating polymer and residual thermo-elastic stresses, cracked regions can recover the electric conductivity during mechanical unloading due to crack closure. During cyclic bending, fatigue degradation is reported. This pinpoints the importance of reducing cyclic stresses caused by vibrations due to transportation and use, in order to limit the effect of cracking in Silicon cells.
authors.affiliation: IMT Institute for Advanced Studies Lucca, Research unit MUSAM - Multi-scale Analysis of Materials, Piazza San Francesco 19, 55100 Lucca, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Paggi
authors.affiliation: Politecnico di Torino, Department of Structural, Geotechnical and Building Engineering, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Berardone
authors.affiliation: Politecnico di Torino, Department of Structural, Geotechnical and Building Engineering, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Infuso
authors.affiliation: Politecnico di Torino, Department of Structural, Geotechnical and Building Engineering, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Corrado