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Thermo-mechanical stability of lightweight glass-free photovoltaic modules based on a composite substrate

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Martins Ana C., Chapuis Valentin, Virtuani Alessandro, Li Heng-Yu, Perret-Aebi Laure-Emmanuelle, Ballif Christophe,
Project ACTIVE INTERFACES - Holistic strategy for PV adapted solutions embracing the key technological issues
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Original article (peer-reviewed)

Journal Solar Energy Materials and Solar Cells
Volume (Issue) 187
Page(s) 82 - 90
Title of proceedings Solar Energy Materials and Solar Cells
DOI 10.1016/j.solmat.2018.07.015

Abstract

Lightweight PV modules are attractive for building-integrated photovoltaic (BIPV) applications, especially for renovated buildings, where the additional load bearing capacity is limited. This work focuses on the develop-ment of a lightweight, glass-free photovoltaic (PV) module (6 kg/m 2 ) composed of a composite sandwich back-structure and a polymeric front layer. Sandwich structures are usually manufactured with a vacuum bag process and thermosetting liquid glues (e.g. epoxy resin). However, due to the long manufacturing process (> 24 h), liquid adhesives are not compatible with conventional solar industry processes. This work presents the devel-opment of a robust glass-free PV module based on a composite sandwich architecture manufactured with a simple process. To simplify the production, the standard thermoset epoxy is substituted by different PV en-capsulant foils (EVA, ionomer, polyolefin). The results show that a particular formulation of polyolefin is the ideal adhesive to produce a stable backsheet structure. The use of this polymer with a high thermal conductive core (aluminum honeycomb) allows a reduction of processing time from 24 h to 30 min. The mechanical properties of the composite sandwich structure showed an excellent stability under thermal cycling and damp-heat with only 1% and 3% loss in bending stiffness, respectively. Two-cell lightweight PV modules manufactured with this backsheet show good electrical performance after thermal cycling and damp-heat tests, for which, respectively, an output power loss of only 3% and 2% is observed. This configuration is up scaled to a sixteen-cell module for which a power loss of only 3% is measured after damp-heat.
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