Improved Robustness Against Thermal Stress for Building-Integrated PV Modules Built on Aluminum Façade Elements

The combination of materials from the photovoltaics (PV) industry and the building industry is often a challenge for building-integrated PV (BIPV). In this work, we combine typical materials for PV module manufacturing with aluminum, a common façade material. We build BIPV modules with crystalline silicon solar cells by directly laminating the solar cell strings on aluminum façade elements. Silicon and aluminum differ twice as much in thermal expansion coefficients than silicon and glass do. This induces high mechanical stress in the BIPV modules when the temperature varies during processing or operation. As a consequence, copper wires interconnecting the silicon solar cells might be ripped off the solar cells or even break. This work analyzes the degradation behavior of such BIPV modules with aluminum sheets on the rear side under variations in temperature. Horizontal crimps in the interconnectors in between the solar cells reduce thermal stresses and prevent the interconnectors from ripping off. Therefore, the horizontal crimps improve the reliability of BIPV modules built on aluminum façade elements. The relative remaining module power after 200 thermal cycles between −40°C and +85°C increases from 92.2% without horizontal crimps to 97.8% with strain relief by horizontal crimps for BIPV modules made of 10 half-cut silicon solar cells that are directly laminated on aluminum sheets.