Enabling curvable silicon photovoltaics technology using polycarbonate-sandwiched laminate design

• Published in: Solar energy Vol. 220; pp. 462 - 472
• Main Authors: Budiman, A.S., Anbazhagan, S., Illya, G., Song, W.J.R., Sahay, R., Tippabhotla, S.K., Tay, A.A.O.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 15.05.2021; Pergamon Press Inc
• Subjects: Aesthetic design; Analytical modeling; Crack propagation; Cracks; Curvature; Design; Electroluminescence; Finite element method; Finite element simulation; Laminates; Lamination; Laser beam cutting; Mathematical models; Microcracks; Modules; Photovoltaic cells; Photovoltaics; Polycarbonate; Polycarbonate resins; Residual stress; Sequences; Silicon; Slicing; Solar cells; Solar energy; Soldering; Synchrotrons; Upper bounds; Wafers; Analytical modeling; Aesthetic design; Curvature; Finite element simulation
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2021.03.021

•Curving of fragile, brittle silicon solar cell is allowed with the Polycarbonate-sandwiched laminate design.•Highly compressive stress state in silicon solar cells is achieved with the unique photovoltaics (PV) module design.•Analytical modelling is done to explain the curvable silicon PV phenomena.•Finite Element simulation is used to demonstrate further the highly compressive stress state.•Aesthetic design for building-integrated, or automobile-integrated PV is enabled. Cracks in brittle silicon solar cells (wafers) are a major concern in the solar photovoltaics (PV) industry. Because of the slicing of the wafers from large ingots and further stressing during subsequent operations such as soldering and laser cutting, silicon (Si) solar cells often contain microcracks that may grow into larger cracks during cell integration into a PV module. Through our previous works on residual stress probing using synchrotron scanning X-ray microdiffraction (μSXRD) experiments, finite-element modelling of the manufacturing sequences (from cells to laminate) have been validated to predict the stresses highly accurately in the conventional PV module design (glass-cell-backsheet). In the present work, we use those validated finite element methodologies to predict the residual stresses in a novel PV module design in which silicon cells are sandwiched between polycarbonate (PC) sheets – the lightweight PC-cell-PC module. It is shown that the post-lamination residual stresses in the cells are highly compressive, which is good for inhibiting crack growth. This feature also enables the novel PV modules to be curved without the cells cracking, which favors its application to building-integrated or automotive-integrated PV modules. We demonstrate the basic feasibility of the concept – with mini curved PC-sandwiched laminates, showing the upper bounds of the achievable curvature (and their associated stress levels) without any observable cracks in the cells as determined by electroluminescence imaging. The curving here is utilized to demonstrate the larger extent of mechanical stresses the same silicon solar cells could withstand with the PC-PC design.