Shading-induced failure in thin-film photovoltaic modules: Electrothermal simulation with nonuniformities

• Published in: Solar energy Vol. 139; no. C; pp. 381 - 388
• Main Authors: Nardone, M., Dahal, S., Waddle, J.M.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.12.2016; Pergamon Press Inc; Elsevier
• Subjects: Cu(In,Ga) Se; Degradation; Electroluminescence; Finite element analysis; Mathematical models; Monolithic modules; Numerical simulation; Photovoltaic cells; Reverse bias breakdown; Simulation; Thin films; Degradation; Monolithic modules; Numerical simulation; Cu(In,Ga) Se; Reverse bias breakdown
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2016.10.006

[Display omitted] •A method for electrothermal simulation of monolithic thin-film modules is described.•Low reverse breakdown spots in CIGS modules carry significant current when shaded.•Thermal runaway leads to a breakdown event and permanent damage.•Ohmic shunts result in excessive module heating and power loss. Finite element electrothermal modeling is employed to study shading-induced failure in monolithically integrated thin-film photovoltaic modules. A key element is spatial nonuniformity in current-voltage characteristics, which causes inhomogeneous current flow when part of a module is under reverse bias due to shading. Time-dependent calculations show that spots with lower reverse breakdown voltage experience greater current density and localized thermal runaway that can cause permanent damage, resulting in ohmic shunts. Such failure events lead to performance loss, especially when the module is in normal operating conditions and shunted currents lead to abnormally high module temperatures. Our simulations of temperature distributions, current-voltage characteristics, and electroluminescence are compared to data from the literature for copper indium gallium diselenide devices.