In the present work a Lamb wave based approach for yield strength characterization of solar cell interconnectors — typical plate-like photovoltaic module components — was evaluated. The sensitivity of this method was investigated by a systematic variation of the ribbon microstructure (by annealing and mechanical loading). Lamb wave approaches previously turned out to be well suited methods for inline material characterization of solar cell interconnectors with respect to its elastic properties (Young’s modulus, Poisson’s ratio). Following the results of this paper, Lamb waves also can be used to examine inelastic mechanical characteristics such as yield strength. This increases the industrial application range drastically and makes Lamb wave measurements even more powerful for inline and non-destructive material characterization.