A method for experimental assessment of the shifting approximation, with application to polysilicon solar cells

A straightforward experimental method is developed for assessing the validity of the shifting approximation, , for polysilicon and other polycrystalline solar cells. The method uses the fact that, in a solar cell for which the shifting approximation is valid, a constant series resistance, independent of illumination, will cause the light and dark curves to be symmetrically displaced with respect to the curve. This symmetry is discussed in detail. The experimental data suggest that the shifting approximation is valid and the series resistance is independent of illumination up to at least one-sun intensity for a variety of polysilicon solar cells in which the intragrain-base minority carrier diffusion length is smaller than or equal to the average grain diameter.