As the partial shadowing on a module had a nonlinear influence on the output current [32–35], the measurements were repeated by means of shadowing the light source instead. The experimental setup was arranged so that a transparent flat glass was placed on the light source and the opal glass was positioned so as to transmit the incoming light to the solar module by scattering. The incident light amount on the opal glass is changed by the sample areas prepared by opaque carton and semitransparent white paper materials and solar module’s short circuit current and open circuit voltage measurements were carried out.