Electro-optical techniques are widely used to study nanodisperse systems and obtain geometrical, electrical, and optical characteristics of particles in the suspension. The theory that describes electro-optical effects in nanodisperse systems employs several generic relations which could benefit from fast numerical calculations. The presented Taylor series expansion and differential equations allow to perform such numerical calculations fast and with a pre-defined accuracy. To take into account the polydispersity of the particles in the solution the optical properties of particles need to be taken into account. The theory that allows to do this is presented.