The classical effective-medium theory for the calculation of the conductivity and Hall coefficient of inhomogeneous semiconductor alloys with the presence of photogenerated nonequilibrium charge carriers is developed. Using the composite spherical inclusions model it is shown that the Hall mobility is always less than the initial one, while the Hall concentration of free charge carriers is defined mainly by the concentration of charge carriers in the connected region and does not coincide with the sample mean concentration. The Lux - Ampère characteristic of inhomogeneous semiconductor alloys is shown to be a linear function for weak and logarithmic function for high illumination intensities.