  We present a Bloch modes' based Green's function scattering formalism for
cost efficient forward modelling of disordered binary surface textures. The
usage of Bloch modes of an unperturbed reference ordered system as ansatz
allows our formalism to address surface scattering beyond the shallow amplitude
regime. The main advantage of our formalism is the possibility to utilize a
small amount of plane waves to represent the assumed Bloch modes thereby
reducing computational costs, while still allowing one to estimate the
scattering response to all channels accessible by the disordered system.
Benchmarking calculations discussed in the paper demonstrate how the usage of
our Bloch modes ansatz provides an excellent estimate of the scattering
response over an important regime of disorder. As an example of our method's
strength, we examine an electrically decoupled binary light trapping texture
and demonstrate how introducing disorder may improve light incoupling into the
considered solar cell structure.
