  We investigate the influence of the variations of energy spectrum of
non-thermal electrons on the resulting GOES classes of solar flares. Twelve
observed flares with various soft to hard X-ray emission ratios were modelled
using different non-thermal electron energy distributions. Initial values of
the flare physical parameters including geometrical properties were estimated
using observations. We found that, for a fixed total energy of non-thermal
electrons in a flare, the resulting GOES class of the flare can be changed
significantly by varying the spectral index and low energy cut-off of the
non-thermal electron distribution. Thus, the GOES class of a flare depends not
only on the total non-thermal electrons energy but also on the electron beam
parameters. For example, we were able to convert a M2.7 class solar flare into
a merely C1.4 class one and a B8.1 class event into a C2.6 class flare. The
results of our work also suggest that the level of correlation between the
cumulative time integral of HXR and SXR fluxes can depend on the considered HXR
energy range.
