  Modeling the interior of exoplanets is essential to go further than the
conclusions provided by mean density measurements. In addition to the still
limited precision on the planets' fundamental parameters, models are limited by
the existence of degeneracies on their compositions. Here we present a model of
internal structure dedicated to the study of solid planets up to ~10 Earth
masses, i.e. Super-Earths. When the measurement is available, the assumption
that the bulk Fe/Si ratio of a planet is similar to that of its host star
allows us to significantly reduce the existing degeneracy and more precisely
constrain the planet's composition. Based on our model, we provide an update of
the mass-radius relationships used to provide a first estimate of a planet's
composition from density measurements. Our model is also applied to the cases
of two well-known exoplanets, CoRoT-7b and Kepler-10b, using their recently
updated parameters. The core mass fractions of CoRoT-7b and Kepler-10b are
found to lie within the 10-37% and 10-33% ranges, respectively, allowing both
planets to be compatible with an Earth-like composition. We also extend the
recent study of Proxima Centauri b, and show that its radius may reach 1.94
Earth radii in the case of a 5 Earth masses planet, as there is a 96.7%
probability that the real mass of Proxima Centauri b is below this value.
