  Due to the high quality constraints available for the Sun, we can carry out
combined analyses using neutrino, spectroscopic and helioseismic observations.
Such studies lay the ground for future improvements of key physical components
of solar and stellar models, such as the equation of state, radiative opacities
or prescriptions for macroscopic transport processes of chemicals which are
then used to study other stars in the Universe. We study the existing
degeneracies in solar models using the recent high-metallicity spectroscopic
abundances by comparing them to helioseismic and neutrino data and discuss how
their properties are impacted by changes in various physical ingredients. We
carry out a detailed study of solar models computed with a high-metallicity
composition from the literature based on averaged-3D models that was claimed to
solve the solar problem. The properties of the solar models are significantly
affected by using the recent OPLIB opacities and the inclusion of macroscopic
transport. The properties of the standard solar models computed using the OPAL
opacities are similar to those using the OP opacities. We show that a modifying
the temperature gradient just below the base of the convective zone is required
to erase the discrepancies in solar models, particularly in the presence of
macroscopic mixing. This can be simulated by a local increase of opacity of a
few percent. We conclude that the existing degeneracies and issues in solar
modelling are not erased by an increase in the solar metallicity in
contradiction to was suggested in recent papers. Therefore, standard solar
models cannot be used as an argument for a high metallicity composition. While
further work is required to improve solar models, we note that direct
helioseismic inversions indicate a low metallicity in the convective envelope,
in agreement with spectroscopic analyses based on full 3D models.
