  CONTEXT: In recent years, the solar chemical abundances have been studied in
considerable detail because of discrepant values of solar metallicity inferred
from different indicators, i.e., on the one hand, the "sub-solar" photospheric
abundances resulting from spectroscopic chemical composition analyses with the
aid of 3D hydrodynamical models of the solar atmosphere, and, on the other
hand, the high metallicity inferred by helioseismology. AIMS: After
investigating the solar oxygen abundance using a CO5BOLD 3D hydrodynamical
solar model in previous work, we undertake a similar approach studying the
solar abundance of nitrogen, since this element accounts for a significant
fraction of the overall solar metallicity, Z. METHOD: We used a selection of
atomic spectral lines to determine the solar nitrogen abundance, relying mainly
on equivalent width measurements in the literature. We investigate the
influence on the abundance analysis, of both deviations from local
thermodynamic equilibrium ("NLTE effects") and photospheric inhomogeneities
("granulation effects"). RESULTS: We recommend use of a solar nitrogen
abundance of A(N)=7.86+-0.12 whose error bar reflects the line-to-line scatter.
CONCLUSION: The solar metallicity implied by the CO5BOLD-based nitrogen and
oxygen abundances is in the range 0.0145<= Z <= 0.0167. This result is a step
towards reconciling photospheric abundances with helioseismic constraints on Z.
Our most suitable estimates are Z=0.0156 and Z/X=0.0213.
