Left panel: NLTE departure coefficients (see Sect. 3.3) for the second and third hydrogen levels calculated with NESSY for the FCHHT-B solar atmosphere model (Fontenla et al. 2009). Right panel: second hydrogen level population in LTE and NLTE cases expressed in terms of the ratio to the total number density. The black curve, corresponding to the left y-axis in both panels, shows the FCHHT-B temperature profile.