Cu2ZnSnSe4 (CZTSe) is a promising quaternary semiconductor material for absorber layers in thin film solar cells [1]. However, CZTSe-based photovoltaic devices often show a low open circuit voltage with respect to the band gap energy, a phenomenon that could be caused by compositional and phase inhomogeneities. Therefore, the detection limits of secondary phases in such absorber layers are an important subject of research. In this work, the sensitivity limits of XANES to the presence of ZnSe and Cu2SnSe3 in CZTSe, two very common and hard to detect secondary phases in such absorbers, are examined. Two sets of samples were studied by XANES in this work. Polycrystalline powders of CZTSe, ZnSe and Cu2SnSe3 have been grown separately by solid state reaction. Later these powders were mixed (CZTSe with 1-20% of ZnSe or CTSe respectively) and investigated by XANES. With the obtained results, we could conclude on the detection and quantification limits of XANES to CTSe and ZnSe as a secondary phase in CZTSe. The second set of samples consisted of an off-stoichiometric CZTSe main phase and ZnSe as secondary phase [2]. Here the main purpose was to clarify the influence of the stoichiometry of the CZTSe standards on the quantification capacity of the XANES method. All of the measurements were performed at the XANES end station of KMC-2 beamline [3] at BESSY II synchrotron at Helmholtz-Zentrum Berlin. Though detection of the CTSe phase was found to be quite limited, it was determined that this method has a very good capacity for detection and quantification of the ZnSe secondary phase in CZTSe. Furthermore, this quantification is stable in when considering the existence of multiple secondary phases in the analysis through the use of the corresponding standards, with the exception of the CTSe phase. It was however discovered that the composition of the CZTSe sample used as the standard can have a strong impact on the analysis, which presents important limitations given the high flexibility in composition of this compound. This study shows that XANES spectroscopy has great potential in the detection of the problematic ZnSe secondary phase within samples of CZTSe and outlines the limitations that may be faced when applying it to this problem.