The purpose of this talk is to utilize a tool chest of soft x-ray and electron spectroscopies (in particular using high-brilliance synchrotron radiation) to gain insights into the electronic and chemical surface properties of candidate materials for solar water splitting. Focus will be placed on GaInP₂- and Cu(In,Ga)(S,Se)₂-based material systems, and how ambient conditions and deliberate tailoring can modify and impact the surface of such materials. It will be shown that photoelectron spectroscopy (PES), x-ray-excited Auger electron spectroscopy (XAES), inverse photoemission (IPES), x-ray emission spectroscopy (XES), and x-ray absorption spectroscopy (XAS) can be suitably combined to derive band edge positions, band gaps, electronic level alignment, and insights into chemical stability, both with experiments in ultra-high vacuum, as well as under in situ and operando conditions.