The storage of intermittent solar energy in chemical bonds, i.e. Solar Fuels, is the most promising way to a future greener energy infrastructure. Chemical specificity in the investigation of the multiscale transient phenomena during semiconductor-driven photoelectrochemical (PEC) redox reactions is the key to a comprehensive understanding and modelling of the processes occurring in Solar Fuel generators. Interfacial energetics and dynamics crucially determine the performance of semiconductor photoelectrodes for (solar) chemical energy conversion. We use a suite of lab- and synchrotron-based X-ray photoemission spectroscopies to investigate interfacial energetics and dynamics in inorganic photoabsorbers. Examples comprise the elucidation of the role of polymorphic marcasite in pyrite (both FeS2)  in enhancing the photoresponse of pyrite based photoelectrodes as well as the evolution and tailoring of surface photovoltage in InP single crystal based model photocathodes for H2 evolution.  Employing XPS based surface photovoltage measurements, we determine the impact of photoreduced surface states in CuBi2O4 photocathodes on their photoresponse. Using the Eindhoven lab-based near-ambient pressure PES facility, the role of varying surface adsorbates could be studied, which is an important step forward towards bridging interface characterization in (ultra-high) vacuum-based and electrochemical conditions. In this lecture, I will highlight the X-ray photoemission methods used and showcase application examples on sulphide, phosphide and oxide photoabsorbers.