This interdisciplinary project aims to systematically investigate the fundamental physical and chemical processes during the synthesis of kesterite materials based on Cu₂ZnSn(S,Se)₄​ crystal structures from a theoretical perspective. Theoretical calculations will be based on Density Functional Theory (DFT) implemented in modern software packages such as CP2K, ORCA, Ambient, and FDMNES. To validate the theoretical results, measurements will be conducted using X-ray techniques—specifically X-ray Emission Spectroscopy (XES) and X-ray Absorption Spectroscopy (XAS)—which will also provide deeper insights into the synthesis process itself. Additionally, a significant portion of the research will focus on environmental impact studies of these new solar materials. Due to the limited scope of the project, we have focused strictly on one type of material; however, all theoretical methods, experimental characterizations, and environmental impact studies are applicable to other essential materials for the green transition, including batteries and catalysts.