Microstructural aspects of interfaces involved in CuGaSe2 (CGSe) based thin film solar cells have been investigated. High resolution transmission electron microscopy and scanning energy dispersive X-ray techniques have been employed for the analysis of complete solar cell cross-sections, revealing details at nanometer scale of the soda lime glass/Mo/MoSe2/CGSe/CdS/i:ZnO/Ga:ZnO heterostructure making up the complete devices. (C) 2003 Elsevier Science B.V. All rights reserved.