Single layers and combined layer systems with Cu(In,Ga)(S,Se)2, ZnS-nanodot (nd) and In2S3 layers were investigated by surface photovoltage spectroscopy in the Kelvin-probe arrangement and compared with the open-circuit voltage (VOC) of solar cells. The In2S3 and ZnS-nd layers were prepared by the spray ion layer gas reaction (ILGAR) technique from Indium chloride (InCl3), Indium acetylacetonate (In(acac)3) and Zinc acetylacetonate, respectively. The surface photovoltage signals of Cu(In,Ga)(S,Se)2 were larger for the Cu(In,Ga)(S,Se)2/ZnS-nd/In2S3 than for the Cu(In,Ga)(S,Se)2/In2S3 layer system showing that a ZnS-nd layer additionally passivated the Cu(In,Ga)(S,Se)2 surface. ILGAR In2S3 deposition from InCl3 precursor solution led to a modification of surface defects of ZnS-nd and to generation of defect states below the band gap of Cu(In,Ga)(S,Se)2, which has not been observed for deposition from Indium acetylacetonate precursor. Defect generation during ILGAR In2S3 deposition with InCl3 precursor resulted in a lower VOC of Cu(In,Ga)(S,Se)2/ZnS-nd/In2S3/ZnO : Al solar cells. Copyright © 2012 John Wiley & Sons, Ltd.