Cu(In,Ga)Se-2 absorbers were investigated by surface photovoltage (SPV) in the Kelvin probe and fixed capacitor arrangements before and after deposition of CdS or In2S3 buffer layers as well as before and after deposition of ZnO window layers. Effects such as passivation of surface states, partial electron transfer from ZnO into In2S3, decrease of the ideality factor after deposition of ZnO and slow electron transfer through In2S3 were demonstrated. The results show that SPV measurements open opportunities for dedicated studies of charge separation at hetero-junctions between ordered and disordered semiconductors. (C) 2013 Elsevier B.V. All rights reserved.