A baseline parameter set for electrical modelling of Cu(In,Ca)Se-2 solar cells with compositionally graded absorber and CdS buffer layer is established. The cases with and without Fermi level pinning as well as with and without a surface defect layer are considered. Simulations with a defect layer are observed to give the best correspondence to measurements. Zn1-xMgxO buffer layers are introduced and initial modelling of the light soaking behaviour is performed. Simulation results are compared with experimental data. (C) 2010 Elsevier B.V. All rights reserved.