Abstract: A method for determining the parameters of a photovoltaic device having at least one multi-junction solar cell is provided. The solar cell includes at least two subcells layered on top of one another and connected electrically and optically in series, each having a p-conductive layer, an intrinsic layer, and an n-conductive layer. At least one reference cell is produced for each subcell. One subcell of each reference cell corresponds to one subcell of the at least one multi-junction solar cell. In contrast, the subcell of each reference cell has at least one layer which corresponds to the i-layer of the multi-junction solar cell, but which is converted into an electrically conductive layer by doping. The spectral sensitivity of the reference cells is measured. For determining the parameters of the solar cell, the reference cells and the solar cell are measured using a solar simulator calibrated to the reference cells.