Each subcell in a multijunction solar cell has different material properties that allow for absorption of a certain range of the solar spectrum. However, the power conversion efficiency and the various photovoltaic losses are different for each subcell and are not easily characterized because the subcells are series-connected within the cell stack. In this thesis, it is demonstrated that detailed characterization of each subcell can be accomplished by measuring the absolute electroluminescence response of the solar cell using a hyperspectral imaging system. The instrumentation used and the methodology to calculate the efficiency and loss parameters are detailed in this work and the physical characteristics of three types of multijunction devices are compared with each other.