In this paper, the design and optimization of advanced multijunction photovoltaic devices, utilizing a newly introduced modeling technique (J. Sol. Energy Mater. Sol. Cells, submitted for publication), is demonstrated. In our opinion, the introduction of this modeling technique to the photovoltaic community will prove to be of great importance in aiding the design and optimization of advanced solar cells. A model of an InGaP/GaAs/InGaNAs/Ge four-junction solar cell is prepared and is fully simulated. The major stages of the process are explained and the simulation results are compared to published theoretical and experimental data. An example of cell parameters optimization is also presented. The flexibility of the proposed methodology is demonstrated. The methodology and design considerations for this process are explained. (c) 2004 Elsevier B.V. All rights reserved.