Numerical modeling of inversion-layer (IL) solar cells is described. The steady-state continuity equations are solved for both electrons and holes. A novel integrated recombination technique is applied to accurately find the one-dimensional current flow. Two-dimensional resistive and grid geometry effects are modeled to predict the output current-voltage curve for the cell. Modeled results are in excellent agreement with those measured for a real cell. The model is used to investigate the operation of IL cells and to determine how their performance can be improved through process changes. Practical AM1 efficiencies up to 17 percent are predicted and a theoretical maximum efficiency of 21 percent is calculated. Many of the modeling techniques and results can be applied to other solar-cell structures.