The shape of grid lines or fingers, used to reduce conductive losses in photovoltaic cells, is shown to be optimized when the current flux in the line remains constant. This result is derived for cells of arbitrary geometry assuming the fraction of the cell area shaded is small. The shapes of grid lines for three special cases are provided. Optimal shapes for grid lines are also derived for cases when the area of the lines is a significant fraction of the cell area. © 1979.