The current-voltage (I-V) curve for a PV cell shows that the current is essentially constant over a range of output voltages for a specified amount of incident light energy. Figure 1: Typical I-V Characteristic Curve for a PV Cell Figure 1 shows a typical I-V curve for which the short-circuit output current, ISC is 2 A. The output power of the PV cell is voltage times current, so there is no output power for a short-circuit condition because of VOUT or for an open. The efficiencyof a PV cell is the ratio of light energy falling on the cell to the light energy that is converted into electrical energy. It is expressed as. The fill factor of a PV cell is an important parameter in evaluating its performance because it provides a measure of how close a PV cell comes to. Several factors determine the efficiency of a PV cell: the type of cell, the reflectance efficiency of the cell's surface, the thermodynamic efficiency limit, the quantum efficiency, the maximum power point, and internal.