Accurate Determination of Photovoltaic Cell and Module Peak Power From Their Current–Voltage Characteristics

We investigate the extraction of the peak power of photovoltaic (PV) cells and modules from their current-voltage (I-V) characteristics. Synthetic I-V curves are generated by numerically solving the two-diode equation in steady-state conditions with representative parameters for crystalline silicon-based solar cells. Parasitic effects that may affect the shape of the current- voltage curves are not considered yet. The cases of high- and low-voltage sampling frequencies are addressed. We propose and qualify a novel fit procedure, where the boundaries are defined as two independent power thresholds, and demonstrate a factor 3-4 improvement on the peak power estimation in comparison with other state-of-the-art approaches. We unveil the dependence of the fit accuracy on the devices parameters, especially their fill factor (FF). Interestingly, we show that an equally good fit accuracy is obtained when only five to ten points are placed neighboring the peak power, provided that these points are placed at the appropriate positions. We then broaden our approach to the extraction of the short-circuit current density and the open-circuit voltage from I-V curves. We validate our guidelines by extracting the maximum peak power from (I-V) curves measured on actual PV devices.