An innovative power converter based technique for on-site photovoltaic I-V characterization under natural irradiance

This paper presents a standalone PV curve tracer designed to extract current-voltage (I-V) and power-voltage (P-V) characteristics, as well as the five parameters of a Multiple-Diode Model (MDM) with identical diodes, effectively reducing it to a single-diode model for parameter extraction, under real sunlight conditions. The system consists of a custom-built synchronous boost converter operating as a programmable electronic load, where the duty cycle of the PWM signal regulates the equivalent resistance. Integrated with voltage and current sensors, along with external solar irradiance and temperature sensors, the system enables the automatic extraction of I-V and P-V curves for PV panels up to 300 W. Experiments were conducted on a 12-cell ET-M53630WW PV panel (V_OC = 21.52 V, I_SC = 1.8 A, V_MP = 17.72 V, I_MP = 1.69 A and P_MP = 30 W), demonstrating the system's performance under realistic operating conditions. A nonlinear least squares fitting algorithm based on the Levenberg-Marquardt method processes the extracted curves to determine the five key parameters of the PV panel with high precision. Experimental validation demonstrated that the estimated and measured I-V curves are nearly identical, with a worst-case current deviation of only 41.5 mA. The reconstructed P-V curve at standard test conditions (G = 1000 W/m², T = 298.15 K) closely matched the manufacturer's datasheet, yielding a maximum power of 27 W compared to the rated 30 W. These results highlight the accuracy of the proposed methodology in parameter extraction and its potential application in PV performance monitoring, degradation analysis, and educational use.