Construction of a broadband impedance spectrum and synchronous DC voltammetry measurement system for solar cells

The current impedance spectroscopy measurement techniques face difficulties in diagnosing solar cell faults due to issues such as cost, complexity, and accuracy. Therefore, a novel system was developed for precise broadband impedance spectrum measurement of solar cells, which was composed of an oscilloscope, a signal generator, and a sampling resistor. The results demonstrate concurrent accurate measurement of the impedance spectrum (50 Hz－0.1 MHz) and direct current voltametric characteristics. Comparative analysis with Keithley 2450 data yields a global relative error of approximately 6.70%, affirming the accuracy. Among excitation signals (sine, square, triangle, pulse waves), sine wave input yields the most accurate data, with a root mean square error of approximately 13.3016 and a global relative error of approximately 4.25% compared to theoretical data. Elevating reference resistance expands the half circle in the impedance spectrum. Proximity of reference resistance to that of the solar cell enhances the accuracy by mitigating line resistance influence. Measurement error is lower in high-frequency regions due to a higher signal-to-noise ratio.