This paper presents the dynamic characteristic of a tandem silicon/amorphous silicon (a-Si:H/a-Si:H) photovoltaic (PV) module measured in the nonstationary regime. The current-voltage (I-V) characteristics of the PV module are generally measured by using a pulsed solar simulator. Distortions of the I-V curves can often be observed when measurements are done under the solar simulator with different pulse durations or different sweeping rates of the curve tracing, a direction of the curve tracing from short circuit to open circuit (SCOC), or from open circuit to short circuit (OCSC). In this paper, the measurements were made on the a-Si:H/a-Si:H tandem PV module consisting of 40 cells in series connection. The PV module area is 0.78 m 2 . Dissimilarities of the I-V curves of the PV modules can be observed by the deviation of power at maximum point (P m ) and fi ll factor (FF). From the experimental results, it is found that the largest deviation of P m is 6.12% for 1 ms sweeping duration with OCSC direction of the curve tracing. Dissimilarities of the I-V curves can be explained by charging and discharging capacitive currents due to a voltage dependence of solar cell parameters. Moreover, the capacitance effects can be described by a dynamic impedance measurement of the PV module in the dark with forward and reverse biasing. The voltage and time-dependent parameters are the diffusion capacitance (C D ), transient or junction capacitance (C T ), series resistance (R s ), and shunt resistance (R sh ),which can be revealed by an impedance plot.Introduction. In previous investigations, the dynamic characteristics of a solar cell and PV module were studied from various aspects such as material properties, carrier transport occurring inside the solar cell, e.g., drift, diffusion, and recombination-generation phenomena, and measuring and analyzing techniques [1][2][3]. The studies were based on dynamic impedance models [4][5][6][7]. There are some applications using the dynamic impedance model to study frequency-dependent PV conversion attenuation, electromagnetic noise, and radiofrequency bandwidth for detection of the arc fault [8,9]. This paper aims to describe distortions of the current-voltage characteristics (I-V curves) when using a pulsed solar simulator under illumination conditions. Distortions or hysteresis effects of the measurements can often be observed while the measurements are done by a fl ash tester with different short pulse durations or short sweeping durations of curve tracing, directions of curve tracing from open circuit to short circuit (OCSC), and from short circuit to open circuit (SCOC). Dynamic impedance measurements or dynamic characterization can be undertaken to explain the capacitive effects [10,11].Static and Dynamic Model of a Solar Cell or a PV Module. The static characteristic of a solar cell or a PV module can be studied by the measurement of current-voltage characteristics either under illumination (I-V curve) or in the dark (called dark I-V curve). In standard measurement, the static...
