Abstract: The power-voltage（P-U）curve of the photovoltaic（PV）array under uniform illumination is a single peak，and the voltage-current（I-U）curve is a single ladder. When the PV array is covered by clouds，mud，trees，etc.，partial shading occurs in the PV array. The output P-U curve of the PV array have multi-peak values，and multiple steps appear in the I-U curve，resulting in a decrease in the output power of the PV array. The author used Matlab/Simulink to construct the model of the PV array under the shadow condition and carried out several simulations. Some characteristics of the P-U curve and the I-U curve were drawn and their regularities were summarized. The research provided the theoretical basis for maximum power point tracking（MPPT）under shadow conditions.

Key words: photovoltaic array, partial shadow, P-U characteristic curve, I-U characteristic curve