To solve the problem of bus voltage fluctuation caused by the switching of working modes during the operation of a photovoltaic unit, a novel smooth switching control strategy is proposed. From the output characteristic curve of the photovoltaic cell, the differential of the output power to the output current is used as the control variable. By tracking different dp/di command values, the PV converter can realize the control of MPPT mode, CVD mode and smooth switching between the two modes. To solve the problem of low power distribution accuracy caused by the difference of line impedance when multiple photovoltaic converters work in the CVD mode, an adaptive droop control strategy based on secondary regulation is proposed. In addition, a sparse communication network between adjacent photovoltaic units is constructed, and a dynamic consensus algorithm is used to achieve global stable convergence of related average information. The simulation and experimental results show that the proposed control strategy can realize the smooth transition of the PV unit working mode switching process and the precise sharing of load power. This work is supported by the National Natural Science Foundation of China (No. 51709028 and No. 51979021).