To address the issues of slow response speed and large tracking oscillations in the traditional Perturb and Observe (P&O) algorithm, a Sub-area Variable Step Perturb and Observe (SAVS-P&O) algorithm is proposed. The algorithm first divides the photovoltaic cell's P-U characteristic curve into three regions—slow variation, steady state control, and rapid variation—based on the cell's output voltage, current, and computed power. Next, in the slow and rapid variation regions, a fixed step algorithm is used to quickly transition to the steady state control region. Once in this region, an adaptive step-size algorithm tracks the MPP, improving tracking performance. Finally, simulation experiments verify the effectiveness of the proposed control algorithm. The results show that the SAVS-P&O algorithm has faster startup speed and smaller tracking oscillations.