The energy utilization efficiency of PV panel can be significantly affected by the partial shadow effect. Traditional solutions mainly focus on panel-level optimization but ignore the partial shadow happens on sub-string level which may also affect the efficiency. In this paper, a novel solar panel power optimizer with self-compensation for partial shadow condition is proposed. The optimizer can realize self-compensation for the unbalanced part inside the PV panel without changing the electrical connection. At the same time, the optimizer, which is implemented by simple multi-winding flyback topology, draws the compensation current from the output of the same panel, so that no other source is required for compensation. The simulation and experimental results show that the output power of the PV panel under partial shadow condition is significantly increased by applying the proposed circuit.