A method comprises operating a plurality of power optimizers connected in series between two input terminals of an inverter, wherein the plurality of power optimizers are connected to a plurality of solar panels to form a plurality of power modules connected in series, measuring operation parameters of the plurality of the solar panels, calculating a maximum power flow of each solar panel based upon the measuring, determining a mode transition range based upon the maximum power flows of the plurality of solar panels and configuring a first power optimizer to operate in a pass-through mode if a maximum power point tracking (MPPT) current of a first solar panel connected to the first power optimizer is within the mode transition range.