On the grid side, the half-bridge topology of the microinverter is of interest for solar rooftop applications because of its high efficiency, low component count, and cost-effectiveness. However, it has an inherent double-line frequency ripple voltage on the dc-link, which causes the injection of a third-order harmonic current when the voltage control loop is closed. Furthermore, in practice, different average voltages or different capacitances of the two capacitors at the dc-link produce a second-order harmonic current that flows into the grid. In this paper, the analytical details of these harmonics are comprehensively described, and a simple and effective low-cost technique using the cascaded connection of two modified notch filters is proposed in the voltage control loop to mitigate their effects. The simulation and experimental results of a 300 W microinverter indicate that the proposed filters represent an effective low-cost solution and perform well in accordance with the IEEE 1547 standard, even if the capacitances at the dc-link are mismatched by 20%. Besides, the prototype is tested when occurring of the changing +1% of the line frequency, or appearing of the distorted waveform of grid voltage with the composition of 6% of fifth-order harmonic. Nomenclature Capital boldface italic letters such as V, represent phasors. Capital italic letters such as C 1 , represent constant variables. Small italic letters such as v dc (t), represent instantaneous variables depending on time. Small italic letters such as ṽ dc (t), represent small ac signals in the time domain. Capital italic letters such as G vp (s), represent transfer functions in the s-domain. Small italic letters such as v dc (s), represent signal variables in the s-domain.

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