Minimization of Leakage current
The leakage current appears because of the high stray capacitance between the PV cells and the grounded metallic frame of each module and the high-frequency (HF) harmonics caused by the modulation of the power converter. Galvanic isolation can help to interrupt the leakage path, but the use of a transformer presents drawbacks such as higher cost and additional losses, leading in general to a reduction of the efficiency. Nevertheless, the transformer is mandatory in some countries because of local regulations. If the transformer is not mandatory, as a second solution, several power converter topologies have been specifically designed to minimize the effect of the HF harmonics on the leakage currents.