A current is generated under this voltage stress, known as leakage current., Na+) on the solar cell surface leads to potential induced degradation (PID). This results in the degradation in the performance of a solar cell.
How to eliminate leakage current in solar PV array system?
There are two distinct methods to eliminate the leakage current in the solar PV array system: (i) obstruct the leakage current, (ii) reduce the variation/constant common-mode voltage. The additional diodes/switches are incorporated in the system to obstruct the leakage current by disconnecting the PV array from the grid side network.
The additional diodes/switches are incorporated in the system to obstruct the leakage current by disconnecting the PV array from the grid side network. The second approach involves the elimination of zero switching states . To address the aforementioned issues, the transformerless SECS is presented in .
The leakage current is induced in the SECS because of having a variation in the common-mode voltage. The typical r.m.s. value of the leakage current is 1.75 A, which is higher than recommended limit of 300 mA, thereby, it violates the VDE-00126-01 standard.
The solar PV array current is not varied, which evinces that maximum power generation is not varied. The grid currents are well-balanced and sinusoidal, which illustrates that the negative sequence power is not injected from the SECS. Fig. 14d shows the waveforms of VCM, ILeak, isa, iLaa.
However, it is unable to suppress the leakage current as a common-mode voltage is not maintained constant throughout the system operation. In this study, a three-phase SECS is presented herein to ameliorate the PQ of the grid and to suppress the leakage current.
Why is stray capacitance a problem in solar photovoltaic arrays?
Owing to the presence of stray capacitance between solar photovoltaic (PV) array and the ground, the variation in common-mode voltage across stray capacitance leads to potential safety issues, electromagnetic interference, and distortion into the injected grid currents.