i would like to know more about the ground leakage currents in photovoltaic systems.
Solar cells are embedded as electronic circuit in a PV module. PV modules are fixed on mounting system that is grounded. In case of framed PV modules, the metal frame is grounded, too. So there is a potential between the cells and the ground and based on this potential a ground leakage current ( nanoamper to microamper range) flows. You can find details in papers about Potential induced degradation - PID. A recent one is:
Examination of PV Silicon Module Degradation Under High Voltage Bias and Damp Heat by Electroluminescence
Article in Journal of Solar Energy Engineering · February 2017
DOI: 10.1115/1.4036056
Check this
[1] Araujo, S.V., Zacharias, P., Sahan, B.: ‘Novel grid-connected non-isolated converters for photovoltaic systems with grounded generator’, IEEE Power Electronics Specialists Conf. (PESC 2008), June 2008, pp. 58–65
[2] Patrao, I., Garcerá, G., González-Medina, R.: ‘Grid-tie inverter topology with maximum power extraction from two photovoltaic arrays’, IET Renewable Power Generation, 2014, 8 (6), pp. 638–648
Dear Sai,
welcome,
The ground leakage current is a consequence of high negative voltage between the grounded frame of the solar panels and the solar cells. This high negative voltage is formed when a large string of the solar cells is formed by series connecting many solar cells together and leaving the terminals of the sting floating or grounding the positive terminal of the string. This large negative voltage causes the sodium positive ions in the soda lime glass of the encapsulation to migrate to the cathode of the solar cell where they accumulate there and alter the conduction state of the solar cells in the areas where they accumulate. Possibly, they make the solar cells less forward biased and thereby decrease their currents.
So, the leakage current is resulting from negative potential between the cells and the grounded frame as a flow of positive sodium ions toward the cathodes of the solar cells.The accumulation of the positive ions on the cathodes of the solar cells causes what is is called potential induced degradation PID.
For more information about this effect please follow the link:http://pubs.rsc.org/en/content/articlehtml/2017/ee/c6ee02271e
Best wishes
@ Marko Topic @ Abdelhalim Zekry
Appreciate for your valuable answers. Allow me to ask further, should we ground the negative pole of solar panels to avoid PID? If not earthing the negative pole of PV system, How great is the potential difference between the cell and grounded frame?