Improvement of partial shading resilience of PV array though modified bypass arrangement

Abstract

Generation of hot spot, due to partial shading and other mismatch conditions, is associated with photovoltaic (PV) systems since its very early applications in satellites, but a simple, economic and effective solution is still unavailable. Conventional hot spot mitigation technique, using a bypass diode (BPD) across each sub-panel, reduces the reverse bias voltage only up to −12 V to −19 V across the shaded cell, which matches exactly with the voltage range at which avalanche breakdown of PV cells occur. Reverse breakdown of an acidic texturized PV cell occurs merely at −13 V and between −15 V and −20 V for alkaline texturized ones. Hence, the standard BPD based circuit is not effective enough in preventing reverse breakdown of PV cells and hot spot generation. In this paper, a modified bypass circuit is proposed which successfully strikes a balance between the increase in reliability through reduction of hot spot temperature and increase in complexity of bypass circuit. The experimental study and simulation reveal that the proposed bypass circuit effectively reduced hotspot temperature of the obscure cell below average temperature of the module, without increasing the power loss, system complexity and cost thereof, substantially.