Suitability of Asymmetrical Multilevel Inverters for Partial Shaded Photovoltaic Systems

Abstract

The efficiency of building integrated photovoltaic (PV) system is greatly affected by the partial shaded conditions. The impact of shading conditions depends not only on the level of shading but also on other factors like array size, type of configuration adopted, pattern and intensity of the shade. The influence of partial shading is much pronounced in series configuration than any other types due to the absence of cross ties. Unless protected by bypass diodes, the thermal stress across the panel increases under shaded conditions and eventually leads to the development of hot spots that can damage the shaded panel permanently. Bypass diode totally isolates the shaded panel from the rest of the of the array leaving the array underutilized. To address this issue, this paper proposes repositioning of the panels to distribute the shade uniformly all over the array. Besides, a hybrid asymmetric multilevel inverter is proposed for power conversion.