1 | Abi International Journal Of Modern Science & Engineering Division – Electrical Engineering ABI International Journal of Modern Science & Engineering (1)1 January-June 2012. pp. 1-10 Asymmetric Multilevel Inverter to Address Partially Shaded Photovoltaic Modules Dr. R.Ramaprabha 1 , A. Fazil Ahamed 2 , M.Indhupriya 3 and A.Devika 4 Associate Professor 1 , U.G. Student 2 , U.G. Student 3 and U.G. Student 4 Department of Electrical and Electronics Engineering SSN College of Engineering, Rajiv Gandhi Salai, Kalavakkam-603110, Chennai, Tamilnadu, India. ramaprabhar@ssn.edu.in 1 (corresponding author) fazil632406@gmail.com 2 , m.indhupriya@gmail.com 3, devika1991@gmail.com 4 Abstract: This paper, Asymmetrical multilevel inverter (AMLI) is used to address partially shaded photovoltaic (PV) modules. AMLI produces staircase waveform from various DC levels which is obtained from shaded PV module. This waveform resembles the sinusoidal waveform with low harmonic distortion, thus reducing filter requirement. Here the need of several DC sources can be decreased, thus maximizing output power and speed. The simulation results are presented with the help of MATLAB software. Keywords: PV System, AMLI, Partial Shading, MATLAB I. INTRODUCTION The solar energy is trapped efficiently using a Solar PV panel. The panel output power varies with temperature and insolation. Though the most modern PV modules with nano-structured substrates can produce practical efficiencies up to 42.3%, it is still a long way in achieving absolute efficiencies from them. The inverters are used for converting DC voltage, obtained from PV module to AC. To improve the quality of this output waveform and make it near sinusoidal, multilevel inverters (MLI) are used. In large arrays of partial shaded PV modules, to avoid the stress on the PV module “bypass Diodes” are used, which gives rise to multiple peaks in characteristics, which in turn make the Maximum Power Point Tracking (MPPT) difficult. This makes it mandatory to use a DC/DC converter link in between the PV modules and the inverter. Use of conventional MLIs, lead to extremely high stress on the DC link. The solution to this problem lies in using Asymmetric Multi Level Inverter (AMLI) which makes use of different DC levels. Different groups of modules based on the Insolation are used as inputs for the AMLIs. In this paper PV fed seven level AMLI is presented. Simulation of the system is carried out using MATLAB [1]-[5].