Introduction

Consumption of electrical energy has increased significantly during the past decades. This has led to a considerable lack of fossil fuel reserves, increase in greenhouse gases and global warming. Therefore, during recent years scientists have concentrated on research to find renewable energy-based solutions to avoid this problem. Photovoltaic (PV), fuel cell (FC), wind and geo-thermal are examples of renewable energy resources (RERs). PVs are more popular due to their simple structure and lower cost and maintenance in comparison with other RERs [1-7]. Simple schematic of a PV-connected power system is shown in Fig.1. Due to low voltage (25-50 V) and low efficiency (12-25 %) of PV panels, their voltage level must be increased to be applicable in grid-connected and/or standalone operations [1]. Two methods are mentioned in literature for boosting voltage level of PV panels:
·      Cascading PV modules or cascading the output ports of each DC-DC converters together
·      Implementation of high step up DC-DC converters [8-11]
First method has some disadvantages: Increasing number of PV panels will need vast installation area. Besides, voltage increment in PV side will cause protection and insulation problems. Partial shading and therefore reduction of PV array efficiency should also be considered [12-15].