Rapid growth of global electricity consumption in recent decades has resulted in increased power generation capacity. The danger of greenhouse effect, limits the usage of traditional power generation methods. Moreover, due to the fact that traditional energy sources are finite, major research is carried out to find new clean methods of power generation which are less pollutant. As a result, the use of renewable energy sources such as wind power and solar energy has grown significantly in recent years. Clean and abundant energy are the desired characteristics of new energy sources. Among the renewable energy technologies, photovoltaic (PV), is being known as the leading technology in recent years. In order to effectively use PV energy, efficiency improvement and cost reduction in these systems is inevitable. One of the modern and popular types of PV systems is AC-Module technology, which is the combination of one PV-Module and a grid-connected inverter. In recent years major research has been carried out on photovoltaic systems, particularly AC-Modules to improve the system efficiency and reduce the cost. Nowadays due to massive production of PV-Modules, modules costs has reduced and thus the cost of power electronic converters in AC-Modules is considerable. Therefore it is important to design and develop cost effective and more efficient grid-connected inverters for AC-Modules. In this thesis, after a short survey on grid-connected photovoltaic systems, AC-modules as the modern technology in PV sytems are investigated. PV inverters as one of the most important parts of AC-Modules are reviwed. Two novel DC-AC topologies suitable for AC-Module applications are proposed. High efficiency, long life time, high step-up ratio and eliminating of ground leakage current are the features of the proposed topologies. The presented simulation and experimental results of these two topologies confirm the theoretical analysis. Keywords: PV systems, AC-Module, DC-AC inverter.
