In recent year applying renewable energy in order to produce the required energy has become more urgent. Photovoltaic (PV) cells among various sources of renewable energy are widely used due to direct conversion of solar power to electrical energy. Many kinds of inverter circuits and control schemes for photovoltaic power generation systems are studied in literature. From noise reduction and safety viewpoints, the ability to ground and isolate the load from the renewable power sources is one of the most important issues for designing and implementing the interface circuit. A conventional photovoltaic system ha power losses due to mismatch between the photovoltaic modules, shadow issues and other obstacles that partially cover the modules. The AC module system is recognized as a useful method for resolving these problems. The AC module is the integration of the inverter and PV module into one electrical device, in which a DC/AC grid-connected inverter is used in each individual PV module, and the inverter operates to provide the maximum power point for PV module. Flyback inverter has been widely used in industrial products for low power applications. The power switch applied in ?yback inverter/converter operates under hard switching. Thus the voltage across the active switch suffers from high voltage spike due to the transformer leakage inductance. The high peak voltage results in the low efficiency and high switching losses. Thus, soft switching ?yback inverters were proposed to increase system efficiency and reduce the switching losses of the active switch. In this thesis a new zero-voltage-switching pulse-width-modulated flyback DC/AC inverter is presented. This inverter has a simple auxiliary resonant circuit which reduces switching losses and EMI. The soft switching is achieved without increasing the voltage/current stress of the switches. In the proposed ZVS inverter, the auxiliary circuit can be disabled at low output voltages. The auxiliary resonant circuit includes a resonant inductance and a resonant capacitance which provides ZVS condition for the main switch and ZCS condition for the auxiliary switch. The proposed inverter is analyzed and simulation results are presented to justify the theoretical analysis. The resonant capacitor is applied to minimize the voltage spike at the transformer primary side, so the voltage stress of the primary switch can be decreased. In a regular flyback converter or flyback inverter, a voltage spike occurs due transformer leakage inductance which resonates with switch output capacitance. In the proposed inverter the energy of leakage inductance is absorbed by the snubber capacitor and then this energy is recovered through the auxiliary switch. Also, the proposed inverter is compared with other soft switching flyback inverters and its advantages over conventional flyback inverters are discussed. Furthermore, interleaving technique is applied to the proposed inverter in order to increase its power handeling capability and to reduce the current ripple. Also in the interleaved circuit the size of passive elements, the size of output filter and the EMI noise are reduced. At first the circuit with two auxiliary circuits was simulated, however, due to many elements applied in the circuit, the circuit was complicated. Finally, the inverter with only one auxiliary circuit is simulated. Therefore, the number of elements is reduced and the circuit is simplified. Keywords: Flyback Inverter, ZVS, Interleaved Flyback Inverter