1 INTRODUCTION: The global renewable sources market has recently increased and the photovoltaic (PV) market will reach 30 GW by 2014, due to the following policy scenario [1]; The role of grid-connected PV systems in power distribution systems will become important, and PV inverter will also play a unique role in this growing market. To achieve higher DC linkage, String type inverters use series connections with many modules to the main electricity through a DC-AC inverter [2], [4]. The asymmetric primary inductance converter (SEPIC) having a non-inverting voltage output [15][16]. Although the boost converter generally has a higher efficiency than the SEPIC, it is nevertheless only applicable in cases where the battery voltage is higher than the PV module voltage. The Buck Boost features of SEPIC extend the applicable PV voltage and thus increase the flexibility of the adopted PV module. The comparison of various buck-b4250 boost converters in terms of voltage gain, efficiency and cost. It is shown in Table 1. Among these converters, although SEPIC is not the best in terms of efficiency and cost, it still has the merits of no polarity reversal, a switch free driving and low pulsation input current. for a high precision MPPT which makes its integral characteristics suitable for low power PV charger system. This article will look at SEPIC with PV module input and Zeta converter with PV module input. Switched Z-source inverter interface with SEPIC and Zeta converters. The Zeta converter provides an output step-up or step-down function, in a manner similar to Buck-Boost or SEPIC converter topologies. The conventional Zeta converter is configured with two inductors, a series capacitor and a diode. ...... middle of paper ......ing N1 and secondary winding N2. To simplify the circuit analysis of the proposed converter, the following assumptions are made. 1) All components are important except the leakage inductance of the coupled inductor T1. The on-state resistance RDS(ON) and all the parasitic capacitances of the main switch S1 are neglected, as are the forward voltage drops of the diodes D1 ∼ D3. . 2) The capacitors C1 ∼ C3 are large enough for the voltages across them to be considered constant. 3) The ESR of the capacitors C1 ∼ C3 and the parasitic resistance of the coupled inductor T1 are neglected. 4) The turns ratio n of the winding of the coupled inductor T1 is equal to N2/N1. The operating principles of continuous conduction mode (CCM) are now presented in detail. The typical waveform of several major components during a switching period. The five operating modes are described as follows.