A new modular dc/ac inverter based on a dual-winding isolated SEPIC/Cuk converter for medium and high power Photovoltaic (PV) applications is introduced. In this system, several current-source submodules (SMs) are connected in series to allow for additional voltage boosting. Each SM is designed as a combination of SEPIC/CUK converter to offer a flexible output range and continuous currents with small ripple at input and output sides. Furthermore, the SMs structure can generate different output voltage polarities. The main purpose of employing small-size high-frequency transformers are to (1) provide galvanic isolation, (2) eliminate PV grounding problems, (3) achieve minimum electromagnetic interference (EMI). The paper presents a description of the proposed topology and investigate its reliability performance in a PV grid-tied system using MATLAB simulations. An experimental prototype has been used and controlled by TMS32028335 DSP, as a proof of concept.