In this paper design analysis of a high step-up DC-DC converter suitable for PV applications was investigated, by using coupled inductors and 1-semiconductor switch. Due to the single-switch structure, an easy control and efficient MPPT is carried out for the proposed converter. The variation of conversion ratio at constant duty cycle and variation of duty cycle at constant conversion ratio the high output voltage has been achived. Design and analysis of the circuit with open loop and closed loop system was examined. Simulation results are confirmed by using MATLAB/ Simmulink Environment.