In this paper, an isolated high step-up single switch dc-dc converter is proposed for photovoltaic source. In the proposed converter, high step-up voltage is obtained by single power switching technique that operates low duty cycle. It alleviates the conventional converters high duty ratio and high voltage stress on power devices. The presented converter recycles the leakage energy by using passive clamp which includes reverse recovery energy of the power diode and improves the efficiency. To achieve high output voltage gain, the isolated transformer primary and secondary terminals are connected in series during switching operation. The proposed scheme experimented with solar cell characteristic. PSIM software has been used for simulation. The operation is verified by simulation and validated by implementing in the hardware model at 40Vdc/400Vdc, 100kHz, 500Watts © Research India Publications.