The solar energy conversion system is an alternative for conventional power generating system. The voltage which is available from solar array is variable and to obtain a stable voltage from solar panels, DC-DC converters are required for constant power production. A PV module is designed in MATLAB-SIMULlNK using the S-function builder and controlled current source. The proposed PV module enables us to obtain its P-V and I-V characteristics at different temperature and radiations. This paper presents the design and simulation of DC-DC converters. In this paper, Boost converter, cascaded Buck Boost and Cuk converter are modelled in MATLAB and their results are compare