Due to air pollution problems caused by fossil fuels, renewable energy sources are considered as an alternative clean energy. Solar energy and wind energy are examples of renewable energy sources. However, these sources are not always available. Therefore, usually combination of theses energies are used. Also, while using PV panels, due to shadow effect, series combination of PV panels is not a proper solution. Therefore, it is better to apply a high step up converter for each panel. A better solution is applying a multi input high step up converter to absorb energy from several sources or several PV panels. In this thesis two new high step up dual input converters are proposed which can be extended to multi input converter. These converters can also operate with one input in an interleaved manner. The proposed converters provide high voltage conversion ratio and also the voltage stress of applied switches is low. Since the transformer leakage inductance alleviates the reverse recovery problem of rectifier diodes, snubber circuit is not required. The proposed converters have high voltage conversion ratio and simple structure and the voltage stress of switches is clamped. Also, the input current is continues which makes them a proper option for renewable energy sources. Futhermore, in the second converter soft switching is attained without applying any additional switch. The proposed converters are analyzed and design considerations are discussed. Also, experimental results are presented to verify theoretical analysis. Keywords : multi input converter, dual input converter, high step up converter, soft switching.