With rising fuel costs, increasing concerns for global climate change, and a growing worldwide demand for electricity, utilizing renewable energy sources such as solar/Fuel power becomes a necessity rather than a luxury. The conversion of renewable energy sources into useful DC or AC power for residential and industrial applications is becoming more popular. But renewable energy re-sources comes with low output voltage (20V to 60V) range, so, in order to utilize this energy effectively, it has to be boosted to high DC voltage by using high efficient power converters & then convert High DC to AC using Voltage fed-Inverter. Isolated boost converter is desirable in the low-to-high dc/dc application where isolation is required or a large step up is in a need. The challenge of designing such a converter for high power applications is how to handle the high current at the input and high voltage at the output. An effective way is to parallel the inputs and series the outputs of the isolated boost converters. Based on this concept, a new interleaved and isolated boost converter is proposed in this paper that has two inductors in parallel at the input to share the current and two capacitors in series at the output to share the voltage. The two Boost converter cells realize demagnetizing by helping each other, which simplifies the transformer structures. With interleaved operation, the current ripple is smaller; therefore, it is possible to use smaller capacitors at the input and output of the converter. All these features make the new interleaved isolated boost converter desirable for high power low-to-high dc/dc applications. At last, a 300 W prototype with 48 V-to-400 V is simulated and tested to verify the theoretical analysis in this paper.