Existing high step-up DC-DC converters suffer from various issues, including limited voltage gain, high voltage stress on semiconductors, using a large number of components, and high current ripple. To solve these issues simultaneously, some of the new converters have been proposed recently, which must be improved by the new ones. Hence, this paper presents an ultrahigh step-up converter with the objective of maximizing the potential use of renewable energy sources (RES). The suggested converter employs a quadratic boost converter (QBC), a switched capacitor network, and a three-winding coupled inductor to produce a substantial gain in voltage while ensuring continuous current in the input and a common ground between load and source. The voltage stress on semiconductor components has been minimized by the placement of the coupled inductor. Comparative analysis showcases the converter's superior voltage gain capability compared to the currently introduced Step-Up DC-DC converters. The converter requires the minimum inductance in order to remain capable of supporting the load with minimal input current ripple, ultimately reducing power loss. The validity of the theoretical analysis of the converter is subsequently proven through experimentation on a prototype with a rated value of 200W output power, 20V input voltage, and 400V output voltage.