An Ultra-low power solar energy harvesting system (EHS) for IoT end node devices is presented in this paper. To provide an uninterrupted power supply to IoT nodes is a challenge. The solar cell is used as an input source and this low input voltage is boosted by using the DC-DC converter. The charge pump is used as a voltage booster and the impedance matching between the solar cell and the converter is achieved through frequency tuning and capacitor value modulation. A hill-climbing technique is used for maximum power point (MPP) achievement. The EHS designed is self-sustainable and the output is in the range of 3-3.55 V with an input of 1-1.5 V. The EHS is designed in CMOS 90 nm technology library. The simulation results validate the proposed concept and the EHS is consuming a power of 22 μW, which is within the Ultra-low power range of IoT smart nodes.