The number Internet of Things (IoT) devices is increasing day by day. These IoT devices require batteries which usually need replacement over time. This causes environmental pollution. Researchers have proposed various ambient energy sources like thermal, solar, vibrational, radio frequency (RF) to power up small IoTs. However, these ambient energy sources are unpredictable or fugacious which effects the reliability of such systems.pdc

In this work, we propose a hybrid solar and radio frequency (RF) energy harvesting system. The solar cell is inkjet printed on a flexible Polyethylene terephthalate (PET) substrate. The solar cell provides an open circuit voltage of 230 mV. The RF energy harvesting system consists of a single band rectifier at 2.4 GHz for RF to DC conversion. Schottky Diode SMS-7630 is used in rectifier as rectifying element. The rectifier is matched to an antenna through a microstrip lines and stubs based single band impedance matching network. The maximum output voltage of the RF energy harvester is 0.57V. The RF to DC conversion efficiency is 32.3% for a typical input of 0 dBm at 2.47 GHz. This system will produce an uninterrupted power supply for low power IoT and will create battery-less nodes.