Efficient Light Energy Harvesting and RF Distribution for Dense IoT Networks

As the proliferation of devices on the Internet of Things (IoT) continues, efficient and sustainable power solutions are becoming increasingly essential, particularly for battery-less systems operating in dense networks. This work comprehensively defines the concepts in IoT devices and categorises them based on their power consumption levels. It introduces a practical framework for power redistribution using light energy harvesting and RF-based wireless power transfer. A novel energy donation mechanism is proposed that enables energy-abundant nodes equipped with photovoltaic (PV) panels to share excess harvested energy with nearby nodes via RF transmission. Through analytical modelling, link-budget analysis, and experimental validation, the study demonstrates the feasibility and effectiveness of the proposed architecture in maintaining reliable operation across densely deployed IoT nodes. To the best of our knowledge, this work presents the first experimentally validated framework that autonomously integrates light-to-RF energy donation, combining indoor light energy harvesting, short-range RF redistribution, and node placement optimisation within a single deployable system. This approach directly addresses the power sustainability challenge, paving the way toward fully autonomous and battery-less IoT ecosystems.