System-Level Performance Evaluation of Indoor Energy Harvesting for Low-Power IoT Applications
Energy optimization is a critical challenge for indoor sensor nodes in Internet of Things (IoT) applications. This paper experimentally evaluates indoor light energy harvesting systems that use different photovoltaic technologies and power management circuits together with a supercapacitor storage element. A system-level metric, the usable system power density, is introduced to quantify the average usable electrical power accumulated in the storage device normalized by the active harvesting area. Measurements under typical office illumination show that one configuration offers the fastest recovery from a fully discharged state, while another maintains the highest and most stable harvested power at higher storage voltages. These results provide practical guidelines for selecting indoor light energy harvesting solutions in compact, energy-autonomous IoT sensor nodes.