Ultra Low-Power Photovoltaic MPPT Technique for Indoor and Outdoor Wireless Sensor Nodes
PhotoVoltaic (PV) energy harvesting is commonly used to power wireless sensor nodes. To optimise harvesting efficiency, Maximum Power Point Tracking (MPPT) techniques are often used. Recently-reported techniques focus solely on outdoor applications, being too power-hungry for use under indoor lighting. Additionally, some techniques have required light sensors (or pilot cells) to control their operating point. This paper describes an ultra low-power MPPT technique which is based on a novel system design and sample-and-hold arrangement, which enables MPPT across the range of light intensities found indoors and outdoors and is capable of cold-starting.