2327-4662 (c) 2017 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JIOT.2017.2768410, IEEE Internet of Things Journal 1 Abstract— Wireless Sensor Networks (WSN) is one of the most effective tools in collecting data autonomously going as recently as 5 to 10 years ago. A low deployment and maintenance cost WSN is highly recognized as one of the more advanced Internet of Things (IoT) networks that can be deployed for a series of purposes namely environmental and industrial monitoring due to the majority of such systems run on expendable power source that offers WSN with a limited service lifetime. The aim of this paper is to review existing renewable energy and prospective approaches in energy harvesting strategy as a means of having a sustainable and low maintenance operation of WSN. Additionally, recent Maximum Power Point Tracking (MPPT) of solar energy harvesting is thoroughly discussed in a new perspective of the WSN framework. Semi-Pilot Cell Fractional Open-Circuit Voltage (SPC-FOCV) MPPT is a fairly new concept in WSN application that features less complicated configuration with reduced hardware requirements and lower cost. Recent research findings are evaluated throughout this paper leading to the SPC-FOCV MPPT materialization. A holistic discussion is made encompassing the advantages and disadvantages of the concept, its performance compared to conventional MPPT approaches and the future insight of the technology in WSN. Index Terms— Internet of Things, Fractional Open Circuit Voltage, Maximum Power Point Tracking, Power harvesting, WSN power consumption. I. INTRODUCTION ith the uncertainty of environmental conditions that are affected by the highly debated issue of global warming, for example the phenomenon of El-Nino is proven to have an impact on the livelihood of the local population [1] and the agricultural yield [2]. In nations that have a higher year round temperature and humidity pattern, it is crucial to foresee and understand the weather pattern of a place in deciding the appropriate time frame for seedlings to be planted in order to 1 Amzar Omairi is currently with the Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia (e-mail: amzaromairi@gmail.com). 2‡ Zool H. Ismail is with the Centre for Artificial Intelligence and Robotics, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia (e-mail: zool@utm.my). 3 Kumeresan A. Danapalasingam is currently with the Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia (e-mail: kumeresan@fke.utm.my). 4 Mohd Ibrahim Shapiai @ Abd. Razak is with the Centre for Artificial Intelligence and Robotics, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia (e-mail: md_ibrahim83@utm.my). yield a munificent harvest [3]. Temperature and humidity reading may also give an idea for planters to choose the variety of subspecies to choose from in accordance to expected temperature patterns in the coming years [4]. For environmental monitoring purposes, the wireless sensors are required to be spread over an extended geographical area to obtain an accurate averaged reading. The sensor distribution may be set up in homogenous (uniform separation) or heterogeneous (islands of sensors separated in accordance to geographical conditions) distribution. A wireless sensor networks node can be defined as a system that combines sensing, computation and communication into a single tiny device [5]. Through a mesh of autonomous sensors, they have the capability to monitor real-time environmental parameters, such as temperature, humidity, pressure, irradiance level, and even radioactive reading. The sensor nodes connect to a network and route the data packet via available network be it intranet or the internet. Like many advanced technology, the development of wireless sensor networks was initially motivated for military applications such as battle ground surveillance and for heavy industrial monitoring [6]. As time goes by, WSN are being used by governments and research institutions for broader use for instance natural disaster deterrence [7] & [8], air quality observation [9], forest fire detection [10] and weather stations [11] to name a few. Future trends for the development of WSN especially in in Internet of Things (IoT) shows that full duplex WSN [12] - [14], which involves two parties of devices to communicate simultaneously in both direction would play a big role in the development of future WSN [15], this type of directionality would require the power scheme of the nodes to be efficient and powerful enough to accommodate the demands of such communication. Although batteries offer the quality of a preferred cost effective aspect of energy storage technology, energy harvesting devices such as photovoltaic cells are emerging as a viable source of power to either add on to a depleting battery capacity or to solely provide power to a scheduled WSN operation [16]. This paper will review four different replenishable sources of energy that could be harnessed to provide WSN system to be self-sustaining with minimal human intervention and providing sustainable and clean energy source for the operation of a prolonged and autonomous sensing catering to the surrounding conditions. Researchers that are currently reviewing on alternative Power Harvesting in Wireless Sensor Networks and Its Adaptation with Maximum Power Point Tracking: Current Technology and Future Directions W Amzar Omairi 1 , Zool H. Ismail 2‡ , Kumeresan A. Danapalasingam 3 and Mohd Ibrahim Shapiai @ Abd. Razak 4