31 Page 31-42 © MAT Journals 2022. All Rights Reserved Journal of Instrumentation and Innovation Sciences www.matjournals.com e-ISSN: 2456-9860 Volume-7, Issue-2 (May-August, 2022) Drives and Methods of Tracking the Suns' Movement–An Overview Nwokeafor, J. C. 1* , Wodi, E. I. 2 , Akpiri, B. F. 3 , Chikere, N. C. 4 , Azubuike, C. O. 5 1 Network Engineer, Ericsson Nigeria. Limited, Nigeria 2,3 Member, Department of Electrical and Electronic Engineering, Rivers State University, Port Harcourt, Nigeria 4 Graduate, Department of Electrical and Electronic Engineering, Michael Okpara University of Agriculture, Umudike, Nigeria 5 Student, Department of Mechanical Engineering, Federal University of Technology, Owerri, Nigeria *Corresponding Author: nwokeaforjoseph@gmail.com ABSTRACT In this study, a review of published techniques for photovoltaic tracking drives and methods of tracking the sun is presented. Solar trackers are broadly classified based on their movement and degrees of freedoms as single axis and dual axis solar trackers. Solar tracking drives can be broadly classified as active or passive. Passive drives are mechanical while active drives are electrical. Active drives are shown to be more efficient when compared with the passive drives. However, in terms of flexibility and cost, passive drives are more viable than active drives. Keywords- Active, Drives, Passive, Photovoltaic, Sun, Tracking INTRODUCTION The major means of a solar tracking system is made up of the tracking device, algorithm of tracking, the unit of control, the position system, the drive mechanism, and the devices for sensing. The algorithm for tracking computes the angles which are used to find the position of solar tracking system. The unit of control carries out the algorithm for tracking and caters for the system of positioning and the drive mechanism. The system of positioning operates the devices for tracking to make them face the sun at the calculated angles. The system of positioning can be either electrical or hydraulic. The drive mechanism is in charge of setting the device in motion for tracking to the position determined by the positioning system. The devices for sensing consist of the tilt angle of the tracker, the light intensity in case of real-time light intensity algorithms and a collection of sensors and measurements that measure the ambient conditions [1, 2] Passive solar tracker drives are based on thermal expansion of a matter (usually Freon) or on shape memory alloys [3]. This tracker is usually composed of a pair of actuators that work against each other. When they have equal illumination, the system is balanced. When the illumination of the actuators is different, an unbalanced force is created and is used to orient the tracking system in the direction where there is equal illumination of the actuators. This causes a balance of forces and hence a balance of the tracking system. In comparison, passive solar trackers are less complex than active trackers but they have low efficiency. Also, passive tracers stop working at low temperatures. Passive trackers are frequently compared with electrical based systems in terms of performance [3]. Passive trackers are not widely researched by scholars and have not yet been widely accepted by consumers even though they are less expensive compared to active trackers. Active tracker drives can be grouped into auxiliary bi-facial solar cell based personal computer (PC) controlled date and time based or microprocessor and electro-optical sensor based. They can also be a combination of the above- mentioned system. In optical active drives, at least one pair of photo-resistors or PV solar cells are used. When they are subjected to equal intensity of illumination, the system is balanced. When balanced, the electric motors are not actuated. In auxiliary bi-facial solar cell, the bi- facial solar cell senses and moves the system to the preferred position and in computer controlled time and date, the computer computes the position of the sun with respect to date and time