Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser Solar tracking systems: Technologies and trackers drive types – A review A.Z. Hafez a,b, ⁎ , A.M. Yousef a,c , N.M. Harag a a Renewable Energy Engineering Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt b Nottingham Transportation Engineering Centre, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom c Mechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria, Egypt ARTICLE INFO Keywords: Solar Tracking Azimuth Elevation Tilt Polar Active Passive Collector PV ABSTRACT This paper presents a comprehensive review on solar tracking systems and their potentials in solar energy ap- plications. The paper overviews the design parameters, construction, types and drive system techniques covering different usage application. There are two main solar tracking systems types that depending on their movement degrees of freedoms are single axis solar tracking system and dual axis solar tracking system, which are ad- dressed in the recent studies. The solar tracker drive systems encompassed five categories based on the tracking technologies, namely, active tracking, passive tracking, semi-passive tracking, manual tracking, and chron- ological tracking. The paper described the various designs and components of the tracking systems. There are 42.57% of the studies discussed and presented single axis tracking systems while 41.58% of these studies to the dual axes tracking systems. In the recent research studies, the most common solar tracker drive type was active tracker by 76.42% usage in applications while in the second most impact type is the chronological solar tracker by 7.55%. Furthermore, in the solar tracking techniques, Azimuth and altitude tracking achieved 16.67% in usage, Horizontal tracking by 16.67%, Azimuth tracking by 10%, and polar tracking by 4.44%. 1. Introduction The solar tracking system plays an important role in different solar energy applications where its benefits not only exist in the power and efficiency gains and increase compared to the fixed systems, but also in the economic analyses of the large-scale solar energy applications. The systems are oriented with optimal tilt angles towards the equator from the horizon to maximize the solar radiation affects on the solar col- lectors and panels. The tracking angles depend on the site latitude and climatic conditions. There are two main solar tracking systems types that depend on the movement degree of freedom are single axis solar tracking system and dual axis solar tracking system. Several sun tracking systems are evaluated and showed to keep the solar panels, solar concentrators, or other solar applications as the recent studies of single axis tracking [1–43], dual axis tracking [44–85], single and dual axis tracking [86–107] with respect to the tracking systems types. A single axis solar tracking system is a technique to track the sun from one side to another using a single pivot point to rotate. This system has main three types: horizontal, vertical, and tilted single axis tracking system. The main CSP applications of the single axis tracker are parabolic trough and linear Fresnel solar systems. The main disadvantage of the single axis tracking system is that it can only track the sun during the daily movement and not the yearly movement, and during the cloudy days, the efficiency of the tracking system is reduced by a large amount due to the rotation around only one-axis. A dual axis solar tracking system is a technique that tracks the sun in two different axes using two pivot points to rotate. Solar tracker system in this type usually has both horizontal and vertical axes. One of the most important applications to dual axis tracker are CSP applications and especially solar dish and solar tower systems where the long distance between the heliostat re- flectors and the receiver point concentration lead to angle errors in the results. The solar tracker drive systems are classified into five types based on their tracking technologies, namely, active tracking, passive tracking, semi-passive tracking, manual tracking, and chronological tracking [1–90,92–96,98–100,108–112]. Active solar tracking system is the system that determines the position of the sun path in the sky during the day with the sensors. These sensors trigger the motor or actuator to move the drive system to the system towards the sun throughout the day. If the solar radiation beams are not perpendicular on the solar tracking system, then this will made a difference in light intensity on one sensor as compared to another leading to act the tracking system to be perpendicular on the sunlight beams. Active tracking system sorted with different control types as microprocessor-based, electric-optical sensor-based, date and time methods, and auxiliary PV cells [64,113]. Active tracking systems using microprocessor and electric-optical https://doi.org/10.1016/j.rser.2018.03.094 Received 15 June 2017; Received in revised form 25 November 2017; Accepted 31 March 2018 ⁎ Corresponding author at: Nottingham Transportation Engineering Centre, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom. E-mail addresses: ahafez@zewailcity.edu.eg, ahmed.mohamed2@nottingham.ac.uk, ahmed.mohamed@nottingham.ac.uk, ahmedzakaria5@gmail.com (A.Z. Hafez). Renewable and Sustainable Energy Reviews 91 (2018) 754–782 1364-0321/ © 2018 Elsevier Ltd. All rights reserved. T