# Orientation and Exposure Efficiency of a Solar Tracking Surface in Clear Sky
## 1 Introduction
The results of this study indicate that the voltage value generated by a dynamic solar cell tracker is greater than that of the static solar cell tracker. Dual axis sun tracker devices that are built using four LDRs produce an average voltage of 19.40 Volt in sunny weather, 18.05 Volt in cloudy weather and 13.60 Volt in rainy weather. Solar dishes that are formed from a plurality of reflective solar panels are commonly employed for concentrating solar energy and directing this energy to a power conversion unit that converts the solar energy into mechanical and/or electrical energy [6]. A typical power conversion unit has a solar receiver which is positioned relative to the solar dish so as to receive the concentrated solar energy reflected by the solar panels. During the operation of the power conversion unit, it is highly desirable that an even flux be maintained on the receiver so as to increase its service life and ensure efficient operation. Variances in the flux transmitted to the receiver are relatively common and generally result from tracking variation and reflective surface variation. Tracking variation is associated with the positioning of the solar dish and generally results from the control interval that is employed to periodically reposition the solar dish, axis tilts, winds, gravity bending, mirror soiling and track errors. Reflective surface variation is associated with the concentrated light that is reflected by the solar panels and generally results from surface waviness, variation in the radius of curvature and the alignment of the facets (solar panels). Solar energy is abundant in nature and its sustainable energy resources are present all around the world. The main challenge with the solar field is the lesser amount of solar energy captured by photovoltaic (PV) systems [7]. Great performance of the PV systems can be achieved if the panel is kept perpendicular to the direction of the radiation of the sun. Hence, a solar tracker system is a method to maintain the optimum position of the PV panel always perpendicular to the solar radiation. This paper aims to review various technologies of solar tracking to determine the best PV panel orientation. The various types of technologies for solar tracking systems are discussed, which include a passive solar tracker, active solar tracker and chronological tracker system. The movement degrees of solar tracking systems have also been addressed, consisting of a single-axis solar tracking system and a dual-axis solar tracking system. This paper also overviews tracking techniques, performance, construction, advantages and disadvantages of existing solar tracking systems. The limitations of solar tracking systems are also highlighted for future improvement. Through this research, the most favorable solar tracking system was identified as the active solar tracker with dual axis rotation. The most important parameters that are crucial for determining optimal position of solar tracking systems are solar irradiance, solar azimuth angle, elevation angle, inclination angle, declination angle and zenith angle, which are used for solar tracking modelling [8]. These systems can be classified into three main categories: passive solar trackers, active solar trackers and chronological solar trackers, based on the techniques that are applied for controlling solar panel movement. Passive solar tracking systems use non-expensive materials that are thermally active, which means that they can expand with the temperature change, rotating a surface of the panel perpendicularly to the sun. There are available technologies utilizing liquid freon [9], aluminium [10] or other shape memory materials [11; 12]. This system is simple in operation and does not rely on any mechanical actuators, what makes it very economic. Nevertheless, due to poor precision in perfectly capturing sun radiation, it is still not sufficiently efficient. Another very important factor is the location of the solar tracker installation in order to attain adequate sunlight for sufficient heating [13].