Depending on the difference in the falling sunlight on gas containers mounted on the eastern and western sides of the PV panel, a difference in gas pressure is created and then the tracker is moved until it reaches an equilibrium position. 32 Passive trackers (PTs) use compressed gas to move the panel. For additional power gain, DAST that has both vertical and horizontal axis is used. 31 The HSAT is used to track the sun toward south and north, which is the sun's seasonal path, while VSAT is used to track the sun toward east and west, which is the sun's daily path. In general, the single-axis solar tracker (SAST) that has one degree of freedom follows the sun's movement in one direction it can be a horizontal single-axis tracker (HSAT), 30 or vertical single-axis tracker (VSAT). Both can be implemented using a single-axis or double-axis tracking structures. Solar trackers can be classified, according to tracking mechanisms, into two main types: passive trackers (mechanical mechanism) and active trackers (electrical mechanism). In this sense, a compromise between efficiency and cost is necessary for solar tracking systems to become competitive. 25- 29 However, equipping the PV panel with a solar tracker will surely increase the system cost. 24 Many researchers have proven that solar trackers maximize the PV energy generation (10%-50%). The maximum power can be extracted from the PV panel when the tilt angle of the panel is synchronized with the daily and seasonal changes of the sun's motions.
In this context, solar tracking systems are the best devices for maximizing the collected energy by the PV panel whose purpose is to keep the PV panel perpendicular to the incident solar radiation. 20, 21 PV panel is placed at a fixed angle and while the collected energy depends on the PV panel position relative to the sun, there is a big loss of energy (10%-100%) due to the changing of the sun angle relative to the PV panel. Increase the collection of solar radiation by the PV panels.15, 16 The maximum power point tracking (MPPT) controllers are the most widely used devices in this context detailed literature of the several MPPT approaches can be found in. Maximize the transfer of power from the PV panel to the load.8 According to “Swanson's Law”, when global photovoltaic production doubles, costs per unit will drop by almost 20%. 12, 13 In recent years, there is a real tendency of fall in the price of panels it is mainly due to the use of new, more efficient, and much cheaper production methods. Decrease the cost of the PV cells/panels.Improve the conversion efficiency of the cells and PV panels.