A solar tracker is a device that directs a payload towards the Sun. Payloads are usually solar panels, parabolic channels, fresnel reflectors, lenses or the mirrors of a heliostat. For flat-panel photovoltaic systems, trackers are used to minimize the angle of incidence between incoming sunlight and a photovoltaic panel. This increases the amount of energy produced from a fixed amount of installed power generation capacity. In standard photovoltaic applications, it was predicted in 2008-2009 that crawlers could be used in at least 85% of commercial installations of more than one megawatt between 2009 and 2012. However, as of April 2014, there is no data for Support these predictions.
In concentrating photovoltaic (CPV) and concentrated solar energy (CSP) applications, trackers are used to enable optical components in CPV and CSP systems. Optics in concentrated solar applications accept the direct component of sunlight and therefore must be properly oriented to collect energy. Tracking systems are found in all concentrator applications because these systems collect the energy of the sun with maximum efficiency when the optical axis is aligned with incident solar radiation.
Generally, the solar panels are stationary and do not follow the movement of the sun. Here is a solar tracking system that tracks the movement of the sun through the sky and tries to keep the solar panel perpendicular to the rays of the sun, ensuring that the maximum amount of sunlight incident on the panel throughout the day. The solar follower begins to follow the sun from dawn, all day until night, and begins again from dawn the next day.
Figure 1 shows the solar tracking system circuit. The solar tracker comprises the comparator IC LM339, the motor controller H-bridge IC L293D (IC2) and some discrete components. The light dependent resistors LDR1 to LDR4 are used as sensors to detect the position of the panel relative to the sun. These provide the signal to the IC2 motor driver to move the solar panel in the direction of the sun. LDR1 and LDR2 are attached to the edges of the solar panel along the X axis, and are connected to comparators A1 and A2, respectively. The VR1 and VR2 presets are set to obtain a low comparator output on pins 2 and 1 of comparators A1 and A2, respectively, to stop the M1 motor when the sun's rays are perpendicular to the solar panel.
When LDR2 receives more light than LDR1, it offers less resistance than LDR1, providing high input to comparators A1 and A2 on pins 4 and 7, respectively. As a result, the output pin 1 of comparator A2 is set high to rotate the motor M1 in one direction (eg counterclockwise) and to rotate the solar panel.
When LDR1 receives more light than LDR2, it offers lower resistance than LDR2, giving low input to comparators A1 and A2 on pins 4 and 7, respectively. As the tension on the pin 5 of the comparator A1 is now higher than the voltage on its pin 4, its output pin 2 is high. As a result, the motor M1 rotates in the opposite direction (for example, clockwise) and the solar panel rotates.
Similarly, LDR3 and LDR4 track the sun along the Y-axis. Figure 2 shows the proposed set for the solar tracking system.