Solar tracker: what it is, how it works and its importance in a photovoltaic plant
A solar tracker, also known as a solar tracking system, is a mechanical structure designed to orient photovoltaic modules so that they follow the apparent path of the Sun throughout the day. Its main aim is to maximise the capture of solar radiation, thereby increasing energy production compared to a fixed structure and improving the overall performance of a photovoltaic plant.
Today, solar trackers have established themselves as one of the most widely used technologies in large-scale solar power stations utility-scale. Thanks to its ability to maintain a more favourable angle of incidence for a greater number of hours, a solar tracker makes it possible to significantly increase electricity generation without needing to increase the area occupied by the installation.
Although the concept may seem simple, a solar tracker is a highly sophisticated electromechanical system. Its operation combines high-strength metal structures, electric drives, motors, gearboxes, sensors, astronomical algorithms and control systems capable of calculating the optimum position of each row of photovoltaic modules in real time.
The development of solar trackers has progressed in tandem with the growth of photovoltaic solar energy. The reduction in manufacturing costs, combined with improved mechanical reliability and the refinement of tracking algorithms, has made this technology virtually indispensable in numerous high-power photovoltaic projects.
At present, the leading manufacturers of solar trackers are developing solutions capable of operating in extreme weather conditions, withstanding high wind loads and automatically optimising energy production through tracking strategies adapted to available radiation, cloud cover or the topography of the terrain.
How does a solar tracker work?
The operating principle of a solar tracker involves continuously adjusting the tilt or orientation of the photovoltaic modules to keep the panel surface as perpendicular as possible to the incident solar radiation. The smaller the angle of incidence between the sun’s rays and the photovoltaic module, the greater the amount of energy that can be converted into electricity.
To achieve this movement, each solar tracker incorporates one or more electric motors that drive the structure via transmission systems specially designed to withstand millions of operating cycles throughout the plant’s service life. These movements are controlled by an electronic unit that calculates the Sun’s position using high-precision astronomical models. Most modern systems do not require optical sensors to track the Sun. Instead, they use astronomical algorithms that precisely determine the Sun’s position based on the date, time and geographical coordinates of the installation. This solution reduces maintenance and improves the reliability of the solar tracker, as it avoids errors caused by shadows, dirt or adverse weather conditions.
In addition to daily monitoring, a solar tracker incorporates various operating modes designed to protect the installation. When the sensors detect high wind speeds, the structure automatically moves into a safety position known as stow position, reducing aerodynamic loads on the modules and minimising the risk of structural damage. In the most advanced models, the control software is also capable of applying backtracking strategies, a technique that slightly adjusts the tracking angle to prevent shading between rows of modules during the early and late hours of the day. Thanks to this feature, the solar tracker maintains high energy output even in installations with a high module density.
Types of solar trackers
From the point of view of their mechanical design, there are various configurations of solar trackers, although two technologies account for the majority of the global market.
- The one-axis solar tracker (Single Axis Tracker) is the most common solution in large-scale photovoltaic plants. In this system, the modules rotate around a single axis, usually oriented north to south, enabling them to track the Sun’s movement from east to west. This configuration offers an excellent balance between increased output, mechanical simplicity, capital cost and ease of maintenance, which is why it is the most widely used technology in projects utility-scale.
- The two-axis solar tracker (Dual Axis Tracker) allows the modules to rotate on both the horizontal and vertical axes. Thanks to this dual movement capability, the panels maintain a virtually optimal angle of incidence throughout the year, maximising the capture of direct solar radiation. However, the greater mechanical complexity, higher installation costs and increased maintenance requirements have limited their use to specific applications, such as research facilities, solar concentration plants or projects where energy efficiency takes precedence over the initial investment.
- Flexible solar trackers In recent years, new configurations have also emerged for sites with steep gradients, irregular plots or complex geotechnical conditions. These solutions incorporate advanced algorithms and tailored structures that enable production to be optimised without the need for major earthworks, thereby reducing both the environmental impact and construction costs.
