Trackers are among the most rapidly evolving technologies in the solar space. Solar tracking systems allow modules to move so that they continuously face the sun. The aim of such a system is to maximise the radiation received by a solar array. Larger modules built to incorporate larger solar cells are also gaining popularity in the market. This requires more developed tracking solutions. Sturdier and flexible solar trackers that are fit to handle heavy modules can help harness the maximum amount of solar energy. Solar tracker technologies are also being enhanced to require fewer parts per module, to help reduce their cost and improve installation efficiency. The new variety of solar trackers can also adapt to bifacial modules to ensure a high energy yield.
Types of trackers
To enhance their performance, solar mounting structures are often equipped with tracking systems that are designed to move manually or automatically, depending on the position of the sun. Based on the degree of freedom they offer, manual tracking systems can be of two types – single axis and dual axis.
The single axis type tracks the sun from east to west, rotating on a single point, moving in unison, by panel row or by section. Dual axis trackers rotate on both the X and Y axes, making panels track the sun directly. Even though single axis trackers collect less energy per unit as compared to dual axis trackers, they have shorter racking heights. Thus, they require less space for installation and are easier to operate and maintain. Single axis trackers can further be categorised as centralised and decentralised. Centralised trackers use a single motor to power a driveline between rows that moves an entire segment of panels, while decentralised systems have one motor per tracking row. In some cases, trackers with motors are present in each set of tracking.
A dual axis solar tracker outperforms a single axis tracker due to its ability to follow the sun’s path with accuracy. Dual axis trackers result in up to 14 per cent more power generation than single axis trackers. However, the land and balance of system costs associated with them are higher, especially since the structures need to be placed farther apart for the same number of panels as compared to a single axis set-up. The structural cost for dual axis trackers is also about three to four times higher. Further, dual axis trackers would need robotic cleaning at an individual level. Hence, due to their high cost, dual axis trackers still lack popularity in the market.
Getting smarter
Combining advanced mechanical design with digital communications and control can help maximise yield and consequently the returns of a project. Tracker-associated software and control platforms can enhance the yield of power plants. Advanced data and digital services can help dramatically improve asset management efficiency by improving monitoring precision and lowering operating costs. Automatic trackers have been developed, which use pre-programmed algorithms to achieve maximum output. These systems are optimised to allow a complete collection of available solar resources and minimise energy wastage. Although automatic trackers have a higher output than their manual counterparts, they entail a higher investment. Further, they have complex hardware and are more prone to damage, which translates into higher maintenance costs.
Towards better tracking systems
One of the ways to ensure a quality tracking system is by subjecting it to various types of tests. One of the key drivers for tracker design is wind tunnel testing. This is a procedure using scale models loaded with fan-driven airflow to predict the responses of a structure, structural components and cladding to actual wind storm conditions. Wind tunnel tests are a good way to see how resilient solar trackers are, which is particularly crucial considering the increasing sizes of solar modules, which exposes them to a greater wind area, increasing the chances of instability in the tracker systems. Moving beyond static modes of designing, it is becoming increasingly important to incorporate dynamic analysis as well when designing trackers.
There are various levels of wind tunnel testing. Levels 1 and 2 require data collection for calculation. While Level 1 uses a static approach, Level 2 uses a dynamic approach. Level 3 uses a 2D simulation to asses instability, whereas Level 4 uses a 3D test for aeroelasticity. Recently, a Level 5 approach for testing has also emerged, which uses aeroelastic data collection. Module compatibility is also crucial for tracker design. The trackers should be validated across various module brands, types, dimensions and weights. Well-performing tracking systems should include slope adaptability according to the terrain, sturdy power backups and sometimes may also use artificial intelligence-driven technology for additional yield. Having multiple fixed points can also help make trackers sturdier. Further, trackers must be designed keeping the local project requirements in mind. Overall, desirable qualities in tracking systems include rigidity, economic feasibility and high adaptability to a variety of solar modules.
