Traditionally fixed racking, which does not actively track the Sun's path across the sky, can have less harvesting potential due to lower sun angles or back shading from other arrays in the system. Solar tracking systems compensate for this by automatically moving to "follow" the sun's movement across the sky. Consequently, the efficiency of the solar panel system also improves. Although the devices come at considerable cost, there are circumstances under which they serve as the best option.
Single-axis and dual-axis trackers are two of the types that are often used. Each has its share of advantages and disadvantages, so you need to familiarise yourself with them before reaching a final decision. Please read on for full information.
What Is a Solar Tracking System?
Tracking is a more advanced technology for mounting and orienting photovoltaic panels. A solar tracking system maximizes your solar system's electricity production by moving your panels to follow the sun throughout the day, which optimizes the angle at which your panels receive solar radiation. Because of their size and weight, solar tracking systems are not usually installed on rooftops, but are ground-mounted.
When solar panels are exposed to sunlight, the angle at which the sun's rays meet the surface of the solar panel (known as the "angle of incidence") determines how well the panel can convert the incoming light into electricity. The narrower the angle of incidence, the more energy a photovoltaic panel can produce. Solar trackers help to minimize this angle by working to orient panels so that light strikes them perpendicular to their surface.
Types of Solar Tracking Systems
The way a solar tracking system moves is dependent on the type of system it is. Solar trackers are categorized into 3, depending on how they work:
1. Manual Solar Trackers
Manual trackers require someone to physically adjust the panels at different times throughout the day to follow the sun. This isn't always practical, as you need someone to constantly monitor the sun and change the position of the solar panel system.
2. Passive Solar Trackers
This is also another type of solar tracker that is not popular. The devices rely on radiations from the sun to tilt. Passive solar trackers contain a low-boiling point liquid that evaporates on exposure to the sun. After the evaporation, the solar panels tilt to the side to face the sun.
3. Active Solar Trackers
Active trackers rely on motors or hydraulic cylinders to change position. The motors in active trackers will move the PV panels so they are facing the sun. Although active solar trackers require more maintenance, they are not tedious, and their efficiency is also high.
Under this category, there are 2 types of solar trackers: single-axis and dual-axis.
Single-axis Solar Trackers
When movement or adjustment of the surface happens by rotating around one axis, it is called single-axis tracking. Single-axis trackers allow panels to rotate on a single point east to west and track the sun from when it rises to when it sets. A single axis tracker can increase production between 25% to 35%. They are common in large-scale projects like communal solar power plants.
We can further categorize single-axis trackers into decentralized and centralized. Decentralized solar trackers serve a single PV module while centralized can adjust a row or several rows of solar panels.
Despite their high upfront installation costs and recurring maintenance costs, single-axis solar trackers can increase your solar system's efficiency enough to quickly make up for your expenses. It's important to install a single-axis tracking system on flat land in an area that is generally warm and dry.
Dual-axis Solar Tracker
When the rotation of the surface happens around two axes simultaneously, it is called dual-axis tracking. Dual-axis trackers have two rotation axis degrees, which are called the "primary axis" and the "secondary axis." A dual-axis tracker allows panel movement on two axes, aligned for both north-south and east-west. This kind of system is designed to further maximize solar energy collection throughout the year as it not only tracks the daily east-west motion of the sun but also adjusts for seasonal variation in the path of the sun.
The dual-axis tracking help to increase the efficiency of solar panels by up to 45%. Although the cost of dual-axis solar trackers is high, it is ideal for commercial solar installation where space is limited, and users are many. As with bifacial solar panels, they can generate enough electricity to meet energy needs.
What Are the Advantages and Disadvantages of Solar Tracking Systems?
There are certainly a few things you should know before deciding to opt for tracking systems over the fixed mounted solutions. This includes its advantages and disadvantages.
Advantages of Solar Tracker
● Single-axis solar trackers increase PV modules' efficiency by up to 25% while dual-axis can improve output by up to 45%.
● More electricity production means you need fewer panels, so you don't need as much space for your solar setup.
● Solar trackers are very beneficial in areas with Time of Use electricity rates. More energy will be able to be produced during peak hours, which means you won't have to pay for grid energy when it's most expensive.
● Solar cells have a lower sensitivity of the photovoltaic effect to dust deposited on the surface, thanks to the better angle of incidence of the Sun's radiation.
If you live in a high latitude where the sun's position in the sky varies dramatically between summer and winter months, a dual-axis tracking system may be a good way to maximize your solar production and collect enough power for your home or property. The best orientation and angle for your solar panels depend entirely on where you are on the globe.
Disadvantages of Solar Tracker
● Solar tracking systems cost more money than standard fixed solar panel systems. This is largely due to having motorized and moving parts.
● With a more complex system comes more maintenance, which add up in maintenance cost over time.
● Deciding to install trackers may require additional site planning and preparation, including digging additional wiring trenches and extra site grading.
● Fixed tracking systems offer more field adjustability than single-axis tracking systems. Fixed systems can generally accommodate up to 20% slopes in the E/W direction while tracking systems typically offer less of a slope accommodation usually around 10% in the N/S direction.
● Solar trackers are generally designed for climates with little to no snow making them a more viable solution in warmer climates. Fixed racking accommodates harsher environmental conditions more easily than tracking systems.
Another disadvantage of a solar tracker is that they are typically too heavy to be used in rooftop solar projects. If you want a solar panel system that has tracking features, be prepared to install a ground-mounted array.
Solar tracking systems make sense particularly when you have space or terrain restrictions and need a compact array for maximum electricity production, or for large-scale commercial or utility installations. In addition, there are pros and cons with both types of trackers, but dual-axis trackers tend to be a better investment in areas with high levels of direct sunlight. Please determine if the extra cost and on-going maintenance will not overshadow the value of the potential gains of the system.
Most solar tracking systems have five-year warranties for drives and controls and 10-year warranties for racking. In the last several years, tracking systems companies have made operational improvements to their systems, developing monitoring software for preventive maintenance and optimizing angles for higher energy yield. Tracking technology will continue to evolve, helping installers maximize the power output of solar projects.