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Dual Axis Tracker: Definition, Types and How it Works

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Published: July 30, 2024

The primary characteristic of dual-axis trackers is their two degrees of freedom, which means that movement occurs independently in two directions. Dual-axis trackers have an extra axis of movement compared to single-axis trackers. Whilst single-axis trackers are only able to move from North to South or East to West, dual-axis trackers have the freedom to move in all four directions. A dual-axis solar tracker consists of 6 main components that work together to ensure that the solar panel accurately tracks the sun in all directions through the sky. These six components are signal processing units, mechanical and electromagnetic motion controllers, power supply systems, light sensors, programmable logic controllers (PLC), and photovoltaic (PV) cells.

Dual-axis trackers work by constantly orienting solar panels towards the sun to maximize their exposure to sunlight and increase their efficiency over the course of a day. This is achieved by allowing the solar panels to move in both a vertical direction (called “elevation”) as well as a horizontal direction (called “azimuth”).

There are two main types of dual-axis trackers: Polar-Axis Trackers and Altitude–Azimuth Trackers. Polar-axis tracking, also called spinning-elevation tracking, refers to dual-axis solar trackers that rotate panels along one vertical axis and one horizontal east-west axis. This axis is similar to the path the sun traces in the sky. The vertical axis enables tilting for seasonal sun angle changes, while the horizontal axis handles the daily transit from sunrise to sunset. Altitude-azimuth tracking, also known as Azimuth-Altitude or Alt-Az dual-axis tracking (AADAT), is a method used in dual-axis solar trackers to orient a payload, such as solar panels, towards the Sun.

Dual Axis Trackers offer several advantages that enhance the efficiency and effectiveness of solar panels. These 4 main advantages are increased energy output, optimized land use, maximized peak time production, and improved efficiency. While dual-axis trackers have significant benefits, there are some drawbacks to consider before installing them. The four main disadvantages of dual-axis solar trackers are higher costs, increased maintenance, shorter lifespan, and performance in cloudy weather.

The average price of a dual-axis solar tracker is currently around $9,921.40 to $66,000, according to market research estimates from specialist retailers like the Solar Store. However, the prices of dual axis solar trackers varies based on several factors such as the brand, model, and the size of the project.

What is a Dual Axis Tracker?

A dual-axis tracker is a device that tracks the sun’s movement along two axes (horizontal and vertical) to maximize the amount of sunlight captured by solar panels. By moving in both a horizontal (East-West) and vertical (North-South) direction, dual-axis trackers improve efficiency by 30-40% compared to fixed panels, according to a study from the International Journal of Energy Research (IJER). The 2015 IJER study, entitled “Development and performance analysis of a two-axis solar tracker for concentrated photovoltaics," was conducted by engineering researchers from the National University of Singapore and Jeju National University in South Korea. The researchers included S.J. Oh, M. Burhan, K.C. Ng, Y. Kim, and W. Chun.

The primary characteristic of dual-axis trackers is their two degrees of freedom, which means that movement occurs independently in two directions. Dual-axis trackers have an extra axis of movement compared to single-axis trackers. Whilst single-axis trackers are only able to move from North to South or East to West, dual-axis trackers have the freedom to move in all four directions. This additional movement allows dual-axis trackers to optimally track the sun throughout the day, increasing the amount of direct sunlight the solar panels receive (compared to single-axis trackers or fixed-frame solar panels). The increased sunlight exposure from the increased tilt and orientation mobility improves the efficiency of the solar panel system by up to 40%. This makes dual-axis trackers particularly useful across seasons and in climates of varying sunlight exposure. Dual-axis trackers are more complex systems than traditional fixed solar panels or even single-axis trackers. The precision design, advanced technology, and high-quality materials required all play a more critical role in their performance, durability, and safety.

A dual-axis solar tracker consists of 6 main components that work together to ensure that the solar panel accurately tracks the sun as it moves in all directions through the sky. These six components are signal processing units, mechanical and electromagnetic motion controllers, power supply systems, light sensors, programmable logic controllers (PLC), and photovoltaic (PV) cells. The signal processing unit processes the signals received from the sensors and sends them to the appropriate components for action. The mechanical and electromagnetic motion controller manages the movement of the solar panels based on the signals received. The power supply system provides the necessary power for the operation of the dual-axis tracker. The light sensors detect the intensity and direction of sunlight and send signals to the signal processing units. The Programmable Logic Controller (PLC) receives signals from the sensors and controls the motor to adjust the position of the solar panels. The Photovoltaic (PV) Cells convert sunlight into electricity. The PV cells are mounted on the tracker, which adjusts their position to maximize their exposure to sunlight.

How Do Dual Axis Trackers Work?

Dual-axis trackers work by constantly orienting solar panels towards the sun to maximize their exposure to sunlight and increase their efficiency over the course of a day. This is achieved by allowing the solar panels to move in both a vertical direction (called “elevation”) as well as a horizontal direction (called “azimuth”).

Dual-axis trackers use a combination of sensors and Global Positioning System (GPS) signals to track the movement of the sun across the sky. These sensors consist of four Light Dependent Resistors (LDR) sensors, two micro servo motors, and a microcontroller. The sensors detect the intensity and direction of sunlight, while the GPS signals provide the latitude, longitude, date, and time of the tracker. With this information, the tracker is able to determine the position of the sun at any given time and adjust the orientation of the solar panels accordingly. The GPS, date/time, and solar position calculations help determine the optimal angle for maximum irradiation.

In terms of functionality, dual-axis solar trackers operate on two axes: a primary axis and a secondary axis. The primary axis allows the tracker to move from East to West, following the sun’s daily path across the sky. The secondary axis enables the tracker to move from North to South, adjusting to the changing height of the sun in the sky throughout the year.

What Is the Importance of Dual Axis Tracker?

Dual-axis solar trackers are important because they have the potential to substantially increase solar energy production compared to single-axis trackers or fixed solar panels. Unlike single-axis trackers that only move in one direction (East-West), dual-axis trackers are able to capture more direct sunlight by moving in two different directions (East-West and North-South). This increased movement allows the trackers to constantly adjust the orientation of the solar panels towards the sun throughout the day, increasing energy yield by up to 40%.

Dual-axis trackers twist and turn to catch the sun, even in tricky spots like uneven ground or around obstacles. Dual-axis do not need much space compared to regular panels. While they cost more upfront, the extra energy they generate pays off quickly, making them a good investment in the long run.

What are the 2 types of Dual Axis Trackers?

There are two main types of dual-axis trackers: Polar-Axis Trackers and Altitude–Azimuth Trackers. The main difference between Polar axis trackers and an Altitude-azimuth solar tracker is that polar axis trackers achieve a high accuracy and efficiency, especially at high latitudes, where the Sun’s elevation angle changes significantly throughout the year, while altitude-azimuth trackers achieve a high accuracy and efficiency, especially at low latitudes, where the Sun’s azimuth angle changes more than its elevation angle. Polar axis trackers rotate around an axis parallel to the Earth’s rotational axis, tracking the sun’s daily motion from east to west and its seasonal motion from north to south. Altitude-azimuth solar trackers rotate around two perpendicular axes. The azimuth axis (horizontal) and the altitude axis (vertical) track the sun’s position in terms of its azimuth angle (the angle measured from the north) and its altitude angle (the angle measured from the horizon).

More information on the two main types of dual-axis trackers is below.

1. Polar-Axis Trackers

Polar-axis trackers, also called spinning-elevation tracking, refer to dual-axis solar trackers that rotate panels along one vertical axis and one horizontal east-west axis. This axis is similar to the path the sun traces in the sky. The vertical axis enables tilting for seasonal sun angle changes, while the horizontal axis handles the daily transit from sunrise to sunset.

Polar-axis trackers are designed to keep the solar panel perpendicular to the sun throughout the day. This maximizes the panel’s exposure to sunlight, thereby increasing the amount of electricity it generates. Polar dual-axis trackers use a programmed controller to actively pivot panels on two axes over the day. The horizontal axis tracks the sunlight's east-west rotation from morning to evening. The vertical axis handles seasonal tilt alterations between summer and winter. This coordinated dual-axis movement ensures that solar panels remain aligned directly toward the sun's position at all times for a minimum angle of incidence. The angle of incidence represents the angle of reflection of the sun's rays as it selects the shortest routes to reach its destination..

The accuracy of polar-axis trackers is high. The “declination drift method” is often used to accomplish accurate polar alignment. This method involves aiming the mount’s polar axis roughly at the polar axis and then adjusting the alignment based on the drift of stars in two equatorial fields. When followed, this method results in very accurate polar alignment.

2. Altitude–Azimuth Trackers

Altitude-azimuth tracking, also known as Azimuth-Altitude or Alt-Az dual-axis tracking (AADAT), is a method used in dual-axis solar trackers to orient a payload, such as solar panels, towards the Sun. The primary axis, which is the azimuth axis, is vertical to the ground, while the secondary axis, often called the elevation axis, is typically normal to the primary axis.

The Altitude-Azimuth Tracking system is based on two coordinates: altitude and azimuth. The altitude is the angle the object makes with the horizon, while the azimuth is the cardinal direction of the object. This system is used to minimize the angle of incidence between the incoming sunlight and a photovoltaic panel. The Altitude-Azimuth Tracking system tracks the movement of the Sun by adjusting the altitude and azimuth angles. As the Sun moves across the sky, the tracker adjusts its position to maintain the smallest possible angle of incidence, maximizing the amount of energy collected.

AADAT is considered accurate as it allows for precise positioning of the solar panels towards the Sun. By continuously adjusting the altitude and azimuth angles, the system ensures that the panels are always oriented toward the Sun, maximizing energy collection. The degree of accuracy of the Altitude-Azimuth Tracking system is high. It effectively reduces the cosine error, which is the loss of power due to the misalignment of the panel with the Sun. By keeping this cosine error to a minimum, the system ensures that a fixed amount of installed power-generating capacity produces the maximum amount of energy.

What are the advantages of using Dual Axis Tracker for your Solar Panel?

Increased Energy Output: Dual Axis Trackers help to increase energy output in a solar cell. By accurately tracking the exact movement of the sun across the sky and keeping the solar panels at a right angle to the energy source at all times, dual-axis solar trackers produce 50-70% more power than rooftop solar or fixed ground-mount systems, and about 20-30% more than single-axis solar trackers, according to researchers Alazone Smith at the Central Washington University. Rooftop solar or fixed ground-mount systems represent the two types of solar mounting options. While the Rooftop solar systems affix to brackets on your roof, the ground-mount systems are built into a foundation at ground level.
Optimized Land Usage: Dual-axis solar trackers optimize land usage by generating more electricity from a smaller footprint compared to fixed-tilt systems. A fixed-tilt system is a solar panel installation system in which the solar panels are mounted at a fixed angle and orientation. Dual-axis solar trackers follow the movement of the sun throughout the day, which increases the amount of solar energy collected by up to 45%. This efficiency advantage allows for more energy production in a given space, making dual-axis solar trackers ideal for optimizing land usage in areas with limited space or where maximizing energy output is a priority.
Maximized Peak Time Production: Peak time refers to the amount of time you maximize electricity generation with your solar panels. Dual-axis solar trackers maximize peak time production by continuously tracking the movement of the sun throughout the day. In certain states like California, Texas, and New York City, some utilities offer Time of Use (TOU) rate plans for solar power, which means the utility will purchase the power generated during the peak time of the day at a higher rate. A dual-axis solar tracker maximizes the energy gains during these peak time periods.
Improved Efficiency: A dual-axis solar tracking device with a cooling system improves energy output, lowers maintenance costs, and extends the panel lifespan. This technique enables solar power generation systems to function at their highest efficiency, improving their viability for large-scale energy production.

What are the disadvantages of using Dual Axis Tracker for your Solar Panel?

While dual axis trackers have significant benefits, there are some drawbacks to consider before installing them. The four main disadvantages of dual axis solar trackers are higher costs, increased maintenance, shorter lifespan, and performance in cloudy weather.

More information about the 4 key disadvantages of dual-axis trackers is listed below.

Higher Costs: Dual-axis solar trackers are slightly more expensive than fixed solar trackers or single-axis solar trackers due to the more complex technology and moving parts necessary for their operation. The cost of dual-axis solar trackers varies depending on the size and location of the project, but it is usually around a $0.08 – $0.10/W increase, depending on the size and location of the project. For example, a standard 4-kilowatt ground-mounted solar system with a fixed tilt costs about $13,000, while a ground-mounted system with a single-axis tracker costs about $22,125, and a ground-mounted system with a dual-axis tracker costs about $29,625, according to researcher Catherine Lane at Solar Reviews.
Increased Maintenance: Dual-axis solar tracking systems require more maintenance than traditional single-axis solar trackers due to their movable parts. The movable parts of a dual-axis solar tracker get damaged easily. Dual-axis solar trackers have more components, which increases their maintenance costs. Maintenance issues that are common with dual-axis solar tracking systems are mechanical wear and tear on bearings, gears, and motors, regular inspections, lubrication, and cleaning of components, as well as sensor calibration and alignment checks. Other common maintenance issues with dual-axis solar trackers are weather-related challenges, such as strong winds, hail, extreme temperatures, and dust and debris accumulation. To minimize maintenance costs and ensure reliable performance, invest in high-quality materials, install the solar panels and tracking systems correctly, and regularly inspect and maintain the systems.
Shorter Lifespan: Dual axis solar trackers have shorter lifespan and lesser reliability. Proper maintenance and high-quality materials extend their lifespan to match or even exceed that of fixed solar panels.
Performance in Cloudy Weather: Dual-axis solar tracker becomes less efficient in cloudy weather conditions. This is because dual-axis trackers rely on direct sunlight to function efficiently. Dual-axis solar tracking systems have the potential to perform well on cloudy and partly cloudy days, depending on the specific design and technology used, according to researchers Amirhossein Fathi, Mohammad Salehi, Amirmahdi Komarizadeh, Kianoosh Choubineh, Saeed Golkar, and Laleh Ghahremani in the Journal of Sustainable Energy Systems.

Where can I shop for a Dual Axis Tracker?

You can shop for dual-axis trackers from a variety of manufacturers and suppliers. The 3 main categories of places you can shop for single-axis trackers for your photovoltaic (PV) solar panels are manufacturer’s websites, specialist solar retailers, and online marketplaces. More information on the 3 specific manufacturers and suppliers is below.

Manufacturer’s Websites: You can visit the websites of any of the companies that produce dual-axis solar trackers and order directly from them. The major manufacturers are Arctech Solar, Array Technologies, NexTracker, Flex Ltd, Trina Solar, PV Hardware, etc. This option offers you more information, customization, and product warranty. However, it may also be cheaper as you shop directly from the manufacturer.
Specialist Solar Stores: You can visit physical or online retail stores that specialize in selling solar products and services. They are Solar Square, Solar Electric Supply, etc. This option may offer you more expertise, guidance, and installation assistance. However, it may also have higher markups, fewer choices, and limited stock.
Online Marketplaces: You can browse various online platforms selling dual-axis solar trackers from different brands and vendors. The major online marketplaces for buying dual-axis solar trackers include Amazon and Alibaba. This option offers you more variety, convenience, and competitive prices. Specifically, purchasing dual-axis solar trackers from Amazon offers you discounted prices with a voluntary 30-day Return Guarantee, while Alibaba offers you three monthly coupons worth US $50, US $20, and US $10, totaling US $80. These coupons are to be redeemed on featured products.

How Much Does Dual Axis Trackers Cost?

The average price of a dual axis solar tracker is currently around $9,921.40 to $66,000, according to market research estimates from specialist retailers like the Solar Store. However, the prices of dual axis solar trackers varies based on several factors such as the brand, model, and the size of the project.

The global market for dual-axis trackers continues to grow, which is likely to increase the cost of dual-axis solar trackers. The demand for dual-axis trackers is predicted to grow from $5.4 billion in 2022 to $16.4 billion by 2030, according to the Compound Annual Growth Rate (CAGR) of 14.8%. This means that the cost of dual-axis trackers is likely to go up, reinforced by increased demand for rising energy due to global warming and rising electricity costs, improvement in efficiency and performance due to technological advancements, and government initiatives and subsidies for installing solar systems.

Can a Residential Solar Panel Installed with a Fixed-Tilt Mount Be Upgraded to a Dual Axis Tracker?

No. Upgrading a residential solar panel system already installed with fixed-tilt mounts to a dual-axis tracker system is generally not feasible or cost-effective for three main reasons. These reasons are structural incompatibility, mounting challenges, and cost considerations.

Most existing roof structures designed for fixed-tilt systems are usually unable to handle the additional weight, wind load, and dynamic forces of a dual-axis tracker. Significant upgrades to the roof structure are usually required and necessary, which adds substantial cost and potential complexity to the upgrade.

Removing existing mounts and installing a new dual-axis tracker system usually require extensive work, potentially involving roof penetration and alterations. This can be disruptive, time-consuming, and pose waterproofing concerns.

Upgrading a residential solar panel system already installed with a fixed-tilt or single-axis tracker requires additional costs. The cost of a dual-axis tracker system itself is much higher than a fixed-tilt system. The total cost of upgrading a residential solar panel becomes significantly higher than installing a new dual-axis system from scratch when you add the cost of the labor and potential roof modifications.

Is there a significant increase in solar energy gain from using the Dual Axis Tracker?

Yes, dual-axis tracking leads to substantially higher solar energy production compared to fixed-tilt systems. A fixed-tilt system typically refers to a solar panel installation where solar panels are fixed at a specific angle, facing south, and set in a stationary position. Correctly designed and operated dual-axis trackers yield around 40% more annual solar energy output from the same installed solar panels, according to researcher Mark Scanlon at Renewable Energy World.

Dual-axis solar trackers continually realign solar panels to face the sun, minimizing the angle of incidence losses and reflection effects. The angle of incidence of a solar panel refers to the angle of the surface of the panel compared to the rays of the sun. When the angle of incidence is greater than zero, there are optical losses due to increased reflections from the module materials that need to be quantified, according to researchers at the National Technology and Engineering Solutions of Sandia, LLC. This angle of incidence losses and reflection effects allows for over a quarter more irradiation to be captured by the photovoltaic surface annually. The energy gain numbers are also consistent across research simulations and extensive commercial system performance data.

An improved tracking system via dual-axis solar tracking has a significant energy gain of about 43.6% as compared to a fixed photovoltaic panel. Experiments further show that an increase of 1.6% in solar energy output is achieved over conventional precise dual-axis tracking systems, according to a study from the SpringerLink Journal. The 2014 SpringerLink Study entitled “Improving the dual-axis solar tracking system efficiency via drive power consumption optimization” was conducted by engineering researchers Yougeshwarsingh Rambhowan & Vishwamitra Oree from the University of Mauritius, Reduit, Mauritius.

Therefore, the use of Dual Axis Trackers can significantly increase the efficiency of solar energy collection, making them a valuable addition to any solar power system.

Is it Costly to Maintain a Dual Axis Tracker?

Yes, maintaining a Dual Axis Tracker is often costly compared to traditional fixed solar panels, or even single-axis trackers. The average maintenance cost of Dual Axis Trackers is currently around $0.011 per watt/dc ($11k/MWdc) per year. The cost of maintaining dual-axis solar trackers relates to factors such as higher complexity, the need for specialized technical support, repair and maintenance costs, and the lost energy production caused by system downtime.

Dual-axis solar trackers are complex systems. Compared to fixed-tilt systems and even single-axis trackers, dual-axis trackers (DATs) have more moving parts like motors, gears, and cables. These components are susceptible to wear and tear over time, requiring regular maintenance and potential replacements.

Dual-axis solar trackers require specialized technical support. Due to their complexity, dual-axis trackers (DATs) typically require trained technicians for maintenance, which often leads to higher labor costs compared to fixed-tilt or single-axis systems, where more general technicians suffice.

Regular preventative maintenance checks ensure optimal performance and prevent costly breakdowns. This includes cleaning the panels and tracker components, checking for wear and tear, and performing software updates. Repair and replacement of any of the components of a dual-axis tracker leads to an increase in the cost of maintenance.

Downtime and lost production make it costly to maintain a dual axis solar tracker. Downtime refers to periods when the solar tracker is not operational. Downtime occurs due to routine maintenance or unexpected issues such as mechanical failures or extreme weather conditions. While preventative maintenance minimizes downtime, unexpected repairs or component failures occur, leading to lost or reduced energy production and potential revenue loss for solar businesses.

Is it better to use a Dual-Axis Tracker in a residential area than a Single-Axis Tracker?

Yes, it is better to use a Dual-Axis Tracker in a residential area than a Single-Axis Tracker, but it depends on specific circumstances. These specific circumstances are the availability of sufficient land space, cost considerations, and areas with unreliable and insufficient grid connections. Dual-axis solar trackers have advantages such as high energy production and efficient land use, as well as disadvantages such as high maintenance costs, increased complexity, potential reliability issues, and aesthetics. Single-axis trackers offer advantages such as lower cost, simpler design, and high reliability, but they also have disadvantages such as low energy production and less efficient land use.

Choosing between a dual-axis solar tracker and a single-axis tracker for your residential area depends on your personal preference. A dual-axis tracker is a better option if maximizing energy production is your top concern. A single-axis tracker is a wiser choice if affordability and simplicity are your top priorities. Other factors to consider when choosing a solar tracker are local climate, availability of roof space, and your budget.

What is the difference between a Dual Axis Tracker and a Single Axis Tracker?

The main difference between dual-axis trackers and single-axis trackers lies in their movement capabilities, which directly impact their efficiency and cost. Dual-axis trackers (DATs) move on two axes, both horizontally (east-west) and vertically (north-south). This allows them to precisely track the sun's movement throughout the day, maximizing exposure to direct sunlight. Single-axis trackers (SATs) only move on one axis (typically horizontal, east-west) to follow the sun across the sky. They tilt throughout the year to optimize the angle of the panels to the sun.

Dual Axis Tracker (DATs) consistently capture more direct sunlight, leading to 40-50% higher energy production compared to fixed-tilt systems and 5-10% more than single-axis trackers (SATs). This benefit is greatest in regions with high sun exposure and longer daylight hours. Single Axis Tracker (SATs) offer a 15-20% increase in energy production compared to fixed-tilt systems. However, their performance may not be as consistent throughout the day, especially in the morning and evening when the sun's angle deviates from its tilt.

In terms of complexity and cost, the additional axis of movement makes dual-axis trackers (DATs) more complex to manufacture, install, and maintain. This translates to higher upfront and maintenance costs compared to single-axis trackers (SATs). When comparing a dual-axis tracker vs a single-axis tracker, single-axis trackers require specialized technicians for maintenance, potentially limiting your options and increasing labor costs. Single Axis Trackers (SATs) have a simpler design, which makes them more affordable and easier to install and maintain. They require less specialized expertise, typically reducing maintenance costs.

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