Most people think of solar as stationary solar panels or those with single-axis trackers. I am talking blue or black solar panels you see on the roofs of many homes or the ground-mounted panels you see when you drive past a solar farm.
Yes, one of the advantages of solar energy is reduced electricity bills; however, you may not know that dual-axis trackers could be a better option than stationary or single-axis solar trackers.
So, what is the difference between single axis and dual-axis solar trackers? And why should you invest in a solar tracking system? I intend to provide you with conclusive answers to these questions and more.
You might also enjoy reading: Different Types of Solar Tracking Systems and how they work?
Single-axis Solar Tracker Vs. Dual-axis Solar Tracker: What Is The Difference?
Their names are self-explanatory, but let me simplify them. In a single-axis solar tracker, the solar panels move on one axis, often east to west, while in dual-axis solar trackers, the panels move on two axes of the compass- east to west and North to south.
Before we dive deep into the differences between the single and dual-axis panels, let me clarify something. Please don’t mistake single-axis solar trackers for stationary or fixed solar panels.
Stationary panels are installed by considering the best direction for optimal energy production. However, single-axis solar tracker follows the Sun’s movement, thus 32.17% more efficient than fixed panels (Source: Solar feeds)
Back to our discussion on dual-axis and single-axis.
Since dual-axis trackers move in two axes, they point more directly at the Sun- the brightest spot in the sky. Therefore, they can help solar panels generate more power.
However, as we will see in the disadvantages, dual-axis is more complex and unreliable than the single-axis solar tracker.
Single-Axis Tracking System
Single-axis move from east to west and are simple, efficient, and low-cost to install and maintain. They perform optimally during the spring and summer seasons when the Sun is highest in the sky.
Nevertheless, its performance significantly drops as they move toward the North. A similar drop in solar power from a single-axis tracker is also experienced at certain times of the year when the Sun strikes horizontally.
If your house is at higher latitudes, you may need vertical-axis trackers to improve solar panel efficiency. The vertical position allows the solar panels to most rays from the Sun during summer and winter.
Consider different types of single-axis trackers and where they work best.
Horizontal Single-Axis Solar Tracker (HSAT)
These solar panels are installed parallel to the ground and rotate at a fixed axis from east to west. It is also cost-effective since it tracks the Sun’s movement from the morning to evening.
And because it is supported along the axis, it is not complex and needs less material to construct. Furthermore, you do not need a special connection to rotate on its center of gravity.
Horizontally Tilted Single-Axis Tracker
It is similar to HSAT, but the panels are installed at a tilted position. They are more complex than HSAT and often need a concrete foundation. Horizontal tilted single-axis trackers are tilted towards the northern or southern hemisphere but still rotate the solar panels from east to west as it tracks the Sun’s movement.
Due to their complexity, they are relatively more expensive than HSAT, with the foundation adding up the cost.
Vertical Single-Axis Solar Tracker
Like all other single-axis solar trackers, they follow the Sun from east to west throughout the day.
This solar tracker system is commonly found at higher altitudes or in the mountains. They are vertical to the ground, allowing them to maintain a consistent angle with the Sun’s rays, especially when the Sun is lower.
Unlike the horizontal axis, the vertical axis has a field layout accommodating a taller profile to prevent energy losses and self-shading.
Vertically-Tilted Axis Solar Tracker
It is the vertical version of the horizontally tilted single-axis tracker. Its tilt is vertical to the ground and rotates on a vertical axis.
Although they can harvest more energy than the horizontal trackers, they are bombarded with high wind loading that the horizontal units.
Vertically tilted single-axis trackers are complex and require concrete and steel to install, hence regarded as expensive.
Check out the New Mexico State University video below to learn more about single-Axis Tracker.
Advantages Of Single-Axis Solar Tracking Systems
We have seen that single-axis solar trackers have one area of rotation aligned to the North-South path.
Here are some advantages of installing this type of solar tracker.
- Single-axis solar tracking systems are reliable.
- They have a longer lifespan.
- They suit companies with a limited budget because they are cheaper than dual-axis trackers.
- They are more efficient than fixed solar panels mounted on the roof or ground.
- They provide consistent power output since they track the Sun from east to west.
- They have the highest density of solar panel placement per square.
- It has a shorter payback period, resulting in a faster return on investment.
Disadvantages Of Single-Axis Solar Tracking System
- Single-axis solar tracking system produces less energy in sunny conditions than dual-axis trackers.
- It offers a limited technological upgrade.
Dual-Axis Solar Tracking System
These sun-tracking solar panels have two rotation axis degrees: primary and secondary axis. The axes can move upward and downward to capture the Sun’s position accurately. And since they have higher accuracy, they provide 40% more output than fixed panels. Nevertheless, they are more complex, which inflates their costs.
Dual-axis trackers always face the Sun to absorb maximum sunlight since they can rotate in all directions.
They are often fitted with an oriented mirror that directs sunlight to a stationary receiver. Therefore, they still produce power whether the Sun is rising or setting.
You can be confident that when the sky is clear, a dual-axis solar tracker will produce maximum energy.
Dual-axis trackers are divided into two categories: Tip-tilt and Azimuth-altitude axis.
Azimuth altitude dual-axis tracker is more popular, but it can be expensive to install. Therefore, they are often used in commercial solar energy systems.
How the dual-axis tracker works, you can change the position of dual-axis solar panels in three ways:
- Manual: The manual version depends on certain personnel deployed to change the solar tracker’s position at different times of the day. It is economically possible in some developing countries where labor cost is still low.
- Passive: This dual-axis solar tracker has a bulb filled with liquid; the liquid evaporates when the Sun heats it. The evaporation causes expansion that pushes and tilts the tracker towards the Sun.
- Active: Hydraulic cylinders or electronic motors adjust the dual-axis solar trackers’ position.
Advantages Of Dual-Axis Solar Tracking Systems
- The system follows the Sun from all angles throughout the day, thus providing maximum power output.
- The excess power from the dual-axis solar tracker can be added to the grid in areas with limited power capacity.
- They preserve space, allowing you to use unused spaces for gardening, parking, etc.
- They produce more power (45-50%) than static solar panels
- You can install them in areas with a complicated ground structure, unsuitable for other solar trackers.
- They have a lower payback period and will prove more profitable during their lifespan.
Disadvantages of Dual-Axis Tracker Systems
- Dual-axis tracker systems are complex, making them susceptible to potential glitches.
- They are less reliable and have a shorter lifespan
- They perform dismally in cloudy weather.
- They are costly
I talked briefly about passive and active solar trackers. Now let’s discuss them in detail.
Active Vs Passive Solar Trackers
Besides the main difference between dual-axis and single-axis solar trackers, you can also divide trackers into active and passive categories.
So, what are active solar trackers? These trackers need an outside power source, like the motor, to move them. Most solar trackers- single-axis or dual-axis are active, which means that you will provide energy to run the motor in your tracking system.
They are often used with complex solar installations for larger projects.
What of passive solar trackers? Passive solar trackers use the Sun to move, meaning they are less advanced and relatively cheap. The Sun’s heat warms the gas, and as it expands, it tilts and pushes the solar panels. Because of their minimal accuracy, passive solar trackers are often used with simple PV systems. During cold temperatures, they may not perform optimally because the liquid in the bulb takes time to heat up.
What to read next:
- 7 Solar Panel Cleaning Equipment and How to Use Them!
- How to Choose Batteries for Solar Panel? (7 Best tips!)
- 6 Best Batteries for Solar Power Storage (Including their pros and cons!)
- How Much Do Solar Panels Generate in Winter? (This much!)
Single-Axis Tracker Vs. Dual-Axis Tracker: Which One Is Better?
While you can track the Sun’s movement from east to west with a single-axis solar tracker and generate more power than stationary solar panels, dual-axis trackers are superior. They are more efficient and precise than single-axis.
With dual-axis solar trackers, you can produce up to 40% more power than stationary solar panels. Dual axis solar tracker is also suitable for people living in areas with varied sun intensity.