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The solar tracking system accurately tracks the path of the sun throughout the day according to the astronomical algorithm plus the tilt sensor according to the local latitude and longitude, and adjusts the angle of the solar photovoltaic panels to increase solar power generation by more than 20% on average.
In this article, we will discuss the advantages and disadvantages of solar tracking system.
1. What is a solar tracking system
The solar tracking system is a control device used to assist photovoltaic modules to accurately track solar energy and improve solar energy utilization. If there is a 25° deviation between the angle between the power generation system and the sun's rays, the output power of the photovoltaic array will be reduced by about 10% due to the reduction of radiant energy from the vertical incidence.
Only by tracking the sun with high precision and stability can we obtain accurate conversion efficiency and large investment returns.
2. How does a solar tracking system work
The working principle of the solar tracking system is to optimize the angle between sunlight and the electronic sheet of the module as much as possible, and make the sunlight directly hit the photovoltaic module by tracking the movement of the sun in real time.
This increases the amount of solar radiation received by the photovoltaic array and increases the overall power generation of the solar photovoltaic power generation system. The general tracking control strategy is the active tracking control strategy, which uses two basic tracking control methods.
① Light control
It use a light sensor. According to the difference in light intensity in different areas of the sky, the position of the sun is determined, and then the motor is driven to rotate the bracket for tracking. The sensors are mounted on a solar cell array(12v 100ah lithium ion batteries) and run in sync with it.
If there is a slight change in the direction of the light, the sensor will be unbalanced and the system output signal will be skewed. When the deviation reaches a certain amplitude, the sensor outputs the corresponding signal, and the actuator begins to correct the deviation so that the photoelectric sensor can reach the balance again.
That is, the solar cell array(12 volt 200ah lithium battery) plane controlled by the sensor output signal stops rotating at right angles to the light ray, and completes an adjustment cycle. This constant adjustment follows the sun's trajectory at all times, forming a closed loop feedback system that realizes automatic tracking.
② Timing control
According to the local latitude and longitude coordinates and time, the astronomical calculation formula is used to calculate the coordinates of the sky where the sun is located, and then the motor is driven to rotate the bracket for tracking.
In time-controlled mode, the GPS module can be used to obtain the local latitude and longitude and time to ensure the accuracy of coordinates and time, thus improving the tracking accuracy. You can also combine the two control methods.
There are two ways to combine them:
With time control as the mainstay, supplemented by light control, when the weather is good, time control is used to track the approximate position of the sun. Then the light control is used for precise adjustment, and in the case of bad weather conditions, time control is used alone for tracking to avoid interference from stray light in the sky.
Light control and time control are switched on. That is, in good weather, the light control is used alone for tracking, and if it encounters rainy weather, it will automatically switch to the time control mode for tracking. Now there is also the application of artificial intelligence technology to solar tracking system.
Smart panel sensors are installed at the end of each solar panel row to provide real-time shadow information, which is then processed by machine learning algorithms that build virtual 3D models.
Real-time power generation is taken as the condition of the controller, and the power of the photovoltaic power station is maximized through a series of algorithms. The system even integrates the latest weather forecasts to calculate and send optimized tracking commands.
3. Types of solar tracking systems
Solar tracking system can be classified according to their movement patterns. The moving surface has multiple axes: two horizontal and one vertical. The surface can be rotated (tilted) around each axis to get the correct angle to receive the most sunlight.
When a surface rotates about one axis and is moved or adjusted, it is called single-axis tracking. When a surface rotates around two axes at the same time, it is called dual-axis tracking.
① Single-axis tracking PV system
● Advantages
Single-axis tracking PV systems offer a single degree of flexibility, with a single rotating axis, typically installed in a north-south arrangement, with key benefits including:
- More reliable.
- It has a longer service life.
- Cheap because they have a simple mechanism and a low cost to run.
- Ideal for projects with low budgets or multi-cloud regions.
- Compared to fixed solar panels, single-axis tracking is almost 32.17%.
- The tracker follows the sun from east to west, providing consistent power output throughout the day.
- Compared to static stations with the same installed capacity, trackers generate 15–16% more electricity per year.
- The payback period of the project is shorter, and the profit has increased significantly.
● Shortcoming
Compared to dual-axis tracking photovoltaic systems, the energy output of single-axis trackers is lower in full sunlight conditions, and technology upgrades are limited.
② Dual-axis tracking PV system
● Advantages
- Continuously tracks the sun and provides a constant power output throughout the day.
- Solar trackers offer a reasonable solution where the power capacity connected to the grid is limited.
- Accommodate smaller spaces and provide the opportunity to use the remaining surrounding area for other additional uses, such as parking, gardening, etc.
- Compared to a static station with the same installed capacity, the annual power output is 45-50% higher.
- Provide the best solution for areas that may hinder solar productivity.
- Some of these areas may have complex ground structures, complex topography, stone protrusions, northerly descent, etc.
- The payback period is short. In addition, during its life cycle, profits will increase significantly.
● Shortcoming
It has a higher technical complexity, which makes it potentially vulnerable to failures. Trackers have a shorter lifespan, lower reliability, and degraded performance on cloudy days.
Solar tracking system, whether single or biaxial, can help generate more energy than stationary PV systems. Of course, we have to consider various factors, including terrain, climate, and the type of high efficiency solar panels being used to decide which type of PV tracking system is appropriate.
4. Features of the solar tracking system
In terms of function, the automatic solar tracking system also has a rainy day cleaning mode, a heavy snow, hail protection mode and wind protection mode. In the rainy day cleaning mode, through the background control, the tracking bracket rotates several times from -50° to +50° of the component, and the bracket is washed by rain.
Heavy snow and hail protection mode allows the module to turn to the optimum inclination angle, avoiding direct hail impact and not covering the module with snow. In the gale protection mode, the wind resistance can reach 55.6m/s under the maximum safety condition.
Therefore, the automatic solar tracking system can be better applied to the environment of frost, snow and dust, and can also work reliably in unattended photovoltaic power stations.
From the point of view of whether the tracking is continuous, the general automatic solar tracking system mostly adopts the step tracking mode, which can greatly reduce the energy consumption of the solar tracking system itself compared with the continuous tracking mode. The PV automatic tracking system will also be equipped with a manual control switch to facilitate commissioning.
5. Conclusion
Solar tracking systems have become a mandatory option for photovoltaic power generation systems.
The photovoltaic automatic follow-up system not only comprehensively improves the utilization efficiency of photovoltaic power generation for solar energy, but also is widely used in the photovoltaic industry because it can be well adapted to complex terrain and adapt measures to local conditions. A well-designed solar tracking system can improve the efficiency of the entire system by more than 40%.
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