The brackets of solar cell modules are mostly installed in a fixed way. This installation method is not only low-cost, but also has a stable structure and simple operation. However, the trajectory of the sun is constantly changing in the sky. Most of the time of the day, sunlight cannot The solar cells are directed vertically, which means that the power generation system cannot make full use of sunlight.
In order to improve the effective sunshine time of photovoltaic power plants and thereby increase the power generation, photovoltaic manufacturers have begun to develop and apply a method that enables the battery modules to track the sun’s trajectory within a certain lighting time, so as to maintain the relative verticality of the light and the solar battery modules. An automatic tracking device that can provide more effective hours of sunshine. The power generation efficiency of a solar cell module has a lot to do with its direct angle of sunlight. When the angle is vertical, it receives the largest amount of radiation. Taking the earth as a reference, the sun is in constant motion, and the selling angle of the electric components and the sunlight is definitely smaller than the angle when the angle is vertical, and its power generation will also be accordingly. If it becomes smaller, if you want to increase the power generation of the system, you can adjust the orientation of the solar cell module so that the photosensitive surface is always facing the sun, so that the solar cell module can maintain this direction.
This kind of real-time solar power generation system that can keep the photosensitive surface of the solar cell module and the sun’s rays vertical is called the solar automatic tracking system. Countries with relatively developed photovoltaic industries, such as Spain, Germany, the United States, Italy, etc., have been born one after another. There are many professional manufacturers who produce integrated systems and have launched various forms of automatic tracking systems; there are also many manufacturers in China currently planning and producing different types of automatic tracking systems. Large and medium-sized photovoltaic power plants generally occupy a large area, and land problems Generally, it is an important factor to consider in the early stage of building a photovoltaic power station. The trajectory of the sun is not repeated day after day, so the automatic tracking system does not block the rear components fixedly during the movement process, and each tracking bracket operates independently. Deserts, grasslands, Gobi deserts, and gardens can be installed without affecting the growth of plants on the site.
Therefore, it can make more full use of land resources, and the use of automatic tracking system can also produce a comprehensive social effect of more environmental protection and more energy saving. Indirectly avoid high pollution and high energy consumption in the production process of battery components. As a new type of energy, solar photovoltaic power generation has less pollution and can provide a more effective guarantee for the sustainable development of human beings. At present, most of the large and medium-sized photovoltaic power stations in the same country use the most traditional fixed installation method. This installation method is not a mainstream development trend.
(1) Flat single axis tracking system
As the name suggests, there is only one axis of rotation to change the angle of the electric module, so that the sunlight is perpendicular to the panel of the battery module, and the light intensity is increased to improve the photovoltaic conversion rate. As shown in Figure 1.
Figure 1 is the control principle diagram of the single-axis tracking system. The single-axis tracking system tracks and rotates at a fixed rotational speed, because the rotation speed of the earth itself is fixed, and it rotates once in about 21h, while the movement angle of the sun is from east to west. Evenly changing, like a 24-hour clock, the flat single-axis tracking bracket, through its rotation in the east-west direction, ensures that the angle between the normal line of the sunlight and the solar panel surface is the minimum value at each moment, so as to obtain greater power generation.
The flat single-axis tracking bracket only changes the inclination angle of the solar cell module from east to west. The inclination angle in the north-south direction is a fixed value. Generally, it can be horizontally connected in a row and run simultaneously. It has a simple structure and stable and reliable operation. All tracking signals come from Sensor, the tracking system does not need initial positioning and can adapt to all kinds of weather. As long as the sensor senses the light signal, the system will automatically track within its setting range, and it will not get lost no matter if it is restarted in any direction, and the light sensor does not sense during the day. When it reaches the light, the tracking system will automatically stop working. Once it is detected, it will immediately track the sensor regardless of the angle between the sensor and the sun. At night, the system stops in the west, and the next morning when the sun rises, the system will adjust in place within a few minutes. , turn east.
(2) Inclined single axis tracking system
If the rotation axis of the single-axis system forms a certain inclination angle with the ground, that is, the azimuth angle of the photovoltaic module is not 0, it is called polar-axis single-axis tracking. The tilted single-axis tracking bracket is based on the fixed tilt angle of the solar cell module, and rotates around the tilted axis to track the sun azimuth to obtain greater power generation. The photovoltaic array of the tilted single-axis automatic tracking system can surround a The oblique axis rotates, and the system tracks the sun in the east-west direction. The oblique single-axis tracking device is mainly composed of a motor rotating device, an oblique rotating axis, a solar cell bracket, a tracking system control device, and a wind and light sensor. Compared with the fixed bracket installation In the single-axis tracking device, the power generation of the inclined single-axis automatic tracking device is relatively large. The advantage of the inclined single-axis automatic tracking system is that the optimal inclination angle of the bracket can be adjusted according to the different conditions of the power station, and the The azimuth angle of the sun is tracked by the transmission system. In the case where both the tilt angle and the azimuth angle can be considered, the oblique single-axis tracking system can greatly improve the power generation efficiency of the photovoltaic system
(3) Dual-axis tracking system
The dual-axis automatic tracking moves along two rotation axes. Unlike the inclined single-axis, the non-fixed value surface of the inclination angle changes. In this way, the trajectory of the sun can be completely tracked. In theory, the angle of incidence can be zero, and the power input of the motor can be input to the turbine vortex to convert the motion of the vertical plane into the rotary motion of the horizontal plane. At the same time, the position sensor is real-time. The rotation angle of the system is collected from the ground, and the collected data is input for the control system, and the automatic tracking control of the horizontal rotation direction is realized from the surface. Single-axis tracking is only tracking the azimuth angle of the sun, and the altitude angle is adjusted seasonally, and dual-axis tracking is two-angle tracking, which is better than single-axis tracking in principle.
(4) Automatic tracking system model
The schematic diagram of single-axis tracking motion is shown in Figure2. The tracking system model is established by single-axis tracking. The tracking angle is ρ, the altitude angle is α, and the sun azimuth angle is γ. When rotating around the axis, the incident rays of the sun can fall on the plane formed by the tracking surface and the normal of the tracking axis. The motion model is:
