①Photovoltaic modules
Photovoltaic module is also called “Solar Module” or “PV Module”. It is obtained by encapsulating multiple single solar cells in series and parallel as required, and then packaged by special materials and special processes. The power is generally represented by “Wp” , Where “p” stands for “peak” in English, which means “peak”.
According to different uses, photovoltaic modules are divided into conventional photovoltaic modules and building materials photovoltaic modules, among which building materials photovoltaic modules are further divided into laminated glass photovoltaic modules, insulating glass photovoltaic modules and tile-type modules.
Common conventional photovoltaic modules include monocrystalline silicon modules, polycrystalline silicon modules and amorphous silicon modules. This type of module is used in the construction of ordinary photovoltaic power stations. Common polysilicon components are shown in Figure 1.
The solar cell of laminated glass photovoltaic module is sandwiched between two layers of glass. The light-receiving surface of the module adopts low-iron ultra-white tempered glass, and the back side adopts ordinary tempered glass. This low-iron ultra-white tempered glass is generally used for photovoltaic daylighting pages and photovoltaic curtain walls. , Its structure is shown in Figure 2.
In addition to the functions of daylighting and power generation, hollow glass photovoltaic modules also have the functions of sound insulation, heat insulation and heat preservation, and are often used as glass curtain wall battery modules for various photovoltaic building integrated power generation systems. This component is separated by a hollow aluminum spacer with desiccant between the cell and the glass, and is sealed with butyl glue, structural glue, etc., and the junction box and the positive and negative leads are also sealed with sealant on the front and back. In the edge selling layer of the glass, it is integrated with the components, which makes the installation of the components and the wiring connection between the components very convenient. Its structure is shown in Figure 3.
Photovoltaic tiles are tiles made of synthetic materials (engineering materials) combined with crystalline silicon solar modules through an automated installation process to form tiles with photovoltaic power generation functions, which have the characteristics of heat insulation, heat preservation, waterproofing and power generation, such as Shown in Figure 4.
②Photovoltaic array
Solar cell square array is also called photovoltaic square array, photovoltaic array 、Solar Array or PV Array. In order to meet the requirements of high-voltage and high-power power generation, the solar cell array is composed of several solar cell modules connected in series and parallel, and fixedly combined by a certain mechanical method.
(1) Series and parallel combination of solar cell modules with the same performance. Solar cell modules can be connected in series, parallel, and series-parallel hybrids.
If the performance of each solar cell module is the same, when the modules are connected in series, the output voltage of the square array can be increased proportionally without changing the output current; when the modules are connected in parallel, the output voltage can be increased without changing the output voltage. , So that the output current of the square matrix increases proportionally; when the series and parallel connections are mixed, the output voltage of the square matrix can be increased, and the output current of the square matrix can be increased.
As shown in Figure 5, the performance of each solar cell module is the same. Its voltage and current are 12V and 3A respectively. The total voltage after 2 series and 3 parallel is 24V, and the total current is 9A.
(2) The performance parameters of all solar battery modules forming a square array of solar battery modules with different performances in series and parallel combinations cannot be exactly the same. All connecting cables, plugs and sockets have different contact resistances, which will cause the operation of each series battery module. The current is limited by the component with the smallest current; and the output voltage of each parallel battery component will be clamped by the battery component with the lowest voltage. Therefore, the square matrix combination will produce combined connection loss, so that the total efficiency of the square matrix is always lower than the sum of the efficiencies of all individual components. The specific conditions are as follows:
1) When two components (A, B) with different performance are connected in series, the voltage is still added, and the current value of the component with the smallest current (component B in Figure 6) is shown by the dotted line in Figure 6.
2) When two components (A, B) with different performance are connected in parallel, the current will increase, but the voltage is only the average of the two, as shown by the dotted line in Figure 7.
