Jul 10, 2021 Solar panels

Do you understand the basics of solar panels?

Understanding solar panels
The solar panel (also called solar cell module or photovoltaic module) is a combined device of the smallest and indivisible solar cell with packaging and internal connections that can provide DC output by assembling multiple solar cells. It is the most important part of the solar power system and the core part of the solar power system.
Crystalline silicon materials (including polycrystalline silicon and monocrystalline silicon) are the most important solar materials, with a market share of more than 90%, and solar cells will still be the mainstream materials for a long period of time in the future.

Solar panel composition and functions of each part
⒈Toughened glass: to protect the main body of power generation (such as cell), the choice of light transmission is required:
①High light transmittance (usually above 91%);
②Super white tempered treatment.

⒉Cells: Mainly play a role in generating electricity. Crystalline silicon solar cells and thin-film solar cells are the mainstream in the main power generation market. Both of them have advantages and disadvantages:
①Crystalline silicon solar cell
Advantages: low equipment cost, high photoelectric conversion efficiency, and generate electricity under outdoor sunlight.
Disadvantages: high consumption and battery cost
②Thin film solar cells
Advantages: low consumption and battery cost, good low-light effect, and can generate electricity under ordinary lights, such as solar cells on calculators.
Disadvantages: The equipment cost is high, and the photoelectric conversion efficiency is only more than half of the crystalline silicon cell.

⒊EVA: Used to bond and fix the main body of power generation (cell) and tempered glass, the quality of transparent EVA material, whether EVA is exposed to the air, the lamination process of solar panel manufacturers, the degree of adhesion of EVA is not up to standard, EVA and tempered glass , The bonding strength of the backplane is not enough, which will cause the life of EVA and affect the life of the solar panel.

⒋Silica gel: the function is to seal, used to seal the junction between the component and the aluminum alloy frame, the component and the junction box. Some companies use double-sided tape and foam instead of silica gel. Silicone is generally used. The process is simple, convenient, easy to operate, and cost-effective. Very low.

⒌Backboard: The function is to waterproof, insulate and seal. Generally, TpT, TpE and other materials must be used and must be resistant to aging. Many solar panel manufacturers have a 25-year warranty. Others are generally no problem. The most important thing depends on whether the backplane and silica gel meet the requirements.

⒍Aluminum alloy: It is a protective laminate, which plays a certain role of sealing and supporting.

⒎Junction box: It protects the entire power generation system and plays the role of a current transfer station. The junction box automatically disconnects and short-circuits the battery string because of the short circuit of the components. The selection of diodes is the most critical to prevent burnout of the entire system junction box, so The selection of diodes should also be selected according to the types of cells in the assembly.

Observation of different types of solar panels
In order to get a direct impression of solar panels, in order to better understand the definition of solar panels, first observe two different types of solar panels (Figure 1, Figure 2), compare their product technical parameters, and see their appearance Where is the difference in structure? Are there any other differences?

Figure 1 Epoxy resin seal solar panel
Figure 2 Laminated encapsulated solar panel

Observation of the solar panel model
It is difficult to see the structure of the solar panel only from the physical object of the solar panel. Here is a schematic diagram of a common laminated packaged solar panel structure to show its sandwich-like structure, as shown in Figure 3. The solar cell is sandwiched between the panel glass and the TPT backplane, and sealed and bonded to the panel glass and the TPT backplane by EVA glue. The junction box is also glued on the TPT backplane. Frames are installed on the edges of the panel glass and TPT backplane and sealed with silicone.

Figure 3 Schematic diagram of laminated solar panel structure

Understand the general production process of solar panels
The solar panel is a combined device of the smallest and indivisible solar cell that is packaged and internally connected and can provide a DC output. Packaging is the key to the production of solar panels. The quality of packaging directly determines the service life and power generation of solar panels. Therefore, packaging involves a lot of content. In addition to packaging processes, it also includes packaging materials and packaging quality inspections. First, make a brief introduction to the production process of solar panels, see Table 1.

Production processesProcess introductionRaw materialsProduction equipment
Sorting testTest and sort the electrical performance and appearance of the cells
Laser scribingCut the battery slices into the required size specifications
Single weldingWeld two ribbons on the main grid on the front of the cell
String weldingWeld the single-piece soldered cells in series
LaminateLay the welded battery string with the panel glass, cut EVA, and back plate according to a certain level, and weld the bus band and lead electrode
laminatedPut the laminated components into the laminator for packaging
Frame and junction boxInstall the laminated components with aluminum alloy frame and junction box
Final testTest the electrical performance of solar panels
Table 1. The general production process of solar panels