Introduction of main raw materials and components of solar photovoltaic modules

Solar photovoltaic cell modules, also known as solar cell modules and photovoltaic modules, are composed of a series of solar cells in different arrays. Single solar cells cannot be used directly as power supplies. For power supply, several single cells must be connected in series, parallel and tightly sealed into components. Solar photovoltaic cell modules (also called solar panels) are the core part of the solar power generation system and the most important part of the solar power generation system. Its role is to convert solar energy into electrical energy, or send it to a battery for storage, or push the load to work.

Main raw materials and components of solar photovoltaic modules

Photovoltaic glass: The panel glass used in the battery module is low-iron ultra-white suede tempered glass. The general thickness is 3.2mm and 4mm. Tempered glass with a thickness of 5 to 10mm is sometimes used for building materials solar cell modules, but the light transmittance is required to be above 90% regardless of the thickness. Low-iron ultra-white means that the iron content of this glass is lower than that of ordinary glass, thereby increasing the light transmittance of the glass. At the same time, from the edge of the glass, this glass is also whiter than ordinary glass, which is greener from the edge. The tempering treatment is to increase the strength of the glass, resist the impact of wind, sand and hail, and play a long-term role in protecting solar cells. After tempering the panel glass, the strength of the glass can be increased by 3 to 4 times compared with ordinary glass.

EVA film: a copolymer of ethylene and vinyl acetate. It is a thermosetting film-like hot melt adhesive, which is a commonly used bonding material in solar cell module packaging. Two layers of EVA film should be added to the solar cell module, and the two layers of EVA film should be sandwiched between the panel glass, the cell and the TPT backplane film to bond the glass, the cell and the TPT together. After it is bonded to the glass, it can improve the light transmittance of the glass, play a role in increasing transparency, and gain the power output of the solar cell module.

Backplane material: The backplane material of solar cell modules can be selected according to the different requirements of solar cell modules. Generally, there are several types of tempered glass, plexiglass, aluminum alloy, TPT composite film, etc. The tempered glass backplane is mainly used to make double-sided light-transmitting building materials for solar cell modules, which are used for photovoltaic curtain walls, photovoltaic roofs, etc. The price is higher and the weight of the modules is also large. In addition, the most widely used is TPT composite film. TPT composite film has the characteristics of airtight, good strength, good weather resistance, long service life, no change in lamination temperature, and firm bonding with bonding materials. These characteristics are suitable for encapsulating solar cell modules. As the backplane material of the battery module, it effectively prevents the erosion and influence of various media, especially water, oxygen, corrosive gases, etc., on EVA and solar cells. In addition to TPT, common composite materials include TAT (composite film of Tedlar film and aluminum film) and TIT (composite film of Tedlar film and iron film) with a metal film interlayer structure in the middle. These composite films also have the characteristics of high strength, flame retardant, durability, self-cleaning, etc. The white composite film can also reflect sunlight, improve the conversion efficiency of battery modules, and also have strong reflection on infrared rays, which can reduce the battery modules. Operating temperature under strong sunlight.

Junction Box and Bypass Diode

The special junction box for solar cell modules is a part that connects the internal output line of the battery module with the external line. The positive and negative bus bars drawn from the battery panel enter the junction box, plug or solder them to the corresponding position in the junction box, and the outer leads are also connected to the junction box by methods such as plugging, welding and screw crimping. There is also a bypass diode installation position or a bypass diode is directly installed in the junction box.

Basic knowledge of solar cell modules

When there are more solar cell modules in series to form a cell array or a branch of the cell array, it is necessary to reverse parallel diodes at the positive and negative output ends of each panel. The diodes connected in parallel at both ends of the module are called bypass diodes.

The function of the bypass diode is to prevent a certain component or part of the component in the square array from being shaded or failing to stop power generation, a forward bias voltage will be formed at both ends of the bypass diode of the component to make the diode turn on, and the working current of the component string bypasses the faulty component and flows through the diode bypass, which does not affect the power generation of other normal components, and also protects the bypassed component from being subject to high forward bias or due to "hot spot effect" heat generation damage.

cell

Crystalline silicon solar cells are divided into monocrystalline silicon cells and polycrystalline silicon cells. The voltage of each cell is about 0.5V, the specifications are mainly 125mm × 125mm, the current is about 5-6A, and the power is about 2.5-3W; 156mm × 156mm, the current is about 8-9A, the power is about 4-5W, and the thickness is generally 170~ 220um. There is a blue anti-reflection film on the surface of the cell, as well as a silver-white electrode grid line. Many of the thin gate lines are the leads that the electrodes on the surface of the battery gather to the main gate line, and the two wider silver lines are the main gate lines, also called electrode lines or upper electrodes. There are also two silver-white main gate lines on the back of the cell, called the lower electrode or the back electrode. The connection between the cell and the cell is realized by welding the interconnection strip to the main gate line. Generally, the front electrode line is the negative electrode line of the cell, and the back electrode line is the positive electrode line of the cell. The size of the area of the battery is proportional to the output current and power generation, the larger the area, the greater the output current and power generation.