Introduction To The Main Raw Materials And Components Of Solar Photovoltaic Modules
May 20, 2024
Solar photovoltaic modules, also known as solar modules and photovoltaic modules, are composed of a series of solar cells arranged in different arrays. Single solar cells cannot be used directly as power sources. To make a power supply, several single cells must be connected in series, parallel and tightly sealed into components. Solar photovoltaic 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 function is to convert solar energy into electrical energy, or send it to the battery for storage, or promote load 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. Building material solar cell modules sometimes use tempered glass with a thickness of 5~10mm, but regardless of thickness, the light transmittance is required to be above 90%. Low-iron ultra-white means that the iron content of this kind of glass is lower than that of ordinary glass, thus increasing the light transmittance of the glass. At the same time, when viewed from the edge of the glass, this kind of glass is also whiter than ordinary glass, which is greener when viewed 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 adhesive film: A copolymer of ethylene and vinyl acetate, it is a thermosetting film-like hot melt adhesive and is currently a commonly used adhesive material in solar cell module packaging. Two layers of EVA film are added to the solar cell module. The two layers of EVA film are sandwiched between the panel glass, cells and TPT backsheet film to bond the glass, cells and TPT together. After it is bonded to glass, it can increase the light transmittance of the glass, play an anti-reflective role, and gain the power output of the solar cell module.
Backsheet material: The backsheet material of the solar cell module can be selected in a variety of ways according to the different usage requirements of the solar cell module. Generally, there are several types such as tempered glass, organic glass, aluminum alloy, TPT composite film, etc. The tempered glass backsheet is mainly used to make double-sided light-transmitting building material solar cell modules, which are used for photovoltaic curtain walls, photovoltaic roofs, etc. The price is higher and the module weight is also heavy. In addition, the most widely used currently is TPT composite film. TPT composite membrane has the characteristics of airtightness, good strength, good weather resistance, long service life, no change at lamination temperature, and strong bonding with adhesive materials.
These characteristics are suitable for packaging solar cell modules. As the backsheet material of the battery module, it effectively prevents the erosion and impact of various media, especially water, oxygen, corrosive gases, etc., on EVA and solar cells. In addition to TPT, common composite materials include composite films with a metal film sandwich structure in the middle, such as TAT (composite film of Tedlar film and aluminum film) and TIT (composite film of Tedlar film and iron film). These composite films also have the characteristics of high strength, flame retardancy, durability, and self-cleaning. The white composite film can also reflect sunlight, which can improve the conversion efficiency of battery components. It also has strong reflection of infrared rays, which can reduce the cost of battery components. Operating temperature in strong sunlight.
Junction box and bypass diode
The special junction box for solar cell modules is a component that connects the internal output circuit of the battery module to the external circuit. The positive and negative bus bars drawn from the battery panel enter the junction box and are plugged or soldered to the corresponding positions in the junction box. The leads are also connected to the junction box through plugging, welding and screw crimping. There is also a location for bypass diode installation in the junction box or a bypass diode is installed directly.
Basic knowledge of solar cell components
When there are more solar cell modules connected in series to form a battery array or a branch of a battery array, diodes need to be connected in reverse parallel at the positive and negative output ends of each solar panel. The diode connected in parallel at both ends of the module is called a bypass diode. path diode.
The function of the bypass diode is to prevent a certain component or part of the component in the square array string from being blocked by a shadow or malfunctioning and stopping power generation. A forward bias voltage will be formed on both ends of the bypass diode of the component to cause the diode to conduct. The operating 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. It also protects the bypassed components from being damaged by high forward bias or heating due to the "hot spot effect" .
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 main specifications are 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 and a silver-white electrode grid. There are many thin grid lines, which are the leads from the surface electrodes of the cell to the main grid lines. The two wider silver-white lines are the main grid lines, also called electrode lines or upper electrodes. There are also two silver-white main grid lines on the back of the cell, called the lower electrode or back electrode. The connection between battery cells is achieved by welding interconnecting strips to the main grid lines. Generally, the electrode line on the front is the negative electrode line of the battery piece, and the electrode line on the back is the positive electrode line of the battery piece. The area of the cell is directly proportional to the output current and power generation. The larger the area, the greater the output current and power generation.
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