What is the structure of the tempered glass laminated battery module?
The tempered glass laminated battery assembly is composed of a front cover (tempered glass), protective film, Upper electrode and lower electrode, sealing materials, filling materials, rear cover (back plate), frame, junction box, interconnecting strips, etc.Next, the structure of the tempered glass laminated battery module is introduced in detail.
(1) Front cover (tempered glass)
The front cover is a piece of ultra-white glass, so it is also called tempered glass. Tempered glass is a 3mm thick transparent glass with low iron content, super white tempered treatment, and suede surface. Ultra-white glass has the following advantages.
①The high transmittance of visible light can reach 91.5% or more, which increases the solar radiant energy absorbed by the solar cell.
② Good color consistency. Since the iron content in the raw material is only 1/10 or even lower than that of ordinary glass, ultra-white glass has less absorption of the green band of visible light than ordinary glass, ensuring the consistency of glass color.
③Low UV transmittance Compared with ordinary glass, ultra-white glass has lower absorption in the ultraviolet band, which can effectively reduce the passage of ultraviolet rays and slow down the aging of the adhesive inside the module.
④ Low self-explosion rate of glass Due to the low impurity content in the raw materials for the production of ultra-white glass, the ultra-white glass has a more uniform composition than ordinary glass, which greatly reduces the probability of self-explosion after tempering.
Suede refers to that in order to reduce the reflection of sunlight, the surface of this glass is subjected to anti-reflection treatment through physical and chemical methods to make the surface of the glass fluffy, thereby increasing the amount of light incident.
The toughening treatment is to increase the strength of the glass, especially to increase the ability to withstand impact loads. Regardless of the impact of wind and rain, dust pollution and wind, sand and hail, it can play a role in protecting the solar cell components.
Viewed from the edge of the glass, this kind of glass is also whiter than ordinary glass, which is greenish from the edge.
(2) Protective film
The silicon surface is very bright and reflects a lot of sunlight, which cannot be used by the battery. For this reason, it is necessary to coat it with a protective film with a very low reflection coefficient (a blue anti-reflection film) to reduce the incident light loss to less than 5%.
(3) Upper electrode and lower electrode
In addition to a blue anti-reflection film on the surface of the component, there are also silver-white electrode grid lines. Many of the thin grid lines are the leads from the surface electrodes of the cell to the main grid lines, and the two wider silver wires are the main grid lines. Also called upper electrode. There are also two silver-white bus bars on the back of the cell, called the bottom electrode. The connection between the battery slice and the battery slice is realized by connecting the interconnection strip and then welding to the lower electrode. Generally, the electrode wire on the front is the negative wire of the battery, and the electrode wire on the back is the positive wire of the battery.
(4) Filling material
The photovoltaic cell filling material is a kind of transparent soft plastic. Because the photovoltaic cell is fragile, the photovoltaic cell is usually embedded in the soft plastic. When the battery module is subjected to an external load, it can reduce the internal stress through the good plastic deformation of the soft plastic, thereby ensuring The battery will not be broken. Transparent soft plastic (such as EVA) tightly surrounds the entire cell, toughened glass, backplane, etc. to form a solar cell module. The transparent soft plastics above and below the photovoltaic cells generally use EVA (ethylene-vinyl acetate copolymer), but also PVB, polysiloxane or TPU. The quality of the transparent EVA material directly affects the life of the components. EVA exposed to the air is prone to ageing and yellowing, thereby affecting the light transmittance of the module and reducing the power generation efficiency of the module. In addition, the EVA viscosity is not up to standard and the bonding strength between EVA and tempered glass and the backplane is not enough, which will cause the EVA to age prematurely and affect the life of the components.
(5) Rear cover (rear panel or back panel)
The rear panel is a metal laminate laminate, composed of PVF-aluminum-PVF or PVF-polyurethane-PVF layers, which play the role of sealing, insulating, waterproofing and making the module durable.
The frame is made of aluminum alloy that has undergone acid-resistant treatment, so the frame is also called an aluminum alloy frame. The frame can protect the laminate and play a certain sealing and supporting role. The aluminum alloy frame is rectangular (hollow inside), or in the form of left and right frames (the right side is in the form of the left frame, and the left is in the form of the right frame). On each side of the long side frame, there are 3 to 4 mounting holes of 6.0 to 9.7 mm. In addition, there is a hole with a diameter of 4.0 to 6.5mm specially used to install the ground wire.
In addition to protecting the laminate and supporting the aluminum alloy frame, it can also play a certain sealing role.