A coated composite solar cell backsheet and its production line

Abstract

The application belongs to the technical field of photovoltaic module production, and particularly relates to a coated composite solar cell backboard and a production line thereof, which comprises a backboard layer and a PET base layer, one side of the PET base layer is coated with a coating layer, and the other side is combined with the backboard layer through an intermediate layer, wherein the PET base layer is directly combined with the intermediate layer and the backboard layer after being coated with the coating layer and solidified through the production line, and the coating layer comprises the following components in mass ratio: fluorine-containing coating 30-55%; solvent 20-40%; cross-linking agent and curing agent 2-6%; and filler 15-40%. Through the integrated production process, the PET base layer is directly combined with the intermediate layer and the backboard after being coated and solidified through the production line, so that the production efficiency is effectively improved, the process flow is simplified, the product quality is not affected by multiple unwinding and winding, and the energy-saving and environment-friendly effect is good.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic module manufacturing technology, and in particular relates to a coated composite solar cell backsheet and its production line. Background Technology

[0002] The backsheet of a solar cell is located on the back of the solar cell and plays a protective and supporting role for the cell. It needs to have reliable mechanical properties, insulation, water resistance, and aging resistance to ensure the life of the solar power generation module. From the perspective of molding process, solar cell backsheets can be divided into coated type, composite type, and coated / composite type. Among them, coated backsheets mainly achieve the functionality of the backsheet by coating a fluorocarbon coating on a PET substrate. Composite backsheets are made by bonding the substrate and a fluorinated film together with an adhesive. Composite and coated / composite types organically combine coating technology and adhesive bonding technology, coating and bonding are performed on both sides of the substrate respectively to obtain a backsheet with one side coated and the other side adhesive bonded.

[0003] However, the coating and lamination of traditional coated composite solar cell backsheets are usually carried out on two production lines, requiring multiple unfolding and rewinding processes, which is inefficient, has a complex process flow, and the product quality is easily affected, and does not meet the requirements of energy conservation and environmental protection. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned technical problems by providing a coated composite solar cell backsheet and its production line. This achieves an integrated production process that combines coating and lamination, avoiding multiple opening and winding operations, improving efficiency, simplifying the process, enhancing product quality, and providing energy-saving and environmentally friendly benefits.

[0005] In view of this, the present invention provides a coated composite solar cell backsheet, comprising:

[0006] Backing layer;

[0007] The PET base layer has a coating on one side and is laminated to the backing layer through an intermediate layer on the other side.

[0008] The PET base layer is coated and cured on the production line and then directly laminated with the intermediate layer and the backing layer.

[0009] In the above technical solution, further:

[0010] The coating comprises the following components in the indicated mass ratios: 30–55% fluorinated coating; 20–40% solvent; 2–6% crosslinking agent and curing agent; and 15–40% filler.

[0011] A production line for coating a composite solar cell backsheet includes:

[0012] Feeding rollers, including PET feeding rollers, intermediate layer feeding rollers and backsheet layer feeding rollers;

[0013] Take-up roller;

[0014] The oven mechanism has a first heating chamber for coating curing and a second heating chamber for bonding and curing the PET base layer and backing layer.

[0015] A self-regulating temperature mechanism is installed on the side of the second heating chamber and is used to self-regulate the temperature of the second heating chamber;

[0016] A coating mechanism is installed in front of the first heating chamber and is used for coating the PET substrate.

[0017] The composite mechanism is installed in front of the second heating chamber and is used for the composite between the PET base layer, intermediate layer and backing layer after the coating is applied and cured;

[0018] The first heating chamber is connected to a steam generator, and a connection hole is provided between the first heating chamber and the second heating chamber.

[0019] In the above technical solution, the oven mechanism further includes:

[0020] The chamber has a first drying tunnel for coating curing and a second drying tunnel for adhesive curing. The first heating chamber is arranged around the first drying tunnel, and the second heating chamber is arranged on both sides of the second drying tunnel.

[0021] A first heat insulation layer is provided between the first drying tunnel and the second drying tunnel, and a second heat insulation layer is provided at both ends of the first drying tunnel and the second drying tunnel, and the second heat insulation layer has slots.

[0022] In the above technical solution, further:

[0023] The second heating chamber includes a serpentine flow channel and a direct flow channel. The serpentine flow channel is located on both sides of the second drying tunnel, and its starting end is connected to the connecting hole. The direct flow channel is located on one side of the serpentine flow channel, and its starting end is connected to the connecting hole, and is used to directly guide steam through the second drying tunnel.

[0024] The self-regulating temperature mechanism includes:

[0025] The first switching component is installed at the connection hole and is used to switch between the connection hole and the serpentine flow channel or the connection hole and the DC channel.

[0026] A drive assembly is installed inside the second drying tunnel and is used to drive the first switching assembly to connect the connection hole and the DC channel when the temperature of the second drying tunnel is too high.

[0027] Both the serpentine flow channel and the direct flow channel are connected to the air outlet pipe.

[0028] In the above technical solution, the further first switching component includes:

[0029] The valve body is installed at the connection hole and has an air inlet communicating with the connection hole, a first air outlet communicating with the direct flow channel, and a second air outlet communicating with the serpentine flow channel.

[0030] The valve core is installed in the valve body and has an L-shaped flow channel inside. One end of the core is always connected to the air inlet, and the other end switches between the first air outlet and the second air outlet.

[0031] The valve stem is connected to the valve core, and one end extends out of the valve body and connects to the output end of the drive assembly.

[0032] The valve seat is installed inside the valve body and is used for a sealing connection between the valve core and the inner wall of the valve body.

[0033] In the above technical solution, the driving component further includes:

[0034] The piston cylinder is installed inside the second drying tunnel, with one end open and extending into the second insulation layer;

[0035] The piston is slidably connected inside the piston cylinder;

[0036] Gears are fitted onto the valve stem;

[0037] A rack is connected to the end of the piston near the opening of the piston cylinder and extends out of the piston cylinder to mesh with a gear;

[0038] The spring is installed inside the second heat insulation layer, and its two ends abut against the inner wall of the second heat insulation layer and the end of the rack away from the piston, respectively.

[0039] The piston can drive the rack and pinion gear to rotate when the temperature in the second drying tunnel is too high.

[0040] In the above technical solution, further:

[0041] The piston cylinder surface is provided with multiple heat exchange fins.

[0042] In the above technical solution, further:

[0043] The end of the serpentine flow channel is connected to the end of the direct current channel, and a second switching component is provided at the connection point;

[0044] The ends of the serpentine flow channel and the ends of the direct flow channel are set perpendicularly.

[0045] In the above technical solution, the second switching component further includes:

[0046] A baffle is installed at the connection between the end of the serpentine flow channel and the end of the straight flow channel, with one end hinged to the inner wall of the connection and the other end extending towards the outlet pipe.

[0047] The partition is inclined and abuts against the inner wall of the DC channel.

[0048] The beneficial effects of this invention are as follows:

[0049] 1. Through an integrated production process, the PET base layer is coated and cured on the production line and then directly laminated with the intermediate layer and back sheet. This effectively improves production efficiency, simplifies the process, avoids multiple opening and winding, avoids affecting product quality, and has good energy-saving and environmental protection effects.

[0050] 2. By employing an oven mechanism having a first heating chamber for coating curing and a second heating chamber for adhesive curing, and by using a self-regulating temperature assembly to adjust the temperature of the second heating chamber (i.e., the temperature of the first heating chamber is controlled by a steam generator, while the temperature of the second heating chamber is adjusted by the self-regulating temperature assembly), the problem of needing two heating chambers with different temperatures due to the different temperatures required for coating curing and adhesive curing can be effectively solved.

[0051] 3. By using the steam used in the first heating chamber as the heat source for the second heating chamber, a good energy-saving effect is achieved, and the thermal energy utilization rate of the steam is improved. At the same time, by changing the flow mode of the steam on the side of the second drying tunnel, the heat exchange time between the steam and the second drying tunnel is changed to control the temperature of the second drying tunnel. The structure is simple and easy to control.

[0052] 4. By using the increase in gas pressure caused by the temperature rise inside the piston cylinder to drive the piston to move and drive the valve core to switch, it can ensure a response to the temperature rise in the second drying tunnel even in an unsealed environment, which has the effects of simplifying the structure and saving energy and protecting the environment. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the structure of the present invention;

[0054] Figure 2 This is a schematic diagram of the production line of the present invention;

[0055] Figure 3 This is a schematic diagram of the oven mechanism of the present invention;

[0056] Figure 4 This is a top view of the oven mechanism of the present invention;

[0057] Figure 5 This is the present invention. Figure 4 Sectional view at point AA;

[0058] Figure 6 This is the present invention. Figure 5 Enlarged view of point B in the middle;

[0059] Figure 7 This is the present invention. Figure 4 Sectional view at CC;

[0060] Figure 8 This is the present invention. Figure 7 Enlarged view at point D;

[0061] Figure 9 This is an exploded view of the first switching component and the driving component of the present invention;

[0062] The markings in the diagram represent: 1. Backing layer; 2. PET base layer; 3. Coating; 4. Intermediate layer; 5. PET feeding roller; 6. Intermediate layer feeding roller; 7. Backing layer feeding roller; 8. Rewinding roller; 9. Oven mechanism; 90. First heating chamber; 91. Second heating chamber; 910. Serpentine flow channel; 911. Straight flow channel; 92. Chamber; 93. First drying tunnel; 94. Second drying tunnel; 95. First insulation layer; 96. Second insulation layer; 97. Slot; 10. Self-regulating temperature mechanism; 11. Coating mechanism; 12. Composite mechanism; 13. Connecting hole; 14. First switching assembly; 140. Valve body; 141. Air inlet; 142. First air outlet; 143. Second air outlet; 144. Valve core; 145. L-shaped flow channel; 146. Valve stem; 147. Valve seat; 15. Drive assembly; 150. Piston cylinder; 151. Piston; 152. Gear; 153. Rack; 154. Spring; 155. Heat exchange fins; 16. Air outlet pipe; 17. Baffle plate. Detailed Implementation

[0063] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0064] Example 1:

[0065] This embodiment provides a coated composite solar cell backsheet, including:

[0066] Backing layer 1;

[0067] PET base layer 2, one side is coated with coating 3, and the other side is bonded to the backing layer 1 through an intermediate layer 4;

[0068] Among them, the PET base layer 2 is coated with coating 3 and cured on the production line and then directly laminated with the intermediate layer 4 and the backing layer 1;

[0069] Meanwhile, coating 3 comprises the following components in the indicated mass ratios: 30-55% fluorinated coating; 20-40% solvent; 2-6% crosslinking agent and curing agent; and 15-40% filler.

[0070] Furthermore, the intermediate layer 4 is an adhesive.

[0071] As can be seen from this embodiment, through an integrated production process, the PET base layer 2 is coated and cured on the production line and then directly laminated with the intermediate layer 4 and the back sheet, which effectively improves production efficiency, simplifies the process, avoids multiple opening and winding, avoids affecting product quality, and has a good energy-saving and environmental protection effect.

[0072] Example 2:

[0073] This embodiment provides a production line for coating composite solar cell backsheets, including:

[0074] The feeding rollers include a PET feeding roller 5, an intermediate layer feeding roller 6, and a backsheet layer feeding roller 7.

[0075] 8 winding rollers;

[0076] The oven mechanism 9 has a first heating chamber 90 for curing the coating 3 and a second heating chamber 91 for bonding and curing the PET base layer 2 and the backing layer 1.

[0077] The self-regulating temperature mechanism 10 is installed on the side of the second heating chamber 91 and is used to self-regulate the temperature of the second heating chamber 91.

[0078] The coating mechanism 11 is installed on the front side of the first heating chamber 90 and is used for coating the PET base layer 2 with the coating layer 3.

[0079] The composite mechanism 12 is installed on the front side of the second heating chamber 91 and is used for the composite between the PET base layer 2, the intermediate layer 4 and the backing layer 1 after the coating 3 is applied and cured.

[0080] The first heating chamber 90 is connected to a steam generator, and a connection hole 13 is provided between the first heating chamber 90 and the second heating chamber 91.

[0081] Meanwhile, the production line also includes multiple free rollers, which mainly serve to change the conveying direction, as well as a tension regulator to adjust the tension during conveying. The composite mechanism 12 includes a drive roller and a clamping roller, and the coating mechanism 11 is a coating machine. Its specific structure is a mature existing technology, which will not be described in detail here.

[0082] As can be seen from this embodiment, by employing an oven mechanism 9 having a first heating chamber 90 for curing coating 3 and a second heating chamber 91 for adhesive curing, and by using a self-regulating temperature assembly to adjust the temperature of the second heating chamber 91, i.e., the temperature of the first heating chamber 90 is controlled by a steam generator, while the temperature of the second heating chamber 91 is adjusted by a self-regulating temperature assembly, the problem of needing two heating chambers with different temperatures due to the different temperatures required for curing coating 3 and adhesive curing can be effectively solved.

[0083] Furthermore, the curing temperature of coating 3 is higher than that of adhesive curing. Therefore, by using the steam used in the first heating chamber 90 as the heat source for the second heating chamber 91, a better energy-saving effect is achieved, and the thermal energy utilization rate of steam is improved.

[0084] Example 3:

[0085] This embodiment provides a production line for coating composite solar cell backsheets. In addition to the technical solutions described in the above embodiments, it also has the following technical features: the oven mechanism 9 includes:

[0086] The box body 92 has a first drying tunnel 93 for the coating 3 to pass through during curing and a second drying tunnel 94 for the adhesive to pass through during curing. The first heating chamber 90 is arranged around the first drying tunnel 93, and the second heating chamber 91 is arranged on both sides of the second drying tunnel 94.

[0087] A first heat insulation layer 95 is provided between the first drying tunnel 93 and the second drying tunnel 94, and a second heat insulation layer 96 is provided at both ends of the first drying tunnel 93 and the second drying tunnel 94, and the second heat insulation layer 96 has slots 97.

[0088] Meanwhile, the first insulation layer 95 is filled with insulation material, and this application does not limit the insulation material, as it is existing technology and can achieve the insulation effect.

[0089] As can be seen from this embodiment, by setting the first heat insulation layer 95, the temperature between the first drying tunnel 93 and the second drying tunnel 94 is avoided from affecting each other, ensuring the temperature stability in the first drying tunnel 93 and the second drying tunnel 94. Furthermore, the setting of the second heat insulation layer 96 further improves the temperature stability in the first drying tunnel 93 and the second drying tunnel 94. The slot 97 facilitates the entry of the coated PET base layer 2 into the first drying tunnel 93 and the PET base layer 2, the intermediate layer 4 and the backing layer 1 into the second drying tunnel 94 after being composited.

[0090] Example 4:

[0091] This embodiment provides a production line for coating composite solar cell backsheets, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0092] The second heating chamber 91 includes a serpentine flow channel 910 and a direct flow channel 911. The serpentine flow channel 910 is disposed on both sides of the second drying tunnel 94, and its starting end is connected to the connecting hole 13. The direct flow channel 911 is disposed on one side of the serpentine flow channel 910, and its starting end is connected to the connecting hole 13, and is used to directly guide steam through the second drying tunnel 94.

[0093] The self-regulating temperature mechanism 10 includes:

[0094] The first switching component 14 is installed at the connection hole 13 and is used to switch between the connection hole 13 and the serpentine flow channel 910 or the connection hole 13 and the DC channel 911.

[0095] The drive assembly 15 is installed in the second drying tunnel 94 and is used to drive the first switching assembly 14 to connect the connection hole 13 and the DC channel 911 when the temperature of the second drying tunnel 94 is too high.

[0096] Both the serpentine flow channel 910 and the straight flow channel 911 are connected to the exhaust pipe 16.

[0097] As can be seen from this embodiment, by changing the flow pattern of steam on the side of the second drying tunnel 94, the heat exchange time between the steam and the second drying tunnel 94 can be changed to control the temperature of the second drying tunnel 94. The structure is simple and easy to control.

[0098] The exhaust pipe 16 facilitates the centralized collection of steam after heat exchange, thus avoiding any impact on the production environment.

[0099] Example 5:

[0100] This embodiment provides a production line for coating composite solar cell backsheets, which, in addition to the technical solutions of the above embodiments, also has the following technical features. The first switching component 14 includes:

[0101] The valve body 140 is installed at the connection hole 13 and has an air inlet 141 communicating with the connection hole 13, a first air outlet 142 communicating with the direct flow channel 911 and a second air outlet 143 communicating with the serpentine flow channel 910.

[0102] The valve core 144 is installed inside the valve body 140 and has an L-shaped flow channel 145L inside. One end of the channel is always connected to the air inlet 141, and the other end switches between the first air outlet 142 and the second air outlet 143.

[0103] The valve stem 146 is connected to the valve core 144, and one end extends out of the valve body 140 and connects to the output end of the drive assembly 15.

[0104] Valve seat 147 is installed inside valve body 140 and is used for sealing connection between valve core 144 and inner wall of valve body 140;

[0105] The valve core 144 has a slot on the side near the valve stem 146, and the valve stem 146 and the valve core 144 are connected by a snap-fit. At the same time, the valve stem 146 and the air inlet 141 are coaxially arranged to ensure that the air inlet 141 always rotates around its axis while the valve core 144 rotates.

[0106] As can be seen from this embodiment, by opening an L-shaped flow channel 145L on the valve core 144, while one end of the L-shaped flow channel 145L is always connected to the air inlet 141, it is possible to switch between the first air outlet 142 and the second air outlet 143 in the vertical plane, and then switch between the serpentine flow channel 910 and the direct flow channel 911 in the vertical plane, ensuring that both the serpentine flow channel 910 and the direct flow channel 911 can be closely attached to the surface of the box 92 located in the second drying channel 94, thereby ensuring its heat exchange efficiency;

[0107] Valve seat 147 can improve sealing performance and prevent steam leakage from affecting the production environment or causing burns to personnel.

[0108] Example 6:

[0109] This embodiment provides a production line for coating composite solar cell backsheets. In addition to the technical solutions described in the above embodiments, it also has the following technical features: the drive assembly 15 includes:

[0110] The piston cylinder 150 is installed inside the second drying tunnel 94, with one end open and extending into the second heat insulation layer 96;

[0111] Piston 151 is slidably connected inside piston cylinder 150;

[0112] Gear 152 is fitted onto valve stem 146;

[0113] A rack 153 is connected to one end of the piston 151 near the opening of the piston cylinder 150, and extends out of the piston cylinder 150 to mesh with the gear 152;

[0114] Spring 154 is installed inside the second heat insulation layer 96, and its two ends abut against the inner wall of the second heat insulation layer 96 and the end of the rack 153 away from the piston 151, respectively.

[0115] Among them, the piston 151 can push the rack 153 to rotate the gear 152 when the temperature in the second drying tunnel 94 is too high;

[0116] Meanwhile, an annular groove is provided on the surface of the piston 151, and a rubber ring is fitted around the annular groove to improve the sealing between it and the inner wall of the piston cylinder 150. The other end of the piston cylinder 150, that is, the end located in the second drying tunnel 94, is closed.

[0117] As can be seen from this embodiment, by placing the piston cylinder 150 and piston 151 within the second drying tunnel 94 and making the interior a sealed structure, it may be convenient to ensure a response to the temperature rise of the second drying tunnel 94 in an unsealed environment. That is, the temperature inside the piston cylinder 150 rises, the air pressure increases, and thus pushes the piston 151 to move, which has the effects of simplifying the structure and saving energy and protecting the environment.

[0118] Meanwhile, the other end of the piston cylinder 150 is open, i.e., a non-sealed environment, which can prevent the piston 151 from being affected by the temperature rise on the other side. Furthermore, the spring 154 is used as the reset force to further prevent the reset from being affected by the temperature. This ensures that the piston 151 can be reset after the temperature in the second drying channel 94 drops, thereby switching the steam flow to the serpentine channel 910 and achieving the effect of automatic regulation.

[0119] Example 7:

[0120] This embodiment provides a production line for coating composite solar cell backsheets, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0121] The piston cylinder 150 has multiple heat exchange fins 155 on its surface;

[0122] The heat exchange fins 155 are arranged at equal intervals, and the piston cylinders 150 adopt an integrated structure.

[0123] As can be seen from this embodiment, by setting multiple heat exchange fins 155 on the surface of the piston cylinder 150, the heat exchange efficiency between the piston cylinder 150 and the second drying tunnel 94 is improved, thereby ensuring the reliability and stability of the piston cylinder 150 in response to the temperature rise in the second drying tunnel 94.

[0124] Example 8:

[0125] This embodiment provides a production line for coating composite solar cell backsheets, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0126] The end of the serpentine flow channel 910 is connected to the end of the direct flow channel 911, and a second switching component is provided at the connection point;

[0127] The end of the serpentine flow channel 910 is perpendicular to the end of the straight flow channel 911.

[0128] As can be seen from this embodiment, by connecting the end of the serpentine flow channel 910 with the end of the direct flow channel 911, i.e. using a single exhaust pipe 16, the structure is further simplified. The second switching component can prevent the temperature of the second drying tunnel 94 from rising. When the second heating chamber 91 uses the direct flow channel 911 for heat exchange, steam is prevented from entering the serpentine flow channel 910, thus affecting the control and regulation of the temperature in the second drying tunnel 94.

[0129] Example 9:

[0130] This embodiment provides a production line for coating composite solar cell backsheets. In addition to the technical solutions described in the above embodiments, it also has the following technical features: the second switching component includes:

[0131] The baffle 17 is installed at the connection between the end of the serpentine flow channel 910 and the end of the straight flow channel 911, with one end hinged to the inner wall of the connection and the other end extending toward the outlet pipe 16.

[0132] The partition 17 is inclined and abuts against the inner wall of the DC channel 911.

[0133] As can be seen from this embodiment, by setting the baffle 17, when the serpentine flow channel 910 is used, the steam will push the baffle 17 to block the direct flow channel 911, and conversely, when the direct flow channel 911 is used, the steam will push the baffle 17 to block the serpentine flow channel 910. The steam flow is automatically regulated, and the structure is simple, stable and reliable.

[0134] Furthermore, a rubber sleeve can be provided on the surface of the partition 17 to further ensure the sealing effect.

[0135] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A production line for coating composite solar cell backsheets, characterized in that, include: The feeding rollers include a PET feeding roller (5), an intermediate layer feeding roller (6), and a backing layer feeding roller (7). Take-up roller (8); The oven mechanism (9) has a first heating chamber (90) for curing the coating (3) and a second heating chamber (91) for bonding and curing the PET base layer (2) and the backing layer (1). The self-regulating temperature mechanism (10) is installed on the side of the second heating chamber (91) and is used to self-regulate the temperature of the second heating chamber (91); The coating mechanism (11) is installed on the front side of the first heating chamber (90) and is used for coating the PET base layer (2) with a coating layer (3). The composite mechanism (12) is installed on the front side of the second heating chamber (91) and is used for the composite between the PET base layer (2), the intermediate layer (4) and the backing layer (1) after the coating (3) is coated and cured; The first heating chamber (90) is connected to a steam generator, and a connection hole (13) is provided between the first heating chamber (90) and the second heating chamber (91). The oven mechanism (9) includes: The box (92) is provided with a first drying tunnel (93) for curing the coating (3) and a second drying tunnel (94) for curing the adhesive. The first heating chamber (90) is arranged around the first drying tunnel (93), and the second heating chamber (91) is arranged on both sides of the second drying tunnel (94). A first heat insulation layer (95) is provided between the first drying tunnel (93) and the second drying tunnel (94), and a second heat insulation layer (96) is provided at both ends of the first drying tunnel (93) and the second drying tunnel (94), and the second heat insulation layer (96) has slots (97). The second heating chamber (91) includes a serpentine flow channel (910) and a direct flow channel (911). The serpentine flow channel (910) is disposed on both sides of the second drying tunnel (94), and its starting end is connected to the connecting hole (13). The direct flow channel (911) is disposed on one side of the serpentine flow channel (910), and its starting end is connected to the connecting hole (13), and is used to directly guide steam through the second drying tunnel (94). The self-regulating temperature mechanism includes: The first switching component (14) is installed at the connection hole (13) and is used to switch between the connection hole (13) and the serpentine flow channel (910) or the connection hole (13) and the direct current channel (911); The drive assembly (15) is installed in the second drying tunnel (94) and is used to drive the first switching assembly (14) to connect the connection hole (13) and the DC channel (911) when the temperature of the second drying tunnel (94) is too high. The serpentine flow channel (910) and the straight flow channel (911) are both connected to the air outlet pipe (16).

2. The production line for coating composite solar cell backsheets according to claim 1, characterized in that, The first switching component (14) includes: The valve body (140) is installed at the connection hole (13) and has an air inlet (141) communicating with the connection hole (13), a first air outlet (142) communicating with the direct flow channel (911) and a second air outlet (143) communicating with the serpentine flow channel (910). The valve core (144) is installed inside the valve body (140) and has an L-shaped flow channel (145) inside. One end of the valve core is always connected to the air inlet (141), and the other end switches between the first air outlet (142) and the second air outlet (143). The valve stem (146) is connected to the valve core (144), and one end extends out of the valve body (140) and connects to the output end of the drive assembly (15); The valve seat (147) is installed inside the valve body (140) and is used for sealing connection between the valve core (144) and the inner wall of the valve body (140).

3. The production line for coating composite solar cell backsheets according to claim 2, characterized in that, The driving component (15) includes: The piston cylinder (150) is installed in the second drying tunnel (94) and has an open end, extending into the second insulation layer (96); Piston (151) is slidably connected inside piston cylinder (150); Gear (152) is fitted onto valve stem (146); A rack (153) is connected to one end of the piston (151) near the opening of the piston cylinder (150) and extends out of the piston cylinder (150) to mesh with a gear (152); Spring (154) is installed inside the second heat insulation layer (96), and its two ends abut against the inner wall of the second heat insulation layer (96) and the end of the rack (153) away from the piston (151), respectively; The piston (151) can push the rack (153) to rotate the gear (152) when the temperature in the second drying tunnel (94) is too high.

4. The production line for coating composite solar cell backsheets according to claim 3, characterized in that: The piston cylinder (150) has multiple heat exchange fins (155) on its surface.

5. The production line for coating composite solar cell backsheets according to claim 1, characterized in that: The end of the serpentine flow channel (910) is connected to the end of the direct current channel (911), and a second switching component is provided at the connection point; The end of the serpentine flow channel (910) is perpendicular to the end of the direct flow channel (911).

6. The production line for coating composite solar cell backsheets according to claim 5, characterized in that, The second switching component includes: The baffle (17) is installed at the connection between the end of the serpentine flow channel (910) and the end of the straight flow channel (911), with one end hinged to the inner wall of the connection and the other end extending toward the outlet pipe (16). The partition (17) is inclined and abuts against the inner wall of the DC channel (911).

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