Method and device for applying an adhesive backing sheet to the rear face of a photovoltaic panel

Abstract

The invention relates to a method and a device for applying an adhesive backing sheet to the rear face of a photovoltaic panel. The backing sheet is a critical element in the reliability of a photovoltaic panel. Made of thermoplastic materials, it ensures the sealing and insulation of the electrical components of the panel. Being subjected to solar radiation during the day and humidity at night, it tends to crack and powder. After a few years, it loses its sealing characteristic, allowing moisture to enter the interior of the panel and causing electrical and thermal defects that may be irreversible. In order to repair this sealing, the new method consists of moving the panel (1) longitudinally between the surface of a drum (2) equipped with a new adhesive backing sheet (3) and a pressure roller (6) which ensures both the driving of the panel (1) and the application of the backing sheet (3).The surface of the drum (2) used is delimited by a first fixed notch (4) in which the front transverse profile is inserted and a second notch (5) adjustable on an arc (dL), depending on the difference in length (L) of the panels, and in which the rear transverse profile is engaged. The method and the device find their main application in the on-site repair of photovoltaic panels in production plants. Figure for the abstract: FIG 1.

Description

Title of the invention: Method and device for applying an adhesive backing sheet to the rear face of a photovoltaic panel

[0001] The present invention relates to a method and a device for applying an adhesive backing sheet to the rear face of a photovoltaic panel.

[0002] The backsheet is a critical element in the reliability of a photovoltaic panel. Made of thermoplastic materials, it ensures the sealing and insulation of the electrical components of the panel. Being subjected to solar radiation during the day and humidity at night, it tends to degrade by decomposition and powdering of the material, then to crack. After a few years, it loses its sealing and insulation characteristics, allowing moisture to enter the interior of the panel and causing electrical and thermal faults that can be irreversible.

[0003] Photovoltaic production plants can comprise more than a million panels which are normally designed to last 25 years. However, for reasons of cost and competitiveness, some panel manufacturers use components of insufficient quality which lead to premature degradation of the performance of these panels. Overall, it is estimated that 16% of the total number of panels used in plants have cracked backsheets and risk irreversible defects in the short term. This mainly concerns backsheets made of polyamide but not only.

[0004] Producers, not having the possibility to repair these defective panels until now, are obliged to dismantle them, deposit them in recycling centers and install new ones. This has a cost for the energy producer, the community and the environment.

[0005] There are, however, certain repair methods but currently, no doubt for technical and economic reasons, none have been adopted.

[0006] Some use adhesive patches stuck on the damaged parts. But in general, the cracks in the backing sheet are extended to the entire surface of the panel.

[0007] Others use a partial or total coating of liquid silicone.

[0008] Others finally, like that proposed in patent EP4040509A1 propose to cover the damaged backing sheet with a new sheet by means of a complex process using a cutting table to first format the new backing sheet, then a drum which is lowered and moved above the table to put the said format in place by suction, then which is raised to let the panel pass upside down on the table, then which is lowered to be applied and moved onto the bottom of the panel.

[0009] The repair method used also consists of covering the defective backing sheet with a new, high-quality adhesive backing sheet in order to restore a lasting seal and a life expectancy of 25 years. We will explain below why the technical problem is difficult, how it was solved and we will appreciate the simplicity of the solutions found and their new and inventive characteristics.

[0010] The technical problem to be solved presents several major difficulties.

[0011] The first difficulty is that the peripheral profiles of the rectangular frame which ensures the rigidity of the panel, are projecting in depth as well as in width compared to the flat rectangular format of the panel to be treated. This makes it impossible to apply the backing sheet using a conventional application method. In fact, the new adhesive backing sheet must be able to be applied right up to the inside of the profiles which for the most part have a U shape with a lower wing which blocks the passage of the new backing sheet. It is clear that the problem is more difficult to solve than that of the initial application which was made on a flat panel before the projecting profiles of the frame were installed and glued.

[0012] The second difficulty is that the application device must be able to be adjusted according to the dimensions and arrangement of the panel components, which are extremely varied. The production panels are formed from an assembly of cells which have a size which can vary from 156 x 156 mm (M1 type cells) to 166 x 166 mm (M6 type cells), the number of these cells can vary from 60 (6 in width and 10 in length) to 72 (6 in width and 12 in length). The junction boxes used are projecting from the bottom of the panel and have varied dimensions and arrangements. Finally, the aluminum profiles used are different in height and width.

[0013] The new method which is the subject of the invention consists of moving the panel longitudinally and upright on a drum equipped with an adhesive backing sheet installed between two transverse and adjustable notches, by means of a pressure roller which ensures both the driving of the panel by friction and the application of the backing sheet.

[0014] The transverse and adjustable notches on the surface of the drum are the solution to the protruding nature of the transverse profiles and the different lengths of the panels to be processed.

[0015] The width of the drum must obviously be less than the internal width of the frame to be able to pass between the longitudinal profiles but it must also be greater than a certain value to solve the problem of automatically inserting the edges of the bottom sheet under each of the wings of the longitudinal profiles. This value is calculated based on the panel width and profile dimensions. If the side face of the drum is too close to the profile flange, the backing sheet may crease during insertion and if the side face of the drum is too far away, the backing sheet will not be able to be inserted automatically under the profile flange and subsequent manual intervention will then be necessary.

[0016] The invention and its variant embodiments will be better understood from the attached drawings:

[0017] [Fig.l] represents a general view of the application process

[0018] [Fig.2] represents the geometry of lateral insertion of the margin

[0019] [Fig. 3] represents a general view of the application device

[0020] [Fig.4] shows a view of the device for adjusting the second notch

[0021] [Fig. 5] shows a variant of the device for adjusting the second notch

[0022] [Fig.6] represents the development of the bottom sheet on the ferrule

[0023] [Fig.7] shows a detailed view of the first notch fitted to the rail

[0024] [Fig.8] shows a detailed view of the second notch equipped with the rail

[0025] [Fig.9] represents special arrangements of the device, to improve its ergonomics.

[0026] [Fig.l] represents a general view of the method which is the subject of the invention. The method consists of moving longitudinally and in the right place the panel (1) with its junction box and its cables, on a drum (2) equipped with an adhesive backing sheet (3) installed between two transverse notches (4) and (5), by means of a pressure roller (6) which ensures both the driving of the panel (1) by friction and the application of the backing sheet (3).

[0027] The surface of the drum (2) used for the application is delimited by the first notch (4) which comprises an adapter shaped as a function of the front transverse profile which is inserted therein and by the second notch (5) which is adjustable over an arc (dL) depending on the difference in length (L) of the panels to be treated.

[0028] [Fig.2] represents the geometry of lateral insertion of the margin of width (m) under the pressing action of the drum (2). If we consider a panel (1) of width (Wp) and a drum (2) of width (Wt), we can clearly see in the figure that the condition for insertion of the margin is that its width (m) is less than the oblique distance (d) between the edge of the drum and the end of the profile wing.

[0029] Let m < d, or m2 < a2 + p2 with (a) distance from the end of the wing to the lateral face of the drum and (p) depth of insertion of the drum relative to the face of the wing.

[0030] Or m = a +1 - r with (1) width of the wing and (r) removal of the margin depending on the thickness of the profile and its glue joint.

[0031] If we replace in the first expression (m) by its value taken from the second expression, we find a < (p2 - (1 - r)2) / 2(1 - r). or Wt > Wp - 21 - 2a , that is: Wt > Wp -21-(p2 - (1 - r)2) / (1-r)

[0032] For example, for a panel with a width of Wp = 1000 mm and an aluminium profile with a total height of 40 mm with a flange (1) of 20 mm and a depth (p) of 30 mm, if the desired shrinkage (r) is 15 mm, then Wt must be between 785 mm and 960 mm.

[0033] [Fig. 3] represents a general view of the device for implementing the method, here represented roller (6) raised awaiting the introduction of the panel (1).

[0034] The frame (7) carries two longitudinal slides (8) which are adjustable according to the width (Wp) of the panel (1).

[0035] It carries the drum (2) equipped with its two notches (4) and (5). The first notch (4) is fixed and equipped with a shaped adapter for the precise insertion of the front transverse profile of the panel (1). The second notch (5) is adjustable to receive at the end of the application of the backing sheet (3), the rear transverse profile of the panel (1) of variable length (L).

[0036] The pressure roller (6) mounted on an articulated arm (9), is raised to allow the introduction of the front profile of the panel, lowered during the pressing of the backing sheet (3) then raised again at the end of the application to allow the rear profile to be released from its notch (5).

[0037] The chassis finally carries the reel (10) of backing sheet (3) and its braking compass.

[0038] The longitudinal slides (8) are adjustable by means of lights (oblong holes adjustment) transverse whose stroke is half the difference between the width of the maximum panel and that of the minimum panel considered. In theory, for a drum of given width (Wt), this difference cannot be greater than the insertion conditions calculated above.

[0039] The height of the axis (11) of the drum (2) is adjustable by means of a screw whose stroke corresponds to the difference in height (p) of the profiles used on the panels.

[0040] Preferably, a retractable indexing finger (12) is provided to immobilize the drum at the start, during or at the end of rotation, for example to facilitate the positioning of the backing sheet (3) or the insertion or release of the profiles of the panel (1).

[0041] Preferably, the necessary pressing force of approximately 1 daN per centimeter is ensured by the own weight of the roller (6) and that of its articulation arm (9).

[0042] Preferably, the drive force is provided by a crank and the grip by rubber straps mounted in grooves of the roller (6).

[0043] [Fig. 4] shows a view of the device supporting the notch (5). The notch (5) is cut out, depending on the length (L) of the panel to be treated, on a sector interchangeable sector (13) mounted on the flange (14) of the drum (2). The drum (2) is equipped with a fixed ferrule portion (15) while the interchangeable sector is equipped with a complementary ferrule portion (16) in which the clearance (17) of the junction box is made, also specific to the model of panel to be treated. There is therefore an interchangeable sector (13) equipped with its complementary ferrule (17) for each model of panel.

[0044] [Fig. 5] shows a variant of the notch adjustment device (5). Here the interchangeable sector (13) can be moved continuously along the slots machined on the flange (14) of the drum (2). The result is that there is only one sector for all panel models. In [Fig. 5], a possible 90° movement of the sector is shown as an example, which corresponds to a displacement (dL) of 565 mm at the periphery of the 720 mm diameter drum. This is more than the difference (dL) in length (L) between the 60 and 72 cell panels. To accompany this displacement, the junction between the complementary shell (16) and the fixed shell (15), instead of being straight as in the device of [Fig. 4], can advantageously be V-shaped so that there is continuity when the pressure roller (6) passes.

[0045] We have just seen the arrangements which allow a backing sheet (3) to be applied to a panel (1) of variable dimensions. In what follows we will discover the arrangements which allow the backing sheet (3) to be formatted directly on the drum (2).

[0046] For this, two rails (18) and (19) are temporarily mounted at the first notch (4) and the second notch (5) to position, put in place and cut the back sheet (3) to the length (L-2r) corresponding to the length (L) of the panel. A cutting stencil (20) corresponding to the clearance (17) necessary for the passage of the junction box is mounted on the complementary ferrule (16).

[0047] [Fig.6] shows the backing sheet (3) developed on the shell of the drum (2), with the means used to format it. The backing sheet (3) coming from the reel (10) is placed on the shell by adjusting the corners of its end at the stops (21) set according to its width and centered on the rail (19). The backing sheet (3) is held by two double-sided adhesive patches (22) secured to the complementary shell (16). The cutting of the clearance (17) of the junction box can then be carried out by means of a cutter operated along the interchangeable cutting stencil (20). The drum (2) is then turned by hand to continue the placement of the backing sheet (3) up to the notch (4). The backing sheet (3) is held by two other double-sided adhesive patches (22). The rail (18) has a slot (23) intended to guide a cutter for cutting the backing sheet (3).The means described above made it possible to format the sheet of . melts directly onto the drum. Now, as is known, the protective film of the adhesive can be removed by hand.

[0048] [Fig. 7] shows a detailed view of the first notch (4) equipped with the rail (18) comprising the cutting slot (23) of the backing sheet (3) shown cut to length (L-2r). The rail (18) can be temporarily mounted in the notch (4) by means of a ball locking device (24) integral with the rail (18). The previously described shape adapter (25) is also shown there.

[0049] [Fig.8] shows a detailed view of the second notch (5) equipped with the rail (19). Unlike the rail (18), it does not have a cutting groove but adjustable positioning stops (21). This makes it possible to eliminate a cutting operation. On the other hand, it is equipped with a hinge (25) and clamping (26) device to apply an upper cutting stencil (27) against the lower cutting stencil (20). The advantage is to clamp the backing sheet well so that it does not slip under the cutting force and above all to visualize the movement of the cutter along the stencil.

[0050] [Fig.9] shows special arrangements of the device to improve its ergonomics. The first arrangement is that the chassis is completely open on the side where the operator (28) intervenes to facilitate the installation of the rails, to take up the end (29) of the backing sheet (3) stored on the reel (10), to adjust its end (29) at the level of the notch (5), to fix it at the level of the patches (22) and to cut the passage (17) of the junction box and finally to turn the drum by hand in order to install the backing sheet (3) up to the level of the notch (4) and finally to cut the backing sheet on the rail (18) temporarily mounted in the notch (4).

[0051] The second arrangement is to install a slack swallower (30) to tension the backsheet (3) during its cutting on the rail (18) and to automatically swallow its end (29) following the cutting. This arrangement allows the end (29) of the backsheet (3) not to fall as in [Fig. 3], but to remain at the level of the operator's hand during the processing of the next panel. The slack swallower (30) is a simple heavy tube (31) guided at its ends on two vertical rods (32), by means of large holes. The advantage of this compliant assembly is that it allows precise positioning of the backsheet (3) on the drum (2), even in the event of a lack of parallelism between the axes of the reel (10) and the drum (2) or a lack of cylindricity of the reel (10).

[0052] The method and device, objects of the invention, find their main application in the on-site repair of photovoltaic panels in production plants. They can also find their use in the application of adhesive sheets on flat panels also having a frame formed of projecting profiles.

Claims

Claims

1. Method for applying an adhesive backing sheet (3) under a photovoltaic panel (1) of rectangular format of width (Wp) and length (L), comprising transverse and longitudinal peripheral profiles projecting in height (p) as in width (1), characterized in that the panel (1) is moved longitudinally and in the right place on a drum (2) equipped with an adhesive backing sheet (3) installed between two transverse notches (4) and (5), by means of a pressure roller (6) which ensures both the driving of the panel (1) by friction and the application of the backing sheet (3).

2. Method according to claim 1 characterized in that the first notch (4) comprises a shaped adapter (25) depending on the front transverse profile inserted therein and that the second notch (5) is adjustable over an arc (dL) depending on the difference in length L of the panels to be treated,

3. Method according to claim 1 and 2 wherein the edge of the backing sheet (3) is applied with a recess (r) under the wing of the width profile (1) characterized in that the width (Wt) of the drum (2) is greater than the value Wp - 21 - (p2 - (1 - r)2) / (1 - r) and less in a known manner than the value Wp-21.

4. Device for implementing the method according to claims 1 to 3 characterized in that it comprises: - A frame (7) carrying two longitudinal slides (8) for receiving the panel. - A drum (2) equipped with a fixed notch (4) and an adjustable notch (5). - A pressure roller (6) mounted on an articulated arm (9). - And a support (10) for the reel on which the backing sheet (3) is stored.

5. Device according to claim 4 characterized in that the longitudinal slides (8) are adjustable by means of transverse lights whose maximum stroke is, for a drum (2) of given width (Wt), half the value (p2 - (1 - r)2) / (1 - r).

6. Device according to claim 4 characterized in that the axis (11) of the drum (2) is adjustable over a stroke corresponding to the difference in height (p) of the profiles used on the panels.

7. Device according to claims 4 and 6 characterized in that the drum (2) can be indexed at the end of its travel by a retractable indexing finger (12).

8. Device according to claim 4 characterized in that the notch (5) adjustable according to the length (L) of the panel is cut in a removable and interchangeable sector (13) mounted on the flange (14) of the drum (2).

9. Device according to claim 4 characterized in that the notch (5) adjustable according to the length (L) of the panel is cut in a sector (13) which can be moved continuously along the slots made in the flange (14) of the drum (2).

10. Device according to one of claims 4, 8 and 9 characterized in that the drum (2) is equipped with a fixed ferrule portion (15) mounted on the flanges (14) of the drum and a complementary ferrule portion (16) mounted on the interchangeable or adjustable sector (13).

11. Device according to claim 10 characterized in that the complementary ferrule portion (16) carries the clearance (17) necessary for the passage of the junction box and the cables of the panel.

12. Device according to claim 10 characterized in that the junction between the fixed ferrule (15) and the complementary ferrule (16) is V-shaped.

13. Device according to claim 4 characterized in that the pressing force is ensured by the own weight of the roller (6) and that of its articulation arm (9).

14. Device according to claims 4 and 13 characterized in that the pressure roller (6) is driven in rotation by a crank.

15. Device according to one of claims 4, 13 and 14 characterized in that the adhesion between the pressure roller (6) and the panel (1) is achieved by means of rubber bands mounted in grooves of the roller.

16. Device according to claim 4 characterized in that the fixed notch (4) can be temporarily equipped with a cutting rail (18) equipped with a cutting slot (23).

17. Device according to claim 4 characterized in that the adjustable notch (5) can be temporarily equipped with a positioning rail (19) equipped with adjustable stops (21).

18. 9 Device according to claim 17 characterized in that the positioning rail (19) is equipped with an articulated cutting stencil (27) which clamps the backing sheet (3) against the interchangeable cutting stencil (20) which carries the clearance (17) of the junction box.

19. Device according to claim 4 characterized in that a slack swallower (30) is arranged on the frame (7) between the reel (10) and the drum (2).

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