FR2583923A1 - Method of manufacturing a photovoltaic panel and panel thus produced - Google Patents

Abstract

The present invention relates to photovoltaic panels. It relates in particular to a method of producing a photovoltaic panel of the type comprising, between an opaque support panel and a transparent or translucent covering panel, a series of photovoltaic cells connected up in series, characterised in that it consists in fixing photovoltaic cells 3 to a support panel 2 of an acrylic resin, in arranging a peripheral flexible seal 5 on the support panel, in placing a covering panel 1, also of an acrylic resin, on the said seal, in clamping the two panels 1 and 2 to one another, in injecting a fluid acrylic resin 8 between the two panels 1 and 2 and in subjecting the compound panel thus obtained to a polymerisation process in order to procure the at least partial hardening of the fluid resin 8.

Description

 The present invention relates to a method for producing a photovoltaic panel of the type comprising, between an opaque support panel and a transparent or translucent covering panel, a series of photovoltaic cells connected in series.

 Photovoltaic panels are known which consist of a rear or support panel of a plastic material and a front panel of reinforced glass between which panels the photovoltaic cells are arranged. The two panels are connected together by a frame and by a layer of plastic material in which the photovoltaic cells are embedded.

 The known panels are relatively not very resistant to mechanical shocks and very often the object of delamination phenomena resulting in the introduction of moisture between the two panels which causes a serious disturbance of the operation of the panel or even total deterioration of the panel. .

In addition, these panels cannot be cut and folded because of the glass front panel which is very difficult to machine or even less to fold operations.

 Other known panels include support and covering panels of different plastics. These panels can be cut if necessary, but in all cases we observe delamination phenomena occurring during this cutting or under normal conditions of use.

 The object of the present invention is to design a process for producing a photovoltaic panel of said type which makes it possible to obtain a particularly homogeneous panel, very resistant and which can be cut and folded without risk of delamination.

 The method according to the invention consists in making by casting a support panel of an acrylic resin, to fix on this support panel by adhesive pads the photovoltaic cells to obtain a certain spacing between the panel and the underside of each cell. , placing on the support panel a flexible seal extending along the periphery of the panel in the direct vicinity of the edges thereof, depositing on said seal the cover panel also produced by casting in an acrylic resin, to be tightened the support and covering panel one on the other to obtain a partial crushing of said joint, to inject between the two panels a fluid acrylic resin for casting to fill the space between the two panels, to subject the complex panel thus obtained in a polymerization process to cause partial hardening of the casting resin.

 The panel obtained according to the invention has a particularly homogeneous structure because the three layers, support panel, intermediate resin and covering panel are made of resins of the same type. It can be cut and folded hot without the risk of delamination. Similarly, under particularly severe conditions, no delamination tendency is observed which could allow the introduction of air humidity into the photovoltaic cells.

 According to a preferred embodiment the method according to the invention consists in carrying out a prepolymerization of said acrylic casting resin and in storing the prepolymerized resin for a period of the order of three days to three months in contact with air .

 In this case, the resin is degassed under vacuum according to the invention after said storage period and before its injection between the two acrylic panels of the photovoltaic panel and this at the latest three hours before the injection of the prepolymerized resin.

 The degassing is of course intended to eliminate the gas bubbles contained in the prepolymerize to avoid delamination under the effect of changes in operating temperatures of the panel obtained.

 On the other hand, the profound function of the storage period after the prepolymerization, which has a critical duration, is currently not fully understood. It is assumed that it serves to stabilize the structure of the prepolymer. In all cases, however, it has been observed that by eliminating this storage phase, the number of delamination effects in a series of panels produced otherwise under identical conditions is very considerably increased.

 Another preferred embodiment of the method according to the invention consists in subjecting the complex panel to an oven polymerization at a temperature of the order of 350C to 450C and then to a burn-in treatment at a temperature of about 1000C.

 Such a final treatment makes it possible to very considerably increase the stability of the structure of the resin injected between the support panel and the covering panel and contributes to the delamination resistance of the panel obtained.

 Advantageously, said prepolymerized resin is injected between said panels within about three hours after having subjected it to said vacuum degassing treatment.

 In addition to stabilize the dimensions of the support panel and to avoid its bending during the polymerization of the casting resin, one embodiment of the method according to the invention consists in subjecting said support panel before the installation of the photovoltaic cells. to a treatment in an oven at a temperature of about 1000C and for at least two hours.

 According to another preferred embodiment, the method according to the invention consists in subjecting its upper surface of said support panel before the installation of the photovoltaic cells to a treatment increasing the contact surface between this panel and the casting resin.

 This surface treatment can be a mechanical treatment, such as an abrasion treatment, or even a chemical treatment producing discontinuities in the upper surface of the support panel. This increases the contact surface with the casting resin and achieves better adhesion between this resin and the support panel.

 The invention also relates to a photovoltaic panel produced according to the method according to the invention.

 In the panel according to the invention, said covering panel is made of a crosslinked acrylic resin while said support panel is made of a noncrosslinked but diffusing acrylic resin. This gives a partially homogeneous structure in which the three constituent layers are made of acrylic resins such as PMMA resin for example.

 According to a preferred embodiment of the panel according to the invention, the resin forming said support panel contains reflective dyes and pigments. A diffusing support panel is thus obtained increasing the efficiency of the photovoltaic cells.

 To increase the bonding between the support panel, the covering panel and the casting resin contain a solvent of the acrylo-butyl type attacking the surfaces of said covering and support panels during the casting of the resin between these two panels.

 Finally, the resin forming the covering panel can comprise luminescent and / or scintillating doping materials forming light cascades as described in French patents No. 7321890 No. 7609321 and No. 7806850 of the present applicant.

As described in these patents, the light cascades significantly increase the efficiency of the photovoltaic cells.

 Other embodiments and advantages of the description will emerge from the description which follows, and with reference to the appended drawings in which: FIGS. 1 to 5 are schematic vertical section views illustrating the different phases of the process according to the invention , and Figure 6 shows the curve of evolution of the polymerization temperature as a function of time in minutes.

 In Figure 1 we see a coating panel in a transparent crosslinked acrylic resin (1) and an opaque support panel (2) but diffusing made of a non-crosslinked acrylic resin to prevent any removal of this panel in the subsequent polymerization phase thus ensuring perfect dimensional stability.

 In a second phase (FIG. 2), a series of photo voltaic cells (3) is fixed on the upper face of the support panel (2). This is preferably done using small diameter adhesive pads (4) which provide a certain distance between the panel (2) and the cells (4). A complete coating of the cells is thus obtained during the subsequent injection of a coating resin (FIG. 4). The cells are connected in series by electrical connectors (not shown here) before or after their installation on the panel (2).

 Then a flexible seal (5) is placed in the vicinity of the edges of the support panel (2) and around the entire periphery thereof, on which the covering panel (1) is arranged as shown in FIG. 3.

 In the next phase, the panels (1 and 2) are tightened tightly one on the other to obtain a partial crushing of the seal (5) which thus delimits a closed casting chamber between the panels (1 and 2). The means used for this purpose are of a known type and shown schematically in (6) in FIG. 4.

Then a fluid acrylic resin (8) is injected between the panels (1 and 2) by a pipe (7).

 According to the invention, this casting resin (8) is subjected beforehand in a known manner to a prepolymerization and a storage in contact with air for a period of three days to three months. In addition, within approximately three hours before being injected between the panels (1 and 2), the resin (8) is subjected to a vacuum degassing intended to remove the gas bubbles contained in the resin.

 After the injection or casting of the resin (8) between the panels (l and 2) the entire complex panel (1, 8, 3,4,2) is subjected to a polymerization treatment in an oven to produce the polymerization of the resin (8). This treatment is carried out at a temperature of the order of 350C to 450C for a period of approximately 500 minutes.

 Then this treatment is extended according to the invention by a burn-in at a temperature of about 1000C for a period of about 120 minutes. This treatment is used to permanently stabilize the structure of the polymerized resin (8).

 Finally, we can now cut the marginal parts of the complex panel with a saw to eliminate the joint (5) and obtain a finished product as shown in Figure 5.

In Figure 6 we see the different phases of the evolution of the temperature of the casting resin (8) during its polymerization and its debugging. The curve shown here is very schematic and corresponds to four phases. The first phase I, which represents the actual polymerization phase, is carried out at a substantially constant temperature of the order of 390 ° C. to 450 ° C. and at a duration of approximately 500 minutes. This phase leads to the usual polymerization of the casting resin between the support panel (2) and the covering panel (1). Then, according to the invention, a temperature rise is produced in phase II for a period of approximately 100 minutes to reach a burn-in temperature of approximately 1000C.
This temperature is maintained during the burn-in phase III, the duration of which is approximately 120 minutes. Then, the polymerized resin is allowed to cool in phase IV for approximately 60 minutes to return to the initial temperature of between 390C and 450C.

 Practice has shown that this implementation according to the invention makes it possible to obtain an exceptionally homogeneous and stable final product which is no longer subject to delamination effects between the various constituents (1,2 and 8).

 The invention also relates to a photovoltaic panel produced according to the method according to the invention.

In the panel according to the invention the three constituent layers (1,2 and 8) are made of an acrylic resin of the type
PMMA (polymethylmethacrylate).

 To increase its diffusion effect, the support panel (2) may contain suitable pigments or dyes.

 It is also possible to increase the contact surface between the casting resin (8) and the upper surface of the support panel (2) by subjecting the latter to chemical and / or mechanical treatment producing discontinuities in this surface.

 Finally, the casting resin (8) may contain a solvent of the acrylo-butyl type attacking during the polymerization the surfaces of the panels (1 and 2) in contact with the resin (8) to produce a better quasi-chemical bonding between the resin (8) and panels (1,2).

 Finally, the covering panel may contain doping materials forming light cascades in a known manner as described in the French patents cited above of the applicant.

 The invention is not limited to the embodiments described and shown here. Many modifications can be made to those skilled in the art without departing from the scope of the invention.

Claims (10)

1) Method for producing a photovoltaic panel of  type comprising between an opaque support panel and a panel  transparent or translucent cover layer a series of  photovoltaic cells connected in series, characterized by  what it is to achieve by pouring a sup panel  port (2) in acrylic resin, to be fixed on this panel  support (2) with adhesive pads (4) photo cells  voltaics (3) to obtain a certain spacing between the pan  neau and the underside of each cell (3), to be arranged  on the support panel a flexible seal (5) extending the  along the perimeter of the panel in the immediate vicinity of the edges of  the latter, to deposit on said joint the covering panel  ment (1) also produced by casting in an acrylic resin  that, to tighten the support (2) and cover (1) panel  one over the other to obtain a partial overwriting of said  joint (5), to inject between the two panels (2,1) a resin  fluid acrylic (8) to fill the space between the two panes  neaux (2,1), to subject the complex panel thus obtained to a  polymerization process to cause hardening at  less partial of the fluid resin (8). 2) Method according to claim 1, characterized in that it  consists in carrying out a prepolymerization of said resin  fluid acrylic (8) and to store the prepolymerized resin  for a period of the order of three days to three months in  contact with air. 3) Method according to claim 2, characterized in that it  consists in degassing the resin under vacuum after  said storage period and before its injection between  two panels (1 and 2) of the photovoltaic panel. 4) Method according to any one of claims 1 to 3,  characterized in that it consists in submitting the panel com  plex (1.8; 2) to an oven polymerization at a temperature  of the order of 350C to 450C and then to a die processing  worming at a temperature of around 1000C. 5) Method according to any one of claims 3 and 4,  characterized in that it consists in injecting said resin  prepolymerized (8) between said panels within a period of  about 3 hours after having subjected it to the die processing  vacuum gassing. 6) Method according to any one of claims 1 to 5, ca  characterized in that it consists in subjecting said panel to  support (2) before the installation of photovoltaic cells  (3) to an oven treatment at a temperature of about 1000  C and for at least two hours. 7) Method according to any one of claims 1 to 6,  characterized in that it consists. to submit its upper surface  of said support panel (2) before the installation of the  photovoltaic cells is3) to a treatment increasing the  contact surface between this panel (2) and the neck resin  age. 8) Photovoltaic panel produced according to the following process  any one of claims 1 to 7, characterized in that  that said covering panel (1) is made of a resi  crosslinked acrylic while said support panel (2)  is made of a non-crosslinked but diffuse acrylic resin  rocket.  9) Photovoltaic panel according to claim 8, character  risé in that the resin forming said support panel (2)  contains reflective dyes and pigments; 10) Photovoltaic panel according to any one of the claims  cations 8 and 9, characterized in that said neck resin  lage (8) contains an attacking acrylo-butyl type solvent  the surfaces of said covering panels (i) and of sup  port (2) when pouring the resin (8) between the two panels  neaux (1,2).