WO2019087111A1

WO2019087111A1 - Method and plant for recycling photovoltaic panels

Info

Publication number: WO2019087111A1
Application number: PCT/IB2018/058560
Authority: WO
Inventors: Andrea ZAMBON; Pietrogiovanni CERCHIER
Original assignee: Universita' Degli Studi Di Padova
Priority date: 2017-11-02
Filing date: 2018-10-31
Publication date: 2019-05-09

Abstract

A method is described for recycling photovoltaic panels of the type comprising a glass attached to a plurality of photovoltaic cells by means of an insulating junction plate, wherein the photovoltaic cells comprise silicon elements and metallic contacts. The method comprises detaching the glass from the photovoltaic cells and subsequently separating the glass from the photovoltaic cells by means of an air flow. In detail, to separate the glass from the photovoltaic cells, the glass and the photovoltaic cells are dropped from a falling point and, during their fall, glass and photovoltaic cells are impinged with an air flow that is directed along a substantially horizontal direction and which is such to obtain a separation of the falling paths of the glass and of the silicon elements sufficient to drop them into a glass collecting element and a silicon collecting element respectively, placed below the falling point. A plant adapted to implement the method is also described.

Description

METHOD AND PLANT FOR RECYCLING PHOTOVOLTAIC PANELS

TECHNICAL FIELD The present invention relates to the recycling processes of photovoltaic panels. In particular, the invention relates to the recycling methods according to the preamble of claim 1 and to plants adapted to implementing such methods.

BACKGROUND

The photovoltaic panels are essentially composed of a frame that encloses a sandwich of materials containing the photovoltaic cells. In detail, the sandwich is typically composed of a transparent glass that allows the transmission of sunlight, an insulating and transparent junction plate, typically made of EVA (Ethylene Vinyl Acetate), photovoltaic cells, a further junction insulation plate of EVA and finally a rear support sheet, called backsheet, generally made of insulating material with low thermal expansion, e.g. Polyvinyl fluoride (PVF) or Polyethylene Terephthalate (PET).

After separation of the frame from the sandwich, the recycling methods essentially involve three treatments: a thermal process, to separate the silicon cells from the glass and the backsheet, a separation process in which the silicon cells are separated from the other materials, and a chemical process to extract silicon from the cells.

The first two treatments can be achieved by means of different technical solutions.

For example, some recycling methods involve crushing the sandwich, subjecting it to thermal processes to detach the glass from silicon and then applying separation techniques that exploit the different characteristics of electrical or magnetic conductivity of the two materials. These methods are however expensive.

Other methods, on the other hand, pursue the separation of the layers of the sandwich by means of a combustion process, in order to separate the glass and the backsheet from the cells by means of a laminar air knife after the treatment. These methods, however, are not always efficient, because if the glass is broken, the air knife cannot effectively separate the materials. Indeed, in most cases the panels to be disposed are collected with the glass already broken. Due to the fact that a tempered glass sheet is used in panels, such sheet is affected by residual stresses which cause it to break into fragments very small when compared to the fragments resulting from the breakage of a non-tempered glass sheet. On the other hand, the breaking of the glass, and the consequent inflection of the panel if the aluminium frame is removed, inevitably causes also the breaking of the fragile silicon cells into small fragments with dimensions comparable to those of the glass fragments.

At the end of the laminar air knife separation process, therefore, some pieces of glass are found mixed together with silicon fragments.

In general, in some recycling plants, it is also known to use vibrating mats, which take advantage of the specific weight difference between the two materials, in order to separate different types of materials. These systems, however, are not suitable for the separation of glass from silicon, as the specific weight of these materials is very similar.

The need is therefore felt to identify efficient and economical methods for separating glass from silicon in a process designed for the recycling photovoltaic panels.

OBJECTS AND SUMMARY OF THE INVENTION

In light of the foregoing, the aim underlying the present invention is to improve the known methods of recycling photovoltaic panels, in particular to improve the separation processes of glass from silicon. In this context, an object of the present invention is to present a method that allows to efficiently separate the glass from the silicon of the photovoltaic panel.

It is also an object of the present invention to provide a method that allows separating the glass from the silicon of the photovoltaic panel economically, reducing the construction and maintenance costs of the plant. These and further objects of the present invention will be clearer from the following description and from the appended claims, which form an integral part of the present description. According to a first aspect thereof, the invention therefore relates to a method for recycling photovoltaic panels of the type comprising a glass attached to a plurality of photovoltaic cells by means of a junction insulation plate, in which the photovoltaic cells comprise silicon elements and metallic connections. The method involves detaching the glass from the photovoltaic cells and subsequently separating the glass from the silicon elements of the photovoltaic cells by means of an air flow. In detail, the method involves dropping glass and silicon elements from a falling point (or station), and impinging glass and silicon elements during their fall with a flow air that is directed along a substantially horizontal direction and which is such as to obtain a separation of the falling paths of the glass and of the silicon elements sufficient to cause them to respectively fall into a glass collecting element and into a silicon collecting element, placed below the drop point.

Unlike the air knife solutions, in this case the air flow is used to impinge the material resulting from the previous baking of the sandwich in a furnace (i.e. glass, silicon elements and metallic contacts of the photovoltaic cells) while it is falling. The separation described in the invention is more efficient because, even if the glass is broken, the air flow is able to give a different rotational momentum to the silicon elements and to the pieces of glass. All or substantially all of the silicon elements are therefore projected into a collecting element different from the glass collecting element.

Preferably, the flow of air is a turbulent flow, in such a way as to increase the probability of generating a rotational momentum in the various falling components and allowing a better separation of the same. In one embodiment, then, the air flow impinges the dropped material at a distance of more than 10 cm, preferably at a distance of 20 cm from the falling point. This embodiment causes the glass and silicon elements to acquire sufficient kinetic energy with the fall before being hit by the flow of air. This makes the separation of the silicon elements from the glass more efficient. To further improving the effectiveness of the method, the above-described separation can be repeated several times on the material recovered in the collecting elements, bringing the material back to the falling position or inserting more blowers arranged in cascade. The invention is also concerning a plant for the recycling of photovoltaic panels, adapted for implementing the method illustrated above and better described in the following detailed description.

In one embodiment, the invention concerns a plant for recycling photovoltaic panels of the type comprising a glass attached to photovoltaic cells by means of a junction insulation plate, said photovoltaic cells comprising silicon elements and metallic connections. The plant includes:

- Detaching means for the detaching the glass from the photovoltaic cells, for example a furnace in which the junction insulation plates can be decomposed by combustion,

- Means for the generation of an air flow to separate the glass from the photovoltaic cells, and in particular from the silicon elements of the cells themselves;

- A falling point comprising means adapted to drop glass and silicon elements of photovoltaic cells;

- A first collecting element for collecting silicon elements falling from said falling position;

- A second collecting element for collecting glass separated from silicon elements.

The means for the air flow generation are placed below the falling position and are adapted to generate an air flow that is directed along a substantially horizontal direction, which intercepts the falling trajectory of the glass and the silicon elements dropped from falling position. The flow is such that, by investing the glass pieces and the silicon elements, a separation of the falling trajectories of the silicon elements and of the glass is obtained, which is such to cause them to fall into the first and second containers respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will be more evident from the following detailed description of certain preferred embodiments, which refers to the accompanying drawings.

The different features in the individual configurations may be combined with one another according to the preceding description, should there be advantages specifically resulting from a specific combination. In such drawings,

- Figure 1 illustrates a plant for the recycling of photovoltaic panels according to an embodiment of the present invention;

- Figure 2 is a flowchart of a method for recycling photovoltaic panels implemented by the plant of figure 1;

- Figure 3 shows an exploded view of a photovoltaic panel that can be recycled in the plant of figure 1;

- Figure 4 shows a first alternative of the plant of Figure 1;

- Figure 5 shows a second alternative of the plant of Figure 1.

DETAILED DESCRIPTION OF THE INVENTION

For the illustration of the drawings, use is made in the following description of identical numerals or symbols to indicate construction elements with the same function. Moreover, for clarity of illustration, certain references may not be repeated in all drawings.

While the invention is susceptible to various modifications and alternative constructions, certain preferred embodiments are shown in the drawings and are described hereinbelow in detail. It is in any case to be noted that there is no intention to limit the invention to the specific embodiment illustrated, rather on the contrary, the invention intends covering all the modifications, alternative and equivalent constructions that fall within the scope of the invention as defined in the claims.

The use of "for example", "etc.", "or" indicates non-exclusive alternatives without limitation, unless otherwise indicated. The use of "comprises" and "includes" means "comprises or includes, but not limited to", unless otherwise 30 indicated.

With reference to figure 1 there is schematically illustrates a plant for recycling of photovoltaic panels - indicated by reference 1 - adapted to implement the method of figure 2. An example of photovoltaic panel 2 that can be treated in the plant 1 is illustrated in figure 3, which shows an exploded view thereof. The panel consists of a frame 20 which encloses a sandwich 200. The sandwich 200 comprises a transparent glass 21, a junction insulation plate 22 (for example made of EVA), a layer of photovoltaic cells 23, a second junction insulation plate 24, and a rear support sheet (called backsheet) 25 which may be made of Polyethylene Terephthalate (PET), Polyvinyl fluoride (PVF) or other insulating material. The panel also comprises some electrical components 26, in particular junction box and cables. Since the photovoltaic panels are known, no further details of the photovoltaic panel 2 will be given here, but, at the same time, attention is payed merely on the fact that the photovoltaic cells 23 comprise silicon elements 23a and metallic contacts 23b.

Considering the recycling process, after the removal of the frame 20 and the electrical components 26, the sandwich 200 of the photovoltaic panel 2 is laid on a conveyor belt 3 which carries it through a furnace 4 in which it is heated to a temperature, preferably higher than 500 °C, sufficient to decompose the junction insulation plates 22 and 24 and the backsheet 25, thus allowing the dismemberment of the sandwich and the detachment of the glass 21 from the photovoltaic cells 23. Preferably, in order to improve the decomposition of the backsheet, the sandwich is placed with glass side 21 on the conveyor belt 3.

Alternatively, the recycling process may comprise a manual removal of the backsheet before the baking in the furnace. In this case, only the part of the sandwich 200 comprising glass 21, junction insulation plates 22 and 24, and photovoltaic cells 23 is heated in the furnace 4.

Regardless of how the backsheet is removed (either mechanically or by baking in the furnace or by a combination of the two methods mentioned here), a mixture of materials 201 is obtained at the outlet of the furnace 4 where in the glass 21 is detached from the photovoltaic cells 23. In detail, the mixture of materials 201 comprises pieces of glass 21, pieces of silicon elements 23a and metallic contacts 23b.

The material 201 coming out of the furnace 4 is delivered by the conveyor belt to a point of fall beyond which the material 201 can fall by gravity. The fall causes the glass 21 (typically in pieces), the metallic contacts 23b and the silicon elements23a of the photovoltaic cells 23 to be divided from each other.

The dimensions of the falling elements vary substantially depending on the nature of the element itself. In particular, the glass pieces 21 have a substantially planar-like shape whose thickness is comprised between 2 mm and 5 mm, and whose surface varies greatly from one piece to the other and has an average area of 3 cm². The silicon elements 23a have a planar-like shape with a similar surface area but a thickness which is different from the one of glass pieces 21 and which is between 150 μιη and 300μιη (three hundred micrometers).

Therefore, the glass has a surface/ thickness ratio of about 60÷150 mm²/ mm whereas the silicon has a surface/ thickness ratio of about 1000÷2000 mm²/ mm, which is one order of magnitude higher.

Below the conveyor belt 3, under the falling point, the plant 1 comprises air flow generating means 5, for example, such means may comprise one or more fans or blowers. The air flow generating means 5 produce a substantially horizontal air flow which intercepts and impinge onto the glass pieces 21, the metallic contacts 23b and the silicon elements 23a of the photovoltaic cells 23 along their falling path.

The intrinsic morphological differences between the glass fragments which, as shown above, have thickness greater than the thickness of the silicon fragments, offer the possibility of exploiting the substantial diversity of the respective fluid dynamic behavior.

In simplified formulation, the three forces considered are:

• Gravity force(G):

G = m X g = p x V x g = p X s x S x g oc s x S wherein p is the density of the material (which is very similar for glass and silicon), V is the volume, g is the gravity acceleration, s is the thickness of the fragments and S is the surface of the fragments. It can be seen that this force is proportional to both the surface and thickness of the fragments.

• The lift force (L): L = l/2 x p_fl X i7² x 5 x C_i « S₁ wherein p_a is the density of the air, v is the velocity of the air flow, CL is the coefficient of the lift force and Si is the surface in the direction of the air flow. The lift force is proportional to the exposed surface in the direction of flow which, in this case, is the horizontal projection. • The drag force (D):

D = 1/2 x ρ_α x v² x S x C_D oc S₂ wherein p_a is the density of the air, v is the velocity of the air flow, CD the coefficient of the drag force and S₂ the surface orthogonal to the flow. The resistance to flow is proportional to the surface exposed in a direction orthogonal to the flow, which, in this case, is the vertical projection.

While gravity causes the fragments to fall vertically, the other two forces cause them to move horizontally.

It will be easy for a person skilled in the art to combine the three components of forces acting on fragments of the shapes found in their specific installation, with the purpose of estimating flight times and the different displacements in the horizontal direction respectively experienced by the silicon fragments and glass fragments, and consequently define the positions of their collecting elements.

In these situations, in fact, the surface offered to the action of the air flow interacting with two fragments of equivalent mass, respectively of glass and silicon, is significantly different.

In the preferred embodiment, the means 5 are placed at a distance A from the point of fall of the material 201 that is greater than 10 cm, and preferably equal to

20 cm. This causes, during the fall, the glass 21, the silicon elements 23a and the metallic contacts 23b, to acquire sufficient kinetic energy, before being impinged by the air flow F. More in particular, regarding glass 21, the value of said kinetic energy is preferably but not necessarily higher than 0.22 mj.

The air flow generating means 5 produce a stream of air, preferably turbulent, characterized by a number of Reynolds comprised between 10³ and 10⁴, for a vertical section D sufficient to exchange a momentum with glass fragments and photovoltaic cells, such that they are sufficiently distanced so that the glass pieces

21 and silicon elements 23a fall into two different collecting elements which, in the preferred embodiment described, are made through containers 6 and 7, for the collection of glass and silicon respectively. Preferably, the vertical extension of the section D invested by the air flow F is at least 30 cm. Preferably, the velocity v of the generated air flow F has a value greater than 1 m/s and less than 11 m/s.

The width 1 of the conveyor belt 3 can be designed according to the desired amount of treated material (e.g.: lm- 120g/ s, 2m - 240g/ s etc.). The volumetric flow rate (expressed in m³/ s) of the air flow F produced by the generating means can be calculated as a product between the velocity v of the air flow F, the dimension of the vertical section D and the dimension of the width 1 of the conveyor belt 3.

The amount of falling material can be determined by the relation: Q_c = vn x l x p^*

Wherein v_n is the conveyor belt speed [m/ s], 1 is the conveyor belt width [m] and p* a parameter whose value can vary between 0 kg/ m² and 12 kg/ m².

Preferably the air flow generating means 5 are placed at a distance of less than 50 cm with respect to the trajectory of the falling elements. In the case of photovoltaic panels with standard size 165x99 cm, assuming that they proceed on the conveyor lm wide, with a speed of 1 cm/ s, in order to drop about 120 g/ s of material, it has been verified that there can be used one or more blowers that generate an air flow with flow rate between 50 and 200 Nm³/min (normal cubic meters per minute). Figure 2 schematically illustrates the main steps of a photovoltaic panel recycling method, which comprises:

- Removing (100) the frame 20 and any electrical components 26 from the photovoltaic panel 2, so as to obtain a sandwich 200 comprising a glass 21, a first junction insulation plate 22, the silicon photovoltaic cells 23, a second junction insulation plate 24 and a rear support sheet (backsheet) 25;

- Baking (101) the sandwich 200 in a furnace 4 until the backsheet 25 and the junction insulation plates 22 and 24 are decomposed;

- Dropping (102) the material 201 resulting from baking in the furnace 4, that is pieces of glass 21, pieces of silicon elements 23a and metallic contacts 23b of the photovoltaic cells; - Impinging (103) with a flow of air F the aforementioned material 201 during its falling path, so as to obtain a separation of the trajectories of the glass and of the cells sufficient to cause them to fall into two separate containers 6 and 7.

As mentioned above, the above-described steps of the method illustrated in figure 2 can be partially modified. For example, the preparatory treatments leading to the separation of the glass from the cells (steps 100 and 101 of figure 2) can be carried out differently, for example, the backsheet can be removed mechanically before baking the sandwich in the furnace, or it is further possible to crush the sandwich before baking it. In other words, the operations that lead to detach the glass from the photovoltaic cells can be carried out in different ways.

As can be seen in figure 1, the narrow and elongated shape, as well as their high density, of the metallic contacts 23b which connect the photovoltaic cells 23, causes them to fall with the glass pieces 21 inside the container 6. It is therefore possible to provide a subsequent phase of separation of the glass from the metal of the contacts 23b; this separation can take place either by sieving or by other known techniques that may be based on, for example, the different electrical conductivity and/ or magnetic permeability of glass and metal or selectively corroding the metallic contacts with an acid solution. Advantageously, since some silicon elements may fall into the glass container 6, in one embodiment it is envisaged to (i) recover the fallen material into the container 6, (ii) drop it again and (iii) re-separate it by a horizontal air flow F that drops the glass into a first container and the silicon into a second container. Preferably, this second operation of separation of the glass from the silicon is carried out in a second separation station, different from the one in which the first separation was carried out, because of production efficiency and separation of the materials. However, this second separation can take place in the same separation station where the first separation between glass and silicon was carried out. Preferably, before carrying out the separation between glass and silicon of the photovoltaic panel, the metallic contacts 23b of the photovoltaic cells 23 are removed.

In an embodiment shown in figure 4, the metallic contacts 23b, the glass pieces 21 and the silicon elements 23a, are dropped into a collecting box 30 provided at the top with a grid 31, the mesh of which allows the passage of the glass pieces 21 and of the silicon elements 23a, while preventing the passage of the metal contacts 23b.

The bottom of the box 30 has an opening door 32. Periodically, the metal contacts 23b are therefore collected from above the grid 31 and the door 32 is opened. In this way the glass pieces 21 and the silicon elements 23a, collected on the bottom of the box 30, fall and are hit by the air flow F generated by the air flow generating means 5, as described above with reference to figure 1. Also in the example shown in figure 4, the means 5 are positioned at a distance A from the falling point which, in this case, corresponds to the bottom of the box 30.

Preferably, the opening of the door 32 and the actuation of the air flow generating means 5 are controlled by a control system able to open/ close the door 32 and turn on/ off the means 5. In an example of embodiment, the control system (not shown in the figures) is configured to turn off the means 5 when the door is closed and turn them on at the same time or a little earlier, for example 5-10 seconds before opening of door 32. In this way, energy is saved by keeping the means5 off, when the door 32 is closed and no material to be separated falls.

From the above description, it is clear how the plant and the method described above allow achieving the proposed purposes. The separation of the glass from the photovoltaic cells is obtained efficiently by a simple construction plant with low construction and maintenance costs.

However, it is clear that many modifications can be made by the person skilled in the art without thereby departing from the scope of protection which results from the appended claims. Although in the above-described embodiments the detachment of the glass from the photovoltaic cells takes place by means of a furnace, which causes the decomposition of the insulating joining plates/ sheets, it is possible to provide other means for detaching the glass from the photovoltaic cells. For example, in an embodiment less preferable to the furnace, such means may comprise solvents for the polymeric material of the joining plates / sheets.

The conveyor belt 3 can be omitted from the plant and the sandwich can be moved manually or otherwise through different treatment stations. In one embodiment, for example, the material resulting from baking the sandwich in the furnace 4 can be moved, manually or automatically, to an inclined slide at the end of which the material, resulting from the baking of the sandwich in the furnace, can fall. Such an inclined slide can also be provided at the end of the conveyor belt to facilitate the fall of the material resulting from the baking of the sandwich in the furnace.

The number and type of air flow generation means 5 may be different. In a variant shown in figure 5, the air flow generating means 5 comprise two blowers, 50 and 51, positioned at two different heights from ground hi and h2, so as to generate two parallel air flows Fl and F2 that sequentially impinge on the glass and silicon wafers that fall from the box 30.

Furthermore, the recycling plant can further comprise a chemical processing station in which the layers of material that coat the silicon wafer of the cells such the metallization, are removed in order to obtain pure silicon and extract other components, such as silver. Finally, instead of the containers for collecting glass and silicon elements after their fall path, it is possible to provide separate conveyor belts, to collect the fallen materials and transport them to a different location. It is therefore clear that instead of the containers represented in the above-described embodiments, it is possible to provide different collection means, which can be containers, conveyor belts or something else.

Claims

1. Method for recycling photovoltaic panels of the type comprising a glass (21) attached to a plurality of photovoltaic cells (23) by means of a junction insulation plate (22), wherein the photovoltaic cells comprise silicon elements (23a) and metallic contacts (23b) and wherein the method comprises the steps of:

- detaching (100,101) the glass (21) from the photovoltaic cells (23), and separating the glass (21) from the photovoltaic cells (23) by means of an air flow (F); characterized in that the step of separating the glass from photovoltaic cells comprises the following steps:

- dropping (102) the glass (21) and the silicon elements (23a) the photovoltaic cells (23) from a falling point;

- let an air flow (F) impinge (103) on the glass (21) and on the silicon elements (23a) during their fall paths, said air flow (F) being directed in a substantially horizontal direction and being such to obtain a separation of the falling paths of the glass (21) and of the silicon elements (23a) sufficient to drop them into a glass collecting element (6) and a silicon collecting element (7) respectively. 2. Method according to claim 1, wherein the metallic contacts (23b) of the photovoltaic cells (23) are removed before the glass (21) and the silicon elements (23a) fall from the falling point.

3. Method according to claim 2, wherein the metallic contacts are removed by means of a grid (31), said grid (31) having a mesh of size and shape adapted to allow the passage of pieces of glass (21) and silicon elements (23a), and adapted to prevent the passage of the metallic contacts (23b).

4. Method according to any one of the preceding claims, wherein the air flow (F) is a turbulent flow.

5. Method according to any one of the preceding claims, wherein the air flow propagates in a volume that develops in a substantially horizontal direction for a vertical length greater than 30 cm

6. Method according to any one of the preceding claims, wherein the air flow (F) impinges the glass (21) and the silicon elements (23a) that are falling, at a distance greater than 10 cm, preferably at a distance of 20 cm, from the falling point.

7. Method according to any one of the preceding claims, wherein, during their fall, the glass (21) and the silicon elements (23a) are impinged by a second substantially horizontal air flow (F2) at a height other than said air flow (Fl).

8. Method according to any one of the preceding claims, wherein

- material present in the glass collecting element is recovered, said material containing glass (21) and silicon elements (23a);

- the material is dropped from a further falling point and

- the material that falls is hit by an air flow (F) directed along a substantially horizontal direction so as to obtain a separation of the fallen paths of the glass (21) and of the silicon elements (23a) sufficient to drop them respectively in a further glass collecting element (6) and in a further silicon collecting element (7).

9. Plant (1) for recycling photovoltaic panels (2) of the type comprising a glass

(21) attached to photovoltaic cells (23) by means of a junction insulation plate

(22) , said photovoltaic cells (23) comprising silicon elements (23a) and metallic contacts (23b), the plant comprising: - detaching means (4) for detaching the glass (21) from the photovoltaic cells

(23);

air flow generating means (5) for separating the glass (21) from the photovoltaic cells (23);

a falling station comprising means for dropping the glass (21) and the silicon elements (23a) of the photovoltaic cells;

- a first collecting element (7) adapted to collect the silicon elements (23a) falling from said falling station;

- a second collecting element (6) adapted to collect the glass separated from the photovoltaic cells; characterized in that: the air flow generating means (5) are positioned below the falling station and are capable of generating an air flow (F) which is: directed in a substantially horizontal direction intercepting the falling paths, from the falling station, of the glass (21) and of the silicon elements (23a), and

- such as to obtain a separation of the falling paths of the glass (21) and of the silicon elements (23a) sufficient to drop them respectively into the first collecting element (7) and into the second collecting element (6) respectively.

10. Plant (1) according to claim 9, wherein the air flow generating means (5) are adapted to generate a turbulent air flow. 11. Plant (1) according to claim 9 or 10, wherein the air flow generating means (5) are adapted to generate an air flow propagating in a volume that develops substantially in a direction horizontal for a vertical length of 30 cm.

12. Plant (1) according to claim 9 or 10 or 11, wherein the air flow generating means (5) are located at a distance of more than 10 cm, preferably at a distance of 20 cm, from the falling station.

13. Plant (1) according to any one of the claims 9 to 12, wherein the air flow generating means (5) comprise at least two vertically spaced blowers (50,51), a first blower (51) of said at least two blowers being able to generate said air flow, and a second blower (50) of said at least two blowers being able to generate a second horizontal air flow.

14. Plant (1) according to any one of the claims 9 to 13, wherein the detaching means comprise a furnace (4), and wherein the plant further comprises a conveyor belt (3) adapted to transport the glass (21) and the photovoltaic cells (23) from the furnace (4) to the falling station. 15. Plant (1) according to any of the claims 9 to 14, wherein the fall station comprises a slide.

16. Plant (1) according to any one of claims 9 to 15, wherein the falling station comprises a collection box (30) provided on top with a grid (31), the mesh of which allows the passage of the pieces of glass (21) and of the silicon elements (23a), while said mesh is adapted to prevent the passage of the metallic contacts (23b).

17. Plant (1) according to claim 16, wherein the collecting box (30) has, at the bottom, a door (32) that can be opened.

18. Plant (1) according to claim 17 further comprising a control system adapted to switching on and off the air flow generating means (5) and to open and close the door (32) that can be opened, wherein the control system is configured to turn off the air flow generation means (5) when the door (32) is closed.