The invention relates to an electrical connection assembly for a photovoltaic cell having rear contacts, i.e. having electrical connection terminals that are placed on its rear face that is opposite from its front face for exposure to light. The invention also relates to a photovoltaic module including, amongst other things, such an electrical connection and support assembly. Finally, the invention relates to a method of fabricating such a module.
In the field of capturing solar energy by means of photovoltaic cells, it is known to make photovoltaic modules by associating a plurality of photovoltaic cells between a support plate and a translucent plate that covers the photosensitive components of the various cells. Within such a module, the cells are generally electrically connected to one another by means of copper conductor strips that extend over the front face of the cell and then under the rear face of an adjacent cell so as to collect electricity produced by the various cells which are thus connected in series. Those conductor strips mask the front faces of the cells to some extent, thereby correspondingly reducing the yield of a module incorporating such conductor strips.
To mitigate that problem, it is known to make photovoltaic cells having a rear face, opposite from the face carrying the photovoltaic components, that is fitted with electrical connection terminals of both positive and negative types. With such cells, there is no longer any need to have an electrical conductor strip located over the front faces of the cells, thereby improving the energy yield of a module incorporating such cells. Devices that are presently available for connecting together such cells comprise printed circuits that are soldered or fitted to the rear faces of the cells, which operation is both complex and onerous to implement. One difficulty arises from the fact that the rear contact terminals of such a cell present two opposite polarities. It is necessary to connect the positive terminals to one another while isolating them from the negative terminals, and vice versa.
The invention seeks more particularly to remedy those drawbacks by proposing a novel electrical connection assembly for a photovoltaic cell, which assembly is particularly simple to implement and is also inexpensive.
To this end, the invention provides an assembly for electrically connecting a photovoltaic cell having a front face for exposing to sun light, and a rear face fitted with positive electrical connection terminals and with negative electrical connection terminals. The assembly comprises:
By means of the invention, the spacer-plate enables a photovoltaic cell to be pre-positioned bearing against a first side thereof while guaranteeing electrical insulation and selective contact between the electrical contact terminals provided on the rear face of said cell and the electrical interconnection ribbons. The spacer-plate also serves to maintain spacing between a support plate and a front plate of a module fitted with such an assembly. The free electrical contact, established without permanent fastener means between the contact elements and the terminals, is particularly easy to implement.
In aspects of the invention that are advantageous but not essential, such a connection and support assembly may incorporate one or more of the following technical characteristics taken in any technically feasible combination:
The invention also relates to a photovoltaic module comprising at least one photovoltaic cell having rear contact terminals, a translucent plate covering the front face of the cell, and a support plate towards which the rear face of the cell faces. This module comprises at least one support and connection assembly as mentioned above placed between the translucent plate and the support plate.
Advantageously, the module includes at least two cells each placed with its rear face bearing against a spacer-plate and a ribbon of conductive material extends in register with two adjacent spacer-plates with its elements in contact firstly with negative terminals belonging to a first photovoltaic cell bearing against a first spacer-plate, and secondly with positive terminals belonging to a second photovoltaic cell bearing against a second spacer-plate.
When the spacer-plate is provided with at least one cell-positioning rib, as mentioned above, provision may be made for said rib to be of a height that is greater than the thickness of the photovoltaic cell.
Advantageously, the tongues of the ribbon exert a resilient thrust force against the cell with the terminals of which they are in contact, which force urges the cells against the translucent plate.
The spacer-plate is rectangular in shape, a rib extends along each of its edges, the ribs of two opposite sides of the plate are spaced apart by a distance slightly greater than the length of the photovoltaic cell, and the ribs of two other opposite sides of the plate are spaced apart by a distance slightly greater than the width of the photovoltaic cell.
Finally, the invention provides a method of fabricating a module as mentioned above, which method comprises the steps consisting in:
a) assembling a plurality of spacer-plates together;
b) installing a plurality of ribbons on one side of the spacer-plates, the ribbons having their respective contact elements engaged in orifices in the spacer-plates;
c) placing a photovoltaic cell on another side of each spacer-plate, the rear face of said cell facing towards the spacer-plate and connection terminals of the cell being in register with orifices of the spacer-plate; and
d) installing the assembly as formed in this way between the translucent plate and the support plate.
Advantageously, during step d), the contact elements of the ribbons are taken from a waiting configuration to a configuration in which each of them exerts a resilient force against a connection terminal of the cell.
The invention can be better understood and other advantages thereof appear more clearly in the light of the following description of an embodiment of an electrical connection and support assembly, of a photovoltaic module, and of a method of fabricating such a module, given purely by way of example and made with reference to the accompanying drawings, in which:
The photovoltaic module 2 shown in
Each photovoltaic cell 4 has its front face 42 facing towards the front plate 8, and in use it is to be oriented towards the light of the sun. Electric current drains 41 meet at nodes 43 that are distributed over the front face 42, as can be seen in part in
Each cell 4 of the module 2 is placed on a spacer-plate 10 made of an electrically insulating material. In the meaning of the present invention, a material is electrically insulating if it presents electrical resistivity greater than 108 ohm centimeters (Ω.cm).
In this example, each spacer plate 10 is made of a synthetic material that presents good ultraviolet performance and good temperature performance over a range extending from −40° C. to +110° C., that is non-flammable, and that can be recycled without giving off gas. It may comprise phenylene polysulfide (PPS) or some other material presenting comparable properties.
Each spacer-plate 10 is generally plane and of rectangular shape, having edges 102, 104, 106, and 108 that present portions in relief 112 and 114 for putting two adjacent plates into continuity. More precisely, the portions in relief 112 provided on the adjacent edges 102 and 104 of a plate 10 constitute projecting tips that may be received in hollow portions in relief formed by housings 114 of shape complementary to the shape of the tips 112 and formed in the edges 106 and 108 of an adjacent plate. It is thus possible to connect together two adjacent plates, by inserting the tips 112 of one of the plates in the housings 114 of the adjacent plate, as shown in
In practice, it is possible to provide two types of plate 10, referred to as “left” or “right” plates, depending on the distribution of the portions in relief 112 and 114 along their edges.
Reference 116 designates a first side or “first face” of the plate 10, as can be seen in
The plate 10 is provided with seven rows of orifices that are of rectangular section, namely four rows R120 of four orifices 120, passing through the plate 10 between its sides 116 and 118, and three rows R122 of five orifices 122, likewise passing through the plate 10 between its sides 116 and 118.
The plate 10 is also provided with fourteen orifices 124, that are of circular section and that are chamfered beside the face 116, these orifices being distributed over the surface of the plate and presenting a diameter that is relatively small, together with five orifices 126 that are likewise of circular or near-circular section, and that are of diameter that is greater than the diameter of the orifices 124.
Notches 128 are provided in the edges 104, 106, and 108 in each of the spacer plates 10.
The orifices 120, 122, 124, and 126, and the notches 128 make the spacer plates 10 lighter and make them less expensive to fabricate.
As can be seen more clearly from
Two mutually perpendicular axes that are parallel to the side 116 of the plate 10 are referenced X-X′ and Y-Y′. The ribs 132 to 138 make it possible to pre-position at the photovoltaic cell placed on the side 116 of the plate 10, in translation along the axes X-X′ and/or Y-Y′. To do this, the ribs 132 and 136 are spaced apart in a direction parallel to the axis X-X′ by a distance d1 that is slightly greater than the length L4 of a cell 4 measured parallel to the rows R46 and R48. Likewise, the distance d2 measured parallel to the axis Y-Y′ between the ribs 134 and 138 is slightly greater than the width l4 of the same cell measured perpendicularly to the rows R46 and R48 and parallel to the faces 42 and 44. Thus, the ribs 132 to 138 form a kind of frame within which a cell 4 can be pre-positioned on the side 116 of a spacer plate 10, with small-amplitude movement being possible parallel to the axes X-X′ and Y-Y′.
The term “slightly greater” is used to mean that the distances d1 and d2 are greater than the dimensions L4 and l4 by less than 10%, and preferably by less than 5%.
If the cell is square, as is usual, then the dimensions L4 and l4 are equal, as are the distances d1 and d2.
Furthermore, a ribbon 20 extends under the two plates 10 that are visible in the top left portion of
The ribbon 20 is made of a material that is electrically conductive, i.e. a material presenting a resistivity of less than 10−6 Ω.cm. For example, the ribbon 20 may be made of brass, of copper, of steel, or of a composite material of the copper and stainless steel type.
As can be seen more clearly in
A longitudinal axis of the strip 204 is referenced X204. Relative to the strips 202, the strips 206 are situated on the opposite side of the strip 204. The strips 206 are offset along the axis X204 relative to the strips 202. It is thus possible to align two ribbons 20 in a direction perpendicular to the axes X204 of their respective strips 204 by engaging the strips 206 of one of the ribbons between the strips 202 of the other ribbon, as shown in
Each of the strips 202 is fitted with four tongues 210 obtained by localized cutting out of the strip 202 and by folding it in such a manner that each tongue 210 extends in part perpendicularly to the plane of the strip 202 to which it belongs. In practice, a window 211 is cut out from the strip 202 about each tongue 210, which is then folded so as to project beyond the strip 202, perpendicularly to its side faces.
In the same manner, each strip 206 is fitted with five tongues 212 having the same shape as the tongues 210 and obtained in the same manner.
As can be seen in
Each spacer-plate 10 rests on the adjacent ribbon 20 via its side 118.
In
Under such conditions, if a photovoltaic cell is placed on each of the plates 10 shown in
Associating two plates 10 with a ribbon 20 thus makes it possible to connect the negative terminals 48 of a first cell 4 to the positive terminals 46 of another cell 4.
Connection takes place between the cells 4 and the ribbons 20 by resilient pressure between the tongues of 210 and 212 against the terminals 48 and 46 respectively, without soldering, without adhesive, and without using a printed circuit, with this being easy to implement, robust, reliable, and inexpensive. In other words, the electrical contact between the terminals 46 and 48 and the tongues 210 and 212 may be said to be “free” since it is established without any permanent fastener means, in particular without soldering and without adhesive, solely under the effect of the resilient force exerted by the tongues.
It can be understood that the situation shown for two cells 4 in
The strips 202 and 206 of a ribbon 20 are used for collecting electricity from the terminals 46 or 48 of a photovoltaic cell 4, whereas the central strip 204 serves to distribute this electricity between the various strips 202 and 206 to which it is perpendicular.
Thus, two ribbons 20 are located in part under each spacer-plate 10, such that one cell 4 placed on the side 116 of a spacer plate 10 is in contact with each of these two ribbons via its terminals 46 and 48 respectively.
Each cell 4 is thus associated with a connection and support assembly that comprises a spacer-plate 10 and two ribbons 20 or their equivalent, and that is located between the plates 6 and 8 of the model.
As can be seen in
A connection assembly associated with a cell 4 may thus equally well comprise a spacer-plate 10, a ribbon 20, and a ribbon 20′, or a spacer-plate 10, a ribbon 20, and a ribbon 20″. For a module 2 having only one cell 4, the connection assembly of the module comprises a spacer-plate 10, a ribbon 20′, and a ribbon 20″.
As can be seen in
The height of a rib 132 to 138 relative to the side 116 of a spacer-plate 10 is written h13. This height is strictly greater than the thickness e4 of a photovoltaic cell 4, as measured between its faces 42 and 44, perpendicularly to the dimensions L4 and l4.
When a module such as the module 2 shown in
The ribbons 20, 20′, and 20″ are then put into place as a function of the connection mode desired for the various cells 4 on the sides 118 of the various spacer-plates 10
In this configuration, the tongues 210, 212, 210′, and 212″ of the ribbons are waiting to make contact with the terminals of the cells.
The various ribbons 20, 20′, and 20″ are then secured to the various spacer-plates 10 by plastically deforming a portion 203 of each tongue 202 or 206, and by inserting it in an orifice 124. This use of plastic deformation for fastening purposes serves, in the example of
The assembly made up of the plates 10 assembled to the ribbons 20, 20′, and 20″ is then placed on the plate 6 on which it rests via curved portions 210A of the tongues 210 and curved portions of the other tongues.
The cells 4 are then put into place on the spacer-plates while aligning the rows R46 and R48 respectively on the rows R122 and R120, as represented by arrows F1 in
When the cells 4 are in place on the spacer-plates 10, the rows R46 of terminals 46 of one cell 4 are connected to the rows R48 of terminals 48 of an adjacent cell or to the end of a column of cells 4 by means of a ribbon 20, 20′, or 20″.
Each cell 4 then bears against the side 116 of a spacer-plate 10, having is movements parallel to the axes X-X′ and Y-Y′ of said plate 10 limited by the ribs 132 to 138, and by bearing against the tongues 210 and 212 of two distinct ribbons 20, 20′, or 20″. More precisely, each photovoltaic cell 4 is in contact via its terminals 46 or 48 with the tongues 210 or 210′ of a ribbon 20 or 20′ and the tongues 212 or 212″ of another ribbon 20 or 20″.
This produces the configuration in
In this configuration, the resilient force E1 exerted by the tongues 210, 212, 210′, or 212″ of the ribbons against the terminals 46 for 48 of the cells is of relatively low magnitude. In a variant, a provision may even be made for the shape of the tongues in this configuration to be such that the resilient force is of practically zero magnitude, or even that the tongues that do not make any contact with the terminals.
When the module 2 is assembled, the support plate 6 is placed under the plates 10 and the ribbons 20, 20′, and 20″, i.e. opposite from the cells 4. The transparent plate 8 is then placed above the cells 4 that rest against the plates 10, i.e. against their front faces 42.
By moving the plates 6 and 8 towards each other, i.e. by going from the configuration of
This approach also has the effect of pushing the portions 210A and their equivalents of the tongues 210 and their equivalents into the orifices 120 and 122, thereby increasing the magnitude or the strength of the resilient force E1, or creating this force if it does not already exist from the previous step.
Each of the various tongues 210 thus exerts a resilient force E1 on the plate 4 with which it is in electrical contact via a terminal 48, which force pushes the photovoltaic cell 4 against the front plate 8, thereby ensuring that the cell 4 is well positioned to recover a maximum quantity of light rays through the plate 8. A comparable resilient force is exerted by the tongues 212 via the terminals 46 of the cell 4. In practice, as a function of the thickness of the ribbons 20, 20′, and 20″ the tongues 210, 212 and their equivalents may be dimensioned and folded in such a manner that the resilient force E1 exerted by each of them in the close-together configuration of the plates 6 and 8 presents a magnitude greater than 0.5 newtons (N).
In other words, the structure of spacer-plates 10 and of the ribbons 20, 20′, and 20″ enables the various photovoltaic cells 4 to be pressed against the front face 8 while making electrical contact between the various tongues 210 and 212 and the terminals 46 and 48 of the cells 4 reliable, and while guaranteeing that this contact is made by virtue of the resilient force E1. The spacer-plates then maintain the spacing between the plates 6 and 8.
As can be seen more particularly from
The transverse dimensions of the orifices 120 and 122 are compatible with the fact that the tongues 210 and 212 remain bearing respectively against the terminals 48 and 46, even if a cell slides over the front face 116 of the plate against which it is resting, within the limits defined by the ribs 132 to 138. In practice, the clearance J is small enough to guarantee that the tongues 210, 212, 210′, and 212″ are properly positioned relative to the connection terminals 46 and 48.
In addition, the spacer-plates 10 guarantee height that is constant between the plats 6 and 8, insofar as the ribs 132 to 138 form distributed bearing zones between the spacer-plates 10 and the front plate 8, while the spacer-plates 10 rest on the support plate 6 via the ribbons 20, 20′, and 20″.
The above-mentioned cells 4 as shown in the figures comprise one particular example with a particular lay-out of the contact terminals 46 and 48. The invention can be implemented with any type of photovoltaic cell having rear contact terminals, the configuration of the spacer-plates 10 and of the ribbons 20, 20′, and 20″ being adapted to the lay-out of these contact terminals 46 and 48.
Number | Date | Country | Kind |
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10 50985 | Feb 2010 | FR | national |