Heat Sink and Associated Solar Panel

Abstract

The present invention refers to a heat sink (5) for bi-facial photovoltaic modules (3) configured to be secured to the back side (3b) of at least one bi-facial photovoltaic module (3) wherein the heat sink (5) comprises a plurality of rods (11) having a thermal conductivity higher than 10 W.m.sup.−1.K.sup.−1 and arranged as a mesh configured to be in contact with the back side (3b) of the bi-facial photovoltaic module (3).

Claims

1. A heat sink for bi-facial photovoltaic modules configured to be secured to the back side of at least one bi-facial photovoltaic module wherein the heat sink comprises a plurality of rods having a thermal conductivity higher than 10 W.Math.m.sup.−1.Math.K.sup.−1 (W/mK) and arranged as a mesh configured to be in contact with the back side of the bi-facial photovoltaic module.

2. The heat sink in accordance with claim 1 wherein the rods constitute a three-dimensional pattern.

3. The heat sink in accordance with claim 1 wherein the rods are metallic rods.

4. The heat sink in accordance with claim 1 wherein the rods comprise a reflective surface configured for reflecting solar rays in a specular manner.

5. The heat sink in accordance with claim 1 wherein the rods are cylindrical.

6. The heat sink in accordance with claim 1 wherein the rods have an elongated cross-section along a direction perpendicular to the back side of the bi-facial photovoltaic module.

7. The heat sink in accordance with claim 1 wherein the rods are arranged to form a first grid configured for being in contact with the back side of the bi-facial photovoltaic module, a second grid arranged parallel to the first grid and a plurality of transverse rods arranged between the first and the second grids.

8. The heat sink in accordance with claim 1 wherein the rods configured to be in contact with the back side of the bi-facial photovoltaic module comprise a flattened portion to improve the contact surface with the back side of the bi-facial photovoltaic module.

9. A solar panel comprising at least one bi-facial photovoltaic module and a heat sink according to claim 1 secured to the back side of the at least one bi-facial photovoltaic module.

10. The solar panel in accordance with claim 9 wherein the heat sink is glued to the back side of the at least one bi-facial photovoltaic module.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [FIG. 1] is a diagram of a side view of a solar panel comprising a heat sink according to an embodiment of the present invention;

[0019] [FIG. 2] is a diagram of a perspective view of the heat sink according to a first embodiment;

[0020] [FIG. 3] is a diagram of a perspective view of the heat sink according to a second embodiment;

[0021] [FIG. 4] is a diagram of a perspective view of the heat sink according to a third embodiment;

[0022] [FIG. 5] is a diagram of a perspective view of the heat sink according to a fourth embodiment;

[0023] [FIG. 6] is a diagram of a perspective view of the heat sink according to a fifth embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The following achievements are examples. Although, the specification refers to one or several embodiments, it does not imply that each reference refers to the same embodiment or that the features apply only to a single embodiment. Simple features of different embodiments can also be combined to provide other embodiments.

[0025] FIG. 1 represents a diagram of a solar panel 1 comprising a bi-facial photovoltaic module 3 and a heat sink 5 disposed on the back side 3b of the bi-facial photovoltaic module 3. A bi-facial photovoltaic module 3 refers to a photovoltaic module configured for receiving solar rays from both sides or faces, namely, the front face 3a corresponding to the upper face receiving solar rays directly from the sun as represented by the arrow 7 and the back face 3b corresponding to the lower face receiving reflected solar rays represented by the arrows 9. Reflection of the solar rays may be achieved on the ground or on any other surfaces reflecting a solar ray toward the back side 3b. The bi-facial photovoltaic module 3 is then configured for converting solar rays coming from both sides into electricity.

[0026] The heat sink 5 comprises a plurality of rods 11 arranged as a tridimensional mesh configured to be (partly) in contact with the back side 3b of the bi-facial photovoltaic module 3. A heat sink 5 may be configured to be disposed a single bi-facial photovoltaic module 3 or on a plurality of adjacent bi-facial photovoltaic modules 3.

[0027] The rods 11 refer to elongated elements (having a dimension much longer than the other dimensions). The cross-section of the rods 11 may be circular to produce cylindrical rods but other shape may also be used. In particular, the cross-section may be flattened to reduce the diameter of the rods 11 in a direction parallel to the back side 3b of the bi-facial photovoltaic module 3 in order to reduce the number of reflected solar rays 9 that are perpendicular to the back side 3b of the bi-facial photovoltaic module impinging the rods 11. Furthermore, the rods 11 may be straight (according to their elongated dimension) but other shapes may also be used such as curved or bended rods 11. The rods 11 are made in a material having a thermal conductivity higher than 10 W.m.sup.−1.K.sup.−1, for example a metal such as aluminum or steel or any other metal. The diameter of the rods 11 is chosen as small as possible to limit the shadow produced by the rods 11. The diameter of the rods 11 and the height of the heat sink 5 may be chosen according to the thermal conductivity of the rods 11. Indeed, a higher conductivity enables the use of rods 11 having a higher length as the heat may be transferred along a longer portion of the rods 11 to be dissipated.

[0028] In a preferred embodiment, the rods 11 comprise a reflecting surface configured for reflecting solar rays in a specular manner in order to enable reflection of solar rays 9 impinging the rods 11 with an angle which is not perpendicular to the back side 3b of the bi-facial photovoltaic module to be reflected toward the back side 3b of the bi-facial photovoltaic module 3. The reflection may be obtained by the material of the rods 11 itself or by a dedicated surface treatment or by a dedicated covering of a reflecting layer on the surface of the rods 11.

[0029] The density of rods is chosen so that most of the reflected solar rays 9 may reach the back side 3b of the bi-facial photovoltaic module 3. The shadow (or orthogonal projection) produces by the heat sink 5 corresponds for example to less than 50% of the back side of the bi-facial photovoltaic module 3. Furthermore, the rods 11 of the heat sink 5 are distributed over the surface of the back side 3b so that heat from the whole photovoltaic module may be dissipated through the heat sink and so that no local hot points remains. Such distribution corresponds for example to the fact that circular surfaces that are not in contact with a rod 11 covers at most a limited surface, for example a surface smaller than 5% of the total surface of the back side 3b.

[0030] FIG. 2 represents a first embodiment of a heat sink 5 comprising a plurality of straight rods 11. The heat sink 5 comprises a first plurality of rods 11 arranged as a first grid and configured to be in contact with the back side 3b of the photovoltaic module 3, a second plurality of rods 11 arranged as a second grid destined to be disposed parallel to the first grid and a third plurality of rods 11 linking the first and the second grids. The third plurality of rods may be arranged perpendicular to the general direction of the first and second grids but may also be arranged in other directions as represented in FIG. 2 or both perpendicular to the first and the second grid and in other directions as represented in FIG. 3. The grids may also be replaced by other two-dimensional mesh patterns, for example crossed rods having angles different than 90°.

[0031] According to another embodiment, the heat sink 5 may comprise a first plurality of rods 11 arranged as a grid configured to be in contact with the back side 3b of the bi-facial photovoltaic module 3 and a second plurality of rods 11 extending outwards from the grid to produce three dimensional patterns such as pyramids as represented in FIG. 4. Other patterns may also be arranged based on straight bars such as simple rods extending perpendicular from the grid as represented in FIG. 5 or tree-like pattern as represented in FIG. 6. Other pattern based on straight or curved rods 11 may also be used to produce a mesh enabling the heat to be transmitted through the different rods 11 and dissipated in the air surrounding the rods 11.

[0032] Besides, the portion of the rods 11 configured to be in contact with the back side 3b of the bi-facial photovoltaic module 3 may comprise a flattened part to increase the contact surface between the rods 11 and the back side 3b of the bi-facial photovoltaic module 3 and to provide a pedestal to ease the fastening of the heat sink 5 to the bi-facial photovoltaic module 3. The cross-section of the rods 11 configured to be in contact with the back side of the bi-facial photovoltaic module may therefore be rectangular to increase the contact surface with the said back side 3b.

[0033] According to an embodiment of the present invention, the heat sink 5 is glued to the back side 3b of the bi-facial photovoltaic module 3. In order to improve the efficiency of the heat sink 5, the thickness of glue may be limited, for example less than 2 mm and the used glue may have thermal conductivity properties obtained for example by the addition of dedicated particles having a high thermal conductivity such as carbon fiber particles. The gluing of the heat sink 5 enables to adapt the heat sink on any types of bi-facial photovoltaic modules 3.

[0034] The use of a heat sink 5 arranged on the back side 3b of a bi-facial photovoltaic module 3 and comprising a mesh of rods 11 presenting large openings enables dissipating efficiently the heat from the bi-facial photovoltaic module 3 while allowing reflected solar rays 9 to reach the back side 3b of the bi-facial photovoltaic module 3 to be converted into electricity. Such heat sink 5 may be adapted to any bi-facial photovoltaic module 3 and does not require any external supply and can therefore be adapted to solar farms located in desert regions.