US20170023277A1

US20170023277A1 - Solar panel

Info

Publication number: US20170023277A1
Application number: US15/117,733
Authority: US
Inventors: Julius PETURSSON
Original assignee: KRISTIANSTADS INDUSTRISERVICE AB
Current assignee: KRISTIANSTADS INDUSTRISERVICE AB
Priority date: 2014-02-14
Filing date: 2015-02-09
Publication date: 2017-01-26
Also published as: EP3105515A1; WO2015122828A1; SE537835C2; SE1450170A1

Abstract

A solar panel comprising a plurality of elongated and flat pipe elements having a first end, a second end and at least one longitudinal and through pipe channel for a heat carrying liquid, wherein the pipe channels are arranged with a height (H) up to 10 mm. the pipe elements are connected to opposite and elongated edge elements. The edge elements are arranged with a longitudinal channel for the heat carrying liquid, wherein the channels in the edge elements are connected to the pipe channels and extend in a direction perpendicular to the pipe channels. The pipe elements are formed with an aperture on opposite sides of at least one pipe channel, and stop devices are connected to the edge elements at selected apertures and extend into the channels of the edge elements to block the channels and guide the heat carrying liquid between the pipe channels.

Description

FIELD OF THE INVENTION

The present invention relates to a solar panel. Solar panels are used for collecting thermal energy from sunlight and use it for heating a suitable heating medium, such as a heat carrying liquid. The heat carrying liquid is circulated through the solar panel, wherein the liquid is heated by the sun and the thermal energy in the heat carrying liquid can be used for heating different types of constructions. Solar panels are generally used in heating systems, such as domestic hot water systems but can also be used for heating buildings, swimming pools and similar.

PRIOR ART

A plurality of different types of solar panels are known in the prior art. One conventional type of solar panel comprises a conduit in the form of a tube or a hose for a heat carrying liquid, so that the liquid can circulate through the conduit for collecting energy from sunlight. The conduit can be arranged between a cover plate, such as a glass or a plastic plate, and a base plate, such as a building panel provided with insulation, absorber and similar.
One type of prior art solar panels comprises flat pipe elements having channels for the heat carrying liquid, wherein a height of the channels is substantially smaller than a width of the channels. A height of the channels can be below 10 mm. The pipe elements can be formed in steel or aluminium, such as extruded aluminium.
One problem with such prior art solar panels is that they can be expensive to produce.
Another problem with prior art solar panels is that they are limited in range of use due to their structure.

SUMMARY OF THE INVENTION

An object of the invention is to avoid the above mentioned problems of the prior art and provide a solar panel resulting in efficient heating of the heat carrying liquid while simultaneously being easy and cost efficient to produce and being adaptable according to the desired conditions of operation.
The present invention relates to a solar panel comprising a plurality of elongated and flat pipe elements having a first end, a second end and at least one longitudinal and through pipe channel for a heat carrying liquid, and wherein the pipe channels are arranged with a height up to 10 mm, characterised in that the first end of the pipe elements are connected to a first edge element, and the second end of the pipe elements are connected to an opposite second edge element, that the edge elements are elongated and arranged with a longitudinal channel for the heat carrying liquid, wherein the channels in the edge elements are connected to the pipe channels and extend in a direction perpendicular to the pipe channels, that the pipe elements on opposite sides of at least one pipe channel are formed with an aperture, and that stop devices are arranged at selected apertures, wherein the stop devices extend into the channels in the edge elements to block the channels and guide the heat carrying liquid between the pipe channels. The pipe elements can be formed in aluminium, such as extruded aluminium profiles. Also the edge elements can be formed in aluminium, such as extruded aluminium profiles. Alternatively, the edge elements can be formed in or provided with a plastic material for insulation. Due to the arrangement of the pipe elements with the apertures, the arrangement of the edge elements with the channels and the stop devices interacting with the apertures to block the channels an efficient and flexible in use solar panel is provided which can be produced in a simple and cost efficient manner and can be used for heating heat carrying liquids for different purposes.
Further characteristics and advantages of the present invention will become apparent from the description of the embodiments below, the appended drawings and the dependent claims.

SHORT DESCRIPTION OF THE DRAWINGS The invention will now be described more in detail with the aid of embodiment examples and with reference to the appended drawings, in which

FIG. 1 is a schematic perspective view obliquely from above of a solar panel according to one embodiment of the present invention, in which a set of pipe elements, a cover plate, an insulating layer, a base plate, edge elements and corner parts of the solar panel are illustrated separately,

FIG. 2 is a schematic perspective view according to FIG. 1, in which the cover plate, the insulating layer and the base plate have been removed,

FIG. 3 is a schematic perspective view of a part of a pipe element according to one embodiment,

FIG. 4 is a schematic front view of the pipe element of FIG. 3,

FIG. 5 is a schematic view of the pipe elements, edge elements and corner parts of a solar panel according to one embodiment, in which one example of a flow pattern of a heat carrying liquid is illustrated,

FIG. 6 is a schematic view according to FIG. 5, in which one alternative example of a flow pattern of a heat carrying liquid is illustrated,

FIG. 7 is a schematic perspective view of a part of a solar panel according to one embodiment,

FIG. 8 is a schematic perspective view of a part of an edge element according to one embodiment,

FIG. 9 is a schematic perspective view of a part of an edge element according to one alternative embodiment,

FIG. 10 is a schematic perspective view of a set of pipe elements, a first edge element, a second edge element and stop devices according to yet another embodiment,

FIG. 11 is a schematic perspective view of a part of the pipe elements, the first edge element and the stop devices according to FIG. 10,

FIG. 12 is a schematic perspective view of a set of pipe elements, a first edge element, a second edge element and stop devices according to yet another embodiment, and

FIG. 13 is a schematic perspective view of a part of the pipe elements, the first edge element and the stop devices according to FIG. 12.

THE INVENTION

Referring to FIG. 1 a solar panel 10 for collecting sunlight and converting energy in sunlight to thermal energy of a heat carrying liquid according to one embodiment is illustrated schematically. For example, the solar panel 10 is arranged for circulating a conventional heat carrying liquid, such as water, water in combination with an anti-freezing agent, glycol or similar conventional liquids for this type of solar panels. By the description of the different components of the solar panel also a method for collecting sunlight and convert energy in the sunlight to thermal energy of the heat carrying liquid is evident, and also the use of a device in the form of the solar panel 10 as described herein for collecting sunlight and convert energy in the sunlight to thermal energy of the heat carrying liquid.
The solar panel 10 comprises a plurality of elongated and flat pipe elements 11 for conducting the heat carrying liquid in a desired pattern through the solar panel 10. In the illustrated embodiment the solar panel 10 comprises eight pipe elements 11 but the solar panel 10 can comprise any desired number of pipe elements 11. The pipe elements 11 are arranged in parallel and in a common plane to form a rectangular or quadratic structure.
The solar panel 10 also comprises a first edge element 12 and a second edge element 13. In the illustrated embodiment the solar panel 10 further comprises a third edge element 14 and a fourth edge element 15 and corner parts 16 connecting the edge elements 12-15. A first end of the pipe elements 11 are connected to the first edge element 12, wherein a second end of the pipe elements 11 are connected to the second edge element 13. The pipe elements 11 together with the first and second edge elements 12, 13 are arranged for circulating the heat carrying liquid through the solar panel 10, which is described more in detail below.
In the embodiment of FIG. 1 the solar panel 10 also comprises a cover plate 17 and a base plate 18. The cover plate 17 is permeable to sunlight. For example, the cover plate 17 is formed in a glass or plastic material, such as polycarbonate. For example, the cover plate 17 comprises an upper and a lower plate having channels between them, wherein the cover plate 17 is arranged in the form of so called corrugated plastic. For example, the cover plate 17 is arranged in a UV resistant plastic material. The base plate 18 is arranged to insulate the solar panel 10. For example, the base plate 18 is arranged in a glass or plastic material, such as polycarbonate. For example, also the base plate is arranged as corrugated plastic. For example, the cover plate 17 and the base plate 18 are connected to the edge elements 12-15. In the illustrated embodiment the solar panel 10 also comprises an insulating layer 18 b, such as an insulation plate. For example, the insulating layer 18 b comprises an aluminium panel filled with air, such as aluminium foils connected to each other and having air between them. For example, the insulating layer 18 b is arranged with a thickness up to 10 mm or up to 5 mm. For example, the total thickness of the solar panel 10, i.e. the height from the outer side of the base plate 18 to the outer side of the cover plate 17, is up to 60 mm or 50 mm. For example, the total thickness of the solar panel 10 is about 50 mm.
In FIG. 2 the pipe elements 11, the edge elements 12-15 and the corner parts 16 are illustrated without the cover plate 17, the base plate 18 and the insulating layer 18 b. As evident more clearly from FIG. 2 the edge elements 12-15 and the corner parts 16 according to the illustrated embodiment are arranged to be connected to each other to form a frame enclosing the pipe elements 11. The first edge element 12 is connected to the first ends of the pipe elements 11, wherein the second edge element 13 is connected to the second ends of the pipe elements 11. For example, the third edge element 14 engages a long side of an outermost pipe element 11, wherein the fourth edge element 15 engages a long side of an outermost pipe element 11 at the opposite side of the solar panel 10. For example, the edge elements 12-15 are arranged in aluminium, such as extruded aluminium. Alternatively, the edge elements 12-15 are arranged in a suitable plastic material. According to yet another alternative embodiment the edge elements 12-15 are formed in aluminium and are provided with an insulating layer of plastics, for example on the outer sides of the edge elements 12-15. The edge elements 12-15 are connected to each other, for example, through the corner parts 16, by conventional fasteners, such as screws.
With reference to FIG. 3 and FIG. 4 the pipe elements 11 are arranged with a first pipe channel 19 and a second pipe channel 20 for the heat carrying liquid. Alternatively, the pipe elements 11 are arranged with at least one pipe channel or more pipe channels, such as three or more. The pipe elements 11 form an absorber of the solar panel 10. The pipe channels 19, 20 extend in the longitudinal direction and through the pipe elements 11 from the first end thereof to their opposite second end. For example, the pipe channels 19, 20 are parallel. For example, the pipe channels are arranged with a height H of up to 10 mm, such as 1-10 mm, 5-8 mm, around 6 mm or about 7 mm. The pipe channels are arranged with a width W being substantially greater than the height H. For example, the width W is 20-200 mm or 30-100 mm, such as 30-50 mm or around 30-35 mm.
The pipe elements 11 are arranged with at least one aperture 21 in their ends, which aperture extends in the longitudinal direction of the pipe elements 11. In the illustrated embodiment the pipe element 11 comprises a first aperture 21, a second aperture 22 and a third aperture 23, wherein the first pipe channel 19 is arranged between the first and second apertures 19, 20, and wherein the second pipe channel 20 is arranged between the second and third apertures 22, 23. For example, the apertures 21-23 are aligned and extend along a common plane. For example, the apertures 21-23 are arranged centrally in the vertical direction of the pipe elements 11. The apertures 21-23 extend in parallel to the pipe channels 19, 20 and to each other. For example, the apertures 21-23 are through and extend between the first end and second end of the pipe elements 11. The apertures 21-23 are, for example, arranged with a circular cross section. For example, the apertures 21-23 are arranged with a diameter of 3-8 mm, 4-6 mm or around 5 mm. The pipe elements 11 are, for example, arranged with a thickness of material below 0.5-2 mm. For example, the pipe elements 11 are arranged with a thickness of material of 1-2 mm or 1-1.5 mm. For example, the thickness of material is greater around the apertures 21-23 than above and below the pipe channels 19, 20. For example, the pipe elements 11 are provided with a black colour.
In the illustrated embodiment a profile or cross section area of the pipe elements 11 is arranged with greater height around the apertures 21-23 than at the pipe channels 19, 20 to form an elevation, such as arc-shaped elevations, on the upper and lower sides of the pipe elements 11 at the apertures 21-23. Hence, a height at a centre line extending radially through the apertures 21-23 is greater than a height of the pipe element 11 at the pipe channels 19, 20.
Referring back to the embodiments of FIG. 1 and FIG. 2 the first edge element 12 and the second edge element 13 are arranged with openings 24. The openings 24 are through and arranged for receiving a fastener in the form of a screw or similar. Further, the openings 24 are aligned with selected apertures 21-23 in the pipe elements 11, wherein the first and second edge element 12, 13 can be connected to the pipe elements 11 by, for example, fastening the first and second edge elements 12, 13 to the pipe elements 11 by screws through the openings 24 and selected apertures 21-23. For example, the edge elements 12-15 are connected to each other and with the pipe elements 11 by means of screws, pins, glue, welding, soldering or a combination thereof or in another suitable manner.
Further, the first and second edge elements 12, 13 are arranged with a longitudinal channel 25 for the heat carrying liquid. The channel 25 is connected to the pipe channels 19, 20, so that the heat carrying liquid can flow between the pipe channels 19, 20 and the channel 25 arranged in the first and second edge elements 12, 13, respectively. The channel 25 connects selected pipe channels 19, 20 with each other, such as the first and second pipe channels 19, 20 of the same pipe element 11 or pipe channels 19, 20 of adjacent pipe elements 11, which is described more in detail below. The channel 25 extends perpendicular to the longitudinal direction of the pipe channels 19, 20. For example, the channel 25 extends through the entire length of the first and second edge elements 12, 13, so that the channel 25 extends from a first end to a second end of the first and second edge elements 12, 13.
The solar panel 10 comprises an inlet 26 for the heat carrying liquid. In the illustrated embodiment the inlet 26 is arranged in a corner part 16, so that the heat carrying liquid can be introduced into the channel 25 in the first edge element 12, for example through a hole in one end of the first edge element 12, and further into the pipe channels 19, 20 in the pipe elements 11. Alternatively, the inlet 26 is arranged directly in the first edge element 12 or in another suitable manner. For example, the first edge element 12 is provided with a corresponding hole 27 in the opposite end. For example, an outlet 28 for the heat carrying liquid is arranged in another corner part 16 than the inlet 26 in a similar manner. For example, the outlet 28 is connected to the channel 25 of the first or second edge element 12, 13. Alternatively, the outlet 28 is arranged directly in the first or second edge element 12, 13.
With reference to FIG. 5 and FIG. 6 different flow structures or flow patterns of the heat carrying medium in the solar panel 10 are illustrated. The flow between the pipe channels 19, 20 is illustrated by means of arrows. As evident from FIG. 5 the solar panel 10 comprises stop devices 29 for guiding the heat carrying liquid between the pipe channels 11. The stop devices 29 are arranged to be received in the channel 25 of the first and second edge elements 12, 13, respectively, and to block the channel 25, so that the heat carrying liquid cannot pass the stop device 29 but instead is guided into the pipe channels 19, 20. Hence, the stop devices 29 are arranged with a height or diameter substantially corresponding to a height of the channels 25. Further, the stop devices 29 are, for example, arranged with a length substantially corresponding to a width of the channels 25, so that the stop devices 29 are arranged with dimensions to substantially correspond to a cross section area of the channels 25 for blocking them. For example, the stop devices 29 are arranged in a flexible material, such as a plastic or rubber material. Alternatively, the stop devices 29 are arranged in metal, such as aluminium. The stop devices 29 are, for example, connected to the pipe elements 11 through the apertures 21-23, wherein stop devices 29 are connected to the pipe elements 11 in selected apertures 21-23 to provide the desired flow pattern. For example, the stop devices 29 are detachably connectable to the pipe elements 11 at the apertures 21-23, so that the stop devices 29 can be positioned at the selected apertures 21-23. In FIG. 5 stop devices 29 in a first end of the pipe elements 11 are arranged at the second aperture 22 of each of the pipe elements 11 and project into the channel 25 of the first edge element 12, so that the heat carrying liquid is guided from the second pipe channel 20 of a pipe element 11 to the first pipe channel 19 of an adjacent pipe element 11 through the channel 25 in the first edge element 12. In the second end of the pipe elements 11 stop devices 29 are, for example, arranged at the first aperture 21 of each of the pipe elements 11, so that the heat carrying liquid is guided from the first pipe channel 19 to the second pipe channel 20 of the same pipe element 11 through the channel 25 in the second edge element 13.
With reference to FIG. 6 the stop devices 29 in a first end of the pipe elements 11 are arranged at the first or third apertures 21, 23 of every other pipe element 11, wherein the stop devices 29 in the second end are arranged at the first or third apertures 21, 23 of the remaining pipe elements 11, so that the heat carrying liquid flow in the same direction in two adjacent pipe channels 19, 20 via the channels 25.
With reference to FIG. 7 a part of the pipe elements 11 and a part of the first edge element 12 are illustrated according to one embodiment of the invention. For example, the second edge element 13 is arranged in a corresponding manner as the first edge element 12. The first edge element 12 is arranged with the channel 25 for interaction with the pipe channels 19, 20. In the embodiment of FIG. 7 the channel 25 is open in a direction towards the ends of the first edge element 25. Further, the first edge element 12 comprises a first groove 30 for receiving the cover plate 17, and a second groove 31 for receiving the base plate 18. For example, the first edge element 12 also comprises a groove for receiving the insulating layer 18 b.
In the embodiment of FIG. 7, the stop devices 29 in the first and second edge elements 12, 13 are arranged with a screw hole 32 for receiving a fastener in the form of a screw 33, so that screws 33 can be inserted through the openings 24 and be connected with the pipe elements 11 through the screw holes 32 arranged in the stop devices 29. Hence, the first and second edge elements 12, 13 are connected to the pipe elements 11 by means of the screws 33 while the stop devices 29 simultaneously are fastened at their apertures 21-23, respectively. For example, the stop devices 29 extend into the apertures 21-23. Alternatively, the stop devices 29 are arranged between the apertures 21-23 and the first and second edge elements 12, 13, respectively, to block the channel 25. For example, the screws 33 extend through the stop devices 29 and into the selected apertures 21-23 of the pipe elements 11. For example, the stop devices 29 also form spacers between an inner wall of the first and second edge elements 12, 13 and the pipe elements 11.
With reference to FIG. 8 a part of the first edge element 12 is illustrated according to one embodiment example, in which the first edge element 12 is an aluminium profile, such as an extruded aluminium profile, with the channel 25, the first groove 30 and the second groove 31. In the embodiment of FIG. 8 an end surface 34 is arranged in the ends of the first and second edge elements 12, 13 at the channel 25 or at a front portion of the channel 25, for example, to keep the pipe elements 11 in position and prevent lateral displacement thereof, such as during assembly of the solar panel 10. Alternatively, the first edge element 12 is formed without the end surface 34.
With reference to FIG. 9 a part of the first edge element 12 according to one alternative embodiment example is illustrated, in which the first edge element 12 is an aluminium profile, such as an extruded aluminium profile, with the channel 25, the first groove 30 and the second groove 31. In the embodiment of FIG. 9 the first and second edge elements 12, 13 comprise the optional end surface 34. Further, the opening to the channel 25 is formed after the profile or cross section area of the pipe elements 11. For example, the front opening to the channel 25 is formed with bores 35 for receiving the material of the pipe elements 11 surrounding the apertures 21-23.
With reference to FIGS. 10 and 11 the stop devices 29 and the edge elements 12, 13 are illustrated according to one alternative embodiment. The pipe elements 11 are arranged in a similar way as described above with reference to FIGS. 3 and 4. In the embodiment of FIGS. 10 and 11 the openings 24 in the edge elements 12, 13 are arranged for receiving stop devices 29, so that stop devices 29 project through the openings 24 and into the channels 25. The stop devices 29 are fastened in the channels 25 by means of fasteners, such as the screws 33 extending through the screw holes 32 in the stop devices 29. For example, the screws 33 extend into the selected apertures 21-23 in the pipe elements 11 to connect stop devices 29 in the desired positions for guiding the flow through the solar panel 10. The stop devices 29 are, for example, arranged in aluminium and are fastened in the apertures 21-23 of the pipe elements 11 by means of the screws 33. In the embodiment of FIGS. 10 and 11 the stop devices 29 are arranged with a flange 36 for sealing engagement with an outer surface of the edge elements 12, 13, so that the liquid in the channels 25 does not leak out through the openings 24.
As evident from FIGS. 10 and 11 the openings 24 in the first edge element 12 are elongated in the lateral direction for receiving a stop device 29 having two screw holes 32 arranged adjacent to each other. The openings 24 extend from an outer side of the edge elements 12, 13 to the channel 25. The screw holes 32 in the stop device 29 are aligned with adjacent apertures 21, 23 of two adjacent pipe elements 11. Hence, the stop device 29 is fastened in two apertures 21, 23 arranged next to each other by screwing, wherein the stop device 29 and the screws 33 also connect two adjacent pipe elements 11. As evident from FIG. 10 the stop devices 29 arranged in the channel 25 of the second edge element 13 are arranged with only one screw hole 23 and are, for example, connected to the centre aperture 22 of each or the selected pipe elements 11 by a single screw 33. For example, the openings 24 in the second edge element 13 are circular for receiving a stop device 29 in the form of a cylinder having a flange for engaging the outer surface of the second edge element 13.
With reference to FIGS. 12 and 13 the stop devices 29 and the edge elements 12, 13 are illustrated according to yet another alternative embodiment. In the embodiment of FIGS. 12 and 13 the edge elements 12, 13 are arranged without the openings 24. For example, the edge elements 12, 13 are formed with a whole and continuous peripheral outer side being impermeable to water. The stop devices 29 are arranged to be positioned inside the channel 25 and be connected to the pipe elements 11 through the apertures 21-23. For example, the stop devices 29 are formed as rectangular parallelepipeds with or without rounded or bevelled corners. For example, the stop devices 29 are arranged in aluminium. The stop devices 29 are connected to the apertures 21-23 in the pipe elements 11 by means of fasteners in the form of pins 37. The pins 37 are introduced into the selected apertures 21-23 and are connected to the pipe elements 11, for example, through spring action in the radial direction. For example, the pin 37 is a spring pin, also called tension pin. Hence, one end of the pins 37 are forced into the desired apertures 21-23, wherein the stop devices 29 are arranged with a recess for receiving an opposite second end of the pins 37. The recesses in the stop devices 29 are, for example, not through but formed with a bottom.
As evident from FIGS. 12 and 13 the stop devices 29 for fastening inside the channel 25 of the first edge element 12 are formed with two recesses, wherein the stop devices 29 for fastening inside the channel 25 of the second edge element 13 are arranged with a single recess. Hence, the stop devices 29 inside the first edge element 12 are fastened to the pipe elements 11 by means of two pins 37, wherein the stop devices 29 inside the second edge element 13 are fastened to the pipe elements 11 by means of a single pin 37. Hence, the stop devices 29 in the first edge element 12 connects two adjacent pipe elements 11 by the adjacent apertures 21, 23 of the pipe elements 11. For example, the stop devices 29 are introduced into the channels 25 through ends of the edge elements 12, 13 and are connected with pins 37 arranged in selected apertures 21-23.

Claims

1. A solar panel comprising a plurality of elongated and flat pipe elements having a first end, a second end and at least one longitudinal and through pipe channel for a heat carrying liquid, wherein the pipe channels are arranged with a height (H) up to 10 mm, wherein

the first end of the pipe elements are connected to a first edge element, and the second end of the pipe elements are connected to an opposite second edge element,

the first and second edge elements are elongated and arranged with a longitudinal channel for the heat carrying liquid, wherein the channels in the first and second edge elements are connected to the pipe channels and extend in a direction perpendicular to the pipe channels,

the pipe elements on opposite sides of at least one pipe channel are formed with an aperture, and

stop devices are connected to the pipe elements at selected apertures, wherein the stop devices extend into the channels of the edge elements to block the channels and guide the heat carrying liquid between the pipe channels.

2. A solar panel according to claim 1, wherein the channel in the first edge element is continuous and extends between opposite ends of the first edge element, and wherein the channel in the second edge element is continuous and extends between opposite ends of the second edge element.

3. A solar panel according to claim 1, wherein the stop devices are detachably connectable to the pipe elements through the apertures.

4. A solar panel according to claim 1, wherein each of the pipe elements are formed with two parallel pipe channels between which an aperture is arranged.

5. A solar panel according to claim 1, wherein the first and second edge elements are connected to a third and fourth edge element forming a frame enclosing a set of pipe elements.

6. A solar panel according to claim 5, wherein the edge elements are connected to each other through corner parts, wherein an inlet for the heat carrying liquid is arranged in a first corner part and is connected to the channel in the first edge element, and wherein an outlet for the heat carrying liquid is arranged in a second corner part and is connected to the channel in the first or second edge element.

7. A solar panel according to claim 1, wherein the pipe channels are arranged with a height (H) of 5-8 mm or 7 mm.

8. A solar panel according to claim 1, wherein the pipe elements are arranged with a width of 50-500 mm or 80-100 mm.

9. A solar panel according to claim 1, comprising a cover plate covering the pipe elements, and a base plate, so that the pipe elements extend in a plane between the cover plate and the base plate.

10. A solar panel according to claim 9, comprising an insulating layer between the base plate and the pipe elements.

11. A solar panel according to claim 9, wherein the first and second edge elements are arranged with grooves for receiving edge portions of the cover plate and the base plate.