IE20070691A1

IE20070691A1 - Solar panel

Info

Publication number: IE20070691A1
Application number: IE20070691A
Authority: IE
Inventors: Sean M Hoolan
Original assignee: Sean M Hoolan
Priority date: 2007-09-26
Filing date: 2007-09-26
Publication date: 2009-04-29
Also published as: WO2009040430A2; WO2009040430A3

Abstract

A solar panel (100) comprises a number of heat pipes (102), a reflecting element (104) and a clamping mechanism (116). The reflecting element (104) comprises a cushioned substrate (110) and a reflective film (112). The cushioned substrate (110) has a number of recessed channels (114) with the reflective film (112) bonded to the substrate (110). The clamping mechanism (106) comprises an elongate clamping member (106a) and fastening mechanism (122). The clamping member (106) has recesses (118) formed therein with a spacing complimentary to the recessed channels (114) of the substrate (110). The heat pipes (102) seat in the recessed channels (114) of the reflecting element (104) contiguous the reflecting element (104). The recesses (118) in the clamping member (106a) locate over the heat pipes (102) and the fastening mechanism (122) retains the clamping member (106a) and the heat pipes (102) in position. <Figure 1>

Description

SOLAR PANEL This invention relates to a solar panel. More particularly, but not exclusively, the invention relates to a solar panel comprisi heat pipe. cuatec , ISlTCLCliSml ϋϋΐ£ΰΙ5^ Currently, solar panels comprising heat pipes are the most ehicienf technology available for domestic installation. However, such solar panels are installed externally of the building in which they are used. This reduces their appeal in the domestic market as home buyers often find such solar panels to reduce the aesthetic appeal of the building. Additionally, the heat pipes of current solar panels are usually exposed to the elements.

Evacuated heat pipes are made of glass and are therefore brittle. The current method of construction of a solar panel consisting of a number of heat pipes is to located each individual heat pipe in an individual cir-clip or tube tie. This is time consuming and labour intensive, for example a solar panel comprising fifteen heat pipes may take upwards of forty five minutes to construct.

In addition to the labour intensive nature of the manufacture of the solar panel, the use of cir-clips can lead to a high rate of breakage of the heat pipes. This is due to the requirement for a large degree of manual handling of the heat pipes and also the possible over-tightening of the circlips. In an attempt to overcome this problem rubber “socks” have been used to protect the ends of the heat pipes. However, this increases the amount of handling of the heat pipes that is required, thereby increasing the opportunity for breakage of the pipe, and also increase the number of steps in production of the solar panel. »070691 A further difficulty associated with current designs of heat pipe based solar panels is that the parabolic reflectors of the solar panels are made from highly polished metal or coated glass. This means that direct contact between the reflector and the heat pipe risks fracture of the heat pipe.

The spacing of the heat pipe from the reflector reduces the efficiency of the solar panel as the intensity of the reflected radiation decreases with distance according to an inverse square law.

According to a first aspect of the present invention there is provided a solar panel comprising a plurality of heat pipes, a reflecting element and a clamping mechanism, the reflecting element comprising a cushioned substrate and a reflective film, the cushioned substrate comprising a plurality of recessed channels, the reflective film being bonded to the substrate, the clamping mechanism comprising an elongate clamping member and fastening mechanism, the clamping member having recesses formed therein with a spacing complimentary to the recessed channels of the substrate, the heat pipes being seated in the recessed channels of the reflecting element contiguous the reflecting element, recesses in the clamping member being arranged to locate over the heat pipes and the fastening mechanism being arranged to retain the clamping member and the heat pipes in position.

The term cushioned as used herein refers to any substrate that undergoes elastic deformation when subject to a load.

The use of a cushioned substrate allows the heat pipes to be seated directly on to the substrate. This in turn improves the efficiency of the solar panel and obviates the necessity for rubber “socks” and cir-clips to retain the heat pipes in position, leading to a simpler construction with reduced breakage of heat pipes during manufacture. Additionally, the IE Ο 7 0 6 91 heat pipe tubes are held in position along their length rather just at their ends which adds to their stability of location.

The recessed channels may be parabolic.

The substrate may comprise a low density polymer material, for example expanded polystyrene. Alternatively, or additionally, the substrate may comprise a fibrous material, for example woven glass fibres.

The use of low density materials in the fabrication of the substrate allows the fabrication of lightweight solar panels. Furthermore, the use of polymeric or fibrous materials for the substrate increases the thermal insulation properties of the solar panel when used a part of a roofing construction.

The clamping member may comprise a bar. The recesses may be arcuate. The recesses may run transversely through the bar. The clamping member may comprise a cushioned material, for example a low density polymer material.

The use of such a clamping arrangement simplifies construction of the solar panel, reducing manufacturing time by as much as two minutes per tube.

The solar panel may comprise an enclosure within which the heat pipes are located. The enclosure may comprise a transparent cover.

The use of an enclosure for the heat pipes redefines the ambient temperature in which the heat pipes are located as that within the enclosure rather than that outside the enclosure. This enhances the performance ofthe heat pipes due to the recycling of thermal radiation emitted from the heat pipes back into them, rather than it being lost if no cover were present.

According to a second aspect ofthe present invention there is provided a method of forming a reflector for a solar panel comprising the steps of: forming a plurality of recessed channels in a polymer substrate; and adhering a reflective film over some or all of the recessed channels.

The method may comprise forming parabolic recessed channels in the polymer substrate. The polymer substrate may comprise expanded polystyrene. The method may comprise hot wire cutting the recessed channels in the polymer substrate.

The reflective film may comprise a polymer film coated with a metal, for example aluminium.

According to a third aspect of the present invention there is provided a clamping mechanism for clamping heat pipes of a solar panel in position comprising an elongate clamping member and fastening mechanism, the clamping member having recesses formed therein with a spacing complimentary to recessed channels of a substrate, the heat pipes being seated in the recessed channels of the reflecting element contiguous the reflecting element, the recesses in the clamping member being arranged to locate over the heat pipes and the fastening mechanism being arranged to retain the clamping member and the heat pipes in position.

According to a fourth aspect of the present invention there is provided a solar panel unit suitable for installation into a roof comprising a solar panel according to the first aspect of the present invention, a rafter configuration ΙΕο 7 0 arranged to receive the solar panel, and flashing, the flashing being arranged to lie over the edges of the solar panel and overlay adjacent roofing materials.

This allows the provision of a solar panel that is substantially flush with the surface of a roof. This improves the appeal of the solar panel to a purchaser of, for example, a house. The solar panel of the first aspect of the present invention provides added insulation, in certain embodiments, due to the polymeric or fibrous nature of the reflective element.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic perspective diagram of a solar panel according to the first aspect of the present invention; Figure 2 is an end view of a solar panel of Figure 1, showing a clamping mechanism according to a third aspect of the present invention, in detail; Figure 3 is an end view of two heat pipes forming part of the solar panel of Figure 1, with clamping bars omitted for clarity; Figure 4 is a perspective view of a rafter configuration arranged to receive a solar panel according to the first aspect of the present invention; and Figure 5 is a perspective partial view of a roof comprising the rafter configuration of Figure 4 and a solar panel according to a first aspect of the present invention.

Referring now to Figures 1 to 3, a solar panel 100 a solar panel comprises heat pipes 102, a reflector 104, clamping bars 106a,b and a transparent cover 108.

The heat pipes 102 are standard and their construction and use will be known to those skilled in the art.

The reflector 104 comprises a cushioned substrate 110 and a reflective film 112. The film 112 is attached to the substrate 110, typically by the use of an adhesive or thermal bonding.

Typically, the substrate 110 is formed from a low density polymer material, for example expanded polystyrene or a fibrous material, for example woven glass fibres. The substrate 110 has a number of arcuate recessed channels 114 extending longitudinally over its upper surface 116. Ina preferred embodiment the channels 114 have a regular pitch. In the case of a polymeric substrate 110 the channels 114 can be formed by hot wire cutting of the substrate 110 prior to the adhesion of the reflective film 112.

The reflective film 112 comprises a polymeric substrate coated with a thin metallic film, for example aluminium. Alternatively, a thin metal foil can be used.

The clamping bars 106a,b are elongate and have rectangular crosssection. Arcuate recesses 118 pass transversely through the clamping bars 106a,b with a pitch complimentary to that of the recessed channels 114 of the substrate 110. Typically, the clamping bars 106a,b are made from a low density polymeric material, such as expanded polystyrene. Where such a polymeric material is used the recesses 118 can be formed by hot wire cutting of the substrate clamping bars 106a,b. A steel crossΙΕο 70 8 9 1 brace 120 locates on the opposite side ofthe clamping bars 106a,b to the recesses 118. The cross-brace 120 gives added rigidity to the clamping bars 106a,b.

In use, the heat pipes 102 seated in the recessed channels 114 ofthe reflector 104. The heat pipes 102 lies in the channels 114 such that they are supported by the reflector 104 over substantially all of their length.

The clamping bars 106a,b locate over the heat pipes 102 such that a free portion of the surface of the heat pipes 102 locates in the recesses 118 of the clamping bars 106a,b. Typically, two clamping bars 106a,b will be used at each end ofthe heat pipes 102. However, it will be appreciated that more than two clamping bars 106a,b may be used and the clamping bars 106a,b may be located at any point along the length ofthe heat pipes 102. Retaining pins 122 passthrough the clamping bars 106a,b into the substrate 110. Thus, the clamping bars 106a,b and the reflector 104 retain the heat pipes 102 in position. Typically, a solar panel 100 made to this construction will comprise a transparent cover 124 as will be exemplified with reference to Figure 3.

Referring now to Figure 3, in particular the cover 124 and walls 126a,b of the solar panel 100 define an internal chamber 128. Within the internal chamber 128 thermal radiation emitted from the heat pipes 102 is recycled back into them.

Furthermore, the temperature within the internal chamber 128 is effectively the ambient temperature in which the heat pipes 102 operate. This effective ambient temperature will be higher than the external ambient temperature. As will be known to those skilled in the art the efficiency of heat pipes 102 is dependent upon the difference between the ambient temperature TA and the manifold temperature TMof the heat pipes 102 according to the following relationship: η (x) = η0 - a-ι x - a2.G.x2 Where: ηο = Conversion factor ai and a2 =loss co-efficients G = insolation level x= [(TM- Ta]/G)] Therefore the closer the ambient temperature is to manifold temperature the more efficient the solar panel will be.

Referring now to Figures 4 and 5, a roof 400 comprises inclined rafters 402, a frame 404, slates 406, a solar panel 408 and flashing 410. One of the rafters 402 is broken and the frame 404 inserted into the gap in the rafter 402. The frame 404 comprises horizontal walls 412a,b, inclined walls 414a,b, and a backing plate 416. The horizontal walls 412a,b attach to the broken rafter 402 whilst the inclined walls 414a,b attach to the rafters 402 adjacent the broken rafter 402. Thus, the provision of the frame 404 within the roof 400 structure does not significantly weaken the roof 400.

The solar panel 408 fits into the frame 404 such that it is substantially flush with finished external level of the roof 400. The polymeric or fibrous nature of the panels reflector adds insulation to the roof 400 in the region of the solar panel 408. The slates 406 are laid on the roof 400 and flashing 410 laid over the junction between the slates 406 and the solar panel 408. This provides a low profile, ideally flush, finish between the slates 406 and the solar panel 408.

It will be appreciated that although described with reference to slates any 5 suitable roofing material can be used, for example, felt, wood or tiles.

Various modifications and improvements may be made to the above without departing from the scope of the present invention.

Claims

1. A solar panel comprising a plurality of heat pipes, a reflecting element and a clamping mechanism, the reflecting element comprising a 5 cushioned substrate and a reflective film, the cushioned substrate comprising a plurality of recessed channels, the reflective film being bonded to the substrate, the clamping mechanism comprising an elongate clamping member and fastening mechanism, the clamping member having recesses formed therein with a spacing complimentary to the 10 recessed channels of the substrate, the heat pipes being seated in the recessed channels of the reflecting element contiguous the reflecting element, recesses in the clamping member being arranged to locate over the heat pipes and the fastening mechanism being arranged to retain the clamping member and the heat pipes in position.

2. A solar panel according to claim 1, wherein the recessed channels are parabolic.

3. A solar panel according to either claim 1, or claim 2, wherein the 20 substrate comprises a low density polymer material,

4. A solar panel according to claim 3, wherein the polymeric material comprises expanded polystyrene. 25

5. A solar panel according to any preceding claim, wherein the substrate comprises a fibrous material.

6. A solar panel according to any preceding claim, wherein the clamping member comprises a bar.

7. A solar panel according to any preceding claim, wherein the recesses are arcuate.

8. A solar panel according to any preceding claim, wherein the recesses run transversely through the bar.

9. A solar panel according to any preceding claim, wherein the clamping member comprises a cushioned material,

10. A solar panel according to any preceding claim, comprising an enclosure within which the heat pipes are located.

11. A solar panel according to claim 10, wherein the enclosure comprises a transparent cover.

12. A method of forming a reflector for a solar panel comprising the steps of: forming a plurality of recessed channels in a substrate; and adhering a reflective film over some or all of the recessed channels.

13. The method of claim 12 comprising forming parabolic recessed channels in the substrate.

14. The method of either claim 12, or claim 13, wherein substrate comprises a polymer substrate.

15. The method of claim 14 wherein the substrate comprises expanded polystyrene

16. The method of either claim 13 or claim 14 comprising hot wire cutting the recessed channels in the polymer substrate.

17. The method of any one of claims 12 to 16, wherein the reflective film comprises a polymer film coated with a metal.

18. A clamping mechanism for clamping heat pipes of a solar panel in position comprising an elongate clamping member and fastening mechanism, the clamping member having recesses formed therein with a spacing complimentary to recessed channels of a substrate, the heat pipes being seated in the recessed channels of the reflecting element contiguous the reflecting element, the recesses in the clamping member being arranged to locate over the heat pipes and the fastening mechanism being arranged to retain the clamping member and the heat pipes in position.

19. A solar panel unit suitable for installation into a roof comprising a solar panel according to anyone of claims 1 to 11, a rafter configuration arranged to receive the solar panel, and flashing, the flashing being arranged to lie over the edges of the solar panel and overlay adjacent roofing materials.