WO2009047528A1

WO2009047528A1 - Improvements in and relating to solar panels

Info

Publication number: WO2009047528A1
Application number: PCT/GB2008/003450
Authority: WO
Inventors: Leo Lamb
Original assignee: Leo Lamb
Priority date: 2007-10-11
Filing date: 2008-10-10
Publication date: 2009-04-16
Also published as: GB2466423A; WO2009047528A4; GB201007661D0

Abstract

A solar panel (10) is constructed from plastics panels (14, 16) of the type having spaced walls (18, 20, 22) joined by spaced webs (24). At least one heat pipe (42) within the solar panel terminates in a condenser (44), whereby heat within the panel can be transferred from the condenser to a heat receiver (50).

Description

TITLE: Improvements in and relating to solar panels

DESCRIPTION

This invention concerns improvements in and relating to solar panels.

Solar panels are made in a variety of formats of the type used to generate hot water generally comprise a weatherproofed, insulated box containing a black metal absorber sheet with built in pipes to be placed in the path of sunlight. Solar energy heats up water in the pipes causing it to circulate through the system by natural convection and the heated water is usually passed to a storage tank.

Flat-plate collector solar panels generally comprise a flat-plate absorber, which intercepts and absorbs solar energy, a transparent cover that allows solar energy to pass through but reduces heat loss from the absorber, a heat-transport fluid, such as air or water, flowing through tubes to remove heat from the absorber, and a heat insulating backing. Flat-plate collectors can be evacuated, to prevent heat loss.

Evacuated or vacuum tube solar panels have evacuated glass tubes which heat up solar absorbers and solar working fluid in order to heat domestic hot water, or for hydronic space heating. The evacuated tubes minimize the re-radiation of infrared energy from the collectors, allowing them to reach considerably higher temperatures than most flat-plate collectors. For this reason they can perform well in colder conditions. The advantage is largely lost in warmer climates, except in those cases where very hot water is desirable, for example commercial process water conditions. An advantage of this design over the flat-plate type is that the constant profile of the round tube means that the collector is always perpendicular to the sun's rays and therefore the energy absorbed is approximately constant over the course of a day. A solar hot water panel is a solar water heater that uses the sun's energy to heat a fluid, which is used to transfer the heat to a heat storage vessel. In the home, for example, potable water would be heated and then stored in a hot water tank. Flat-plate solar-thermal collectors are usually placed on the roof, and have an absorber plate to which fluid circulation tubes are attached. The absorber, usually coated with a dark selective surface, assures the conversion of the sun's radiation into heat, while fluid circulating through the tube carries the heat away where it can be used or stored. The heated fluid is pumped to a heat exchanger, which is a coil in the storage vessel or an external heat exchanger where it gives off its heat and is then circulated back to the panel to be reheated. Fluid circulation can be assisted by means of a mechanical pump or by allowing convection to circulate the fluid to the storage vessel mounted higher in the circuit, also known as a thermosiphon.

Many of these types of solar panel are expensive to produce and so there is a need to find a construction that can be less expensive to produce than conventional solar panels and preferably to provide enhanced performance.

According to a first aspect of the present invention there is provided a solar panel constructed from plastics panels of the type having spaced walls joined by spaced parallel webs.

The solar panel preferably comprises at least one heat pipe within the panel and terminating in a condenser, whereby heat within the panel can be transferred from the condenser to a heat receiver.

The heat pipe may extend from the enclosure, whereby the condenser is outside of the enclosure. Alternatively, the heat pipe condenser may be within the enclosure.

According to a second aspect of the present invention there is provided a solar panel comprising an enclosure having top and bottom panels of plastics material, at least one heat pipe within and terminating in a condenser.

The preferred plastics material for the panels is polycarbonate. Such panels are relatively inexpensive to produce and are currently used as, for example, glazing material for conservatory roofs. The top and bottom panels are preferably of plastics material having at least two spaced skins connected by webs. More preferably the plastics panel have a layer intermediate the outer skins. Alternatively, plastics panels having top and bottom sheets either side of a honeycomb structure may be used.

In one preferred embodiment the solar panels of the invention will be based on a closed box having top and bottom panels of the plastics material sealed together along their edges by spacers. The spacers may be strips of the same plastics material as the panels. The components of the box are preferably joined together using a high temperature resistant adhesive.

In another preferred embodiment of the invention sides of the solar panel may be provided as a frame for the top and bottom panels. The frame preferably has internal shelves to receive and retain the top and bottom panels respectively. The frame may be of metal, such as aluminium or steel, or of plastics material, such as polyethylene. The top and bottom panels preferably have a gap between them of about 25mm to 35mm.

The heat pipes are preferably of a heat conductive material, such as copper, and may be relatively thin, having a diameter say of the order of about 8mm. The heat pipes are partly evacuated and contain a liquid or gas. The liquid may be water or a refrigerant gas may be used. The heat pipes are is preferably coloured black and are preferably supported above the bottom panel preferably at discrete locations. The heat pipes are preferably provided with one or more fins of conductive material. The fins are preferably provided by a strip of conductive material, on which the heat pipe is mounted. The strip of conductive material is of, for example, copper, brass foil or aluminium foil, and the conductive strip is preferably coloured black on its upper surface. The fins are preferably rotatable to suit the direction of the sun. Rotation may be manually or electrically driven, even computer controlled to, for example, follow the sun as it moves during the day.

The condenser of a heat pipe is preferably a chamber of greater diameter than the heat pipe. The condenser will typically be a tubular chamber.

The solar panel of the invention is preferably associated with a heat receiver preferably in the form of a manifold having locations for the heat pipe condensers. The manifold is preferably attachable to an end of the solar panel, such as by clips. The manifold may alternatively be provided on the inside of the solar panel. The locations for the condensers are preferably apertures in the manifold, into which the condensers can be sealingly secured. The manifold preferably has an inlet and an outlet for a medium, such as water, to be heated by transfer of heat from the heat pipe condenser through the manifold. The medium being heated is preferably pumped through the manifold. The manifold is preferably of insulated material or provided with heat insulation. A pump may be provided for driving water through the manifold.

Solar panels of the invention may be of any suitable dimensions, typically 1m by 1 m. The solar panels of the invention may be installed on a roof or may be incorporated into the roof structure in place of tiles, slates or other roofing material. It is envisaged that solar panels of the invention may be incorporated into a roof structure place of conventional roofing materials. Preferably the solar panels will be installed between roof trusses and preferably in multiples in side by side relationship. More preferably solar panels will be installed between roof trusses without individual top panels so that they are generally flush with the tops of the trusses. Then a top panel can be laid over the trusses to complete the solar panels. A similar arrangement may be possible with framed wall structures.

By virtue of preferred materials the solar panels of the invention may be lightweight and easy to handle.

This invention will now be further described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows schematically a solar panel according to the invention;

Figure 1 A shows a variation of the solar panel of Figure 1 ;

Figure 2 is a section through the solar panel of Figure 1 ;

Figure 3 shows internal detail of the solar panel of Figure 1 ;

Figure 4 shows schematically a manifold for use with the solar panel of Figure 1 ; and

Figure 5 shows a roof incorporating solar panels; and

Figure 6 is a section through the roof of Figure 5.

Referring to the accompanying drawings, a solar panel 10 comprises an enclosure 12 having a top panel 14 and a bottom panel 16 made from polycarbonate sheet. The polycarbonate sheet is of the type having spaced walls 18, 20, 22 connected by webs 24 forming elongate passages 26. This type of sheet is used as glazing material in conservatory roofs.

The two panels 14, 16 are spaced and parallel being connected along their edges by a rectangular frame 28. The frame is made from side and end members 30 and 32 respectively mitred at the corners and connected by screw blocks in the corners and screws through the screw blocks (not shown). The frame members 30, 32 have upper and lower spaced channels 34, 36 arranged internally of the frame and each channel receives an edge of one of the polycarbonate panels 14, 16. Thus, the frame 28 and the polycarbonate panels 14, 16 form an insulated enclosure. Along the bottom panel 16 inside the solar panel 10 are spaced parallel strips of copper 38 in the form of fins. Supported approximately 6mm above the bottom panel 16 by spaced supports 40 to avoid heat loss. Alternatively the heat pipes may be supported only at each end. The fins may be rotated to face the direction of the sun either selectively or automatically. The copper strips 38 are painted black on their upper surface. On top of each copper strip 38 is adhered a heat pipe 42 also of copper and painted black. The heat pipes 42 extend from the end of the solar panel and terminate with a condenser 44 in the form of an enlarged tube. The heat pipes 42 are preferably copper or brass tubes that are partially evacuated and contain an amount of a substance that evaporates in the partially evacuated tube. The liquid may be water or a refrigerant gas. Preferably a complete seal around the emerging ends of the pipes is not made to allow for expansion.

A manifold 50 is associated with the condenser 44. The manifold 50 has an inlet 52 and an outlet 54 for passage of water or other suitable medium to be heated. The manifold 50 has a series of apertures 56, into which the condensers 44 are inserted and sealingly retained. Typically around each aperture will be an outwardly screw threaded ring 58 and each condenser will have an internally threaded collar 60 to fit a ring and seal the condenser in the manifold. Thus, the medium will be heated directly by the condensers.

As shown in Figure 1 A, the manifold 50 may be internal of a solar panel 10'. The manifold has an inlet-70 and an outlet 72 for water to flow through the manifold. The heat pipes 38 locate in the manifold as in Figure 4.

Typically, a solar panel will be about 1m by 1m and contain nine heat pipes. The solar panels may be used individually or in an array. The solar panel will usually be located in a position to receive solar heat, such as on a roof. The solar panel may even be incorporated in the roof in place of tiles or slates.

The solar panel operates in the following manner. Air within the solar panel, which is an enclosed space, will be heated by infrared solar radiation and consequently the copper strips will conduct that heat to the heat tubes. The heat pipe temperature rises accordingly and the heat generated therein is removed via the condensers, to the manifold where the water passing through the manifold is heated. The heated water may be used directly or may be stored.

Referring to Figures 5 and 6 of the accompanying drawings, a roof 50 comprises trusses 52 normally supporting roof covering materials, such as tiles or slates on bearers across the rafters. Instead of such conventional roofing materials solar panels 54 are incorporated into the roof in the following manner.

The solar panels 54 are of the same type as shown in Figures 1 to 4 of the drawings expect that the top panel 14 of polycarbonate is left off for installation of the solar panels between the trusses preferably in multiples in side by side relationship. Then a top panel 56 of polycarbonate is laid over the multiple solar panels and secured the trusses.

Incorporating solar panels in a roof in this manner is unobtrusive and saves on the cost of conventional roofing materials. The part of the chosen for the solar panels will preferably be the optimum for receiving direct sunlight.

Claims

1. A solar panel constructed from plastics panels of the type having spaced walls joined by spaced parallel webs.

2. A solar panel as claimed in claim 1 further comprising at least one heat pipe within the panel terminating with a condenser, whereby heat within the panel can be transferred from the condenser to a heat receiver.

3. A solar panel comprising an enclosure having top and bottom panels of plastics material, at least one heat pipe within the enclosure and terminating with a condenser.

4. A solar panel as claimed in claim 2 or 3, wherein the condenser is outside the panel.

5. A solar panel as claimed in claim 2 or 3, wherein the condenser is within the panel.

6. A solar panel as claimed in any one of claims 1 to 5, wherein the plastics material for the panels is polycarbonate.

7. A solar panel as claimed in any one of claims 1 to 6, wherein the top and bottom panels are of plastics material having at least two spaced skins connected by webs.

8. A solar panel as claimed in claim 7, wherein the plastics panels have a layer intermediate the outer skins.

9. A solar panel as claimed in any one of claims 1 to 8, wherein the solar panels are based on a closed box having top and bottom panels of the plastics material sealed together along their edges by spacers.

10. A solar panel as claimed in claim 9, wherein the spacers are strips of the same plastics material as the panels.

11. A solar panel as claimed in claim 9 or 10, wherein the components of the box are joined together using a high temperature resistant adhesive.

12. A solar panel as claimed in any one of claims 1 to 8, wherein sides of the solar panel are provided as a frame for the top and bottom panels.

13. A solar panel as claimed in claim 12, wherein the frame has internal shelves to receive and retain the top and bottom panels respectively.

14. A solar panel as claimed in claim 12 or 13, wherein the frame is of metal or plastics material.

15. A solar panel as claimed in any one of claims 1 to 14, wherein the top and bottom panels have a gap between them of about 25mm up to 35mm.

16. A solar panel as claimed in any one of claims 2 to 15, wherein the heat pipes are of a heat conductive material.

17. A solar panel as claimed in any one of claims 2 to 16, wherein the heat pipes have a diameter of about 8mm.

18. A solar panel as claimed in claim 16 or 17, wherein the heat pipes are partially

^■ j evacuated and contain a liquid or gas.

19. A solar panel as claimed in claim 18, wherein the liquid is water.

20. A solar panel as claimed in claim 18, wherein the gas is a refrigerant gas.

21. A solar panel as claimed in any one of claims 2 to 20, wherein the heat pipes are coloured black.

22. A solar panel as claimed in any one of claims 2 to 21 , wherein the heat pipes are supported above the bottom panel.

23. A solar panel as claimed in claim 22, wherein the heat pipes are supported at discrete locations.

24. A solar panel as claimed in any one of claims 2 to 23, wherein the heat pipes have fins.

25. A solar panel as claimed in any one of claims 2 to 24, wherein the fins are strips of conductive material.

26. A solar panel as claimed in claim 25, wherein the strips of conductive material are of copper, brass or aluminium.

27. A solar panel as claimed in claim 25 or 26, wherein the conductive strip is coloured black on its upper surface.

28. A solar panel as claimed in any one of claims 23 to 27, wherein the fins are rotatable around their longitudinal axis.

29. A solar panel as claimed in any one of claims 2 to 28, wherein the condenser of a heat pipe is a chamber of greater diameter than the heat pipe.

30. A solar panel as claimed in claim 29, wherein the condenser is a tubular chamber.

31. A solar panel as claimed in any one of claims 2 to 30 associated with a heat receiver in the form of a manifold having locations for the heat pipe condensers.

32. A solar panel as claimed in claim 31 , wherein the locations for the condensers are apertures in the manifold, through which the condensers are sealingly inserted.

33. A solar panel as claimed in claim 31 or 32, wherein the manifold has an inlet and an outlet for a medium to be heated by transfer of heat from the heat pipe condensers through the manifold.

34. A solar panel as claimed in claim 33, wherein the manifold is outside the enclosure.

35. A solar panel as claimed in claimed 33, wherein the manifold is within the enclosure.

36. A solar panel as claimed in claim 33, 34, or 35 further comprising pump means for pumping the medium being heated through the manifold.

37. A solar panel substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

38. A roof incorporating one or more solar panels as claimed in any one of claims 1 to 37.

39. A roof as claimed in claim 38, wherein the solar panels are installed between roof trusses.

40. A roof as claimed in 39, wherein a top panel for the solar panels is applied over the trusses.

41. A roof substantially as hereinbefore described with reference to and as illustrated in Figures 5 and 6 of the accompanying drawings.