GB2045423A

GB2045423A - Solar energy collector

Info

Publication number: GB2045423A
Application number: GB8004630A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-03-22
Filing date: 1980-02-12
Publication date: 1980-10-29
Also published as: IT8020823A0; YU78180A; PT70975A; FR2452073A1; IT1131028B; AU5559380A; GB2045423B; GR67213B

Abstract

A solar energy collector comprises two substantially parallel walls 1, 2, particularly of plastics material, connected edgewise and between which are formed at least one inlet channel 14 and one outlet channel 15, and a plurality of connection channels 16 between the inlet and outlet channels for a heat exchange fluid. At least one wall has on its side facing the other wall a plurality of projections 7, 8 and/or ribs 3-6, 17, 18 for the formation of the connection channels 16 and the other wall is connected at least regionally with the elevated surfaces of the projections 7, 8 and/or ribs 3-6, 17, 18. <IMAGE>

Description

SPECIFICATION Solar energy collector This invention relates to a collector for the absorption of solar energy comprising two substantially parallel walls, particularly of plastics material, which are connected edgewise and between which are formed at least one inlet channel and one outlet channel as well as a plurality of connection channels between the inlet and outlet channels for the heat-exchange fluid.

Such collectors are arranged on surfaces exposed to solar radiation, e.g. the roof surfaces of houses, and connected to a means for circulating the heat-exchange fluid. The circulation means can, inter alia, have a heat-exchanger and if desired a pump.

Known collectors use a system of tubes, particularly glass tubes as flow channels for the heat-exchange fluid exposed to the solar radiation.

Such systems are relatively expensive in production, assembly and maintenance, and furthermore the disadvantage that the tubes of the collector always cover only a part of the irradiated surfaces so that additional measures are required in order to reflect the solar radiation falling on the irradiated surfaces on to the tubes.

In order to remove this disadvantage it has already been proposed to design a collector at first of laminar form, which is constructed from relatively economical materials, particularly plastics materials. For this purpose an interlayer permeable to the heat-exchange fluid may be arranged between the walls, which for example can be formed from a flattened tube of foil. This interlayer can, for example, consist of an openpore foamed material or a fleece. The interlayer not only produces a desired spacing between the two walls but also defines a desired flow resistance for the fluid, which correspondingly can flow with a substantially predetermined rate of flow through the collector. In such a collector the heat absorbed is given off over the entire surface directly to the heat-exchange fluid.Accordingly the conditions as a whole can be so adjusted that the temperature of the absorption surface is only slightly higher than the temperature of the heatexchange fluid itself. Since the known collector also has only a low weight, in arranging it on a roof of a house the roof construction is only immaterially stressed. Even so such a collector is still capable of improvement.

An object of this invention is to provide a solar energy collector relatively simple to produce and construct.

Accordingly this invention provides a solar energy collector comprising two substantially parallel walls connected edgewise and between which are formed at least one inlet channel and one outlet channel, wherein a plurality of connection channels between the inlet channel and the outlet channel for a heat exchange fluid, is formed by profiling of at least one wall on its side facing the other wall.

Preferably, at least one wall on its side facing the other wall has a plurality of projections or ribs for the formation of connection channels and the other wall is connected at least regionally with the elevated surfaces of the projections and/or ribs.

In the collector according to the invention because of the profiling of one or both walls an inter-layer, permeable to the heat exchange fluid, can be completely dispensed within the arrangement. Accordingly the production and also the construction of the collector is simplified.

Basically it is sufficient if one of the two walls is profiled on its side facing the other wall. This can be achieved, for example, in that the wall is extruded and is provided with profiles from the heat of extrusion through rolling, pressing or the like. Obviously also both walls can be thus profiled or indeed in any other way.

It is recommended, for simplicity of production and fabrication of the walls, to arrange the ribs and/or projections uniformly.

The possibility does exist of profiling the outer sides of the walls, for example, when foils forming the walls are rolled between rollers with profiles and counter-profiles. Then, however, dust pockets can form on the outer sides of the walls. An embodiment is therefore preferred in which the outer sides of the wall are smooth. This ensures at the same time that the projections and/or ribs of the walls consist of complete material and are integral with the wall.

If both walls are profiled various possibilities exist for the connection between both walls. In one embodiment, in which the base surface of the projections and/or ribs is smaller than the surfaces of the zones lying between the projections and/or ribs, the possibility exists to connect the elevated surfaces of the projections and/or ribs of the one wall with those zones (between the projections and/or ribs) leaving connection channels. There is accordingly obtained a very flat collector, which nevertheless has a plurality of connection channels for the heat-exchange fluid.

In another embodiment the two walls can be connected with one another through the elevated surfaces of their projections and ribs. The possibility then exists, for example, to guide the connection channels through the arrangement and formation of the projections and/or ribs, so that they are tracked not only in a plane substantially parallel to the other of the walls but also out of this plane and again back into it.

A preferred embodiment of the invention is accordingly characterised in that the two walls show a plurality of ribs parallel to one another. The two walls can be connected with each other in such a way that their ribs form an angle especially an angle of about 900. Such a collector has advantages not only in production technique, since the ribs of the walls or at least of one wall can be produced if desired readily by extrusion of the wall. The formation of the ribs through rolling or the like likewise presents no difficulties.With reference to function such a collector has the advantage that the heat-exchange fluid must pass in its course from inlet channel to outlet channel a plurality of obstructions and must accordingly flow alternately from the region of one wall to the region of the other, which ensures not only a good heat absorption but also the formation of turbulence, which promotes heat-exchange within the heat-exchange fluid. At the same time through the arrangement and formation of the ribs the flow resistance for the heat-exchange fluid is permitted to lie in favourable zones.

An embodiment of simple production technique is accordingly characterised in that the other wall is a single plate or foil and that ths ribs have slot passages for the heat-exchange fluid. For construction of the collector according to the invention it suffices that one wall is profiled on one side. The other wall can be formed from a single smooth plate or foil, which is laid on the profiled side and is connected with this.

Accordingly production and construction of the collector are essentially simplified without its operability being adversely influenced. As before connection channels are also formed from the profilings of an inlet channel and an outlet channel between said channels. When the profilings are of rib-like construction slot passages for the heatexchange fluid are arranged, which can thus flow from-the inlet channel to the outlet channel.

Preferably the size of the slot passages and/or the spacings of the projections is different, and accordingly no smooth through flow channels are formed but flow restrictions which develop turbulence and accordingly provide for a good intermixing of the heat-exchange fluid in the region of the collector. This effect can be further improved when the slot passages and/or the projections are displaced relative to one another in the flow direction.

In one preferred embodiment of the invention the ribs extend substantially parallel to the inlet channel or to the outlet channel. The possibility also exists, however, of so arranging the ribs that they extend inclined to the inlet channel or to the outlet channel.

In all cases the desired flow condition is defined by the profiling of the profiled side of the one wall.

Because of this it is not necessary in putting together and connecting the two walls to align these walls exactly.

The inlet channel and the outlet channel can also be defined by ribs wherein the spacing of two ribs adjacent the edges for the formation of the inlet channel or the outlet channel is greater than the spacing of the remaining ribs.

For reasons of stability the edgewise ribs can have a greater breadth than the remaining ribs.

This is particularly valid when it is a question of ribs defining the inlet channel and/or the outlet channel.

The ribs preferably have a trapezoidal crosssection. This is favourable for the production and also for the connection of the two walls, which is generally effected by pressing together under pressure and heat the surface zones to be connected: The trapezoidal shape acts favourably therein.

According to a preferred embodiment of the invention each wall should have two ribs for the formation of the inlet channel and outlet channel, wherein the ribs arranged at an angle to these channels terminate at the channels. Then the two walls can be united so that each wall defines one part, particularly the half of an inlet channel and outlet channel. In the region lying therebetween the ribs of the one and other wall define the connection channels.

It may be suitable to produce the side of the collector receiving radiation from a radiationpermeable material and a radiation-impermeable material on the other side, in order thereby to enhance the absorption capacity. Thus the plastics material of at least one wall can have an admixture of bitumen. In this way the properties of the plastics material can be approximated to those of a black body, which only absorbs radiation but virtually reflects no radiation. A preferred plastics material is a copolymer of ethylene and propylene.

Other materials may, however be used, provided they possess suitable properties, e.g. a comparatively small heat conductivity.

When the collector according to the invention may form directly the roofing or at least a part of the roofing of a building it can have an insulating layer on its radiation-free side. For the rest an adhesive layer can be present on the radiation-free side or on the insulating layer for attachment, e.g.

to a roof.

A collector of the kind described can be produced in a simple way in that the walls with their projections and ribs can be rolled from an (extruded) plastics material and then combined under the use of pressure and heat. In production in hot regions the certainty however must be given that in the production of the collector the spacing between the profilings of the two walls remains ensured, and accordingly a uniformly stronger fluid film can flow between the two walls. In order to attain this it may be advantageous, to roll the two walls on a heated-fluid permeable mat. This mat functions during the production as heat carrier, whose specific heat is sufficient to attain a connection of the two walls to be joined by thermal influence. In the completed collector the mat forms an artificial joint face, which contributes to moderation of the flow of the fluid serving as heat-exchange medium flowing through the collector.

The mat may be made of a coarse-meshed fabric of metal-, plastics-, or ceramic fibres.

In order to facilitate and simplify the laying of the collector, e.g. on a roof it is proposed to connect the walls to each other laterally displaced to one another for the formation of a single-layer edge strip. That has the advantage that with several collector sheets laid besides each other their single-layer edge strips can be arranged overlapping and then can be connected with each other. For example it is possible to weld the single layer edge strips together or to fasten them through nailing if desired with the assistance of clamping strips on a roof surface.

In order to improve a collector of the described type in relation to the assembly, i.e. particularly in setting the collector on a roof or the like, the connected walls can form an extended sheet with through-going inlet channel and outlet channel, wherein cross-pieces free from flow-through are arranged in the sheet with mutual spacing, which extend between the inlet channel and the outlet channel.

Such a collector can be produced continuously in the form of a more or less long sheet. Wherein the sheet, if desired rolled into a roll can be stored and transported. At the place of assembly segments of the desired lengths are cut from this sheet and particularly in the region of the crosspieces are so cut through that, in the central region of the sheet, which is penetrated by the connection channels for the heat-exchange fluid, a closing-off is present at the end of the segment concerned. The inlet channel and outlet channel however remain open, which however can be closed without difficulty or can be attached to extensiori conduits. The separation of the sheet segments can be carried out with a knife of other tool. The open inlet- or outlet channels can if desired be welded together in known manner.The separation surfaces present after the cutting off a determined sheet segment or the remainder of cross-pieces can if desired be adapted for the connection of extending collector segments, e.g.

in overlapping or other arrangement. For the rest the remaining residues of cross-pieces can be used for connection of the relevant collector segments to the roof.

According to the desired purpose of use and the requirements resulting therefrom the cross-pieces can be arranged with regular or irregular spacings.

In each case the dimension of the cross-piece in the longitudinal direction of the sheet should be a multiple of the corresponding dimension of a connection channel, so that a collector segment of desired length can be separated from the sheet without difficulty.

According to a preferred embodiment the sheet in the region of the cross-pieces has the same thickness as in the remaining regions. That indicates that in one embodiment, in which only one wall is profiled and the other wall is laid on the elevated surfaces of the profilings and connected therewith, the cross-pieces also are formed on the profiled wall and at a height which corresponds to the height of the rest of the profilings.

This invention will now be further described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a plan view of a wall of a collector element; Figure 2 a section in the direction Il-Il through a collector element from two connected walls; Figure 3 is a perspective view of a collector element with partially separated walls; Figure 4 shows another embodiment of a collector with partially separated walls; Figure 5 shows schematically a device for the production of a collector from two walls and a mat; Figure 6 a part cross-section through several collector sheets laid alongside one another, which form a roofing; Figure 7 a plan view of the profiled side of a profiled wall of a portion of a sheet-like collector for the absorption of'solar energy; and Figure 8 a part-section in the longitudinal direction of the sheet-like portion according to Figure 7.

The collector element illustrated in Figures 1 and 2 consists of two walls 1, 2, of plastics material, connected with one another. The walls 1, 2 have on their sides facing the other respective wall, between edgewise ribs 3, 4 or 5, 6, a plurality of uniformly arranged projections 7 or 8.

The projections 7 or 8 have a substantially quadratic base surface and a substantially trapezoidal cross-section. The base surface between the projections 7 or 8 is smaller than the remaining surface between these projections 7 or 8, so that after the joining of the two walls 1, 2, the elevated surfaces of the projections 7 or 8, lie against the projection-free zones 9 of the other walls, and these are welded by use of pressure and heat with these zones 9. In addition the ribs 3 and 4 of the wall 1 are also welded with the associated ribs 5 or 6 of the other wall 2.It will be understood, that the edges 10 or 11 of the two walls 1 or 2 are also welded fluid-tight with one another, wherein in the region of the edge 11, between the ribs 3, 5 or 6, 4 and the neighbouring series of the projections 7, openings remain through which the heat-exchange fluid can enter in the collector element in the direction of the arrow 12 and leave the collector element in the direction of the arrow 13.

It is seen that between the welded ribs 3 and 5 or 6 and 4 as well as the neighbouring series of projections 7 and 8 there is formed an inlet channel connected to the opening 12, as well as an outlet channel connected to the opening 13.

Between the inlet channel 14 and the outlet channel 1 5, because of the arrangement of the projections 7 or 8 a plurality of connection channels 16 are formed, through which the heatexchange fluid can flow. It is seen that these connection channels 1 6 are also formed, when the projections 7 or 8 extending transversely to the ribs 3-6 are joined to transverse ribs.

In the embodiment illustrated in Figure 3 the lower, in the figure, wall 1 has in addition to the edgewise ribs 3 and 4 a plurality of longitudinal ribs 17 extending parallel to ribs 3 and 4. The distance of the edgewise ribs 3 or 4 from the next adjacent longitudinal ribs 1 7 is greater than the distance between the remaining ribs 17, so that the inlet channel 14 and the outlet channel 1 5 are formed between the edgewise ribs 3, 4 and the relevant neighbouring longitudinal ribs 17. For reasons of rigidity the edgewise ribs 3, 4 and the relevant neighbouring longitudinal ribs 1 7 are made somewhat broader than the other longitudinal ribs 1 7. All ribs have a substantially trapezoidal cross-section.The upper wall 2 in turn has the edgewise ribs 5 and 6 adjoining which, extending in the longitudinal direction of the wall 2 are rib-free zones for the formation of the inlet channel 14 or outlet channel 15. A plurality of transverse ribs 1 8 extend between these rib-free zones, the profile and strength of which corresponds substantially with those of the longitudinal ribs 17.

After joining the two walls by pressure and heat, the edgewise ribs 3 and 5 or 4 and 6 respectively are welded together. In addition the elevated surfaces of the longitudinal ribs 1 7 and the transverse ribs 1 8 are zonally welded together.

It will be understood that the edges 10 and 11 are also welded together fluid-tight, wherein in the region of the edge 11 openings remain to the inlet channel 14 and the outlet channel 1 5, through which the heat-exchange fluid can enter the inlet channel 14 in the direction of the arrow 12 and leave outlet channel 1 5 in the direction of the arrow 1 3. Longitudinal ribs 1 7 and transverse ribs 1 8 form a plurality of connecting channels between the inlet channel 14 and the outlet channel 15, wherein the connection channels run alternately in the region of the lower wall 1 and the upper wall 2, so that a turbulent flow results in the passage of the heat-exchange medium, which promotes the transfer of heat within the heat exchange medium. Preferably an ethylene propylene co-polymer is used as the material for the walls, wherein the material of at least one wall can have an admixture of bitumen, so that these walls obtain properties which approximate to those of a black body.

In the embodiment illustrated in Figure 4 the lower wall 1 has, in addition to the edgewise ribs 3 and 4, a plurality of longitudinal ribs 1 7 extending parallel to these ribs 3 and 4. The distance of the edgewise ribs 3 or 4 from the relevant next adjacent longitudinal rib is greater than the distance between the other longitudinal ribs 17, so that an inlet channel 14 and an outlet channel 1 5 are formed between the edgewise ribs 3, 4 and the relevant adjacent longitudinal rib 1 7.

For reasons of stability the edgewise ribs 3, 4 and the relevant adjacent ribs 1 7 are made somewhat broader than the remaining longitudinal ribs. All ribs have a substantially trapezoidal cross-section.

In the illustrated embodiment the longitudinal ribs 1 7 extend substantially parallel to the inlet channel 14 or the outlet channel 1 5. In other embodiments, not shown, the ribs 17 can however also extend at an angle to the inlet channel 14 or the outlet channel 15. All longitudinal ribs 1 7 are interrupted at intervals by slots 40 or 41 for passage of the heat-exchange fluid. It will be noted that the size of the slot passages 40 or 41 differs. Each second longitudinal rib 1 7 has either larger slot passages 40 or smaller slot passages 41. In the embodiment illustrated each longitudinal rib 1 7 has either larger slot passages 40 or small slot passages 41. Adjacent longitudinal ribs have slot passages of unequal size.For the rest, the slot passages 40, 41 are displaced laterally in the direction of flow, which corresponds substantially to an orthologonal connection between the inlet channel 14 and the outlet channel 1 5. Other slot arrangements, not illustrated, are of course possible. For example the rib segments can be made longer than those illustrated, and/or the ribs can be arranged inclined to the inlet channel 14 or the outlet channel 1 5.

The collector has an upper wall 2 which in the embodiment illustrated is a single foil with smooth sides.

The two walls 1, 2 are united by pressure and heat, wherein the edgewise ribs 3, 4 are connected with the associated edge portions 5, 6 of the wall 2. The interlying zone of the wall 2 is connected with the upper side of the profiles, i.e.

in the embodiment illustrated the longitudinal ribs 1 7. In the completed collector there thus results not only the inlet channel 14 and the outlet channel 1 5 but also between the two a plurality of connection channels which are formed on the one hand by the slot passages 40 and 41 and on the other hand by the grooves existing between the ribs. The heat-exchange medium entering the inlet channel 14 in the direction of the arrow 12 and leaving by the outlet channel 1 5 in the direction of the arrow 1 3 therefore flows through these connection channels with a turbulent flow which promotes the heat transfer within the heat exchange medium.

An ethylene propylene copolymer is preferably used as material for the walls 1, 2, wherein the material of at least one wall can have an admixture of bitumen, so that this wall receives the properties which approximate to a black body.

In one practical embodiment the breadth of the collector is approximately 11 50 mm. The breadth of the connection channels between the longitudinal ribs 17, 18 lies between 2 and 3 mm, whilst the height of the connection channels is approximately 1.5 to 2 mm. The ratio of the length of individual segments of the longitudinal ribs 17 to that of the inter-disposed slot passages 40 or 41 lies somewhat between 4:1 and 5.1.

It has not been shown in these drawings that in the use of the collector element as roofing an insulating layer can be arranged on the radiation free side and that the radiation-free side or the insulating layer has an adhesive layer for attaching to a roof.

Basically the above described embodiment of a collector can be produced in that the walls 1, 2 with their projections 7, 8, or their ribs 3 to 6 or 17, 1 8 are produced in that the extruded plastics material is rolled between profiled rollers.

Subsequently the walls 1, 2 are united into a collector with the use of pressure and heat either in rollers or between presses. This method of production can give rise to difficulties particularly in hot regions since the heated and soft plastics material is easily deformed so that the guiding channels formed between the two walls 1, 2, when these latter are connected may be partially or completely closed by the deformation of the material.

It is shown in Figure 5 how these difficulties can be overcome. The two profiled walls 1,2 are fed to a driven pair of pressure rollers 20, 21. At the same time a mat 22 is introduced with walls 1,2 into the connecting gap. The mat 22 is led previously to a heating device, which in the illustrated example, consists of heating radiators 23, 24. The mat consists of a relatively widemeshed fabric of metallic-, plastics or ceramic fibres and serves as heat-carrier, which gives off its heat in the roller gap to the surfaces of the profiles to be connected. The heated surfaces weld with the mat 22 so that this is integrated.into the collector.

Figure 6 explains how the collector sheets can be formed individually, in order to facilitate an even setting, of several collector sheets alongside one another on a roof as a coherent cover. It is seen that the two walls 1,2 are arranged placed laterally, so that the single layer edge strips 30, 31 are formed, which are arranged overlapping with corresponding edge strips 31 or 30 of adjacent collector sheets, so that a double layer results in the overlapping zone. The overlying edge strips 30, 31 can then be welded to one another. It is also possible however to fasten the edge strips 30, 31 directly to the roof, e.g. through nailing, wherein if desired clamping strips can be laid on the edge strips 30, 31.

The collector, shown in Figures 7 and 8, for the absorption of solar energy consists of two walls 1 and 2, of plastics material, wherein the lower wall 1 is profiled on one side, whilst the other, upper wall 2 is smooth on both sides. The two walls 1,2 are, for example, extruded wherein the wall 1 is subsequently profiled through rollers, presses or the like.

The wall 1 has on its profiled side two edgewise ribs 3, 4 and profiles 17 between them.

Profile-free zones remain between these profiles 17 and ribs 3 or 4, which zones define an inlet channel 1 4 and an outlet channel 15, through which the heat exchange fluid can flow in the longitudinal direction of the illustrated collector segment. The profiling 1 7 not shown in detail but indicated only by shading consist for example of a plurality of projections or ribs arranged tightly alongside one another which define between them connection channels, through which the heat exchange fluid can flow from inlet channel 1 4 to outlet channel 1 5.

The profiling 1 7 is arranged segmentally and interrupted by cross-pieces 35 spacedly arranged.

The cross-pieces 35 are, in the embodiment illustrated, arranged with uniform spacing. The spacings may however also be irregular. The cross-pieces 35 consist of solid material and have the same height as the profilings 1 7 or the edgewise ribs 3 and 4. For the rest, the crosspieces 35 extend between the inelt channel 14 and the outlet channel 1 5.

For the formation of a sheet-like collector the two walls 1,2 are so guided on to each other, that the smooth wall 2 fiefs with one sfde on the elevated surfaces of the profiles 3, 4, 1 7, 35 of the other profiled wall 1. The sheet-like collector so formed has between the inlet channel 14 and the outlet channel 1 5 a plurality of connection channels, defined by the profilings 1 7. The crosspieces 35 define the free through-flow zones.

The sheet-like collector so produced can, for example be rolled up and transported to a building site. The desired length of a collector segment is there cut off from the sheet. The segment of desired length is separated in the region of a cross-piece 35 as shown for example by dotted line 36. This section cutting takes place in the region of a cross-piece 35 so that at the end of a separated segment only an inlet channel 14 and an outlet channel 1 5 are open, which can however if required be closed in a known manner.

Claims

1. A solar energy collector comprising two substantially parallel walls connected edgewise and between which are formed at least one inlet channel and one outlet channel, where a.plurality of connection channels between the inlet channel and the outlet channel for a heat exchange fluid, is formed by profiling of at least one wall on its side facing the other wall.

2. A collector as claimed in claim 1 wherein the profiling is in the form of projections anql/or ribs and connection between walls isat least regionally with the elevated surfaces of the projections and/or ribs.

3. A collector as claimed in claim 1 or 2, wherein the projections and/or ribs are uniformly arranged.

4. A collector as claimed in claim 1,2 or 3 wherein the outersides of the walls are smooth.

5. A collector as claimed in any one of claims 1 to 4 wherein both walls are profiled.

6. A collector as claimed in any of claims 1 to 5 wherein the base surface area of the projections and/or ribs is smaller than the surface area of the zone lying between the projections and/or ribs and the elevated surfaces of the projections and/or ribs of the one wall are connected so as to leave connection channels with these zones of the other wall.

7. A collector as claimed in any one of claims 1 to 5, wherein the walls are connected with one another through the elevated surfaces of their projections and/or ribs.

8. A collector as claimed in any one of claims 1 to 7 wherein the profiling comprises parallel ribs.

9. A collector as claimed in claim 8 wherein the two walls are joined to each other in such a way that their sets of ribs are at an angle to each other.

10. A collector as claimed in claim 9 wherein the angle between the sets of ribs of the two walls is 900.

11. A collector as claimed in any one of claims 1 to 4 wherein one wall is unprofiled and the ribs of the other wall are interrupted to provide passages for the heat exchange fluid.

12. A collector as claimed in claim 11, wherein the size of the passages and/or the spacing of the projections is different.

13. A collector as claimed in claim 11 or 12, wherein the passages and/or the projections are arranged displaced to one another in the direction of flow.

14. A collector as claimed in claim 11, 12 or 13, wherein the ribs extend substantially parallel to the inlet channel or to the outlet channel.

15. A collector as claimed in claim 11, 12 or 13, wherein the ribs extend at an angle to the inlet channel or to the outlet channel.

1 6. A collector as claimed in any one of claims 1 to 15, wherein the spacing of two ribs arranged near to the edge is greater than the spacing of the remaining ribs for the formation of the inlet channel and/or the outlet channel.

1 7. A collector as claimed in any one of claims 1 to 16, wherein the edge ribs are wider than the remaining ribs.

18. A collector as claimed in any one of claims 1 to 17, wherein ribs are trapezoidal in crosssection.

19. A collector as claimed in any one of claims 1 to 18, wherein the ribs arranged at an angle to the inlet channel or the outlet channel terminate at these channels.

20. A collector as claimed in any one of claims 1 to 19, wherein one wall is of radiation permeable material and the other wall is of dark colour.

21. A collector as claimed in any one of claims 1 to 20, wherein the walls are made of plastics material.

22. A collector as claimed in claim 21, wherein the plastics material of at least one wall has an admixture of bitumen.

23. A collector as claimed in claims 21 or 22 wherein the plastics material is an ethylene/propylene co-polymer.

24. A collector as claimed in any one of claims 1 to 23 having an insulation layer on the radiationfree side.

25. A collector as claimed in any one of claims 1 to 24 wherein the radiation-free side or the insulating layer has an adhesive layer for fixing the collector to a surface.

26. A collector as claimed in any one of claims 1 to 25 having a fluid-permeable mat of coarsemeshed fabric of metal-, plastics- or ceramic fibres arranged between and connected with the walls.

27. A collector as claimed in any one of claims 1 to 26 wherein the walls are connected laterally displaced to one another to provide single-layer edge-strips.

28. A collector as claimed in any one of claims 1 to 27, wherein the connected walls form a longitudinally extending sheet with longitudinally extending inlet and outlet channels and spaced cross-pieces free from flow-through are arranged in the sheet and which extend between the inlet channel and the outlet channel.

29. A collector as claimed in claim 28, wherein the cross-pieces are uniformly spaced.

30. A collector as claimed in claim 28, wherein the cross-pieces are irregularly spaced.

31. A collector as claimed in claim 28,29 or 30, wherein the dimension of the cross-pieces in the longitudinal direction of the sheet is a multiple of the corresponding dimension of a connection channel.

32. A collector as claimed in any one of claims 28 to 31, wherein the sheet in the region of the cross-pieces has the same thickness as in the remaining region.

33. A process for the production of a collector according to any one of claims 1 to 32, characterised in that the walls with their profiling are rolled from a plastics material and then connected with one another by the use of pressure and heat.

34. A process for the production of a collector according to any one claims 26 to 32 wherein the two walls are rolled on to the heated fluidpermeable mat.

35. A solar energy collector substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.

36. A process for the production of a solar energy collector substantially as hereinbefore described with reference to any of the accompanying drawings.