GB2031141A

GB2031141A - Solar panels

Info

Publication number: GB2031141A
Application number: GB7929579A
Authority: GB
Original assignee: OFFSHORE ENG Ltd
Current assignee: OFFSHORE ENG Ltd
Priority date: 1978-05-24
Filing date: 1979-08-24
Publication date: 1980-04-16
Also published as: GB2031141B

Abstract

A solar heating system comprising one or more units, each unit comprising a translucent or transparent panel or sheet (not shown) permeable to solar radiation, a support member for the panel or sheet, the support member and the panel or sheet jointly defining a conduit (6) for a heat exchange fluid, the conduit being tortuous and having an inlet (9) and an outlet (10) for the heat exchange fluid. The support member may be formed of a foamed polyurethane structure (2a) and an aluminium pressing (2b). The unit may form a roof tile. <IMAGE>

Description

SPECIFICATION A solar heating system The present invention relates to a solar heating system and, more particularly, to a system which can either form an integral part of, for example, the roof of a house or be a discrete structure.

Known solar heating systems generally include one or more translucent or transparent panels through which heat from the sun can pass, such heat being absorbed by a heat exchange fluid, usually water, located beneath the panel or panels. The water is usually contained in one or more pipe coils. Such systems have certain disadvantages. Firstly, the amount of water which can remain exposed to the heat of the sun at any one time is generally limited. Secondly, the length of time in which the water is exposed to the heat is also limited. Generally, therefore, known solar heating systems do not operate at optimum efficiency. Thirdly, such a system is generally installed above the tiles or slates of a conventional roof.This is obviously undesirable from an economic standpoint since both the slates or tiles and the solar heating system must be installed separately and, effectively, the roof space of a house is doubly covered.

Moreover, if any damage is caused to the slates or tiles and/or the solar heating system, repairs are both complicated and expensive. If attempts are made to incorporate the heating system in a conventional roof, further problems arise, the chief of which is the problem of sealing the roof in the region where the solar heating system abuts or overlaps the conventional tiles or slates. Finally, known solar heating systems are not, generally, aesthetically pleasing.

The present invention seeks to provide a solar heating system which operates as, or more, efficiently than known systems and which obviates, or at least reduces the extent of the aforementioned disadvantages.

According to the present invention, there is provided a solar heating system comprising one or more units, each unit comprising a transparent or translucent panel or sheet permeable to solar radiation, a support member for the panel or sheet, the support member and the panel or sheet jointly defining a conduit for a heat exchange fluid, which conduit is tortuous and has an inlet and an outlet for the heat exchange fluid.

Preferably, each support member is interconnectable to a unit adjacent thereto or to a conventional tile or slate.

Advantageously, the support member comprises an aluminium pressing fixedly mounted on a foamed base structure, the major pressed portions of the aluminium being spaced from the edges of the pressing. Desirably, the foamed base structure is made of polyurethane.

Advantageously, the major pressed portions of the aluminium define a channel for the heat exchange fluid, said channel, together with the translucent of transparent panel or sheet, defining the conduit first unpressed portions of the aluminium surrounding said channel and second unpressed portions forming ribs constituting the lateral edges of the channel, which ribs divide the channel into runs.

Alternatively, the support member comprises a tile or slate having a portion hollowed out from its upper face, said hollowed-out portion being spaced from the edges of the tile or slate, a plurality of ribs extending alternately from opposed edges of the portion and protruding into said hollowed-out portion defining the tortuous conduit for the heat exchange medium.

Further alternatively each support member comprises a support structure and an insert member, the structure and the insert member being so shaped that the insert member is insertable into, and is capable of being retained by, the support structure.

The invention will be further described, by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a first embodiment of a solar heating unit in accordance with the present invention.

Figure 2 is a longitudinal section through a pressing forming part of the unit shown in Fig. 1.

Figures 3a, b and carve sectional views through the pressing shown in Fig. 1 taken along the lines A-A, B-B and C-C respectively of Fig. 1.

Figure 4 is a perspective view of a second embodiment of the present invention.

Figure 5 is a longitudinal section through a third embodiment of the present invention, and Figure 6 is a transverse section through the end regions of laterally adjacent units of the type shown in Fig. 5.

In the embodiment shown in Fig. 1, there is shown a solar heating unit 1 in accordance with the present invention. The unit is, in this embodiment, in the form of a tile. The unit 1 comprises a support member 2, the support member 2 being formed of a foamed polyurethane structure 2a and an aluminium pressing 2b. The pressing 2b is located on the upper surface of the structure 2a and has bent-over lateral edge flanges which, when the pressing is located on the structure, lie adjacent the lateral edges of the structure. The upper surface of the structure 2a corresponds in shape to the lower surface of the aluminium pressing 2b. From Fig. 1, it will be observed that in the central portion of the pressing, a recess 3 extending from substantially one end edge of the tile to the other is provided. A plurality of ribs 4, 5 extend transversely across the recess 3.One rib 4, suitably spaced from the one longitudinal edge of the recess 3 extends fully across the recess such that a discrete recess 3a is formed. This discrete recess 3a is, in use located at the upper end of the tile and serves to receive the lipped lower end portion of an adjacent tile, which may be identical to the tile presently being described or may be a conventional roofing tile.

The remaining ribs 5 each extend from one or other lateral edge of the recess 3 to a point adjacent to the other lateral edge thereof. It will be appreciated, particularly by referring to Fig. 1, that this defines a tortuous channel 6 in the recess. On the rib 4, a boss 7 is formed which projects perpendicularly from the upper surface of the pressing 2b. As shown, this boss is in the form of a truncated, rectangular based, hollow pyramid. In its face 8 facing the recess 3a, an aperture 9 is formed, the purpose of which will be described hereinafter. The base of the pyramid overlaps the rib 4 so that the hollow interior of the pyramid communicates with the first, uppermost, run of the channel 6.Communicating with the lowermost run of the channel 6 is an outlet pipe 1 0. This outlet pipe 10 is dimensioned so as to fit, with suitable sealing means, into the aperture 9 formed in the next adjacent tile, it therefore being necessary for the pipe 10 to project beyond the end of the tile.

A separate transparent or translucent covering (not shown) is then fixedly mounted on the pressing 2b. This may be effected in a variety of ways such as by using an adhesive, by providing co-operating pegs and recesses in the covering and pressing or by making the covering a snap-fit onto the pressing. The covering may be a polypropylene film or sheet made by vacuum forming or injection moulding or may be a polyester resin moulding reinforced with any suitable material. The covering is substantially flat and therefore forms the upper surface of the channel 6.

Located at certain positions within the channel 6 are a plurality of baffles 11. These baffles are merely projections formed during the formation of the pressing 2b. The purpose of these baffles will be described hereinafter.

A heat sink material may be affixed to the underside of either the foamed structure 2a or the pressing 2bto retain and yield up, when desired, heat which is in excess of that required for immediate use. The tile structure described hereinbefore may, if desired, be coloured by, for example, dyeing and anodising the aluminium of the pressing or by utilising a tinted sheet or film of transparent or translucent material. Moreover, if desired, a two-ply sheet of transparent or translucent material may be employed, an air gap being defined between the two plies. This provides a double-glazing effect, whilst the structure 2a has been described as being made of a foamed polyurethane, it could be made of any other foamed material suitable for building use or of concrete.

The tile is manufactured by first pressing an aluminium sheet to the desired shape. The outlet pipe 10 is also formed from the aluminium sheet and is welded to the pressing such that water or any other heat exchange fluid flowing down the channel 6 can pass into the outlet pipe. The support structure is then moulded, in any suitable manner, so that the pressing forms the upper face of the moulding. The foamed material expands around the outlet pipe 10, and, when the material has set, has the outlet pipe firmly embedded therein. The translucent or transparent sheet or film is then affixed to the upper surface of the pressing 2b as described hereinbefore.

In use, a plurality of such tiles are laid endto-end from the apex of the roof of a house to the eaves. A heat exchange fluid, usually water, is passed into the aperture 9 of the tile nearest the apex of the roof. The water flows out through the base of the boss 7 in which the aperture 9 is formed and into the uppermost run of the channel 6. Since a roof is generally inclined, the water will flow, under gravity, along the tortuous path of the channel 6. When it reaches the lowermost run of the channel 6, it passes through the outlet pipe 10, the end of which terminates in the hollow interior of the boss 7 of the next lower tile.

The water then flows through this next lower tile and so on until it reaches the lowermost tile. As the water passes through the tile or tiles, it is exposed to the heat of the sun through the transparent or translucent covering. The water thus absorbs some of the heat and, when it has passed through the channel 6 of the lowermost tile, is led off into, for example, a domestic hot water system. Alternatively, the heated water may be pumped back to the apex of the roof so as to be passed through the same or a different run of tiles to absorb further heat. The baffles 11 are provided in the path of the water in the channels 6 so as to cause the water to be exposed to the heat of the sun for a longer period, thereby gaining more heat.

Although it has been stated that the ribs 5 extend transversely across the tile, it is desirable if they are either tapered towards their free ends or if the ribs themselves are angled slightly towards the lower end of the tile. This is to ensure, as far as possible, that no water can remain trapped in the channel 6. If the water does remain trapped in the channel 6 and the ambient temperature drops to below freezing point, such water will freeze and the expansion occurring due to the freezing may cause damage to the unit.

In the embodiment shown in Fig. 4, a conventional roof tile has been modified to form a solar heating unit, which unit is similar to the unit shown in Fig. 1. In such arrangement, a substantially rectangular portion of the upper face of the tile is hollowed out from the centre of the tile to form the recess 3.

However, when hollowing out the tile, portions projecting alternately from each lateral edge of the rectangle are not removed. The projecting portions effectively form a plurality of ribs 5. None of the ribs extends to the other lateral edge of the rectangle. By so doing, a tortuous path acting as a water channel is again provided.

The upper face of the rectangle is then covered by a film or sheet 1 2 of translucent or transparent material which is permeable to the rays of the sun. The fixing of the sheet can be effected in any desired manner, the simplest of which is merely to fold the sheet double and trapping the ends thereof in a suitable recess provided in the tile or between two adjacent tiles. Water inlets and outlets 10 are provided respectively in the opposed end faces of the tile. It is highly desirable that the inlets and outlets are provided in identical locations on each end face of the tile so that if two units are interconnected, the outlet from one unit leads directly into the inlet of the other unit.It will be quickly appreciated that such a system is advantageous in that the solar heating system may be made as large or small as is desired and the system can be simply connected to conventional tiles. In this embodiment and in the embodiment shown in Figs. 1 to 3, it is, of course, necessary to ensure that the end tiles of the system must be provided with suitable connections to a supply of water and to a receiver for the heated water respectively. The manufacture of such a modified tile is relatively simple in that the tiles are generally made by moulding and the hollowing out and the provision of water inlets and outlets can be effected at the moulding stage.It will be quickly seen that the major differences between the embodiment shown in Figs. 1 to 3 and that shown in Fig. 4 reside in the materials used for the construction of the tile and in the manner in which water is supplied to and removed from the unit.

In the embodiment shown in Figs. 5 and 6, a plurality of units each comprising a panel and associated support member are provided.

Each panel and each support member are identical. Each support member comprises a support structure 1 5 and an insert member 1 6. The structure 1 5 comprises an elongate base portion 1 7 and two end members 1 8 and 1 9 which end members are located, respectively one at each free end of the base portion.One end member 1 8 has a first portion 1 8a extending substantially at right angles to the base portion, a second portion 18bextending at an acute angle to the portion 1 boa so as to be directed generally towards an extension of the base portion, and a free end portion 18cextending at an obtuse angle to the second portion so as to be substantially co-planar with, but spaced apart from, the base portion.The other end member 1 9 together with the base portion 17, defines what is substantially a Z-shape in that it has a first portion 1 9a extending in substantially the same general direction as the first portion of the first end member but at an acute angle relative to the base portion, and a free end portion 19bextending substantially parallel to the base portion. The pupose of such end portions will be described hereinafter. It should, perhaps, be pointed out at this stage that the base portion 1 7 and the end members 1 8 or 1 9 may be made of, or incorporate, a material which acts as a heat sink, that is to say, a heat retaining material such as metal or a plastics material.

When viewed in cross-section, the base portion 1 7 and the end members 1 8 and 1 9 define an open-topped channel 20, one side wall 21 of the channel being inwardly inclined. Into this channel is force-fitted the insert member 1 6 which supports a sheet or panel 23 which is permeable to the rays of the sun. The insert member 16 has a shape which is generally complementary to that of the base portion 1 7 and the end members 1 8 and 1 9 of the support member, in that it has end portions which lie inwardly of and adjacent to the end portions of the support structure.The base portion of the insert member 1 6 lies substantially parallel to, but is spaced apart from, the base portion 1 7 of the support structure 1 5. The base portion 24 of the insert member is stepped adjacent one end region so as to overlie a part of the free end portion 1 9 b of the end member 1 9 of the support structure 1 5.

The insert member 1 6 is provided, at each of its ends, with means for retaining a panel in the form of a plate or sheet of translucent or transparent material permeable to the rays of the sun. This panel 23 has substantially the same surface area as the base 1 7 of the support structure. Between the panel 23 and the base 1 7 of the support structure a plurality of spacer members 25 are provided so as to define a plurality of interconnected channels. A heat exchange fluid, generally water, is caused to flow through these channels so as to follow a tortuous path.

The units are generally, but not essentially, employed in or on a sloping roof structure and are located substantially in line with one another from the apex of the roof to the eaves. Opposed end portions of adjacent support members overlap one another in such an arrangement. In the present embodiment the base portion 1 7 of one support member lies, parallel to, and in abutment with, the free end portion 18e of the end member 1 8 of the support member adjacent thereto.Similarly, the free end portion 1 8c of the first end member 1 8 overlaps a part of the outward facing surface of the insert member 1 6 of the adjacent unit, the second end member 1 9 of the adjacent support member being located between the middle portion of the Z and the free end portion of the first end portion 18 of the other support member.

Obviously, to allow the water to pass into and be discharged from the channels 20, an inlet and an outlet therefor must be provided.

The inlets and outlets, not shown, are so located that the water leaving one such unit is passed directly into the adjacent unit. This is effected by fitting each support member 15, along at least one of its lateral edges, into a retaining member 26. Such retaining member 26 is substantially channel-shaped and extends from the apex of the roof to the eaves.

The support members are force-fitted into these channels but a gap is left between the lateral edge of the support members and the base of the channel so as to define a path for the water, which path extends generally downwardly from the apex of the roof at an angle corresponding to the inclination of the roof. In this gap, substantially horizontally extending spaces are provided for diverting the water into each unit.

Each support member 1 5 carries a layer of thermal insulating material 27 which is affixed to the face of the base portion of the support structure and which extends to the end of the free end portion 18 c of the first end member 18. By so doing, an arrangement is provided which permits the roof space of the building to be insulated from the solar heating system.

Adjacent units may be interconnected by slate nails 28, which nails pass through the free end portion 18cof the first end member 18 of one unit and the base portion 1 7 of the support member 1 5 of the unit adjacent thereto.

Various modifications of such a system are, of course, possible. By locating the sheet or film 1 2 between the base portion 24 of the insert member and the base portion 1 7 of the support structure, an air gap can be defined above the tortuous water channel. This provides a double glazing effect. It will be realised that, in such a case, at least the base portion of the insert member must be permeable to the rays of the sun. Moreover, if it is so desired, two parallel rows of units may be provided by providing a retaining member which is double channel-shaped, the open face of the two channels facing away from one another.

Such an arrangement is rather more aesthetically pleasing than some known systems since there is a slight spacing between the insert members of adjacent units. By so doing, the roof of a house does not present the appearance of a single sheet of material permeable to the rays of the sun.

In all of thewabove-described systems, more water can be maintained exposed to the rays of the sun for a longer period of time than has hitherto been possible.

Various minor modifications can be made to the system of the present invention without departing from the scope thereof. Thus, a pump may be utilised to supply the water to the system. The pump may be controlled by a heat sensor switch. In such a case, if the heat sensor switch causes the pump to be inactivated, the water may drain from the roof into a storage receiver until re-heating thereof is required. Additionally, the panels permeable to the rays of the sun may be made in lenticular form to improve the heating efficiency. Such systems can be installed in any suitable location as long as the system is inclined relative to the horizontal.

Claims

1. A solar heating system comprising one or more units, each unit comprising a translucent or transparent panel or sheet permeable to solar radiation, a support member for the panel or sheet, the support member and the panel or sheet jointly defining a conduit for a heat exchange fluid, the conduit being tortuous and having an inlet and an outlet for the heat exchange fluid.

2. A system as claimed in claim 1 wherein each support member is interconnectable to a unit adjacent thereto or to a conventional tile or slate.

3. A system as claimed in claim 1 or 2 wherein the inlet and outlet for the heat exchange medium are provided in opposed end regions of said channel.

4. A system as claimed in claim 1, 2 or 3 wherein the support member comprises an aluminium pressing fixedly mounted on a foamed base structure, the major pressed portions of the aluminium being spaced from the edges of the pressing.

5. A system as claimed in claim 4 wherein the foamed base structure is made of concrete.

6. A system as claimed in claim 4 wherein the foamed base structure is a polyurethane foam.

7. A system as claimed in any one of claims 4 to 6 wherein the major pressed portions of the aluminium define a channel for the heat exchange fluid, said channel, together with the translucent or transparent panel or sheet, defining the conduit, first unpressed portions of the aluminium surrounding said channel and second unpressed portions forming ribs constituting the lateral edges of the channel, which ribs divide the channel into runs.

8. A system as claimed in claim 7 wherein the outlet comprises a pipe communicating with one end run of the channel, which pipe is fixedly connected to the pressing and projects from an end face of the support member.

9. A system as claimed in claim 8 wherein the inlet comprises a hollow projection communicating with the other end run of the channel, said projection carrying means for receiving the projecting end of an outlet pipe provided on a like adjacent unit.

10. A system as claimed in claim 9 wherein said projection is in the form of an open rectangular based, hollow truncated pyramid, which pyramid is mounted on one of the ribs such that, in use, heat exchange fluid entering the projection through said receiving means drops through said open base into said other end run of the channel.

11. A system as claimed in any one of claims 6 to 10 further comprising third unpressed portions of the aluminium, said third unpressed portions projecting upwardly from the base of said channel, said projections forming baffles located in the path of said heat exchange fluid.

1 2. A system as claimed in any one of claims 1 to 3 wherein the support member comprises a tile or slate having a portion hollowed out from its upper face, said hollowed-out portion being spaced from the edges of the tile or slate, a plurality of ribs extending alternately from opposed edges of the portion and protruding into said hollowedout portion defining the toruous conduit for the heat exchange medium.

1 3. A system as claimed in any one of claims 6 to 1 2 wherein each rib tapers along its length towards its free end.

14. A system as claimed in any one of claims 6 to 13, wherein each rib is so shaped that, in use, the heat exchange fluid flowing in the channel always has a component of movement in a direction from the inlet to the outlet.

1 5. A system as claimed in any one of claims 1 to 3 wherein each support member comprises a support structure and an insert member, the structure and the insert member being so shaped that the insert member is insertable into, and is capable of being retained by, the support structure.

1 6. A system as claimed in claim 1 5 wherein the insert member carries means for retaining the translucent or transparent panel or sheet.

1 7. A system as claimed in claim 1 6 wherein a retaining member is provided for retaining a plurality of units in alignment with one another, the retaining member being provided with means for diverting the heat exchange fluid successively through a plurality of units.

1 8. A system as claimed in any preceding claim further including a thermal insulator for insulating the unit from a structure on which it is adapted to be mounted.

1 9. A system as claimed in any preceding claim further including heat storage means mounted on or affixed to each unit for storing heat collected by said heat exchange fluid.

20. A system as claimed in any preceding claim wherein the transparent or translucent sheet or film lies flush with the upper surface of the support member.

21. A system as claimed in any preceding claim wherein two layers of transparent or translucent sheet or film are provided, an air gap being defined between said layers.

22. A solar heating system constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 3, Fig. 4 or Figs. 5 and 6 of the accompanying drawings.