GB2278618A - Adjustable solar energy convertor tile, e.g. photovoltaic tile - Google Patents

Abstract

The tile incorporates a rectangular frame (13) having a right hand overhang member (16) and a left hand underhang member (18), adapted to engage adjacent tiles, allowing sliding in an up and down direction hut not separation laterally. The rear face of each tile (10) includes a plurality of tracks (19) including shaped slots (21); a plurality of hook members is adapted to slide in the slots (21), permitting support of the tile on an existing roof structure, while allowing up-and-down adjustment of the position of the tile (10). Once the position of the tile has been optimised, the hooks may be fixed relative to the tile (10) and the roof structure. Optimal sealing of the roof incorporating the tiles according to the invention may be achieved, whilst also optimising the surface area of the PV cells exposed to solar radiation. <IMAGE>

Description

A Tile This invention relates to a tile, in particular but not exclusively a roof tile. More particularly, the invention relates to a roof tile incorporating a solar energy convertor. By "solar energy convertor" is meant any device which converts radiant solar energy into energy useable eg. in buildings and vehicles.

The two most common forms of solar energy convertors are photovoltaic (PV) devices and thermal energy convertors. PV devices create an electrical potential difference when solar energy is incident upon them. Therefore, useable electrical current may be generated from a judiciously designed PV device.

Thermal energy convertors operate by allowing solar radiation to be absorbed by a radiation absorber such as a black body. The temperature of such a black body rises as a consequence, and it is then possible to transfer the energy in the form of heat by conduction, for example in a simplified form of heat exchanger. The resultant thermal energy is then available, for example to be piped around a building by means of a suitable working fluid.

The roof tile of the invention may employ either type of solar energy convertor7 but particularly preferred embodiments employ PV devices.

It is known to provide a roof tile comprising a PV device made up of a series of rows of PV cells. The company Newtec Plaston AG of Büntelistrasse CH-9443 Widnau Switzerland published a paper in October 1992 entitled "Solar Tile: A Special PV-Module Integrated in Clay Tile Roofs", which gave details of such a tile.

However, the Newtec Plaston AG tile as disclosed therein suffers numerous disadvantages.

Building regulations commonly specify that the overlap of an upper row of tiles over a lower row of tiles in a roof must be at least a certain minimum, to ensure stability of the roof and water tightness of the overlap. In the U.K., the minimum overlap distance is 75mm. This requirement applies to roof tiles incorporating solar energy convertors just as much as to conventional, clay tiles.

The Newtec Plaston AG proposal achieved an adequate overlap, and hence water tightness, by the provision of extrusions secured to the upper and lower edges of the tiles. Each extrusion incorporates a pair of lips which grip about the upper and lower faces of the tile to secure the extrusion thereto. The extrusions secured along the upper edges of the tiles have upwardly extending ribs. The extrusions secured along the lower edges of the tiles have downwardly directed recesses into which such ribs on the extrusions secured to a lower row of tiles are intended to be received.

The extrusions secured to the upper edges of the tiles also have members extending downwardly beyond the general envelope of the profile of the tile, to permit securing of the extrusions to, e.g., wooden roof battens.

Thus, each tile of a lower row of tiles in the Newtec Plaston AG proposal is secured in use in the region of its upper edge to a batten.

The upper edges of such lower tiles are also in interlocking engagement with the lower edges of an upper row of tiles.

This arrangement is disadvantageous firstly because the number of components needed to assemble a roof is large.

Moreover, the positions of the tiles relative one to another and to the remainder of the roof are fixed according to the engagement of the respective upper and lower edges. This means that the gauge length of several rows of Newtec Plaston AG tiles cannot be varied. (By "gauge length" is meant the dimension of a tile, in the up-and-down direction, i.e. the gauge is the visible length of the tile in what is termed the "up slope" direction in the roofing art. The phrase "gauge length" is also used to refer to the spacing between adjacent battens in a roof.

Therefore when the Newtec Plaston AG tiles are incorporated into a roof comprising clay tiles of a different gauge from the Newtec Plaston AG tiles, an excessive overhang of the clay tiles over the uppermost row of Newtec Plaston AG tiles may be required in order to avoid misalignment of tiles partway along a row of clay tiles. This requirement causes potential problems concerning the waterproofing of a roof comprising the Newtec Plaston AG tiles. Additionally, it is very likely that a substantial portion of the gauge length of at least the uppermost row of the Newtec Plaston AG tiles would be covered by the overhang of clay tiles constituting the row above, thereby significantly reducing the energy conversion efficiency of a roof comprising such tiles.

According to a first aspect of the invention, there is provided a tile, e.g. a roof tile, comprising a solar energy convertor; a support for the converter; means adapted to engage a further tile, whereby lateral separation of the tile and the further tile may be prevented; and support means adapted to engage e.g. a roof and secured on the tile by means of a mounting, the positions of the support means relative to the tile being selectively adjustable whereby the position of said tile on e.g. a roof may be adjusted in at least one direction.

In practical embodiments of the tile according to the invention, the overhang and underhang are secured extending respectively along the right hand and left hand edges of a rectangular tile, to permit engagement of adjacent tiles in a row to prevent lateral separation of tiles of the row and to form a watertight joint whilst simultaneously permitting movement of the tiles in an up and down direction as is described below.

The adjustability of the positions of the roof engaging support means on the tiles permits movement of the tile to an optimum position from the point of view of exposure of the solar energy convertor to incident solar radiation and also from the point of view of integration of the tiles with rows of conventional clay tiles in a roof. The adjustability allows alteration of the effective gauge length of a tile, and of the overlap.

As indicated above, the solar energy convertor preferably is a PV device. In particularly preferred embodiments, the PV device comprises an array of electrically connected photovo;ltaic cells. The PV cells may be connected in series or in parallel as desired. Particularly effective performance of the tiles according to the invention has resulted from series connection of the PV cells.

Conveniently, the tile includes a recess and a junction box for electrical connections mounted in the recess, wherein the junction box includes a socket electrically connected to the PV device permitting electrical connection of the tile to a further such tile or to a load.

In preferred embodiments, the junction box is secured in a recess formed in the rear or lower surface of the tile.

Preferably, the junction box includes a removable lid, the lid including the socket, and the junction box and lid co-operate such that the lid may selectively be secured to the junction box in a plurality of positions, thereby permitting positioning of the socket in a plurality of locations on the tile.

An advantage of this arrangement is that the socket may be positioned to avoid fouling on, e.g., a roof batten in the vicinity of a rafter.

In preferred embodiments of the invention, the support comprises a framework carrying a generally rectangular plate, the PV device being secured to the plate. However, the plate and indeed the tile need not be rectangular. Nor need the plate, and hence the tile, be flat. It is envisaged that the tile can be manufactured having a profiled edge portion to mate with rows of profiled clay tiles at the boundary of an array of tiles according to the invention.

Conveniently, the overhang is secured along one end of the rectangle defined by the plate, and the underhang is secured along an opposite edge of the rectangle. It is further preferable that the overhang comprises a rigid strip of generally "r"-section material secured along said edge with the trough of the "r"-section facing downwardly. The underhang may conveniently comprise such a strip with the trough of the "r"-section facing upwardly. If, as specified above, the overhang and underhang are respectively secured on the right hand and left hand edges of a tile, it will be apparent that adjacent tiles constituting a row of tiles may overlap one another in a watertight fashion whilst still being capable of relative sliding movement in an up and down direction.

Conveniently, the support means comprises one or more hooks secured via the mounting on the rear face of the tile. Hooks have been found to be particularly convenient, because when appropriately dimensioned they fit readily over existing roof battens without the need for modifying such battens. Therefore, tiles according to the invention can readily be incorporated into a roof under construction, and additionally existing roofs can incorporate tiles according to the invention if the originally installed clay tiles are simply replaced by the tiles according to the invention.

Conveniently, the mounting comprises a track secured to the tile adapted slidably to engage at least a portion of such a hook, whereby the position of the hook relative to the tile is adjustable. It will be appreciated that when the hook engages e.g. a roof batten, the position of the tile in the direction in which the track extends relative to the hook and hence the roof batten may be adjusted. Therefore, in particularly preferred embodiments of the invention the track is secured on a rear face of the tile and it extends in an up and down direction.

Preferably, the tile includes position indicating means, e.g. a distance gauge, for clarifying or indicating the position of the or each hook.

Optionally, the track may include a T-slot channel and the or each hook may include a corresponding T-section portion adapted for sliding engagement in the T-slot. Thus, each hook is retained loosely captive on the rear face of a tile in preferred embodiments, and the position of the hooks relative to the tiles may be adjusted in one direction only.

In preferred embodiments, the hooks include means whereby their positions relative to the tiles may be secured once the adjustment has been carried out. The preferred means is a pair of holes formed in a flange forming part of the hook, whereby once the position of each hook has been determined it may be screwed or nailed to the track.

It is preferable that the tile includes a plurality of tracks secured thereto.

Preferably, the support for the convertor includes one or more apertures adapted to permit cooling of, the tile, to prevent condensation. It has been found that roof tiles comprising solar energy convertors are prone to condensation under certain meteorological conditions. It is desirable for prevention facilities to be provided.

According to a second aspect of the invention, there is provided a roof including one or more tiles as defined above Optionally, where more than one such tile is incorporated into a roof, a filler member may be provided, the filler member being adapted for securing between a pair of tiles thereby to close or extend any gap therebetween.

According to a third aspect of the invention, there is provided a method of constructing a roof as defined above, the method comprising the steps of: (i) securing as many rows of conventional roof tiles as required on a lower portion of said roof; (ii) securing at least one tile according to the invention in a predetermined row of tiles located above the said rows of conventional tiles by means of the support means; (iii) adjusting the position of said roof tile relative to said support means; (iv) fixing the support means in a desired position relative to said roof tile; (v) repeating steps (ii) to (iv) until a desired number of said roof tiles is secured; and (vi) securing any further conventional roof tiles as desired to complete the roof.

Conveniently, when a plurality of roof tiles according to the invention is secured in overlapping rows, step (iii) may include the substep of maximising the exposed area of the convertor in a lower such row by adjustment of the positions of the tiles according to the invention in an upper such row.

There now follows a description of a preferred embodiment of the invention, by way of example, with reference being made to the accompanying drawings in which: Figure 1 is a plan view of a roof tile according to the invention; Figure 2 is a front elevational view of the tile of Figure 1; Figure 3 is an underneath plan view of the tile of Figures 1 and 2; Figure 4 is a view on arrows 4-4 of Figure 1; Figures 5a and 5b are respectively a side and an end elevational view of a filler panel for use with adjacent tiles; Figures 6a to 6c are respectively a side elevation, an end elevation and a plan view of a hook suitable for securing the tile; Figure 7 is a view on arrows 7-7 of Figure 1; and Figure 8 is a view on arrows 8-8 of Figure 1.

Referring to the drawings, there is shown a roof tile according to the invention indicated generally by the reference numeral 10. Tile 10 includes a solar energy convertor in the form of an array of electrically interconnected PV cells 11.

The PV cells 11 are supported on the underside of a plate 12 of non-reflecting glass. Plate 12 which is best seen in Figure 2, is rectangular and is secured within an aluminium frame 13.

As best shown in Figures 1, 7 and 8, the members constituting the frame 13 are generally formed as L-section members which are mitred together at the corners of the rectangular frame, thereby providing a boundary region of frame material surrounding the array of PV cells on the uppermost surface of the tile. The frame member 13' shown in Figure 1 at the top edge of the tile is of a larger dimension in the up and down direction as shown in Figure 1, to allow adjustment of the overlap between rows of such tiles in a manner to be described below and to cover a junction box, also described below. The frame member 13' also accommodates an electrical junction box 14, which is also described below.

An overhang 16 is provided extending from top to bottom along the right hand edge of the tile as shown in Figure 1. As is best seen in Figures 2 and 4, the overhang is constituted by a generally "r"-section strip which is screwed to the adjacent frame member 13. In preferred embodiments, the frame members 13 are made of extruded aluminium and the overhang member 16 is made from extruded plastics material. The overhang member 16 is secured with the trough 17 of the "r"-section facing generally downwardly.

A similar "r"-section member 18 is secured extending from top to bottom of the tile as shown in Figure 1 along the left hand edge thereof to constitute an underhang. The trough 17 of the member 18 faces generally upwardly. Therefore the member 18 is essentially an inverted version of the member 16.

It will be appreciated that if two tiles 10 are positioned side by side in a roof, the overhang 16 of one tile will overlie the underhang 18 of the adjacent tile, thereby providing a weatherproof boundary between the tiles. Engagement of the overhang wall in the underhang trough and vice versa prevents lateral separation of the tiles after installation. However, relative movement of the tiles in the up and down direction is not prevented by the arrangement of members 16 and 18.

The underside of each tile 10 includes a plurality of tracks 19 which extend between the top and bottom of the tile at intervals as shown in Figure 3.

As best shown in Figures 2 and 4, each track 19 has formed therein a longitudinally extending T-slot 21 which is open at either end. The T-slots 21 are dimensioned to receive a T-shaped projection 20 formed on a hook member 22 shown in Figures 6a to 6c. It will be appreciated that the T-shaped projection 20 can be inserted into one or other end of one of the tracks 19, to support the hook 22 in a loosely captive fashion on the rear face of the tile 10. When initially engaged in a T-slot 21, such a hook 20 is moveable on the rear face of the tile in an up and down direction.

Since a plurality of tracks is provided, it is possible to insert a plurality of hooks into the respective slots 21. The hooks 22 are such that the hook arms 23 thereof are able to pass under e.g. a roof batten on which it is intended to support the tile 10. Each hook arm 23 includes an aperture 24 by means of which the hook may be secured to a batten by e.g. screws.

Each hook 20 also includes a pair of flange plates 26 which, on insertion of the T-shaped projection 20 into a slot 21 slidingly engage the outermost surface of the track 19. Each flange plate 26 includes an aperture 27 by means of which the hook may be rigidly secured to the relevant track 19, by e.g. screws.

It will be appreciated, therefore, that the fixing of a tile according to the invention in a roof is a simple matter. An appropriate plurality of hooks 22 is secured in the tracks 19 as desired. The positions of the hooks 22 are then desirably adjusted so that some of the hooks 22 are disposed towards the lower edge of the tile 10 and some towards the upper edge. On insertion of the tile into a roof, those hooks disposed at the upper edge of the tile can be manipulated to engage a roof batten. Those hooks disposed at the lower edge of a tile can be manipulated to engage the upper edge of a lower tile, be it a conventional clay tile or a further tile according to the invention.

Until the hooks 22 are secured respectively to the batten (if appropriate) and to the track members 19, the position of the tile is adjustable in an up and down direction, but not in a side to side direction, assuming that there is already in place a fixed tile with which the overhang 16 or underhang 18 of the tile being installed may engage. Thus, the tile according to the invention can be properly aligned in the row in which it is incorporated. Moreover the overlap of the tile over a lower tile can be correctly adjusted to accord with the relevant building regulations.

If the tile in question constitutes part of an uppermost row of tiles according to the invention, the position adjustment may also be effected to maximise the area of the PV device exposed to incident radiation. Therefore, the efficiency of the tile may be maximised. It is also possible to adjust the exposed areas of the PV devices in other rows. Such adjustment may be desirable to provide a neat appearance, with the rows of tiles according to the invention aligned with the rows of conventional tiles.

The up and down or gauge dimension of the frame member 13' is important in allowing adjustment of the overhang of tiles to maximise the exposed area of the PV device whilst allowing building regulations to be satisfied.

Once the tile position has been chosen, a screw or nail may be inserted via the apertures 24 in those hooks 22 which engage roof battens, thereby to secure those hooks relative to the roof battens. All the hooks 22, whether they engage roof battens or lower rows of tiles, can then be secured to the tracks 19 by means of screws inserted via the apertures 27. Thus, the positions of the tiles once chosen may be fixed.

It will further be appreciated that removal of a single tile is simple matter, it being necessary only to remove as necessary the screws inserted into the various apertures 24 and 27 and simply slide the tile free of the row in a downward direction. As this occurs, the hooks 22 travel upwardly in the tracks 19 relative to the tile 10, and eventually emerge from the open upper ends of the tracks. Replacement of a single tile is a simple reversal of this process.

Figures 5 and 5a show a filler panel which may be hooked over two adjacent tiles in a row to fill any gap occasioned by incongruity of the lateral dimensions of the tiles according to the invention with conventional clay tiles in a roof.

It will be seen from, e.g., Figure 4 that the cross section of a tile according to the invention comprises on an outer edge the frame member 13, the underside of the innermost edge of which retains the glass plate 12. The array of PV cells 11 and the associated wiring is disposed beneath the glass plate 12, and beneath the array of cells 11 is a generally rigid, planar waterproof membrane 28. The tracks 19 are secured to the underside of the waterproof membrane 28, and each track 19 is connected to at least one neighbouring track by means of web 29.

The webs 29 incorporate a series of slot-like apertures 30 which are intended to provide for cooling of the PV cells, thereby preventing the formation of condensation in the tile. Obviously, if the tile is configured employing thermal cells instead of PV cells, the need for cooling slots would most probably not arise.

The region of the tile 10 beneath the frame member 13' is, as best shown in Figure 7, constituted as a series of recesses or voids in the regions intermediate the tracks 19. Each recess is defined in part by the frame member 13 and additionally an intermediate Z-section member 32 which defines the forwardmost, downwardly extending edge of the recess when the tile is viewed as shown in Figure 7.

The lower horizontal limb of the Z-section member 32 is secured to the assembly of the tracks 19 and 29, by means of a screw 33. The upper, horizontal member of the Z-section member 32 is secured to the lower surface of the frame member 13' by means of a glue joint 34.

The forwardmost edge of the recess (i.e. the right hand edge of the recess as shown in Figure 7) is formed as a slot by virtue of the lower horizontal member of the Z-section member 32 and the frame member 13' overhanging the edge of the recess. The glass plate and waterproof membrane 28 are received in this slot, and a suitable sealing compound or member 35 secures these components in place.

A similar arrangement exists at the lowermost edge of the tile, with the glass plate and the membrane 28 being received in a zone of sealing compound 35 within a slot defined by the frame member 13, which in that vicinity is of S-section.

Referring again to Figure 7, one of the recesses between a pair of adjacent tracks 19 accommodates an electrical junction box 36. Junction box 36 includes a lid incorporating a socket (not shown) by means of which the tile may be connected electrically to a further tile or to a load. The lid of junction box 36 may be removed therefrom, and may be replaced in any of a plurality of positions, with the socket still connected to the terminals of the various PV cells which are connected in the junction box. Therefore, the socket may be positioned in any of a variety of orientations, and this feature is useful if it is necessary to position the socket to avoid fouling on e.g. a roof batten.

It will be appreciated that tiles according to the invention may be manufactured in a variety of configurations. For example, it is not essential that the tiles be manufactured as rectangular shapes as shown.

Triangular, octagonal and other polygonal shapes may readily be constructed.

Moreover, as previously indicated it is possible to manufacture the tile of the invention such that the upper and lowermost edges mate with the ridges and depressions in profiled clay tiles. Indeed, the region of the tile incorporating the PV cells need not be flat, but can itself be profiled if desired. It is most likely, however, that integration with profiled tiles can be achieved simply by the attachment of profiled conversion members at appropriate points.

It has been found that the materials mentioned are the most expedient for the manufacture of the tile. However, the use of other materials is not precluded. For example, although the frame members 13, 13' are preferably constructed from extruded aluminium, extruded plastics, timber and various other materials could be employed.

Similarly, non-reflective glass has been found to be the most effective covering for the PV cells. However, numerous translucent materials could alternatively be employed. Nevertheless, it is desirable for as little as possible of the solar radiation to be lost through, e.g., reflection.

It will be appreciated that the tile of the invention is such that it may be incorporated into existing designs of roof without the need for re-design. However, it is conceivable that new roof designs could be developed to suit the tile of the invention. For example, it may be desirable to replace the wooden roof battens with some extruded section to mate with specifically designed hooks, thereby to provide a more positive fixing and greater accuracy in the positioning of the tiles.

A further desirable feature which may be incorporated is a distance gauge marked on the tracks 19, whereby the positions of the hooks therein can readily be determined. Such a feature would make it easier to reposition tiles correctly after removal for e.g. maintenance, and also would make the construction of a roof more rapid since it would be easy for a fitter to secure the hooks in the correct position prior to hanging of the tiles.

It will also be noted that use of the tile is not restricted to the construction of roofs of buildings. Appropriately sized versions of the tile can be employed e.g. as cladding for solar powered vehicles or to construct modular solar panels.

The majority of the above description relates to the use of a tile according to the invention in the construction of a pitched roof, and the phrase "up and down direction" is intended to refer to the direction of inclination of the roof. However, the tile need not be used exclusively in pitched roofs. In the case of flat roofs and other applications, the term "up and down direction" should be construed accordingly.

Claims (24)

1. A tile, e.g. a roof tile comprising a solar energy convertor; a support for the converter; means adapted to engage a further tile, whereby lateral separation of the tile and the further tile may be prevented; and support means adapted to engage e.g. a roof and secured on the tile by means of a mounting, the positions of the support means relative to the tile being selectively adjustable whereby the position of said tile on e.g. a roof may be adjusted in at least one direction.

2. A tile according to Claim 1 wherein the solar energy convertor is a photovoltaic device.

3. A tile according to Claim 2 wherein the photovoltaic device comprises an array of electrically connected photovoltaic cells.

4. A tile according to Claim 3 including a recess and a junction box for electrical connections mounted in said recess, wherein the junction box includes a socket electrically connected to said photovoltaic device permitting electrical connection of the tile to a further such tile or a load.

5. A tile according to Claim 4 wherein the junction box includes a removable lid, the lid including the socket, and the junction box and lid co-operate such that the lid may selectively be secured to the junction box in a plurality of positions, thereby permitting positioning of the socket in a plurality of locations on the tile.

6. A tile according to any of Claims 1 to 5 wherein the support comprises a framework carrying a generally rectangular plate, the photovoltaic device being secured to said plate.

7. A tile according to Claim 6 including an overhang secured along one edge of the rectangle defined by the plate.

8. A tile according to Claim 7 including an underhang secured along an opposite edge of the rectangle.

9. A tile according to Claim 6 wherein the overhang comprises a rigid strip of generally "r"-section material secured along said edge with the trough of the "r"-section facing downwardly.

10. A tile according to Claim 7 wherein the underhang comprises a rigid strip of generally "r"-section material secured along said opposite edge with the trough of the "r"-section facing upwardly.

11. A tile according to any preceding claim, wherein the support means comprises one or more hooks secured via the mounting on the rear face of the tile.

12. A tile according to Claim 11 wherein the mounting comprises a track secured to the tile and adapted slidably to engage at least a portion of a said hook, whereby the position of the hook relative to the tile is adjustable.

13. A tile according to Claim 12 comprising position indicating means for the or each hook.

14. A tile according to Claim 12 or Claim 13 wherein the track extends between an upper and a lower boundary of the tile, whereby the positions of the hooks are adjustable in the direction of the track.

15. A tile according to any of Claims 12 to 14 wherein the track includes a T-slot channel and the or each hook includes a corresponding T-section portion adapted for sliding engagement in the T-slot.

16. A tile according to any of Claims 12 to 15 including a plurality of tracks secured thereto.

17. A tile according to any preceding claim wherein the support for the convertor includes one or more apertures adapted to permit cooling of the tile.

18. A roof including one or more tiles according to any preceding claim.

19. A roof according to Claim 18 including a pair of tiles according to any of Claims 1 to 12 and a filler member adapted for securing between said tiles thereby to close or extend any gap therebetween.

20. A method of constructing a roof according to Claim 18 or Claim 19 comprising the steps of (i) securing as many rows of conventional roof tiles as required on a lower portion of said roof; (ii) securing at least one roof tile according to any of Claims 1 to 15 in a predetermined row located above said rows of tiles by means of the support means; (iii) adjusting the position of said roof tile relative to said support means; (iv) fixing the support means in a desired position relative to said roof tile; (v) repeating steps (ii) to (iv) until a desired number of said roof tiles is secured; and (vi) securing any further conventional roof tiles as desired to complete the roof.

21. A method according to Claim 20 wherein when a plurality of roof tiles according to any of Claim 1 to 16 is secured in overlapping rows, step (iii) includes the sub-step of maximising the exposed area of the convertor in a lower row by adjustment of the positions of the roof tiles in an upper row.

22. A roof tile generally as herein described, with reference to or as illustrated in the accompanying drawings.

23. A roof generally as herein described, with reference to or as illustrated in the accompanying drawings.

24. A method generally as herein described, with reference to or as illustrated in the accompanying drawings.