Patent Description:
In accordance with global demand for clean energy generation, there is an increasing trend towards use of solar power to generate electricity. Photovoltaic cells or solar cells convert light energy to electrical energy and are increasingly used for generation of energy in domestic and commercial settings. Solar cells are maximally efficient when located in an elevated position in direct sunlight. Therefore, optimal positioning of solar panels on a rooftop is beneficial. Securing solar panels to rooftops can be problematic because the solar panels are fragile and easily damaged but must be securely attached to a roof to withstand prevailing weather. In addition, provision must be made to harvest the electrical energy generated from solar cells by accommodating wires, cables and electronics within the roof structure to provide a means of drawing power from the solar roof covering. Again, there is a need to protect these electronic components from prevailing weather. Conventionally this may be achieved by providing a hole through the body of the roof tile and passing a cable from the rear of the solar panel to the electronics mounted underneath the roof tile; however, this can weaken the structural integrity of the roof tile and can result in an increased risk of leaks. Furthermore, there are certain aesthetic factors to consider. Roof coverings are often required to be uniform and discrete in appearance. It is common for solar panels to be used only over a suitable part of a roof; often, next to standard roof tiles, resulting in two types of roof covering in adjacent relation. Such juxtaposition of mismatching roof coverings can adversely impact the overall appearance of a roof. Given the large areas over which roof coverings are utilised and the competitive commercial market, there is also a requirement to minimise costs associated with such roof coverings.

<CIT> and <CIT> describe a photovoltaic cell module tile in which a photovoltaic cell module is positioned within a recess in a top surface of the tile body. The photovoltaic cell module is retained within the recess by a fitting section and a pressure member which retain the photovoltaic cell module within the recess.

In view of the above, it is an object of the present invention to provide a solution that alleviates at least one of the aforementioned problems in relation to solar roof coverings.

According to a first aspect of the invention, there is provided a photovoltaic roof covering comprising:.

Optionally, the base tile is a standard tile. The base tile may conform to any predetermined specification for approved roof tiles. Thus, the dimensions, materials, physical characteristics, strength and shape of the base tiles may comply with appropriate regulations governing roof tiles in any appropriate country, jurisdiction or region.

It may be advantageous that the base tile is a standard tile rather than a specially adapted or modified tile since this removes any additional requirement for the photovoltaic roof covering to fulfil a separate accreditation or approval process. Photovoltaic panels may simply be coupled to existing base tiles and the photovoltaic panels themselves may be shaped and specially adapted to accommodate the differing requirements of each specific application.

Alternatively, it may be advantageous that the base tile is of a larger than standard format / dimension since this may reduce or remove the need to cut standard dimensioned solar cells during manufacture of the roof covering. This may provide cost and / or efficiency savings.

Optionally, the base tile comprises cast concrete. Optionally, the base tile has a relatively high strength and a low weight. The base tile may be shaped to provide enhanced strength while minimising weight. The base tile may comprise ribs to enhance strength of the tile. The ribs may comprise a region of increased thickness. The ribs may be longitudinal ribs.

The anchor portion comprises a hook portion. The hook portion is configured to hook over a part of a roof structure in use.

Optionally, the anchor portion of the base tile is configured to anchor the base tile to a roof baton in use. Optionally, the anchor portion of the base tile is configured to anchor the base tile to a horizontal wooden roof baton in use.

Optionally, the base tile has first and second opposing faces, wherein the first face is adapted to abut a roof structure in use and the second face is adapted to juxtapose the photovoltaic panel. The first face may be the lower face and the second face may be the upper face in use. Optionally, the anchor portion of the base tile is located on the first lower face of the base tile in use. Optionally, the anchor portion is located towards an upper edge of the lower face of the base tile in use.

Optionally, at least one side edge of the base tile has a connecting portion arranged to interconnect the base tile with an adjoining tile. Optionally, opposing side edges of the base tile have complementary interconnecting portions. Optionally, opposing side edges of the base tile have lip and groove interconnecting portions respectively. Therefore, two or more photovoltaic roof coverings laid side by side may be coupled by complementary interconnecting portions.

Optionally, the first lower face of the photovoltaic panel is coupled to the second upper face of the base tile in use.

Optionally, the first lower face of the photovoltaic panel is releasably coupled to the base tile. Releasable coupling of the photovoltaic panel and the base tile has the advantage that the relatively expensive photovoltaic panel may be reused or refitted to another base tile in the event that a base tile is broken or cracked. Such imperfections or breakages are relatively common, where base tiles are manufactured from fragile materials such as concrete, which may be easily broken, cracked or chipped under loading. In this scenario, the more costly photovoltaic panel may be removed from the damaged base tile and reattached to another base tile for re-use.

The first lower face of the photovoltaic panel may be releasably fastened to the base tile. The photovoltaic panel may be releasably fastened using a mechanical fastener such as hooked metallic fixings or clips. Alternatively, the photovoltaic panel may be attached to the base tile by means of complementary interconnectable hook and loop type fasteners, for example, Velcro®, in accordance with the disclosure of <CIT>.

Alternatively, the first lower face of the photovoltaic panel is fixed to the base tile. Optionally, the first face of the photovoltaic panel is adhesively bonded to the base tile. Optionally, strips of adhesive are located between the base tile and the photovoltaic panel to bond the base tile and photovoltaic panel.

Optionally, a separator is located between the base tile and the photovoltaic panel to separate the base tile from the photovoltaic panel by a predetermined distance. Optionally, the separator is located towards an edge of the base tile and photovoltaic panel. Optionally, the separator is located around a perimeter of the base tile and photovoltaic panel. Optionally, the separator is attached to an underside of the photovoltaic panel. Optionally, the separator comprises a rubber material. Optionally, the separator is at least <NUM> thick. Optionally, the separator is at least <NUM> thick. Optionally, the separator is around <NUM> thick. Optionally, the separator comprises a neoprene strip.

The separator is advantageous since it provides a small reliable gap between the base tile and the photovoltaic panel to ensure that the relatively rough surface of the base tile does not come into contact with and/or cause defects to the photovoltaic panel. The separator can also facilitate heat dispersion.

Optionally, the photovoltaic panel is substantially rectilinear with a low profile and the two opposing faces are substantially planar. Optionally, the photovoltaic panel has a smaller width relative to the width of the second face of the base tile.

Optionally, the photovoltaic panel is bonded to the second face of the base tile in an offset relation. Thus, the photovoltaic panel may not be aligned with the second face of the base tile.

Optionally, the photovoltaic panel overhangs the second face of the base tile along one side edge. Optionally, the photovoltaic panel is inset relative to the second face of the base tile along an opposing side edge. The dimensions of the inset may be greater than the dimensions of the overhang.

Optionally, when two photovoltaic roof coverings are laid side by side, a longitudinal gap is created between the inset of one roof covering and the overhang of the adjacent roof covering. Optionally, the longitudinal gap is a drainage channel.

Optionally, where the separator is attached to the underside of the photovoltaic panel, the separator is positioned to at least partially reside under said overhang of the photovoltaic panel such that when two photovoltaic roof coverings are laid side by side, the underside of the separator of one roof covering is in abutment with an upper surface of the inset of the other roof covering base tile in order to at least partially seal the edge of the longitudinal gap from the ingress of fluid therebetween.

Optionally, the photovoltaic panel extends beyond the second face of the base tile at a leading upper edge. The leading edge may be the upper edge of the photovoltaic roof tile in use. Optionally, the photovoltaic panel has a greater length than the length of the base tile. Thus, the photovoltaic panel may overhang the upper end of the base tile.

Optionally, the photovoltaic roof tile comprises an electronics recess. Optionally, the electronics recess is a protected area for housing electronics associated with the photovoltaic panel. The electronics recess may be protected by a portion of the first lower side of the photovoltaic panel and an end face of the leading edge of the base tile. Thus, the electronics recess may be created by the overhang resulting from the extended length of the photovoltaic panel compared with the base tile. Optionally, the electronics recess may house at least one of the following: a junction box, cables, wires, and connectors.

The electronics recess is advantageous since it provides a protected space for the physical electrical connectors from the photovoltaic panel in an area sheltered from weather. In addition, the electronics recess results from an overhang of the photovoltaic panel, which is created by pre-selecting the dimensions of the photovoltaic panel without any modifications to the base tile. The electronics recess accommodates the electronics and provides an area to draw power output from photovoltaic cells within the photovoltaic panel. Conventional solutions for recovering power from the photovoltaic cells require the drilling of holes to embed wires within the base tile. The conventional approach substantially weakens the tile and can compromise the structural integrity thereof. It can also increase the risk of leaks - especially where any issues have been encountered during installation. The present solution has the further advantage that there is no requirement during installation for complicated routing of electric wires, which is time consuming and increases scope for error during installation. The solution of the present invention allows the electronics to be easily connected below the lower face of the upper end of each photovoltaic panel.

The spacer is adhesively bonded to the second upper face of the photovoltaic panel. The spacer is located towards an upper leading end of the photovoltaic panel. The spacer is located towards an upper end of the second upper face of the photovoltaic panel in use.

Optionally, the spacer may be bonded along a strip of the second face of the photovoltaic panel. Optionally, the spacer may be bonded along a lateral strip covering at least a portion of the width of the second face of the photovoltaic panel. The spacer may be bonded along at least <NUM>% of the width of the photovoltaic panel. Optionally, the spacer is bonded along at least a portion of the predetermined contact area with an adjacent tile. Optionally, the spacer comprises a support strip bonded along the full width of the second upper face of the photovoltaic panel.

Optionally the thickness of the spacer is selected such that the spacer supports an overlaid upper tile in an appropriate position to ensure that a lower surface of the overlaid base tile is spaced from the photovoltaic panel along its full length. It is advantageous that the rough base tile does not make direct contact with any part of the photovoltaic panel, which is easily scratched and fragile. Optionally the spacer has a width from longitudinal edge to longitudinal edge of at least <NUM>. Optionally, the spacer has a width from longitudinal edge to longitudinal edge of at least <NUM>. Optionally, the spacer has a width from longitudinal edge to longitudinal edge of at least <NUM>. Optionally the spacer has a width from longitudinal edge to longitudinal edge of around <NUM>.

Optionally, the spacer comprises a rubber strip. Optionally, the spacer comprises a neoprene strip. Optionally, the spacer comprises a neoprene strip having adhesive provided on one side thereof for bonding to the photovoltaic panel.

Optionally, the base tile may comprise a custom-made base tile. Optionally, the spacer is integrated with the structure of the base tile. Optionally, the base tile may comprise a standard or larger than standard format.

Optionally, at least two photovoltaic roof coverings are overlaid in use on a roof such that the upper photovoltaic roof covering is supported by the spacer of the lower photovoltaic roof covering and a part of the roof. Therefore, the upper photovoltaic roof covering is spaced from and does not make direct contact with the photovoltaic panel of the lower roof covering.

According to a second aspect of the invention, there is provided a roof covering comprising:.

Optionally, at least two roof coverings according to the second aspect of the invention are provided and interconnected at the connecting portions to create a drainage channel therebetween. Optionally the drainage channel is located between the inset side edge of the cover panel and the overhang of the cover panel of the adjacent roof covering. Optionally, the drainage channel provides a conduit allowing for the removal of precipitation on the roof.

The anchor portion comprises a hook portion for hooking over part of a roof structure to anchor the roof covering thereto in use. Optionally, the base tile is a standard cast concrete base tile.

Optionally, the base tile and the cover panel are releasably coupled. Alternatively, the base tile and the cover panel are fixed to one another.

Optionally, the connecting portion of the base tile comprises a complementary connecting portion such that each tile interconnects with an adjacent tile when laid side by side in use. Optionally, the connecting portion of the base tile comprises two complementary connecting portions located on opposing sides of the base tile such that each tile interconnects with an adjacent tile when laid side by side in use. Optionally, the complementary connecting portion comprises a groove portion at one side edge and a complementary lip portion at an opposing side edge. The groove and lip portions are shaped and configured to interconnect. Optionally, the groove and lip portions are configured to provide a channel therebetween to act as a drain for precipitation in the region of the interconnect between adjacent tiles in use.

The photovoltaic panel comprises solar cells for the conversion of light energy into electrical energy.

Any and all combinations of optional features of the first aspect of the invention may be used in conjunction with and applicable to the second aspect of the invention where appropriate.

The invention of the first and second aspects may also be utilised with a photovoltaic roof covering comprising a multi-layer composite, wherein at least one layer of the multi-layer composite is selected and configured to impart a predetermined colour to the appearance of the roof covering.

According to a third aspect of the invention, there is provided a roof comprising a plurality of photovoltaic roof coverings according to either of the first or second aspects of the invention.

Any of the first, second, and / or third aspects of the invention may be combined with any other aspect, embodiment or feature of the invention described herein, where appropriate.

Further features and advantages of the first, second, and third aspects of the present invention will become apparent from the claims and the following description.

Embodiments of the present invention will now be described by way of example only, with reference to the following diagrams, in which:-.

A photovoltaic roof covering in the form of a solar roof tile is shown generally at <NUM> in the attached figures. The solar roof tile <NUM> is shown in differing views in <FIG> and comprises a base tile <NUM>, a photovoltaic panel <NUM> and electronics <NUM>.

The base tile <NUM> is cast from concrete. The base tile <NUM> has a substantially planar rectilinear upper face and an opposing lower face having longitudinal ribs <NUM> of increased thickness to improve strength of the base tile <NUM> whilst reducing mass. As shown in <FIG>, a first side edge of the base tile <NUM> has an interconnecting groove <NUM> extending along the length thereof. A second opposing side edge has an interconnecting lip <NUM> extending along the length thereof. The interconnecting groove <NUM> and lip <NUM> are shaped to form an interlock between adjacent tiles <NUM> when two such solar roof tiles <NUM> are laid side by side as will be described subsequently. As shown in <FIG>, the thickness and profile of the lip <NUM> and the depth of the groove <NUM> are marginally mismatched such that a tile drainage channel <NUM> is created therebetween when a first tile is interlocked to a second tile so as to provide a conduit for the transportation of precipitation away from a roof and towards a gutter or downpipe in use.

As shown in <FIG>, an upper end of the underside or lower face of the base tile <NUM> is provided with a hook portion <NUM> that is arranged to hook over an edge of a truss or wooden baton <NUM> (<FIG>) of a roof in use. An opposing lower end of the base tile <NUM> has a profiled portion <NUM> that supports the solar roof tile <NUM> on a lower tile <NUM> in use.

In the present embodiment, the base tile <NUM> is of a standard construction and complies with existing dimensional, strength and regulatory requirements in the region of use, such that the solar roof tile <NUM> of the present invention may be used in place of standard tiles without requiring recertification or modification to existing roof structures. This also means that solar roof tiles <NUM> of the invention may be used to replace existing tiles or may be retrofitted to existing roof coverings.

The solar tile <NUM> of the present invention comprises a photovoltaic panel <NUM>. The photovoltaic panel <NUM> includes a plurality of photovoltaic cells that are electrically connected and encapsulated within the multi-layer composite panel <NUM>. Each solar cell is capable of receiving light energy from the sun and converting this into electrical energy using the photoelectric effect as is well known and documented in the art.

The photovoltaic panel <NUM> is a substantially low profile rectilinear multi-layer module having a slightly smaller width and a greater length relative to the upper planar face of the base tile <NUM> to which the photovoltaic panel <NUM> is attached. According to the present embodiment, the photovoltaic panel <NUM> is designed to colour match the surrounding standard roof tiles which are dark grey in colour.

As shown in <FIG>, the photovoltaic panel <NUM> comprises several layers of different materials and components. A base layer <NUM> or backing layer comprises a black plastic sheet of PPE (polyphenylene ether). This imparts a dark colour to the panel <NUM> (in the specific embodiment this may be RAL <NUM> Anthracite Grey; however, of course many other specific colours / tones may be provided as desired). Above the PPE base layer <NUM>, there is a protective polymeric layer in the form of an EVA (ethylene vinyl acetate) encapsulate sheet <NUM>. A photovoltaic layer in the form of a monocrystalline silicon solar cell matrix <NUM> covered with suitable black / dark coloured tape is sandwiched between the lower protective polymeric layer and another similar upper layer of EVA encapsulate sheet <NUM>. The solar cells within the matrix <NUM> are stringed in series using interconnecting ribbons, which are then covered with suitable dark tape for a 'full black' appearance. The layers of EVA encapsulate sheet <NUM> provide a resin barrier to protect the solar cell matrix layer <NUM>. An upper or cover layer of chemically etched <NUM> glass <NUM> is laid atop to impart a dark colour to the panel <NUM>.

All layers <NUM>, <NUM>, <NUM>, <NUM> are prepared and cut to the desired dimensions of the photovoltaic panel <NUM>. Thus, the layers <NUM>, <NUM>, <NUM>, <NUM> have a slightly smaller width and a greater length than the dimensions of the planar upper face of the base tile <NUM>. The layers <NUM>, <NUM>, <NUM>, <NUM> are assembled on top of one another in a pre-laminate as shown in <FIG> and in accordance with the tolerances required for the photovoltaic panel <NUM>. The pre-laminate is then inserted in a membrane type vacuum laminator where polymerisation of the EVA encapsulate sheet <NUM> is achieved by maintaining the panel <NUM> at a temperature of around <NUM> for twenty minutes. Following lamination, the EVA layers <NUM> become substantially transparent such that the photovoltaic panel <NUM> appears a dark grey colour adapted to match the colour of surrounding tiles. Thus, the multi-layer composite allows light to be transmitted through the glass layer <NUM> and the transparent resin layer <NUM> to the solar cell matrix <NUM>. The layers of the composite also serve to protect the solar cell matrix <NUM> from prevailing weather and other environmental harm.

According to the present embodiment, the resulting photovoltaic panel <NUM> is measured as RAL <NUM> Anthracite Grey using an electronic colour meter. Thus, the above method of manufacture allows the colour of the photovoltaic panel <NUM> to be modified to colour match the surrounding tiles.

According to alternative embodiments the surrounding tiles may be different colours, such as russet, red, orange, brown and black, and therefore components of the previously described composite may be modified to achieve the desired aesthetic. Examples of how this might be achieved include either by selecting differently coloured plastic backing <NUM> and / or a different appearance of glass layer <NUM>.

Prior to attachment of the base tile <NUM> and the photovoltaic panel <NUM>, the lower edge of the photovoltaic panel <NUM> is aligned with the lower edge of the base tile <NUM>. Given the greater length of the photovoltaic panel <NUM>, such lower edge alignment results in an upper edge overhang of the photovoltaic panel <NUM> relative to the base tile <NUM>. This overhang creates an electronics recess or protected area defined by the lower face of the photovoltaic panel <NUM> in the region of the overhang and the end edge of the base tile <NUM>. The protected area provides a recess or storage area for the electronics <NUM> such as the junction box, cables and connectors for the transfer of power generated by each solar tile <NUM>. Cables from the photovoltaic panels <NUM> may extend to a junction box or other receiving station where the electric current may be conditioned and made available for use, or stored in a battery system.

With particular reference to <FIG>, side edges of the photovoltaic panel <NUM> are not aligned with side edges of the base tile <NUM>. Rather, a first side edge of the photovoltaic panel <NUM> is inset from the side edge of the upper planar face of the base tile <NUM>. At the opposing side edge, the photovoltaic panel <NUM> overhangs <NUM> the side edge of the base tile <NUM>. The inset <NUM> is greater than the overhang <NUM> such that when the solar tiles <NUM> are laid side by side and interconnected, a solar drainage channel <NUM> is created. The solar drainage channel <NUM> is around <NUM> wide and designed to create a larger conduit than the standard base tile <NUM> drainage channel <NUM>. As a result, the solar drainage channel <NUM> can accommodate greater volumes of precipitation that are required to drain away from the roof covering in use. Furthermore, the solar drainage channel <NUM> is staggered relative to the standard tile drainage channel <NUM>, reducing the likelihood of water ingress through the tiles <NUM> to compromise the integrity of the roof.

According to the present embodiment, the photovoltaic panel <NUM> and the base tile <NUM> are adhesively bonded in the offset configuration described above. Alternatively, the photovoltaic panel <NUM> may be attached to the base tile <NUM> by means of complementary interconnectable hook and loop type fasteners, for example, Velcro®, in accordance with the disclosure of <CIT>. As shown in <FIG>, a separator in the form of a <NUM> neoprene single-sided adhesive strip <NUM> is applied around a perimeter of the lower face of the photovoltaic panel <NUM>. The adhesive strip <NUM> is located towards the edges of the join between the photovoltaic panel <NUM> and the base tile <NUM> to ensure that there is adequate spacing between the base tile <NUM> and the photovoltaic panel <NUM>. The adhesive strip <NUM> ensures that the base tile <NUM> and the photovoltaic panel <NUM> do not contact one another so that the relatively rough hard surface of the concrete base tile <NUM> does not damage or otherwise mechanically interfere with the relatively smooth and fragile photovoltaic panel <NUM>. The adhesive strip <NUM> may also facilitate heat dispersion. The base tile <NUM> and the photovoltaic panel <NUM> are bonded by adhesive <NUM> placed in strips between the lower face of the photovoltaic panel <NUM> and the upper planar face of the base tile <NUM>. Alternatively, patches or drops of adhesive may be applied wherever required on between the base tile <NUM> and the rear of the photovoltaic panel <NUM>. The adhesive bonding process between the base tile <NUM> and the photovoltaic panel <NUM> may be completed offsite in a factory or warehouse setting, thereby advantageously saving time during installation. Furthermore, a clean offsite environment may result in better attachment and improved bonding between the photovoltaic panel <NUM> and the base tile <NUM> by minimising the risk of impurities in the bond between the two components.

According to alternative embodiments, the photovoltaic panel <NUM> and the base tile <NUM> is releasably coupled using mechanical fasteners. One alternative example includes complementary interconnecting hook and loop type fasteners that are provided on both the photovoltaic panel <NUM> and the base tile <NUM>. Another example is the use of clips to releasably attach the base tile <NUM> and the photovoltaic panel <NUM>. Releasable coupling can be advantageous in the event that the base tile <NUM> is cracked or otherwise damaged and has to be discarded. The relatively expensive photovoltaic panel <NUM> may be released from the damaged base tile <NUM> and reattached to another base tile <NUM> such that the photovoltaic panel <NUM> is not needlessly wasted and discarded with the damaged base tile <NUM>.

An upper surface of the photovoltaic panel <NUM> has a spacer bonded thereto towards its upper end in the form of a strip of single sided adhesive neoprene <NUM>. The neoprene strip <NUM> is around <NUM> thick, <NUM> across its width from one longitudinal edge to the other longitudinal edge and extends along the entire width of the photovoltaic panel <NUM>. As a result, the neoprene strip <NUM> provides a narrow continuous spacer along the photovoltaic panel <NUM> to support the underside of an overlaid tile. The neoprene strip <NUM> ensures that overlaid tiles do not come into direct contact with the underlying photovoltaic panel <NUM> and the strip <NUM> supports an overlaid tile such that the overlaid tile is spaced from the underlying photovoltaic panel <NUM> along its entire length.

According to the present embodiment, the solar tiles are pre-prepared off-site and colour matched as described hereinbefore to a dark grey colour prior to installation on a roof. The pre-prepared solar tiles <NUM> are then transported to a roof on which they will be installed.

A typical roof includes an A-frame with roof trusses, a waterproof membrane, insulation and horizontal batons <NUM>. As shown in <FIG> and <FIG>, the hook portion <NUM> of each solar tile <NUM> is used to anchor the tile <NUM> to a suitable roof truss or horizontal baton <NUM>. According to the embodiment shown in <FIG>, a clip <NUM> may be used to secure the attachment of the hook portion <NUM> against the baton <NUM>.

The solar tiles <NUM> are laid out in a grid like pattern <NUM> to maximise weather resistance as shown in <FIG>. The solar tiles <NUM> provide the roof with further protection from the weather and prevent damage to, or puncture of, the underlying membrane. The solar tiles <NUM> interconnect in a side-by side relationship by means of the interconnecting lip <NUM> and groove <NUM>. Upper rows of tiles <NUM> are staggered and positioned centrally over the join between lower rows of tiles <NUM> as shown in <FIG> and <FIG> to provide further protection from the weather. This overlying interlocking configuration substantially restricts solar tile <NUM> movement during high wind conditions.

The lower profiled underside <NUM> of each base tile <NUM> rests on the neoprene strip <NUM> of the solar tile <NUM> therebelow. Therefore, the concrete base tile <NUM> is not resting on the fragile glass layer <NUM> of the photovoltaic panel <NUM>. In addition, the neoprene strip <NUM> acts as a spacer to lift the underside of each base tile <NUM> away from the overhang <NUM> at the upper end of the photovoltaic panel <NUM>. The unsupported overhang <NUM> at the upper end of each photovoltaic panel <NUM> is particularly vulnerable to damage from the relatively heavy and rough base tile <NUM>. With reference to <FIG>, the spacer function of the neoprene strip <NUM> acts to open a gap <NUM> between overlaid solar tiles <NUM> and space the overhang <NUM> of the photovoltaic panel <NUM> from the underside of each base tile <NUM>.

As shown in <FIG>, the dimensions of the gap <NUM> alter according to the solar tile <NUM> position on the roof. The lower solar tiles <NUM> have a narrower gap <NUM> (as illustrated in <FIG>) compared with the solar tiles <NUM> higher on the roof (as illustrated in <FIG>). Therefore, the thickness and position of the spacer strip <NUM> are carefully selected to ensure that, even at the most acute angle of solar tile <NUM> position, there remains a sufficient gap <NUM> to space the underside of each base tile <NUM> from the photovoltaic panel <NUM> beneath.

Opening such a gap <NUM> between overlaid tiles <NUM> can be problematic and counterintuitive, since gaps can create a leak path for precipitation and moisture on the roof. No water ingress is desirable for a roof covering and furthermore, solar tiles <NUM> are particularly vulnerable to water damage given the proximity of vital electronic components to the roof tiles <NUM>. However, provision of the neoprene spacer strip <NUM> along the full width of the void provides a weather resistant barrier that allows the system to conform to required regulations and specifications in the construction industry.

The photovoltaic panels <NUM> of each of the plurality of solar tiles <NUM> on the roof may be connected in series to create an additive voltage. The electronics <NUM> located in each electronics recess are joined along the underside of the roof to collect the power output from the photovoltaic panels <NUM>. The power output may be drawn away from the roof and conditioned for immediate use or storage.

As shown in <FIG>, the functioning solar tiles <NUM> are used to cover only part of the roof, with some dummy full tiles <NUM> and dummy half tiles <NUM>, utilised along the edges, above and below the functioning solar tiles <NUM>. The use of these dummy tiles <NUM>, <NUM> forms a continuous visual appearance over the whole of the resultant roof. Indeed, if desired, all tiles on the roof may include the solar tiles whether or not those solar tiles are functional. In other words, in areas (typically around the periphery of the roof profile) where it is not possible or desirable to provide functioning solar roof tiles (perhaps due to the need to cut such tiles when arranging them on the roof profile) such solar roof tiles may in any case be provided, but not electrically connected to the system. This ensures that an identical visual appearance is provided over the entire surface of the roof. This hence results in there being no visual contrast between the active main surface roof tiles and the inactive periphery roof tiles, and this contributes to the desirable aesthetics of the resultant roof covering by ensuring that there is no visual distinction between the two. As an alternative, rather than all tiles being solar tiles, a similar overall visual effect may be achieved by providing inactive tiles which are provided with an appropriate coating, or comprise only certain components of the neighbouring active solar tiles, in order to retain the same or similar visual appearance in those inactive tiles as the neighbouring active tiles and hence achieve the same or similar overall visual effect as that previously described.

With reference to <FIG>, in an alternative embodiment, the base tile may be of a larger than standard format in order to accommodate a set of solar cells which do not require to be cut during manufacture of the roof covering. In this specific embodiment, the roof tile may be of a width of at least <NUM> in order to accommodate a pair of solar cells side by side which are of a standard solar cell dimension (each typically <NUM> in width). However, alternative format and dimensions of roof tile and solar cell may alternatively be utilised.

With such an arrangement, and with particular reference to <FIG>, since the base tile is custom-made the base tile design can also be adapted during manufacture thereof in order to provide an integrated spacer <NUM> along the lower edge of the base tile. This spacer <NUM> may take the place of, and provide similar mechanical advantages to, the previously described mechanically separate neoprene or other spacer strip <NUM> otherwise provided on the upper face of the roof covering. Alternatively, this spacer <NUM> may be complementary to the previously described mechanically separate neoprene or other spacer strip provided on the upper face of the roof covering. In other words, the integrated spacer <NUM> may be rested upon a mechanically separate neoprene or other spacer strip also provided on the upper face of the roof covering below if desired. Where the base tile is custom-made it may also be made to a standard or larger than standard format if desired.

Although particular embodiments of the invention have been disclosed herein in detail, this is by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the statements of invention and/or appended claims. Relative terms such as "upper", "lower", "greater" and "smaller" are used illustratively and are not intended to limit the scope of the invention.

Claim 1:
A photovoltaic roof covering comprising:
a base tile (<NUM>) having a hook portion (<NUM>), wherein the hook portion (<NUM>) is configured, when in use, to anchor the base tile (<NUM>) to part of a roof;
a photovoltaic panel (<NUM>) having a first lower face that is configured to abut the base tile (<NUM>) and a second opposing upper face that is arranged to receive light;
wherein the base tile (<NUM>) and the photovoltaic panel (<NUM>) are coupled to one another; and
a spacer (<NUM>) configured, when in use, to support a portion of another overlaid base tile (<NUM>), by spacing the overlaid tile from the photovoltaic panel (<NUM>);
characterised in that the spacer (<NUM>) is adhesively bonded to the second upper face of the photovoltaic panel towards an upper leading edge of the second upper face of the photovoltaic panel (<NUM>) when in use.