WO2009114905A1

WO2009114905A1 - Tile unit

Info

Publication number: WO2009114905A1
Application number: PCT/AU2009/000321
Authority: WO
Inventors: Tomas Blach
Original assignee: Sotek Australia Pty Ltd
Priority date: 2008-03-18
Filing date: 2009-03-18
Publication date: 2009-09-24
Also published as: AU2009225948A1

Abstract

A tile unit comprising a support frame having an upper surface area and a lens assembly substantially covering the upper surface area of the support frame. One or more photovoltaic cells are located beneath the lens assembly to convert solar energy passing through the lens assembly into electrical energy. A thermal assembly, comprising a heat transport system, is located adjacent the one or more photovoltaic cells. The heat transport system contains a fluid to capture thermal energy and transport it external the support frame.

Description

TILE UNIT

FIELD OF THE INVENTION

The present invention relates to the field of energy generation. More particularly, this invention relates to a tile unit for harnessing energy derived from sunlight.

BACKGROUND OF THE INVENTION

It is well known that fossil fuels are in decline and so alternative forms of energy production must be sought. Renewable energy sources such as sunlight, wind and hydro power are particularly interesting as they are "clean" energies meaning they are not damaging to the environment.

Solar energy is rapidly growing in popularity in countries such as Australia which have a relatively sunny climate. Large numbers of people are choosing to install solar energy generating systems to heat their water and power household appliances. If substantial amounts of electrical energy are generated and not consumed, the house owner may recoup some of the costs of installing the system by "selling" power back to the grid, thereby making this form of green power more attractive.

Typically, these systems take the form of arrays of photovoltaic cells.

Standard arrays are less than ideal in their performance for a number of reasons. Generally, they do not make the best use of all the available sunlight as, when the sun moves from an optimal position in the sky, the number of photons per unit area of photovoltaic cell decreases rapidly as both the flux level declines and an increasing proportion of the light is reflected from the surface of the solar array rather than being captured and converted to electricity.

Shading of one or more cells in a cascading array can lead to power being blocked from other cells and so the performance of the array as a whole is reduced significantly. The arrays themselves are placed on top of existing standard roof tiles and tend not to blend in well and so many people consider them something of an eyesore. The existing roof structure may also not be in an optimal position to receive maximum sunlight. At least some of these problems must be addressed before the public will be convinced to fully embrace this kind of technology to the extent that green power generation can become the dominant form of energy production.

International application WO/2008/020462 describes a tile whose primary role is to harness the heat energy from sunlight to heat a fluid which can be used in general household heating. The tile also employs some photovoltaic cells to simultaneously generate a moderate amount of electricity. The tile described has a standard plastic or metal surface which may have a small fresnel lens inserted therein to allow light to enter the tile body. Once within the tile body the light rays are reflected around an internal cavity by means of a reflecting plate on the lower surface and an opaque or reflective inner surface of the tile cover. Eventually the light rays will strike the fluid containing pipes within the cavity and the fluid is heated for later use. Although this represents an improvement of sorts in that the thermal energy from sunlight is being harnessed, to a degree, the overall result is still unsatisfactory in that the photovoltaic cells are not harnessing a large proportion of the available light and the energy production per unit roof area is not maximised, even taking into consideration the fluid heating aspect. Accordingly, it is an aim of the present invention to overcome or alleviate at least some of the disadvantages of current solar arrays and otherwise to provide consumers with a more convenient choice.

SUMMARY OF THE INVENTION The present invention provides for a tile unit adapted to harness at least solar energy and which may be at least partially integrated with current roofing technology so as to enable standard roof tiles to be replaced with the tile units of the invention.

In one form, although it need not be the only or indeed the broadest form, the invention resides in a tile unit comprising: (a) a support frame having an upper surface area and a lens assembly substantially covering the upper surface of the support frame;

(b) one or more photovoltaic cells located beneath the lens assembly to convert solar energy passing through the lens assembly into electrical energy; and (c) a thermal assembly located adjacent the one or more photovoltaic cells, the thermal assembly comprising a heat transport system; wherein the heat transport system contains a fluid to capture thermal energy and transport it external the support frame. Preferably, the thermal assembly further comprises at least one heat absorption layer.

Suitably, the thermal assembly further comprises at least one heat reflective layer.

The heat transport system may be located between and is in thermal communication with, the at least one heat absorption layer and the at least one heat reflective layer.

Preferably, the heat transport system is in physical contact with the heat absorption layer and the heat reflective layer.

The heat transport system may have a plurality of independent fluid circuits.

Suitably, the one or more photovoltaic cells are in thermal communication with an upper surface of the thermal assembly.

The lens assembly may comprise one or more adjacent convex lenses. If required, the tile unit may further comprise a motion transducer to generate electricity from the relative movement of one or more components of the tile unit.

Preferably, the motion transducer is one or more piezoelectric and/or electromagnetic transducers. The piezoelectric transducer may be a quartz or ceramic piezoelectric transducer. Suitably, the tile unit further comprises a thermal insulating layer.

Preferably, the thermal insulating layer is located beneath the thermal assembly.

The support frame may be adapted to connect with existing roof tile support systems.

Suitably, the tile unit further comprises one or more electrical assemblies having an inverter.

Typically, each electrical assembly is independently connected to each photovoltaic cell. If required, the electrical assembly may also comprise a microcontroller system to measure the temperature in the tile unit and alter a flow rate of the heat transport system in response to the temperature.

The tile unit may further comprise a thermoelectric device.

One or more features of the tile unit may be shaped to resemble a standard roof tile.

The lens assembly, a circuit board assembly and the one or more photovoltaic cells may be manufactured as a single unit substantially encapsulated in an optically transparent material.

Further features of the present invention will become apparent from the following detailed description.

Throughout this specification, unless the context requires otherwise, the words "comprise", "comprises" and "comprising" will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. BRIEF DESCRIPTION OF THE FIGURES

In order that the invention may be readily understood and put into practical effect, preferred embodiments will now be described by way of example with reference to the accompanying figures wherein like reference numerals refer to like parts and wherein: FIG 1 is an exploded diagrammatic representation of the components of a tile unit according to an embodiment of the invention; FIG 2 shows a top view of a tile unit according to an embodiment of the invention;

FIG 3 shows a front view of a tile unit according to an embodiment of the invention; FIG 4 shows a side view of a tile unit according to an embodiment of the invention; and

FIG 5 is a diagrammatic representation of the components of a tile unit according to a further embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION The tile unit embodiments which are discussed herein are described in relation to their use as roof tiles. It should be understood, however, that they may also be useful when fitted to any part of a building or other structure so long as they are exposed to sunlight and so their applicability is not limited to use as roof tiles. FIG 1 is an exploded diagrammatic representation of the components of a tile unit according to an embodiment of the invention. Tile unit 10 has a lens assembly 11 disposed on the upper surface of a number of photovoltaic cells 12. The lens assembly 11 shown in FIG 1 is simply represented by a rectangular box shape for convenience but in reality will take a suitable convex shape or the like. Printed circuit board (PCB) assembly 13 provides the necessary electrical connections for the operation of photovoltaic cells 12 and has an electrical connector 14 connecting the photovoltaic cells 12, independently or as a unit, with an electrical assembly.

Below the PCB assembly 13 is a thermal assembly which, in the embodiment shown, comprises a heat absorption layer 15, a heat reflective layer 16 and a heat transport system 17. Insulator 18 can be seen to sit between the thermal assembly and support frame 19. Frame 19 has a docking apparatus 20 incorporated for connection of electrical assembly 21 via connector 22 and/or for the connection of a power supply. Docking apparatus 20 may also serve as a physical docking point for the connection of tile unit 10 to the roof structure. Lens assembly 11 may comprise one or more convex lenses, is made of substantially optically pure material and serves to maximise the amount of light which is focused on the photovoltaic cells 12. This enables the utilisation of sunlight which would normally be reflected or scattered away as well as providing a focusing mechanism to concentrate light rays upon the photovoltaic cells 12. The lens assembly 11 , therefore, by its substance and shape effectively captures a much larger proportion of the available sunlight, in comparison to prior art devices, whatever the position of the sun in the sky, and focuses it upon the photovoltaic cells 12 to thereby maximise electricity generation. This is of great benefit as it greatly reduces the need for a separate sun tracking assembly which can be impractical for domestic use for a number of reasons, including expense. It also serves to provide structural support and strength to the tile unit 10.

Lens assembly 11 may take a number of forms in that there may be provided an individual lens to cover each individual photovoltaic cell 12 or, alternatively, one large lens may cover a number of photovoltaic cells 12, as is shown in FIG 1. If individual lenses are used then they may be assembled into one rigid whole. Further, lens assembly 11 may optionally incorporate features which improve its ability to capture light, for example, lens assembly 11 may include a system of prisms or grooves on the sub-millimetre scale which act to capture light efficiently at a variety of incident angles.

As a further function, lens assembly 11 can help to trap heat energy in the space between itself and the photovoltaic cells 12. This greenhouse effect can be used to great advantage as the heat energy will be taken up by the thermal assembly.

Lens assembly 11 may be manufactured from materials such as transparent UV resistant plastics and reinforced glass as well as other silicon derivatives. The final choice will depend on the optical properties, thickness and transmission losses which are expected from the lens assembly 11 but the material chosen will always result in a lens which is capable of efficient light capturing and directing. In a preferred embodiment of the present invention, lens assembly 11 is shaped to resemble a common roof tile to thereby provide a more aesthetically pleasing finish to a roof covered with tile units 10. This is achieved while still maintaining the substantially convex shape necessary to achieve its aim of capturing and directing light onto the photovoltaic cells.

Photovoltaic cells 12 are well known in the art and are typically manufactured from amorphous silicon, polycrystalline silicon, microcrystalline silicon and the like. So long as they are compatible with the other components of the tile unit 10, any form of photovoltaic cell 12 may be considered for use with the present invention.

The printed circuit board (PCB) assembly 13 provides the electrical connectivity between and physical support for, photovoltaic cells 12 and their use is well known to the skilled addressee. Printed circuit boards which are used with existing solar cell technologies are considered suitable for use with the present invention. Those constructed from ceramic substrates, however, are preferred due to their superior thermal conductivities. Electrical connector 14 allows for the connection of a number of the photovoltaic cells 12 to an electrical assembly.

In one particular embodiment of the present invention, the lens assembly 11 , photovoltaic cells 12 and PCB assembly 13 may be substantially encapsulated by a transparent material such as a clear silicone to form a single unit. A channel must be left for connection to the rest of the tile unit and the electrical assembly. This allows these three components to be assembled as a unit during manufacture and enables the final product to be more easily assembled. It is important that the encapsulating process or material should not negatively impact upon the light capturing efficiency or optical properties of the lens assembly 11 and should be secure enough to provide protection from the weather.

The heat absorption layer 15, heat reflective layer 16 and heat transport system 17, collectively make up the thermal assembly of the tile unit 10. The purpose of the thermal assembly is generally to capture and distribute heat which is generated within the tile unit 10, due mostly to the incident sunlight and the effect of lens assembly 11.

In the embodiment represented by FIG 1 the heat transport system 17 is located between and is in thermal communication with, the heat absorption layer 15 and the heat reflective layer 16. This helps to maximise the physical contact of transport system 17 with these layers and, hence, the available heat energy which can be utilised from the tile unit 10. Although not shown in FIG 1 due to the exploded nature of the representation, the photovoltaic cells can be placed in thermal communication with the upper surface of the thermal assembly, in this case the heat absorption layer 15.

The heat absorption layer 15 may take the form of more than one physical layer each of which may be the same or different and may be made from any material which has good heat absorbing properties such as a sheet of metal or metallic foil, for example copper or aluminium. Alternatively, the heat absorption layer 15 may be manufactured from a number of polymers which can be graphite loaded. Further, the absorption layers may be coated with a matt black finish to avoid reflection of any light which may be incident upon them to thereby maximise heat absorption.

The heat reflective layer 16 can be one or more layers of rigid material which are the same or different and will act to reflect heat back into the heat transport system 17. It will also provide some mechanical stability to tile unit 10. Due to its heat reflecting properties reflective layer 16 also functions as an insulating layer to prevent heat energy entering the house. Conversely, this layer serves to minimise the amount of heat energy which is lost from the thermal assembly by reflecting energy which has passed through the heat absorption layer 15 and the heat transport system 17 back up into the heat transport system 17.

The heat reflective layer 16 may be constructed from any material which has good heat reflective properties such as a polished sheet of metal or a polymer coated with aluminium film.

The heat transport system 17 may take any form of conduit which results in an optimised thermal contact between it and the heat absorption layer 15 and the heat reflective layer 16, and allows for the heat energy to be removed from the tile unit for further usage. In the embodiment represented by FIG 1 , heat transport system 17 takes the form of one or more pipes 17. Typically, there will be at least two pipes 17 which run independently the length of the tile unit.

Pipes 17 will circulate a heat transport fluid which will absorb the heat energy which is transferred to it by the absorption layer 15 and reflective layer 16, and thereby continually remove the energy from tile unit 10 for household use or storage while simultaneously cooling tile unit 10. The particular choice of fluid will depend on the use for the heat energy being transported but the fluid will suitably be a fluid which is non-flammable at the operating temperatures, with a relatively high heat capacity. The fluid may be water which can be directly run into a hot water tank for domestic use, pool water which can be used to heat a swimming pool or spa or heating oil which will allow storage of the heat energy for later use in radiators and other heating applications. The pipes 17 will connect, as will be described later, with pipes in adjacent tile units 10 and ultimately be connected to some form of circulating pump to circulate the fluid around the entire roof tile system. In an alternative embodiment the heat transport system may consist of a section of parallel channels extruded from aluminium, polymers or silicates.

The tile units can be configured to have a number of independent fluid circuits running through separate pipes. In this manner the heat energy can be used for a number of applications simultaneously. The pipes themselves should be made of a material which facilitates the efficient transfer of heat from the surrounding absorption and reflective layers to the circulating fluid. The internal surface of the pipes 17 may be non-corrosive to allow their use in transporting drinking water, if required.

It is an advantage of the present invention that, as described above, the heat energy which is generated within the tile units 10 can be harnessed to a large degree and used or stored to supplement the energy demands of the household. This is a form of energy which is ignored by most other prior art solar arrays and makes the present system more efficient and quicker to recoup the costs of the initial outlay in installing the tile units. The cooling effect of the heat transport system on the tile units may also help improve the efficiency and operational lifetime of the photovoltaic cells.

In one particular embodiment of the present invention a device such as a Peltier ceramic heat pump may be located between the PCB assembly 13 and the lower extent of the thermal assembly. This will allow electricity to be generated based upon the heat gradient between the upper layers of the tile unit 10 and the thermal assembly. This will only be employed if the heat gradient which is likely to be generated is large enough to justify the additional expense.

It is difficult to harness all of the heat energy produced by the sun and so it is a further advantage of the present tile units 10 that they contain a layer of insulator 18 which, in combination with heat reflective layer 16, reduces the amount of heat transferred to the interior of the house. Conversely, this reduced loss of heat also contributes to the efficiency of the transfer of energy into the heat transport system, pipes 17, as it cannot escape easily. This greatly reduces the need for cooling systems such as air conditioning units which have high energy consumptions.

The layer of insulator 18 may be used alone or in conjunction with standard roof insulation technologies to also prevent heat generated within the house from escaping through the roof. Thus the need for extra energy expenditure in heating the house during winter and cooling it during summer is substantially reduced. The provision of insulator 18 and heat reflective layer 16 within the tile unit 10 may also reduce the cost to the house owner of insulating the roof and roof space using standard technologies as less insulation will be required in light of these layers.

Insulator 18 may be any suitable thermal insulating material such as alumina, fibre glass sheeting, paper, polymer foams or any combination thereof. In one non-limiting example the insulator 18 is a combination of foam and aluminium foil. The final choice of material will be a compromise between insulating efficiency, cost and weight. A lightweight material will clearly aid in reducing the overall weight of tile unit 10 and the more efficient the material is as a thermal insulator then the thinner the layer and the tile unit can be. Typically, insulator 18 will be a soft or flexible insulating material as opposed to the rigid reflective layer 16 which also has some insulating properties.

Optionally, the insulator 18 may also have, on its lower surface, a sheet of an optically reflective barrier (not shown in FIG 1). When present, this can act as a final barrier to thermal radiation and so, heat energy, from entering the house. Any infra red and/or light reflective material may be considered suitable, for example those discussed for reflective layer 16.

The tile unit 10 requires a support structure such as a support frame 19 to provide mechanical support to the tile and to enable it to be attached to the roof. Frame 19 will have side edges (not shown in FIG 1) to contain the various tile components and an upper surface area defined being between the upper end of the side edges. Advantageously, frame 19 is designed so as to be able to fit onto current standard roofing structures. To this end a supporting rail system (not shown in FIG 1) may be included on the lower surface of frame 19 which will make a simple connection with standard roofing tile technology. This connection may take the form of a snap on system or engaging rails. This will make the installation of tile unit 10 much less time consuming and cheaper, hence making the whole technology more affordable. The connection should be corrosion resistant and provide for good mating between the tile units.

As mentioned previously, docking apparatus 20 may comprise the necessary connections to secure the tile unit 10 to the existing roof structure, such as the rail system described above. In one embodiment, the docking apparatus 20 may connect with a U-channel steel piece which is either fixed to the current cross beams of the roof structure or, alternatively, which maybe used to replace said cross beams. Frame 19 may be made from any lightweight and sturdy material such as various metals or plastics. Frame 19 must also incorporate a docking apparatus 20 which may allow for attachment to the roof structure instead of or in addition to the supporting rail structure described above. Docking apparatus 20 can also allow for connection of an electrical assembly 21. In this respect docking apparatus 20 provides a passage for the electrical connections from the photovoltaic cells 12 to enter an electrical assembly as well as for the power cables.

Additionally, docking apparatus 20 may also be adapted for the electrical assembly 21 to physically connect and engage therewith. Docking apparatus 20 may also house a digital communication device which communicates between adjacent tile units and any central control unit which may be necessary to aid in managing and optimising the overall performance of the power generating roof system of connected tile units. Electrical assembly 21 connects the photovoltaic cells 12 to the circuitry which enables the power produced by the cells to be used to power household appliances or to be donated into the grid. Advantageously, an electrical assembly 21 can connect independently to each of the photovoltaic cells 12 in tile unit 10 rather than following the typical prior art methodology of the power being drawn from a collection of photovoltaic cells which are connected in series. This independent connection to each cell 12 means that the negative impact of shading on photovoltaic cells which are connected in series is reduced or eliminated.

Electrical assembly 21 will contain a high efficiency inverter which can convert the low DC voltage and high current produced by each photovoltaic cell 12 into an AC voltage, synchronised with the grid, which is then suitable for use in powering household appliances and the like. It is anticipated that each tile unit 10 could supply voltages of up to 60V AC which can be integrated across the entire roof assembly and passed to a transformer for conversion to mains voltage. Further, to minimise costs and increase efficiency only one high current transformer will be needed to electrically isolate the mains power from the power generated by the connected tile units.

The electrical assembly 21 is housed in a separate watertight capsule which can be snapped onto or otherwise attached to the tile unit 10 via connector 22 engaging with docking apparatus 20. This means that if the electrical assembly 21 should become damaged or otherwise deficient then it can easily be removed without affecting the rest of the tile unit 10. Further, should the electronics within electrical assembly 21 be updated in the future then they can easily be substituted for the original assembly. The positioning of the electrical assembly 21 on the underside of the tile unit 10 and beneath the insulator 18 means the electronics are kept relatively cool and are not exposed to direct sunlight. The provision of an electrical assembly containing an inverter for each tile unit 10 means a separate one does not have to be purchased and installed during fitting of the tile units 10. This also eliminates any possible compatibility problems which might otherwise arise. Depending on the size of the tile unit or assembly of individual tile units, the inverter within electrical assembly 21 will be chosen to handle the different power output which may be supplied.

In one embodiment of the present invention the electrical assembly 21 may further include a microcontroller system which monitors the temperature within the tile unit 10 and passes this information on to a heat transport fluid flow controller which will speed up or slow down the flow of the heat transport fluid as necessary. The microcontroller system can communicate with other tile units on the roof assembly via the low voltage power grid to direct the heat transport system accordingly.

FIG 2 shows a top view of a tile unit according to an embodiment of the invention. The tile unit 30 in this particular embodiment is seen to consist of two rows of six photovoltaic cells 31. The cells 31 lie under a lens assembly (not shown in FIG 2) which, as described earlier, may take the form of one large lens covering all of the cells 31 or an individual lens straddling each photovoltaic cell 31. Structural support or support frame 32 provides mechanical support for the entire assembly of cells 31 and thermal assembly and, on its underside, will have a snap on or rail system allowing it to connect with the roof structure. The pipes 33 which form the heat transport system can be seen to emerge through support frame 32 at one end of tile unit 30. This is the end which will connect with the underside of an adjacent tile unit and so the pipes 33 will align with a similar set of pipes which open onto the underside of the second tile unit. When the tiles are connected the two sets of pipes are joined so as to form a continuous fluid path. In this manner the pipes form a continuous network throughout the entire roof area due to the linking up of the pipes 33 disposed within each individual tile unit. Although in the embodiment shown in FIG 2 there are two separate pipes 33, there may be more depending on the number of independent fluid systems required for individual heating applications. Pipes 33 are shown as being roughly circular in cross section but may be flattened or similarly modified to maximise contact between the pipe surface and the heat absorption layers. Further, pipes 33 may simply run in a linear fashion through the tile unit 30, being turned down at one end and up at the other to connect with adjacent tile units 30, or, alternatively, they may follow a snaking or circuitous path through the tile unit 30 to maximise contact with the heat absorption and reflection layers and thereby enhance the efficiency of heat transfer from the tile unit 30. Pipes 33 may also be manufactured from an extrusion and may resemble a parallel set of channels connected via a network of connectors to the pipes of the adjacent tile unit. Channels 34 and 35 are seen to run between the photovoltaic cells 31 and would be mirrored in the lens assembly on the tile unit 30 upper surface. It is desirable to minimise the width of these channels 34, 35 so as to maximise the amount of the tile unit which is covered by the photovoltaic cells 31 and hence available for energy production. The channels may have some uses, however, in providing run off channels between adjacent lenses for rain as will be discussed later. FIG 3 shows a front view of a tile unit according to an embodiment of the invention. Tile unit 40 can be seen to have on its upper surface lens assembly 41 which is shaped to maximise the amount of light incident on the photovoltaic cells 43. Lens assembly 41 may take the form of a single lens for each photovoltaic cell 43 or an elongate lens may cover all of the photovoltaic cells 43 on one side of the tile unit 40. A channel 42 is formed between the adjacent lenses. This will allow an easy run off route for rain water. It is apparent that lens assembly 41 covers substantially all of the upper surface of the tile unit. Only where channels 42 are formed between the adjacent lenses 41 is the upper surface not formed of optical material shaped to capture and direct light into the photovoltaic cells.

When a roof surface is entirely covered with tile units 40 it will be understood that almost the entire surface will be dedicated to collecting and using light in an efficient manner to generate electricity and useful thermal energy. This represents a distinct improvement over prior art devices wherein most of the available light is lost through surface reflections due to the absence of a lens assembly or the provision of a lens on only a minor portion of the available roof surface, such as in the tile of WO/2008/020462.

The various components described in relation to FIG 1 can be seen in FIG 3. The PCB assembly 44 runs underneath and connects photovoltaic cells 43. The heat absorption layer 45 and heat reflective layer 46 are seen to sit above and below the heat transport system, which in the embodiment shown takes the form of pipes 47. Insulator 48 is seen to sit below the heat reflective layer 46. For clarities sake the support structure and electrical assembly for tile unit 40 are not shown in FIG 3.

FIG 4 shows a side view of a tile unit according to an embodiment of the invention. Tile unit 50 has a lens assembly 51 on its upper surface which, in the embodiment shown, takes the form of one continuous lens running over the surface of the photovoltaic cells 52 (convex shape not shown in FIG 4). Lens assembly 51 is seen to be offset from the body of tile unit 50 in the embodiment shown. This leaves a section of the surface free for mating with an adjacent tile unit and allows the connection of the heat transport system as described above.

Once again, PCB assembly 53 is seen beneath the photovoltaic cells

52. The heat transport system, in the form of pipe 56, is located between heat absorption layer 54 and heat reflective layer 55. Pipe 56 is seen to have an upper connection 57 which will engage with the pipe opening of the adjacent tile unit to form a continuous heat transport fluid flow system.

The pipes in adjacent tile units may mate in any number of ways. In the embodiment shown, pipe 56 is provided with a snap connector 61 which will connect with the upper connection of the adjacent tile unit. Other connections such as a watertight interference fit may also be suitable.

Insulator 58 sits below heat reflective layer 55 and can be pre-cut to allow for components such as pipe 56 to pass through it. Docking apparatus 59 allows the physical connection of the tile unit 50 to the roof structure as well as connecting with the low voltage power distribution network. Electrical assembly 60 is located below connector 62 which allows the passage of the electricity generated by the individual photovoltaic cells to the electrical assembly. The structural support or frame is not shown in FIG 4.

FIG 5 is a diagrammatic representation of the components of a tile unit 70 according to a further embodiment of the invention. The representation shown is a cross section and the lens assembly 71 is shown on the upper surface of tile unit 70. In the embodiment shown the lens assembly 71 takes the form of more than one convex lens which each straddle adjacent tile units 70 and which have a channel 72 between adjacent lenses.

The photovoltaic cells 73 are present as wafers located directly beneath lens assembly 71 with a gap between adjacent wafers reflecting the location of channel 72, above. The thermal assembly sits below the photovoltaic cells 73 as a continuous layer having, firstly, a heat absorption layer 74 in thermal communication with a number of pipes 75 which act as the heat transport system. The photovoltaic cells 73 may be anchored in or in some way in thermal communication with the thermal assembly. FIG 5 shows the photovoltaic cells 73 located adjacent the heat absorption layer 74. The heat absorption layer 74 acts as a heat sink and is substantially as described previously. A sandwich is formed by a layer of insulator 76 and heat absorption layer 74, with pipes 75 in the middle. In the embodiment shown a heat reflection layer may not be present or, preferably, it is formed by a reflective upper surface of insulator 76.

In a preferred embodiment of the present invention, tile unit 70 is provided with one or more motion transducers 77 which, in the embodiment shown in FIG 5, take the form of a piezoelectric device. A recess 78 is provided in the device which receives a portion of the thermal assembly, such as the heat absorption layer 74 or a heat reflection layer, if present. Certain components of the tile unit 70 are not rigidly fixed such that the wind or rain can cause movement of the motion transducer 77 which converts this compression and expansion energy into electrical energy which can be harnessed by tile unit 70.

It will be appreciated that there may be more than one motion transducer 77 located within tile unit 70 and that it may take more than one form. A piezoelectric device uses ceramic crystalline materials which, when subjected to a mechanical force, become electrically polarized. The force of the wind and driving rain on the lens assembly 71 will cause a downward pressure which is transferred to the one or more piezoelectric transducers and results in compression of the material therein and hence generation of electricity. Suitable piezoceramic materials are well known in the art and include various ceramics including zirconates and titanates such as lead- zirconate titanate or barium titanate as well as quartz. It is possible to generate in the order of two watts of electrical energy from each tile unit using this kind of motion transducer which can be multiplied to a few hundred watts for a standard house roof surface. To enhance this effect, the lens assembly may be shaped in such a way as to promote wind turbulence over the surface, thus promoting an oscillatory force on the transducers. To reduce noise, the lens assembly 71 may be insulated from the supporting frame 79 by a thin foamy insulator that would not obstruct downward motion, but cushion any side motion of the lens assembly 71. The shaping of the lens should not negatively impact upon its light-capturing ability. In an alternative embodiment the motion transducer 77 is one or more electromagnetic transducers. These devices are well known in the art and, as for the piezoelectric device, enable movement of tile components to be converted into electrical energy which can be harnessed and/or stored.

The components of the tile unit 70 are held in place by a support frame or outer case 79 which may also comprise attachment points for connection of the tile unit 70 to the roof of a house or the like. These attachments and electrical components are not shown in FIG 5 for the sake of clarity. Support frame 79 has side edges to contain the various tile components and an upper surface area between the upper end of the side edges. It should be understood that the lens assembly 71 substantially covers this upper surface area of the support frame.

In certain embodiments of the invention the lens assembly will entirely cover the upper surface area of the support frame i.e. when looking at a tile unit from above the entire upper surface which will be exposed to the elements is formed by the lens assembly (one complete lens per tile unit). This would mean that when a roof assembly is formed by the individual tile units the entire roof surface would be displaying lens assemblies apart from the borders of adjacent tiles.

In alternative embodiments, each tile unit lens assembly will comprise more than one lens and so the upper surface of the tile unit exposed directly to the sunlight will be formed substantially from the lens assembly i.e. the only areas not formed from lens material will be the thin drainage channels between each individual lens.

In any event it should be understood that the tile units of the present invention all have an upper surface which is substantially formed by the lens assembly which provides distinct advantages over the tiles of WO/2008/020462 which only have a relatively small portion of their upper extent displaying a fresnel lens with the rest of the surface formed from standard materials. The tile units of the invention can capture and utilise practically all light incident on their surface due to the lens effect and so a minimal amount is reflected off whereas the prior art tiles referred to will fail to capture a large portion of incident light with such a small lens component and so are much less efficient in terms of energy production.

The entire tile unit or parts thereof such as the visible surface, that is, the lens, may resemble standard roof tiles. This presents the consumer with a pleasing choice and enables them to choose the area of roof covered by the tile units and thus the amount of power they wish to generate to drive their household appliances, thereby reducing their energy bills and allowing the excess to be shared via the national grid. It also offers the possibility of progressive upgrades in covering a larger and larger area of roof with the tile units as each is an independent solar powered generator.

In broad terms, the present invention provides a tile unit comprising an upper surface formed substantially by a lens assembly with one or more photovoltaic cells located beneath the lens assembly to convert solar energy into electrical energy. A thermal assembly, located adjacent the one or more photovoltaic cells, comprises a heat transport system containing a fluid to capture thermal energy and transport it external to the tile unit.

Tile units of this kind allow the heat energy produced by sunlight and the lens assembly heating effect to be harnessed within a heat transport system to provide hot water or heating oil to the household. If such heat is not needed immediately then the heat transport system may be connected to an external storage body separate from the roof structure thereby further reducing the amount of heat which may enter the house from the roof. In colder climates a heat storage body may be incorporated at a point around the house, such as under the driveway, to enable the heat transport fluid to be circulated to reduce the ice build up in that area. The fluid circulating within the tile units will help to greatly reduce the build up of snow and ice on the roof. If heating is not required elsewhere then the heated transport fluid may simply be circulated throughout the roof assembly thereby ensuring snow and ice does not collect. It is likely that temperatures of up to 7O⁰C can be achieved in the heat transport fluid depending on incident sunlight and the nature of the fluid and thermal assembly components. This will reduce the danger of roof collapse and also keeps the lens assemblies and photovoltaic cells exposed to the sunlight to maximise power generation.

Any excess heat transfer between the interior of the house and the exterior is significantly reduced by the provision of an insulator in the tile unit. This reduces the need to run energy expensive appliances such as air conditioners in hotter weather or heaters in colder climates.

The present invention further provides for tile units which, via one or more motion transducers, can harness some of the energy provided by wind and rain which is effectively ignored by prior art solar devices. This, in combination with the photovoltaic cells and thermal assembly, enables an optimal amount of energy to be harnessed per unit surface area on a roof. An advantage of the roof tiles fitted with a motion transducer is that the roof tiles are generating electricity even on cloudy, windy and wet days when the more traditional solar panels are minimally effective at best. This represents a distinct improvement over the prior art including the tiles disclosed in International Application WO/2008/020462. The tiles disclosed therein may have a fresnel lens at the apex of the tile cover which acts to direct light rays into the tile body. The fresnel lens, however, represents only a small fraction of the available tile surface area and the rest is manufactured from typical plastic or metal materials which, depending on the angle of the sun will reflect a substantial portion of the available light rays. This results in up to 90% less light being made available to the photovoltaic array than is the case with the present tile units wherein substantially the entire exposed surface of the tile has a lens disposed thereupon resulting in almost an entire roof surface which is actively capturing and directing light onto the photovoltaic cells whatever the angle of the sun.

Further, although the tiles of WO/2008/020462 are primarily designed to harness heat energy they are not optimally efficient in this role either. The cavity with these prior art tiles is designed to act as a greenhouse by use of a reflecting plate and an inner surface of the tile cover being opaque or coated with a reflective material. Clearly, if the inner surface of the tile cover is opaque or reflective then, even though the cover is purported to be transparent, this must decrease the amount of light which is able to enter the tile compared to the clear lenses employed in the present invention. WO/2008/020462 uses the light rays being contained within this cavity to heat up the gas within the pipes located therein. A further drawback of this approach is that a proportion of the light rays will inevitably contact the photovoltaic cells which, due to their colouration and nature will absorb some of the energy as heat. Since the photovoltaic array is not in thermal communication with the pipes then this energy is wasted.

In the present invention the photovoltaic arrays are located adjacent the thermal assembly and so any heat energy they absorb or generate will be transferred to the heat absorption layer and hence on to the heat transport fluid. Wastage of the available solar and thermal energy is thus minimised.

The use of a thermal assembly comprising a heat absorption layer and a heat reflective layer with a heat transport system in between means that a maximal amount of heat energy is harnessed by the two layers and effectively transferred to the heat transport fluid due to the close proximity of all three components.

The combination of one or more of the above-mentioned features is hitherto unknown in the prior art and represents an effective means of harnessing an optimal amount of energy per unit area of a roof or other exposed surface. Although the embodiments discussed herein have been with reference to a single tile unit it is a further advantage of the present invention that the units can be made available in pre-configured modules of a plurality of tile units. For example, the tile units may be factory assembled into kits of two, four or sixteen tiles combined to form one large roof tile unit. This will simplify the process of installation of the tile units as it will clearly be easier to install large blocks of sixteen individual tile units which are already interconnected in a suitable manner. This may also help to reduce costs for the consumer by allowing them to buy tile units in larger bulk quantities while offering the option of smaller units for those on a smaller budget.

The individual tile units will be physically connected and will have their heat transport fluid and electrical systems connected so as to form a complete electrical and thermal grid. This allows the generation and even the storage of substantial amounts of energy for the consumers use.

As described previously, in one embodiment, the tile unit may comprise a U-channel steel piece which is either fixed to the current cross beams of the roof structure or, alternatively, which maybe used to replace said cross beams. The opposite ends of the channels of the U-shape may contain a PCB like device. The end or ends of the channels will have connectors to connect the generated power to a transformer, thereby connecting it with the mains grid. The lens assembly, photovoltaic cells, thermal assembly etc can then simply clip into or in some way attach to the top of the U-channel steel device.

It will be appreciated that a tile unit has been disclosed herein which comprises a number of features which contribute to the formation of an efficient energy producing final product. Not all of the features disclosed must necessarily be present to produce a useful tile unit. For example, the motion transducer or the insulator component may be absent but a tile unit would still be provided which has substantial advantages over the prior art. Alternatively, the heat reflective layer may be replaced by a second heat absorption layer or layers if it is found that this provides a greater capacity for transfer of heat into the heat transport system than the use of a reflective layer. The thermal assembly may only comprise a heat transport system. This would still function to remove heat energy from the tile unit for further use, and so may be useful, but would not be as efficient at doing so without the heat absorption and/or reflective layers.

Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill in the art that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention.

Claims

1. A tile unit comprising:

(a) a support frame having an upper surface area and a lens assembly substantially covering the upper surface area of the support frame;

(b) one or more photovoltaic cells located beneath the lens assembly to convert solar energy passing through the lens assembly into electrical energy; and

(c) a thermal assembly located adjacent the one or more photovoltaic cells, the thermal assembly comprising a heat transport system;

wherein the heat transport system contains a fluid to capture thermal energy and transport it external the support frame.

2. The tile unit of claim 1 wherein the thermal assembly further comprises at least one heat absorption layer.

3. The tile unit of claim 1 or claim 2 wherein the thermal assembly further comprises at least one heat reflective layer.

4. The tile unit of claim 3 wherein the heat transport system is located between and is in thermal communication with, the at least one heat absorption layer and the at least one heat reflective layer.

5. The tile unit of claim 1 wherein the heat transport system comprises a plurality of independent fluid circuits.

6. The tile unit of claim 1 wherein the one or more photovoltaic cells are in thermal communication with an upper surface of the thermal assembly.

7. The tile unit of claim 1 wherein the lens assembly comprises one or more adjacent convex lenses.

8. The tile unit of claim 7 wherein the one or more convex lenses have a system of grooves or prisms on their outer surface.

9. The tile unit of claim 7 wherein a drainage channel is formed between adjacent convex lenses.

10. The tile unit of claim 1 further comprising a motion transducer to generate electricity from relative movement of one or more components of the tile unit.

11. The tile unit of claim 10 wherein the motion transducer is one or more piezoelectric and/or electromagnetic transducers.

12. The tile unit of claim 1 further comprising a thermal insulating layer.

13. The tile unit of claim 12 wherein the thermal insulating layer is located beneath the thermal assembly.

14. The tile unit of claim 1 wherein the support frame is adapted to connect with existing roof tile support systems.

15. The tile unit of claim 1 further comprising one or more electrical assemblies having an inverter.

16. The tile unit of claim 15 wherein the one or more electrical assemblies comprise a microcontroller system to measure the temperature in the tile unit and alter a flow rate of the heat transport system in response to the temperature.

17. The tile unit of claim 15 wherein the one or more electrical assemblies are each independently connected to a photovoltaic cell.

18. The tile unit of claim 1 further comprising a thermoelectric device.

19. The tile unit of claim 18 wherein the thermoelectric device is a peltier heat pump.

20. The tile unit of claim 1 wherein the tile unit is shaped to resemble a standard roof tile.

21. The tile unit of claim 1 further comprising a circuit board assembly.

22. The tile unit of claim 21 wherein the lens assembly, the circuit board assembly and the one or more photovoltaic cells are manufactured as a single unit substantially encapsulated in an optically transparent material.