GB2448920A

GB2448920A - Solar energy collector for obtaining electrical and thermal energy

Info

Publication number: GB2448920A
Application number: GB0708599A
Authority: GB
Inventors: Martin Dicks
Original assignee: SPECIAL INNOVATIONS GROUP Ltd
Current assignee: SPECIAL INNOVATIONS GROUP Ltd
Priority date: 2007-05-03
Filing date: 2007-05-03
Publication date: 2008-11-05
Also published as: GB0708599D0

Abstract

A solar energy collection device for obtaining electrical energy and thermal energy from incident solar energy is presented. The device comprises a transparent cover plate 12 covering at least part of a side of a heating chamber 14 for converting solar energy into thermal energy using fluid supplied to the heating chamber. The device also comprises a photovoltaic cell 24 for converting solar energy into electrical energy. The photovoltaic cell is positioned within the heating chamber such that fluid supplied to the heating chamber can be positioned between the covered side 26 of the heating chamber and the photovoltaic cell and between the opposite side 28 of the heating chamber and the photovoltaic cell, thereby enabling at least two sides of the photovoltaic cell to conduct thermal energy to the supplied fluid. Preferably, the solar energy collection device is in the form of a roof tile 10. A batten (50, fig.4) for use with a solar energy collection device is also disclosed, where the batten comprises one or more electrically conductive links (52, fig.4) adapted to electrically connect together a first and a second solar energy collection device.

Description

Solar Energy Collection Device This invention relates to a device for

collecting solar energy and, more particularly, to a device for obtaining electrical energy and thermal energy from incident solar energy.

With a recent focus on the topic of climate change, research and development has, in part, been directed to making effective use of sunlight (solar energy) as a source of energy. Of particular importance has been the need to develop systems that use sunlight to reduce the amount of energy used for lighting and heating domestic and/or commercial properties.

Solar power systems for collecting thermal energy from the sun or for converting sunlight into electrical energy are known. However, such systems are typically required to be added to an existing structure of a property, difficult to install, and/or cause undesirable changes a structure to which they are added.

At present, no useful technology has been developed which can efficiently derive both thermal energy and electrical energy from solar energy, which is aesthetically correct and easy to install.

According to the invention, there is provided a solar energy collection device for obtaining electrical energy and thermal energy from incident solar energy comprising: a transparent cover plate covering at least part of a side of a heating chamber for converting solar energy into thermal energy using fluid supplied to the heating chamber; and a photovoltaic cell for converting solar energy into electrical energy, the photovoitaic cell being positioned within the heating chamber such that fluid supplied to the heating chamber can be positioned between the covered side of the heating chamber and the photovoltaic cell and between the opposite side of the heating chamber and the photovoltaic cell, thereby enabling at least two sides of the photovoltaic cell to conduct thermal energy to the supplied fluid.

An example of the invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 is a plan view of a solar energy collection device according to an embodiment of the invention; and Figure 2 is a cross-sectional view of the device of Figure 1 along line A-A; Figure 3 is a cross-sectional view of the device of Figure 2 along line B-B; Figure 4 is a plan view of a solar energy collection device and batten according to an embodiment of the invention; and Figure 5 is a cross-sectional view of the device and batten of Figure 4 along line C-C.

One specific example of the invention has been described above. However, it will be readily apparent to the skilled person that various changes and modifications can be made without departing from the invention.

Referring to Figures 1 through 3, there is shown a roofing tile 10 comprising a solar energy collection device according to an embodiment of the invention.

The tile 10 comprises a transparent protective cover plate 12 on its upwardly facing surface. The transparent protective cover plate 12 covers a heating chamber 14 which is formed within the body of the tile 10.

The heating chamber 14 is adapted to receive a fluid, such as water, from an inlet valve 16 via a first tube or conduit 18. Received fluid can then be heated within the heating chamber 14 by exposure of the contents of the heating chamber 14 to solar energy (sunlight) which enters the chamber 14 through the transparent protective cover plate 12. Thus, the heating chamber is adapted to convert incident solar energy into thermal energy using fluid supplied to the heating chamber.

The heating chamber 14 is also adapted to expel or remove the fluid through an outlet valve 20 which is in fluid communication with the heating chamber 14 via a second tube or conduit 22. Thus, fluid which has been heated within the heating chamber 14 can be supplied to a thermal storage unit which is separate from the tile 10. Of course, it will also be appreciated that the outlet valve 20 may be adapted to connect to an inlet valve of another adjacently positioned solar energy collection device according to the invention for further heating.

Such a connection may be made via a push fit connector, and holes may then be provided on the upper surface of the tile 10 to allow a purpose built tool to be inserted therein to release the connection should the tile 10 need replacing.

The tile 10 also comprises an array of photovoltaic cells 24 (i.e. a solar panel) for converting solar energy into electrical energy The array of photovoltaic cells 24 is positioned within the heating chamber 14 such that it is spaced apart from the upper 26 and lower 28 walls of the heating chamber 14. In other words, the array of photovoltaic cells 24 is spaced apart from the side of the heating chamber 14 comprising the transparent protective cover plate 12, and also spaced apart from the side of the heating chamber 14 which is opposite the transparent protective cover plate 12 It will therefore be appreciated that fluid supplied to the heating chamber 14 can be positioned between the transparent side 26 of the heating chamber 14 and the array of photovoltaic cells 24 and also be positioned between the opposite side 28 of the heating chamber 14 and the photovoltaic cells 24, thereby enabling at least two sides of the array of photovoltaic cells 24 to contact the fluid.

By exposure of the photovoltaic cells 24 of the solar panel to light energy (such as solar energy), which enters the chamber 14 through the transparent protective cover plate 12, the photovoltaic cells 24 converts the light energy into electrical energy Photovoltaic technology, and its use for converting light energy into electrical energy, is already known and will not be described in any further detail, Instead, it should be understood that appropriate photovoltaic technology is to be used for the solar panel, and that such a solar panel may even comprise a commercial off-the-shelf array of photovoltaic cells.

However, it is noted that an issue which is associated with the use of photovoltaic cells to generate electricity from light is their temperature. When a photovoltaic cell is exposed to significant levels of light, the photovoltaic cell heats up, which in turn causes inefficiencies in the conversion of light energy to electrical energy. Similarly, the energy conversion efficiency of a photovoltaic cell is reduced when operating at low temperatures.

The embodiment of Figures 1 to 3 addresses the above temperature-related problem by combining thermal energy collection technology with photovoltaic technology. For example, the fluid flowing over the photovoltaic cells 24 collects thermal energy from the cells 24 via conduction and carries it away when expelled from the heating chamber 14, thereby cooling the cells 24 and helping to optimise the operating temperature.

Also, the present embodiment heats the fluid to a higher temperature when compared to conventional solar heating technology which relies on straight-forward heating of the fluid by exposure to sunlight. Because the photovoltaic cells are arranged to enable the fluid to flow around the heating chamber and contact more than one side of the cells 24, the surface coming into contact with the fluid and heating the fluid by conduction is increased The arrangement according to the invention therefore increases the amount of thermal energy that can be collected by the fluid and stored in an associated thermal storage unit.

To store electrical energy which is produced by the photovoltaic cells 24, the tile also comprises electrical energy storage means 30, such as plurality of capacitors or batteries, embedded within the body of the tile 10 The electrical energy storage means 30 are electrically connected to the array of photovoltaic cells 24 and further connected to first 32 and second 34 electrical connections provided on opposing edges of the tile 10. The first 32 and second 34 electrical connections are each adapted to connect to a respective electrical connection of an adjacently positioned tile 10 of Figures 1 to 3. The tile 10, therefore, comprises an electrical connection for supplying electrical energy from the photovoltaic cells 24 to external circuitry, wherein the tile 10 may also be interconnected with other adjacently positioned tiles. A plurality of tiles 10 according to the present embodiment may therefore be arranged in an array and have their respective fluid inlets/outlets and electrical connections connected together, thereby forming an array of solar energy collection devices that are in electrical and fluid communication with each other.

So that the tile 10 may be attached to a surface or part of a roof, the tile 10 is formed with spaced apart holes 36 passing through the tile body. The holes 36 are adapted to receive attachment means, such as a screw, for locating and holding the tile 10 in position as required. To aid positioning of the tile 10 in place, one end of the tile 10 is also formed with first and second protrusions 38 extending from its underside (downwardly facing surface). Each protrusion 38 acts as a lip which can be positioned against a receiving shoulder (i.e. a batten) so as to prevent movement of the tile 10 in a direction and align its position as necessary.

It will be understood that a tile 10 according to an embodiment contains its own electrical energy generation and storage facility allowing low levels of light energy to provide electrical energy, whereby optimum operating levels are maintained within the tile 10 by circulation of a fluid which acts as a heat sink for the electrical components.

The transparent cover plate 12 may be fabricated so as to have a refractive index value greater than the fluid provided to the heating chamber, for example water which has a refractive index of about 1.33. Light passing through the transparent cover plate 12 from the air outside of the tile will be refracted towards the normal. This refracted light will then cross the boundary between the transparent cover plate 12 and the fluid in the heating chamber and, due to the lower refractive index of the fluid, the light will be refracted away from the normal. However, the amount by which the light is refracted away from the normal by the fluid is less than that which would be caused by air. The arrangement thereby modifies the angle of incidence of the light on the underlying photovoltaic cells 24 to be closer to 900 whilst also enabling the photovoltaic cells 24 to be spaced apart from the transparent cover plate to allow cooling/heating of the cells 24.

It will be understood that, for the above arrangement (in which the refractive index value of the transparent cover plate 12 is greater than that of the fluid), it will be preferable to minimise the difference in the refractive index values, so as to minimise the amount by which the light is refracted away from the normal at the boundary between the transparent cover plate 12 and the fluid. Thus, the fluid may be specifically chosen and/or modified so as to better meet this criterion. For example, if the transparent cover plate 12 is made from a polycarbonate having a refractive index of 1.6, and the fluid comprises water having a refractive index of about 1.33, it may be desirable to add an anti-freeze solution to the water which will increase the refractive index value of the fluid (to 1 4 or so) More preferably, the transparent cover plate 12 may be fabricated so as to have a refractive index value greater than the air outside of the tile 10 and less than that of the fluid provided to the heating chamber 14. In this way, light passing through the transparent cover plate 12 from the air outside of the tile will be refracted towards the normal, and this refracted light will then be further refracted towards the normal as it crosses the boundary between the transparent cover plate 12 and the fluid in heating chamber.

The tile 10 of Figures 1 to 3 also looks similar to a conventional tile and preferably has similar properties to a conventional roofing tile, i.e. is of similar strength, colour and functionality.

Referring now to Figures 4 and 5, a solar energy collection device and batten according to an alternative embodiment of the invention will now be described.

The solar energy collection device is a tile 40 and similar to that of Figures 1 to 3. However, the tile 40 of Figures 4 and 5 differs from the tile 10 of Figures 1 to 3 in that it does not comprise first and second electrical connections on opposing edges of the tile. Instead, first 42 and second 44 electrical connections of the tile 40 of Figures 4 and 5 are formed in first 46 and second 48 spaced apart holes, respectively, wherein the first 46 and second 48 holes are longitudinally and laterally spaced apart from each other.

The batten 50 is similar in shape to that of a conventional batten. However, the batten 50 comprises parallel and spaced apart electrically conductive strips 52 running along the longitudinal length of the batten 50. The electrically conductive strips 52 are housed within an electrically insulating strip holder 54 that is provided on the wooden body 56 of the batten 50, and the electrically insulating strip holder 54 and the wooden body 56 of the batten is covered by a rubber seal 58.

The first 46 and second 48 spaced apart holes are positioned in the body of the tile 40 so that when the protrusions 38 of the tile 40 are positioned against a side of the batten (with the insulating strip holder 54 on the upper side of the batten 50 and below the lower surface of the tile 40), as shown in Figures 4 and 5, the first 46 and second 48 holes are each positioned above a respective electrically conductive strips 52 of the batten 50.

With the first 42 and second 44 electrical connections being formed in first 46 and second 48 spaced apart holes, respectively, each of the electrical connections can be connected to a respective electrically conductive strip 52 of the batten 50 via an electrically conductive screw 60. For example, in Figure 5, a screw 60 is passed through the second hole 48 and is screwed/turned so as to urge the tile 40 against the batten 50. The shaft of the electrically conductive screw 60 contacts both the second electrical connection 44 and corresponding electrically conductive strip 52 so as to create an electrical connection therebetween. Preferably, the electrically conductive screw 60 passes through the electrically conductive strip 52 in order to make a secure electrical connection.

The conductive strips 52 of the batten 50 provide a bus connection for a plurality of adjacently positioned tiles 40. Thus, a first solar energy collection device (a first tile) may be electrically connected to a second solar energy collection device (a second tile), wherein the batten 50 is adapted to provide the connection between respective electrical connections of the devices.

Blocking diodes may be provided within a solar energy collection device according to a specific embodiment. The blocking diodes may prevent a first highly (electrically) charged solar energy collection device from charging a second lower (electrically) charged solar energy collection device connection to the same bus. Blocking diodes may also be provided between the solar panel 24 and the electrical energy storage means 30.

Some advantages associated with embodiments of the invention include: Easy installation, The solar panel may be maintained at an optimum temperature for improved energy conversion efficiency; Embodiments may be made to look and function like a conventional roofing tile; Installation methods may be unchanged from existing methods; Embodiments may comprise electrical storage facilities; The need for additional electrical wiring and/or plumbing may be avoided; Embodiments may be made to fit existing structures so that they can be added to existing arrangements.

Installations costs for a tile incorporating the invention may remain the same as for conventional roof tiling, and installation engineers will not require any additional training. Plumbing and electrical connections can be made automatically as the device is laid and/or fixed in position, and fixings may be carried out in the same way as conventional roof tiles.

While specific embodiments have been described herein for purposes of illustration, various modifications will be apparent to a person skilled in the art and may be made without departing from the scope of the invention.

For example, an embodiment may comprise an air release mechanism.

Because roofing tiles are typically placed at an angle from horizontal when fitted to a roof, fluid flowing through the system will push air to the top of the tile. Preferably, this air should be expelled in an efficient manner, If left to installation engineers to expel the air, the installation process may be prolonged and impractical. Thus, a preferable embodiment may comprise an air outlet mounted vertically within the main body/casting of the tile to allow air to escape via a snorkel mechanism. The air outlet may further be adapted to connect to a second overlying tile via a pipe, in order to allow air to travel upwards to the second tile from which the air may escape via a snorkel mechanism.

Of course, embodiments may comprise any suitable arrangement of inlets and outlets to enable inter-connection of adjacent devices in series and/or in parallel.

The bottom edge of a solar energy collection device may also comprise vertical flutes leading to a horizontal flute that stretches from one side of the device to the other. When the device is used as a roofing tile, this feature may help to prevent water from passing under the device and up the slope causing leaks into the roof space.

Alternative arrangements may be used to electrically connect a solar energy collection device to a batten. One such alternative arrangement may use connectors, which are similar to bed of nails connectors, mounted on either side of the fluid connection valves (inlet/outlet) and protected with a rubber or other sealing method. Here, the fluid connections can have a gripping element which provides the holding force for the electrical connection. Thus, should the solar energy collection device need to be replaced, the electrical connections should not interfere with the disconnection process.

By way of example, an alternative connection method may comprise cone shaped pins mounted on the underside of the solar energy collection device.

These pins penetrate a sealing layer in the batten to make an electrical connection with a conductive strip provided by the batten. The connection can then be held in place by a conventional nail or screw fixing arrangement.

Claims

Claims 1. A solar energy collection device for obtaining electrical

energy and thermal energy from incident solar energy comprising: a transparent cover plate covering at least part of a side of a heating chamber for converting solar energy into thermal energy using fluid supplied to the heating chamber; and a photovoltaic cell for converting solar energy into electrical energy, the photovoltaic cell being positioned within the heating chamber such that fluid supplied to the heating chamber can be positioned between the covered side of the heating chamber and the photovoltaic cell and between the opposite side of the heating chamber and the photovoltaic cell, thereby enabling at least two sides of the photovoltaic cell to conduct thermal energy to the supplied fluid.

b
2. A solar energy collection device according to claim 1, wherein the solar energy collection device is in the form of a roof tile.
3. A solar energy collection device according to claim 1 or 2, further comprising a fluid inlet and a fluid outlet for respectively supplying fluid to and removing fluid from the heating chamber, and wherein the fluid inlet and the fluid outlet is adapted to connect, respectively, to an outlet and an inlet of an adjacently positioned solar energy collection device.
4. A solar energy collection device according to any preceding claim further comprising an electrical connection for supplying electrical energy from the photovoltaic cell to external circuitry.
5. A solar energy collection device according to claim 4, wherein the electrical connection is adapted to connect to an electrical connection of an adjacently positioned solar energy collection device.
6. A solar energy collection device according to any preceding claim, further comprising electrical energy storage means adapted to store electrical energy from the photovoltaic cell.
7. A solar energy collection device according to any preceding claim, wherein the transparent cover plate is fabricated so as to have a refractive index value greater than air.
8. A solar energy collection device according to claim 7, wherein the refractive index of the transparent cover plate is less than or equal to the refractive index of fluid supplied to the heating chamber.
9. A solar energy collection device according to claim 7, wherein the refractive index of the transparent cover plate is greater than the refractive index of the fluid supplied to the heating chamber.
10. A batten for use with a solar energy collection device according to claim 4, wherein the batten comprises one or more electrically conductive links adapted to connect an electrical connection of a first solar energy collection device to an electrical connection of a second solar energy collection device.
11. A batten according to claim 10, wherein the one or more electrically conductive links comprises an electrically conductive strip surrounded by electrical insulator, and wherein the electrical insulator can be pierced by an electrically conductive connector of the first solar energy collection device and pierced by an electrically conductive connector of the second solar energy collection device in order to connect an electrical connection of a first solar energy collection device to an electrical connection of a second solar energy collection device via the electrically conductive strip.
12. A solar energy collection system for obtaining electrical energy and thermal energy from incident solar energy comprising: a solar energy collection device according to any of claims 1 to 9; and a batten according to any of claims 10 to 11.