GB2476657A

GB2476657A - Solar energy collection apparatus

Info

Publication number: GB2476657A
Application number: GB0922687A
Authority: GB
Inventors: Luke Anthony William Robinson
Original assignee: SUNFISH ENERGY Ltd
Current assignee: SUNFISH ENERGY LTD
Priority date: 2009-12-30
Filing date: 2009-12-30
Publication date: 2011-07-06
Also published as: WO2011080508A3; WO2011080508A2; GB0922687D0

Abstract

A solar energy collection apparatus comprises an optical array layer 2 and a collection layer 3, where the optical array layer gathers incoming light and focuses it substantially on the plane of the collection layer. At least one of the layers moves (4, fig.4) predominantly parallel to the plane of the other layer and/or a third redirecting layer 5 is provided that moves predominantly parallel to the planes of the optical array layer and the collection layer. When a third layer is provided, it may comprise at least one flexible optically engineered transparent film larger than the area of the collection layer with different portions of the film being arranged to be exposed to different angles of solar radiation at different times so as to redirect or focus different angles of incident light. Preferably, the optical array comprises inflated lens elements. A method of laterally displacing, in one or two axes, the relative positioning of an array or layer is also disclosed. In a further aspect, a lighting or display apparatus comprising a light emitting array layer and an optical array layer of divergent optical elements is presented. In use, changes in the lateral alignment enable solar tracking.

Description

Concentrated Solar Apparatus

Description

Field of the Invention

This invention relates to an optical array for concentrating solar energy or for lighting or for displaying an image. In the case of concentrating solar energy, it includes mechanical means of reducing or removing the need for angular tracking of the sun.

Background

Figure 1 shows a typical prior art heliostat used for solar tracking. As can be seen tracking a large area of panel requires a lot of structural support. The support pedestal (c), the rack assembly and torque tube (a) and joint (b) have to be able to take the wind load from the panel and drive and position the panels precisely under these loads. As a result of this heavy foundations are typically used (d). Hence such an assembly has high costs and is rarely practical for typical roof installations.

Figure 2 shows a conventional roof mounted installation on a house (18) for non concentrated solar power (17). The figure shows the sun (14) and sun's rays incident on solar panels (1). The wind loading and protruding nature of a heliostat driven concentrated solar structure is rarely suitable for locations like this (or would not be allowed by regulations). The roof mounted installation of Figure 2 is inefficient, as it does not track the sun.

There is a need for an improved structure. The invention in certain embodiments seeks to bring the advantages of concentrated solar panels (whether thermal or photovoltaic) to markets where a slim, low visual impact, light weight, low wind load structure is more appropriate.

The invention can be used in relation to thermal applications, photovoltaic applications and is some cases the redirecting of light and the injecting or coupling of light into some form of wave guides it can be converted or used at some other location.

Summary of the Invention

In accordance with the present invention, a solar energy collection structure is provided comprising an optical array layer and a collection layer, where the optical array layer gathers incoming light and transforms it into a plurality of focal points or lines that are substantially on the plane of the collection layer, wherein: at least one of the layers of the collection structure moves predominantly parallel to the plane of the other layer, and/or a third, redirecting layer is provided that moves predominantly parallel to the planes of the optical array layer and the collection layer.

The moving layer does not need to substantially change its angular orientation with respect to the incident solar radiation by its movement. Movement of said layer or layers acts to facilitate the alignment of the array of focal points or lines generated by the optical array or arrays with an array of elements designed to take advantage of the concentrated solar energy as the structure's angle with respect to the sun changes. This effectively implements, or reduces the need for single axis tracking (or 2-axis tracking depending on the nature of the embodiment and or the number of movable layers used) The moving layer(s) preferably comprise at least one thin flexible optically engineered transparent film larger than the area of the apparatus exposed to the sun, where different portions of the film are designed to be exposed to the different angles of solar radiation at different times so as to redirect or focus different angles of incident light. The portions of film not designed for a particular range of angles of incident light at a particular time can be stored and or moved in a fashion that could be taken from one or more of: a roll or rolls; rollers; a wheel; a folded structure (e.g. concertina-like). They do not interfere with the effective functioning or application of the apparatus, because the film is moved across the structure in way that keeps or selects the region of film that is appropriate for the light angle that happens to be incident on the device at a particular time. In so doing the film facilitates directly or indirectly the focusing or directing of light onto the array of elements designed to take advantage of the array of associated concentrated solar energy regions, effectively implementing what could be described as a substitute for either single axis tracking (or 2-axis tracking of the structure depending on the nature of the embodiment and or the number of movable layers used).

In accordance with another aspect of the invention, a method is provided that comprises laterally displacing, in one or two axes, the relative positioning of (i) at least one optical array of focusing elements with: (ii) an array of elements designed to take advantage of the concentrated solar energy from the optical array or arrays or (iii) a third, redirecting layer, wherein the lateral displacement causes relative movement between the array of light collection elements relative to one of the other layers.

The collection layer may comprise photovoltaic cells, thermal energy collection means or and entrance to a waveguide structure. Some or a combination of the following group of optical properties and or elements are preferably used: Fresnel optics, plurality of prisms, holographic optics, diffractive optics, reflective optics, reflective optics with a multiplicity of prisms, reflective optics with Fresnel optics, Schmidt optics, Cassegrain optics, Maksutov-Cassegrain optics, non-imaging optics, layered dielectrics, total internal reflection, patterned structures, embossed structures, photonic crystal structures, photonic band gap structures, other optically engineered materials.

Some of the optical elements in the array are curved and or stepped to facilitate focussing over a range of sun angles and/or reducing the negative impact of aberrations, particularly those associated with off axis rays.

At least one of the optical elements is preferably arranged or positioned in a way to enhance the evenness of light irradiating the individual elements of the array of elements designed to take advantage of the concentrated solar energy.

At least some part of the device may comprise one or more thin flexible films and/or composite films, and/or structured films, for one or a combination of the following reasons: low cost; engineered optical properties; optical properties; compactness; stowabil ity; transportability; flexibility; ability to inflate; durability; strength; thermal properties; and electrical properties.

At least some part of the device may take advantage of tensile forces to maintain structural integrity. Support lines cables or wires internally or externally may provide structural support.

Fluid such as air may be utilized in association or as part of the device for reasons that may be one or a combination of the following group of reasons: dielectric, thermal, buoyancy properties, density, weight. For example, the array of optical elements may comprise inflated lens elements.

The structure preferably contains active or passive design elements (or a combination thereof) for the purpose of heat extraction or removal as either waste and or in a form that can be utilized.

Angular adjustment of the structure in one axis or two axes may be used to facilitate the operation of the device.

The structure may utilizes elements designed to translate one or more of the layers together and/or independently and where it utilizes elements to control positioning of a layer or layers so as to optimize the positioning of the array of focal points or lines onto the array of elements designed to take advantage of the concentrated solar energy.

Control of the positioning of the layer or layers so as to optimize the positioning of the array of focal points or lines may take the form of power feedback and positioning software for controlling one or more drive motors or stepper motors to adjust the positioning throughout the daily solar cycle, and or a range of different clock timers may be used. Alternatively (or in combination), almanac data may be read out of a memory to provide or adjust for the incident sun angle for any time of day throughout the year.

A housing may be provided for protecting the structure from the surrounding environment.

The housing may serve other functions like optical functions and heat dissipation functions.

In another aspect of the invention, a lighting or display apparatus is provided comprising a light emitting array layer and an optical array layer of divergent optical elements focused substantially on the plane of the light emitting array layer. At least one of the layers moves predominantly parallel to the plane of the other layer.

A detailed description of various embodiments of the invention is now provided, by way of example only, with reference to the drawings.

Brief Descriition of the Drawincis Figure 1 shows a typical prior art heliostat used for solar tracking.

Figure 2 shows a conventional roof mounted installation on a house.

Figure 3 is a cross-sectional view of a shows a concentrated solar energy structure in accordance with a first embodiment of the invention.

Figure 4 shows the structure of Figure 3 in a second position.

Figure 5 is a cross-sectional view of a concentrated solar energy structure in accordance with a second embodiment of the invention, with certain regions enlarged.

Figure 6 shows a stylized cross-sectional image of the laterally moveable large flexible optical element or film of Figure 5 fully unrolled.

Figure 7 shows a two dimensional image of off axis sun rays striking two laterally moveable large flexible optical elements in accordance with the third embodiment.

Figure 8 shows, in plan view, the rolls and their associated flexible optical elements or films mounted but unrolled.

Figure 9 shows the rolls and their associated flexible optical elements or films unrolled unmounted side-by-side.

Figure 10 shows a reflective optical array in accordance with a fourth embodiment of the invention.

Figure 11 shows one possible arrangement or embodiment where an enclosure is used to house the different elements that make up the structure.

Figure 12 shows a series of two dimensional cuts through possible lens arrays that utilize Fresnel optics.

Figure 13 shows stylized top views of optical array arrangements.

Detailed Description of the Preferred Embodiments

Referring to Figure 3, a cross-sectional view is shown of rays from the sun (1) striking a layer (2) containing a laterally moveable optical array of convergent lenses that focuses light onto a layer containing an array of receivers (3). The array of lenses may be an array of line focusing elements or an array of point focusing elements. The array of receivers may be a two-dimensional array of photovoltaic cells. For ease of explanation, associated support structures are not shown.

In the case of an array of line focussing elements, each line focuses sunlight onto a line (column or row) of receivers such as photovoltaic or other receivers. In the case of an array of point focusing elements, each element preferably focuses sunlight onto a single receiver.

The array of lenses is movable in a plane parallel to the plane of the array of receivers (3) back and forth in the direction of the arrow shown. In the case when the optical array is an array of point focusing elements, movement of the array along an axis perpendicular to the arrow (in the axis out of the page) is also possible. In alternative embodiments the array (3) of receivers can also move.

Figure 4 shows off-axis rays (1) from the sun striking a laterally moveable optical array (2) and being focused onto an array of receivers (3). The displacement (4) allows the array of focal points to still strike the array of receivers. It can be seen that the individual lenses are convergent concavo-convex lenses. These have the advantage (over bi-convex lenses or piano-convex lenses) of focussing light from different angles to substantially the same plane (i.e. focal distance).

Rays that have been scattered from edges can be seen. Appropriate optical design can reduce this and also reduce aberrations associated with off axis rays. One such design employs an optical array consisting of an array of curved specially designed Fresnel lenses, but other optical design approaches are also possible.

Figure 5 shows off-axis rays (1) from the sun striking a laterally moveable large flexible optical element or film (5) that is being used to redirect incoming rays into the axis of an array of optical elements (2) that may or may not be moveable. The large flexible optical element or film (5) is much larger than the array of optical elements (2), and different portions of it are used to redirect light of different incident angles. It can be thought of as a very large Fresnel lens with a continuous variation in the shape and/or angle of a series of small prisms embossed into the surface of a flexible optical film. The portions of the film (5) that are not suitable for incoming light rays at a particular time of day or year can be stored on rolls (6a, 6b). These rolls can be driven by motors (not shown) and used together to translate the structure back and forwards. One possible design of (5) is shown in magnification in portions (7 and 8). Portion (7) has a series of small prisms that refract light from right to centre. Portion 8 has a series of small prisms that refract light from left to centre.

In operation, the large optical element is moved laterally across the surface of the array. As the sun moves from left to right, portion (7) is appropriate for afternoon sun while portion (8) that was used for the morning sun is stored. As a large Fresnel lens can be thought of as continuously variable, the portion covering the lens array will also vary hence (5) should be significantly larger then (2).

Figure 6 shows the laterally moveable large flexible optical element or film (5) fully unrolled and shows how the different potions bend incoming light rays (1) in different angles. The film (5) helps to collimate the incoming light rays. A Fresnel lens (15) with very few prisms is shown for comparison, It has just 20 facets. So few facets would not be appropriate and many more would be required as illustrated in the magnified views of portions (7 and 8). A possible way how the different portions of the large optical film would relate to incoming rays from the sun (14) at different times of the day is also shown.

Figure 7 shows a two-dimensional image of off-axis rays (1) from the sun striking two laterally moveable large flexible optical elements (5a, 5b) that are being used to redirect incoming rays into the axis of an array of optical elements (2) that may or may not be moveable. The large flexible optical elements (5a, 5b) are much larger than the array of optical elements (2) and different portions of it are used to redirect light of different incident angles, those portions which are not suitable for incoming light rays at a particular time can be stored on rolls (6a, 6b, 6c, 6d). Elements 5a and 5b can be used to track different axes and may run back and forward along the same axis (using elements as illustrated in Figure 9). Alternatively, they may run at right angles to each other (as shown in Figure 8) so that rolls (6c) and (6d) are actually positioned into and out of the page rather than on top of each other.

Figure 8 shows the rolls (6a, 6b, 6c, 6d), and their associated flexible optical elements or films unrolled and extending beyond the dimensions of the area of a structure that could be used to house the associated arrays. Additionally, how different portions of the film (5a) could be designed for different angles of the sun (14) and different times of the day are shown. A second flexible optical element (5b) is seen to run at right angles to the first element (5a). This film may have an optical design to make adjustment for seasons if the array (16) is orientated in a north-south arrangement. The series of lines on the large optical films are just stylized to be indicative of the pattern that a Fresnel lens could have, but other optical arrangements are also possible.

Figure 9 shows the rolls (6a, 6b, 6c, 6d), and their associated flexible optical elements or films fully unrolled. The series of lines on the large optical films are merely stylized to be indicative of an alternative arrangement of the large optical elements. If two films are used they do not have to be oriented at right angles to each other. The stylized figure illustrates that the series of embossed prisms on films 6a and 6b are angled in different directions relative to the direction of movement of the films. For example, movement of one film can cause incident light to be refracted in the x-dimension and movement of the other can cause it to be angled in the y-dimension. Films 6a and 6b may carry an array pattern, or a regular array of focusing elements. In general, the angle of x and y bending of the light is dependent on a combination of movements of films 6a and 6b. Thus, the angle of the sun (14) at different times of the day and its association with different regions on either film (5a or 5b) is not to be considered a constraint on how the structure has to be set out, in any particular embodiment.

Figure 10 shows that a reflective optical array can also be used within the scope of the invention. The figure indicates that layers (3) and (2) can be reversed. In this embodiment, layer (3), which is the array of photovoltaic elements, is transparent and layer (2) is a reflective layer of focussing elements.

Additionally, one can envisage other optical arrangements that may utilize multiple mirror and lens arrangements, multiple reflections, total internal reflection and or non-imaging optics or any other optical design that is only limited by the scope of the claims.

Figure 11 shows one possible arrangement or embodiment in which an enclosure (10) houses the different elements that make up the structure. For simplicity not all elements are shown. A transparent protective layer (e.g. glass) can be seen (9), along with support and protective structures. A protective structure is optional. Some elements outlined in the claims can serve multiple purposes. Motors or actuators or some means to drive the translation of the film and or the rotation of (Ga) and or (6b) are not shown but assumed to be part of this embodiment.

Figure 12 shows a series of two-dimensional cuts through possible lens arrays that utilize Fresnel optics (ha, lib), (12a, 12b) and (13a, 13b). In these designs, an extended view and a close up view can be seen such as in (11 a) and (11 b). These optical arrays are not the only options; they are just designed to demonstrate some possible optical array designs.

(13a) and (13b) show a lens array structure that could be inflated and in which tension is used to maintain shape. These particular lens arrays could use line focusing optics or point focusing optics.

Figure 13 shows stylized top views of optical array arrangements. These stylized views or different optical array arrangements are presented in a way to illustrate an array of Fresnel optical elements. Arrays (2a) and (2b) can be thought of focusing light to an array of points while array (2c) can be thought of as focusing light to an array of lines. These elements nned not be perfectly designed to direct light to a point as this can sometimes create uneven distributions of solar energy on the receiving elements which for example in the case of photovoltaics can limit performance. Hence the optical array may have design elements and/or be positioned in a way to enhance the evenness of the distribution of solar energy on the receiving elements. Array (2b) is one possible design that may be more appropriate if the individual elements in the array of receiving elements are rectangular. The arrangements presented are only for the purpose of explanation and many other arrangements can be envisaged that are only limited by the scope of the claims.

In one embodiment, where many alternatives are possible and are only limited by the claims, the structure can be constructed as follows.

Take a condensing lens array like the 2D image of one shown in (Figure 3, (2)) where the focal points of the lens array form a hexagonal lattice on a plane in the (x,y) axis and where the sub elements of the lens array are convex and or designed so as to reduce off axis distortions of the focal points away from their true focal planes. Couple the lens array with an array of photovoltaic (PV) cells and associated electronics mounted on an (x,y) translatable metallic backing structure that that can act as a support for the PV cells and a heatsink (Figure 3, (3)). Position the translatable metallic backing structure containing the PV cells in the focal plane of the lens array (Figure 3). Couple the translatable metallic backing structure with appropriate motor drives, electronics and software so that the backing structure and associated PV cell array can be positioned in a way that maintains the array of PV cells aligned with the array of focal points of the lens array as the angle between the plane of the lens array and the sun changes during the day. Figure 4, shows the translation of the backing plate in relation to the lens array. Let the top surface of the lens array serve also as a protective top surface of a sealed enclosure that also includes protective sides and backing so as to isolate the structure from the environment. Mount the structure in manner and in locations that are normally only appropriate for non-concentrating PV modules for reasons of bulk visual impact and wind load like the location in Figure 2.

Another preferred method of construction of a structure in accordance with the invention is as follows.

Take a condensing lens array like the 2D image of one shown in Figure 3, (2), where the focal points of the lens array form a hexagonal lattice on a plane. Couple the lens array with an array of photovoltaic (PV) cells and associated electronics mounted on an (x,y) translatable metallic backing structure (3) that that can act as a support for the PV cells and a heatsink. Take a large area of polyolefin film where one of the dimensions X is the same width as the lens array and the other dimension Y is many times greater than the width of the lens array, micro-emboss the film with a very large Fresnel pattern designed to track the sun in one axis and so that one end on the Y dimension redirects early morning sun and the other end redirects evening sun, and the regions of the film in-between redirect light associated with the hours in-between predominantly into the axis of the lens array. Such a film with connected rollers and how different portions relate to different sun angles can be seen in Figure 6. Fix each end of the long dimension Y to rollers or reels so that the film can be rolled up and stored partly on both reels and by the appropriate turning of the reels the film can be transferred from one reel to the other. Mount the two reels either side of the lens array so that a portion of the film is held taut over the lens array and couple the reels with appropriate motor drives and feedback electronics so that the film can be translated across the surface of the lens array and positioned so that the potion covering the lens array at a particular time is a portion that most effectively redirects incident light into the axis of the lens array in one axes as seen in Figure 5. An alternative embodiment that utilizes a single large translatable Fresnel lens film can also be seen in Figure 1 1 (5a). Mount a secondary large Fresnel lens and associated rollers or reels as in steeps 3 -5 but mount it above and perpendicular to the first large Fresnel lens and associated rollers so that the remaining axis associated with angular orientation of the sun with respect to the lens array can be tracked so that when both Fresnel lenses operate together light across the day and the seasons can be redirected into the axis of the lens array as demonstrated and seen in Figures 7 and 8.

Couple the structure with appropriate mounts, drives, electronics and software to control and position the large Fresnel lenses, in a way that most effectively optimizes power output from the structure. Enclose the structure in an appropriate housing to protect it from the environment like the enclosure seen in Figure 11 (the enclosed structures seen in Figure 11 differ from this particular embodiment). Mount the structure in manner and in locations that are normally only appropriate for non-concentrating PV modules for reasons of bulk visual impact and wind load such as a location like that seen in Figure 1.

In one embodiment, the structure will take advantage of a continuous optical array, that in some cases could be thought of as a matrix of small curved Fresnel lenses (Figure 12, Figure 13). The curvature of the small Fresnel lenses can help to reduce aberrations like coma that become a problem when other types of lenses are used with off-axis light. Such an array can then effectively track the sun onto an array of receiving optical elements simply via lateral displacement of the relative position of the optical array with respect to an array of solar cell targets (Figure 3 and Figure 4). The lateral displacement can be achieved by a small motor drive that pushes or pulls one layer laterally in one axis or two axes in reference to the other layer or layers. Hence the need and associated disadvantages with controlling and constructing structures that can change their angular orientation with respect to the sun is reduced.

In another embodiment one or two very large flexible Fresnel films are used that can be translated across the face of an optical array, where the portion of the large flexible Fresnel film that happens to be covering the array at any one time is a portion designed to match the angle of incoming light so that it can redirect the incoming incident light to an angle that is more on axis in reference to the optical array (Figure 5 and Figure 6), where each large film addresses different tracking axis (Figure 7, 8 and 9). The large film can be designed so that the left side of the film redirects morning sun, the central part of the film takes noon sun and the right portion takes evening sun (Figures 6, 8 and 9).

An embodiment is now described in which the structure has just one large flexible Fresnel film for tracking in a singlesolar axis. The structure comprises a focusing array of optical elements for focusing onto a matching array of solar cells (Figure 5). The large Fresnel film is stretched across the optical array and supported by two rolls or reels, where the rollers serve to move the film and also store film not in use and/or not appropriate for the incident sun angle at a given time. The large Fresnel film sits between the optical array and the incoming sun. Movement of the film (or films) occurs in a way much like reel to reel transfer in movie projection equipment. In this particular embodiment the film can be wound forward or backward and in so doing it is transferred from one roll or reel to another so that a particular segment of the film is positioned over the array of optical elements that is appropriate for the incident light.

Considering such a structure that is exposed to morning sun, there is a large optical Fresnel film of which one region is stretched across the exposed portion of the optical array and the unused portions are stored on reels or rolls to the left and right of the device. The left side of the film is designed for morning sun, the middle is designed for noon sun and the right is designed for afternoon sun. When the structure is exposed to morning sun, the portion of the film designed for morning sun covers the optical array and very little or no unused film is stored on the left reel or roll and most of the unused film is stored on the right reel or roll. As the day progresses the film is pulled across the structure in a way that covers the array of optical elements with film appropriate for redirecting the angle of light incident on the device at a particular time. As the angle of the sun with respect to the device changes through the day the optical Fresnel film will be pulled across the face of the structure so that the appropriate region of the film covers the array at the appropriate time. As the day goes on, the roll of film on the left roll will grow until eventually the film is sent back to the roll on right so the structure is ready again for the sun of the next morning.

The above embodiment is just one particular embodiment. In another embodiment, the film also has reflective properties and in this case it can be is position behind the optical array, or it may not be continuous and may contain some optical array itself. Its motion can be continuous or stepped and its unused portions do not have to be stored on reels or rolls.

The structure could also use a wide range of optical engineering techniques that could include holographic techniques or other techniques or combinations of optical techniques.

The structure could also use more than one large optical film that could be for the purpose of tracking two axis of incoming light, for example to take into consideration seasonal variations in sun angle (see Figures 7, 8 and 9).

Additionally, reflective optical arrays can also be envisaged (Figure 10 and Figure 11). Other optical array arrangements that could be envisaged may utilize multiple mirror and lens arrangements, multiple reflections, total internal reflection and or non-imaging optics or any other optical design that is only limited by the scope of the claims. The optical arrays used can be engineered in a wide variety of ways that are only limited by the scopes of the claims made, possible cut through views and top views can be seen in Figure 12 and Figure 13.

These figures are stylized to be indicative of Fresnel optics.

The structure, in any of its embodiments, can operate in reverse to provide a lighting or display apparatus. Such an apparatus comprises a light emitting array layer and an optical array layer of divergent optical elements focused substantially on the plane of the light emitting array layer. At least one of the layers moves predominantly parallel to the plane of the other layer.

1 5 This invention is not limited by these descriptions and is only limited by the claims made. It is assumed the invention can utilize associated support structures and control structures as well as structures to protect the structure from the environment which could be an enclosure.

Certain elements in the invention could play multiple roles such as optical and support or environmental protection. These examples are just particular embodiments and are designed just to give an understanding of the advantages and some possible embodiments of the invention.

Other combinations and embodiments In other embodiments where many alternatives are possible and are only limited by the claims made the optical array may be replaced by a Fresnel lens array.

In other embodiments the lens array may be replaced by more complicated optical arrangements that may utilize, parabolic mirrors or reflective Fresnel lens arrays (like seen in Figure 10 (2), Figure 11(2)). Additionally, multiple optical element arrays may be used so that the structure can take advantage of reflective Fresnel lens arrays, Schmidt optics, Cassegrain optics, Maksutov-Cassegrain optics, holographic optics or any other optical set up. When constructing the structure in certain embodiments like that shown in Figure 10 (3) and Figure 11(3) the PV array and electronics may be mounted on a transparent optical layer rather than a metallic backing layer.

For example, a Cassegrain optical type array may be used in combination with the two scrolling structures of Figure 7. Such an arrangement can be thought of as having five layers: two optical array layers, two large scrolling Fresnel layers and a collection layer. An anti-reflective film may be added.

In other embodiments certain elements of the structure may be suspended including elements of the lens array and the structure may or may not be enclosed In other embodiments certain elements of the structure or the whole structure may utilize inflation. For example the small lenses of the lens array may be embossed Fresnel patterns on a thin flexible film and the lens array layer may be bonded with a second layer and inflated to give each small lens a curvature as seen in Figure 12 (13a, 13b). Additionally the lens array pattern in 20 my take a range of different forms, it may be a square array, a hexagonal array, an array of line focusing elements or other alternatives that meet the requirements that it allows the production of a substantially flatter structure then what would be possible from a single lens. Some 2D arrangements of Fresnel lens can be seen in Figure 13.

In other embodiments the optical array may be designed to disperse light over its associated PV chip array in a way that reduces the chance of hot spots on the PV chips this can be done by designing the optical array so that it disperses the focal points over the area of the PV sub units.

In other embodiments the large translatable lens elements for redirecting light into the optical array may not be positioned at right angles to each other and may have patterning like that shown in Figure 9 where the angel of the Fresnel patterning runs 45 degrees to the axis of translation as opposed to 90 degrees like that indicated in Figure 8.

In other embodiments the PV chip array may be replaced by an array of elements designed to utilize thermal energy and or a combination of PV and thermal.

In other embodiments the array of elements designed to receive the concentrated solar energy may be the entrances to a wave guide structure or a series of waveguide structures.

And these waveguide structures may join to facilitate the collection of solar energy.

By combining optical arrays with translatable structures many of the disadvantages associated with controlling, constructing and engineering structures that can change their angular orientation with respect to the sun are reduced or eliminated.

The structure allows the advantages of concentrated solar energy to be realized in new locations, in a light weight structural form, and at reduced costs. The structure can be made substantially planner and has no or reduced need for angular tracking of solar radiation.

Hence, the advantages of the structure being presented can be in terms of reduced need for active PV material (such as Silicon), higher temperatures, reduced bulk, reduced weight, reduced visual impact and the elimination of the wind load stress on tracking. These advantages will help take concentrated solar energy to new locations and new structural forms that normally would not be possible.

The apparatus in any of its embodiments can be constructed to operated in reverse to provide a lighting or display apparatus. Such an apparatus comprises a light emitting array layer (in place of the collection layer) and an optical array layer of divergent optical elements focused substantially on the plane of the light emitting array layer. At least one of the layers moves predominantly parallel to the plane of the other layer. Such an apparatus can, for example, provide a steerable beam of light in the manner of a spotlight.

Claims

Claims 1. Solar energy collection apparatus comprising: an optical array layer and a collection layer, wherein the optical array layer gathers incoming light and focuses it substantially on the plane of the collection layer, and wherein: at least one of the layers of the collection structure moves predominantly parallel to the plane of the other layer, and/or a third, redirecting layer is provided that moves predominantly parallel to the planes of the optical array layer and the collection layer.
2. Apparatus in accordance with claim 1 wherein the third layer is provided and is moveable relative to the collection layer and comprises at least one flexible optically engineered transparent film larger than the area of the collection layer, different portions of the film being arranged to be exposed to different angles of solar radiation at different times so as to redirect or focus different angles of incident light.
3. Apparatus in accordance with claim 2 comprising drive means for driving and controlling the relative movement of the third layer and the collection layer
4. Apparatus in accordance with claim 3, wherein the drive means cause the at least one film to be moved across the optical array layer in a manner that selects a region of the film that is appropriate for the light angle incident on the apparatus at a particular time, the apparatus further comprising storage means for storing portions of the film not arranged for a particular range of angles of incident light at a particular time.
5. Apparatus in accordance with claim 4, wherein the storage means comprise one or more rolls, rollers or wheels or a folding structure.
6. Apparatus in accordance with any one of the preceding claims, wherein some of the optical elements in the array are curved and/or stepped to facilitate focussing over a range of sun angles and/or reducing the negative impact of aberrations particularly those associated with off-axis rays.
7. Apparatus in accordance with claim 2, further comprising a fourth layer comprising a flexible optically engineered transparent film larger than the area of the collection layer, different portions of the film being arranged to be exposed to different angles of solar radiation at different times so as to redirect or focus different angles of incident light, the fourth layer being moveable relative to the collection layer in a plane parallel to the collection layer, and being moveable relative to the third layer in a plane parallel to the third layer.
8. Apparatus in accordance with claim 7 wherein the fourth layer is moveable in a direction perpendicular to the direction of movement of the third layer.
9. Apparatus in accordance with any one of the preceding claims wherein the array of optical elements comprises inflated lens elements.
10. Apparatus in accordance with any one of the preceding claims, comprising drive means to control relative positioning of the layers so as to optimize the positioning of the array of focal points or lines onto the array of elements.
11. Apparatus in accordance with any one of the preceding claims, further comprising a housing for protecting the structure from the surrounding environment.
12. A method comprising laterally displacing, in one or two axes, the relative positioning of (i) at least one optical array of focusing elements with: (ii) an array of light collection elements designed to take advantage of concentrated solar energy from the at least one optical array or (iii) a third, redirecting layer, wherein the lateral displacement causes relative movement between the array of light collection elements relative to one of the other layers.
13. A method in accordance with claim 12, wherein at least one film is moved across the array of light collection elements in a manner that selects a region of the film that is appropriate for the light angle incident on the apparatus at a particular time.
14. Lighting or display apparatus comprising: a light emitting array layer; and an optical array layer of divergent optical elements focused substantially on the plane of the light emitting array layer, wherein at least one of the layers moves predominantly parallel to the plane of the other layer.Amendments to the claims have been filed as follows Claims 1. Solar energy collection apparatus comprising: an optical array layer and a collection layer, wherein the collection layer comprises an array of targets, and wherein the optical array layer gathers incoming light and focuses it substantially on the plane of the collection layer, and wherein the optical array layer comprises: (i) an array of optical elements for reducing the profile of the solar energy collection apparatus, (ii) curved optical elements for reducing coma from off axis rays, (iii) optical elements that do not sharp focus onto the collection layer for even illumination and even thermal load at the targets, and wherein: at least one of the layers of the collection apparatus moves predominantly parallel to the plane of the other layer, and/or a third, redirecting layer is provided that moves predominantly parallel to the planes of the optical array layer and the collection layer.2. Apparatus in accordance with claim 1 wherein the third layer is provided and is (\J moveable relative to the collection layer and comprises at least one flexible optically engineered transparent film larger than the area of the collection layer, different portions of C\J the film being arranged to be exposed to different angles of solar radiation at different times so as to redirect or focus different angles of incident light.3. Apparatus in accordance with claim 2 comprising drive means for driving and controlling the relative movement of the third layer and the collection layer 4. Apparatus in accordance with claim 3, wherein the drive means cause the at least one film to be moved across the optical array layer in a manner that selects a region of the film that is appropriate for the light angle incident on the apparatus at a particular time, the apparatus further comprising storage means for storing portions of the film not arranged for a particular range of angles of incident light at a particular time.5. Apparatus in accordance with claim 4, wherein the storage means comprise one or more rolls, rollers or wheels or a folding structure.6. Apparatus in accordance with any one of the preceding claims wherein the optical array layer comprises of: facets, or prisms, or optical scattering regions, sized relative to the targets in the collection layer and or positioned relative to the targets in the collection layer for even illumination and or even thermal load on the targets in the collection layer.7. Apparatus in accordance with claim 2, further comprising a fourth layer comprising a flexible optically engineered transparent film larger than the area of the collection layer, different portions of the film being arranged to be exposed to different angles of solar radiation at different times so as to redirect or focus different angles of incident light, the fourth layer being moveable relative to the collection layer in a plane parallel to the collection layer, and being moveable relative to the third layer in a plane parallel to the third layer.8. Apparatus in accordance with claim 7 wherein the fourth layer is moveable in a direction perpendicular to the direction of movement of the third layer.9. Apparatus in accordance with any one of the preceding claims wherein the optical array layer comprises inflated optical elements.10. Apparatus in accordance with any one of the preceding claims, comprising drive means to control relative positioning of the layers..-lS 11. Apparatus in accordance with any one of the preceding claims, further comprising a housing for protecting the structure from the surrounding environment.0 12. A method comprising laterally displacing, in one or two axes, the relative positioning C\J of (a) at least an optical array layer comprising: (i) an array of optical elements to reduce 0 profile, (ii) curved optical elements to reduce coma from off axis rays, (iii) facets or prisms or uniform scattering regions of similar size to the targets in a collection layer for even illumination and even thermal load with: (b) a collection layer comprising an array of light collection elements designed to take advantage of concentrated solar energy from the at least one optical array or (c) a third, redirecting layer, wherein the lateral displacement causes relative movement between the collection layer relative to one of the other layers.13. A method in accordance with claim 12, wherein at least one film is moved across the array of light collection elements in a manner that selects a region of the film that is appropriate for the light angle incident on the apparatus at a particular time.