WO2015092363A2

WO2015092363A2 - Improvements in or relating to apparatus for cooking

Info

Publication number: WO2015092363A2
Application number: PCT/GB2014/053635
Authority: WO
Inventors: Stirling Howieson
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-12-16
Filing date: 2014-12-08
Publication date: 2015-06-25
Anticipated expiration: 2016-06-16
Also published as: GB201421795D0; GB2522535A; WO2015092363A3; GB201322166D0; GB2522535B

Abstract

An apparatus for cooking comprising, a frame member, an oven mountable to the frame member,and at least one lens element mountable to the oven, wherein the at least one lens element is a modular lens element comprising a plurality of lens elements, and wherein, in use, the at least one lens element is arranged to provide focused sunlight to the oven.

Description

Improvements in or relating to apparatus for cooking

The present invention relates to a cooking apparatus, particularly, but not exclusively, to a solar powered cooking apparatus. The present invention also relates to an oven for a solar cooking apparatus and a modular lens.

Solar powered cooking apparatuses use the solar electromagnetic radiation from the Sun to cook food. Known solar devices may be used to provide enough energy to cook food. However, such solar devices are limited in that the heat achieved to cook the food in the device properly occurs during the day. This is inconvenient, as the time when food is required is often after the Sun has set. Known solar devices are limited in their thermal efficiency, particularly if food is to be kept hot for

consumption several hours after sunset.

The inventor has appreciated the shortcomings in known solar cooking apparatuses.

According to a first aspect of the present invention there is provided an apparatus for cooking comprising:

a frame member;

an oven mountable to the frame member; and

at least one lens element mountable to the oven or the frame member;

wherein the at least one lens element is a modular lens element comprising a plurality of lens elements, and

wherein, in use, the at least one lens element is arranged to provide focussed sunlight to the oven. The term "lens element" used here and throughout the specification is considered to be an optical device that transmits, refracts and

concentrates electromagnetic radiation, particularly inside the visible and near infrared spectrum.

The term "sunlight" used here and throughout the specification is considered to be the portion of electromagnetic radiation given off by the Sun, particularly near infrared, visible, and ultraviolet light. The cooking apparatus may be termed a solar cooking apparatus.

The frame member may be configured to permit the oven to at least partially rotate relative to the frame member about at least one axis of rotation. The frame member may be configured to permit the oven to at least partially pivot relative to the frame member about at least one axis of rotation.

The frame member may be free-standing. The frame member may include a ground engaging base portion. The cooking apparatus may be arranged such that the oven substantially lies within an area defined by the footprint that the ground engaging base portion of the frame member makes on the ground, or other supporting surface.

The frame member may include one or more support members. The one or more support member may be support legs. The one or more support members may be pivotably connectable to the oven. The one or more support members may be telescopically arranged, such that their length may be variable. The frame member may include three support members. Two of the three support members may be connected to the base of the oven and the third support member may be connected towards an upper portion of the oven. The one or more support members may include ground engaging members. The ground engaging members may be pivotably connectable to the support members. The frame member may provide support to the oven. The frame member may provide support to the at least one lens element. The frame member may provide support to the oven and the at least one lens element.

The frame member may be configured to permit the oven to at least partially rotate relative to the frame member about two axes of rotation. The two axes of rotation may be orthogonal to each other.

The frame member may be configured to permit the oven to at least partially rotate relative to the frame member about a first axis of rotation and at least partially rotate relative to the frame member about a second axis of rotation. The first axis of rotation and the second axis of rotation may be orthogonal.

The oven may at least partially rotate about the first axis of rotation and the oven may at least partially rotate about the second axis of rotation.

The oven may at least partially rotate about the first axis of rotation and the oven may at least partially pivot about the second axis of rotation. The frame member may be configured to permit the oven to rotate between a first position and a second position about the first axis of rotation. The frame member may be configured to permit the oven to rotate between a first position and a second position about the second axis of rotation. The frame member may be configured to permit the oven to rotate between a first position and a second position about the first axis of rotation and to pivot between a first position and a second position about the second axis of rotation.

The frame member may include oven support arms. The oven support arms may be attached or formed with the ground engaging base portion of the frame member. The oven support arms may be arranged such that the oven is located there between. The oven support arms may be configured to pivotably support the oven. The oven may at least partially rotate or pivot with respect to the oven support arms.

The frame member may include an oven receiving member. The oven receiving member may receive the oven in an aperture, or opening, therein. The oven receiving member may receive and secure the oven thereto. The oven receiving member may be ring-shaped. The oven receiving member may be a ring. The oven may be received within the ring.

The oven receiving member may be pivotably attached to the oven support arms of the frame member. The oven receiving member may be pivotably attached between the oven support arms of the frame member. The oven receiving member and the oven, when located therein, may thus pivot with respect to the oven support arms of the frame member.

The oven receiving member may provide support to the oven when located therein.

The oven may be configured to rotatably engage with the oven receiving member. The oven may be rotatably engageable with the oven receiving member. The oven may include one or more rolling members. The one or more rolling members may be mounted to an outer surface of the oven. The one or more rolling members may be wheels, bearings, rollers or casters. One or more casters may be mounted to the oven. The casters are configured such that they are pivotably connected to the oven. The wheel of the caster is arranged such that it automatically aligns itself to the direction of travel.

The one or more rolling members allow the oven to be rotatable relative to the oven receiving member and frame member. In this arrangement, the oven may at least partially rotate about the first axis of rotation.

Where the oven receiving member is a ring, the one or more rolling members of the oven may be configured to engage with the ring, such that the one or more rolling members of the oven run on an upper surface of the ring as the oven rotates.

The frame member may further comprise an oven support plate. The oven support plate may be configured to provide support to a lower portion of the oven. The oven support plate may be configured to provide support to the bottom portion of the oven. The oven support plate may be configured to provide support to the oven as it rotates about the at least one axis of rotation. The oven support plate may be configured to provide support to the oven as it rotates about the first axis of rotation.

The oven support plate may be pivotably connected to the frame member. The oven support plate may be pivotable between a first position and a second position relative to the frame member. The oven support plate may be pivotable between a first position and a second position relative to the ground engaging base portion of the frame member. The oven support plate may be configured such that it can be held in a pivoted position relative to the ground engaging base portion of the frame member. The oven support plate may be adjustably connected with the frame member, such that the pivot position adjusted as required during use.

The frame member may include a tilt support member. The tilt support member may be configured to support the oven in a tilted position relative to the frame member. The tilt support member may be configured to hold the oven in a tilted position relative to the frame member.

The oven support plate may be fixedly engageable with the tilt support member. The oven support plate may be engageable with the tilt support member such that it can be held in a pivoted position relative to the ground engaging base portion of the frame member. The oven support plate may be adjustably engageable with the tilt support member, such that the pivot position may be adjusted as required during use.

The tilt support member may include a slot. The slot may be configured to receive at least a portion of the oven support plate therein. The slot allows the oven support plate to move between the first position and the second position relative to the frame member. The slot may be curved.

The oven support plate may include a slot engagement portion. The slot engagement portion may be configured to engage with the slot of the tilt support member. The frame member may further comprise a releasable fixing member configured to hold the slot engagement portion of the oven support plate in a fixed engagement with the slot of the tilt support member. The releasable fixing member may be a thumbscrew and washer, or the like. The oven may include at least one further rolling member. The at least one further rolling member may be attached to a lower portion of the oven. The at least one further rolling member may be mounted to an outer surface of the oven. The at least one further rolling member may be mounted to a supporting arm connected to the base portion of the oven. The at least one further rolling member may be a wheel, bearing, roller or caster. One or more casters may be mounted to the oven. The casters are configured such that they are pivotably connected to the oven. The wheel of the caster is arranged such that it automatically aligns itself to the direction of travel.

The at least one further rolling member may be configured to be

engageable with the oven support plate. The at least one further rolling member allows the oven to be rotatable relative to the oven support plate. In this arrangement, the oven may at least partially rotate about the first axis of rotation.

The oven support plate may define a track on at least a portion of its upward facing surface. The track may be configured to allow the at least one further rolling member to roll thereon as the oven rotates.

The at least one lens element may be adjustably mountable to the oven. The at least one lens element may be releasably mountable to the oven. The at least one lens element may be adjustably mountable to the frame member. The at least one lens element may be mountable to the oven such that the at least one lens element may pivot relative to the oven and the frame member. The at least one lens element may be fixed relative to the oven and frame member. The oven may further comprise support arms for supporting the at least one lens element. The support arms may be arranged such that the at least one lens element is connectable to one end of each support arm. The at least one lens element may be adjustably connectable to the support arms such that the at least one lens element may pivot with respect to the support arms. The support arms may be located towards the top of the oven. The support arms may be located towards the bottom of the oven. The support arms may be L-shaped. The support arms may be pivotably connected to the oven. The support arms may be pivotably connected to opposite sides of the oven. The support arms may be fixedly attachable to the oven. The support arms may be arranged such that a weight, or counterweight, may be attached to the arms at the opposite end of the at least one lens element. The weight, or counterweight, may be pivotably connectable to the support arms of the oven.

The oven may be substantially cylindrical. The oven may have a substantially cylindrical body portion.

The oven may include at least one removable end portion. The oven may include a removable lid. The oven may include two removable end portions. The oven may include a removable base portion.

The walls of the oven may be insulated. The walls of the oven may be insulated with foam. The insulation may be phenolic foam. The insulation may be cellular glass. The insulation may be rock wool, or mineral wool. The insulation may be a combination of any of phenolic foam, cellular glass, rock wool, or mineral wool. At least a portion of the oven may be made from metal. The metal may be copper, aluminium or galvanised steel. The internal walls of the oven may be made from copper, aluminium or galvanised steel. The outer wall may be made from a polymer material. The outer wall may be made from polypropylene.

The oven may include a first chamber and a second chamber. The first chamber may be a cooking chamber and the second chamber may be a reflection chamber.

The first chamber may be configured to receive cooking utensils, such as pots and the like. The first chamber may include a base plate located towards a lower end of the first chamber. The base plate may be made from stone. The first chamber may include a cooking plate located towards an upper end of the first chamber. The cooking plate may be a frying plate or a pizza plate. The cooking plate may be positioned closely to the underside of the lid of the oven, such that an upper facing surface of the cooking plate is exposed when the lid of the oven is removed. The cooking plate is removable from the oven. The cooking plate may be made from stone, Teflon (TM) coated steel or fired clay.

The walls of the first chamber may be made from metal. The metal may be copper, aluminium or galvanised steel.

The second chamber may be configured to receive the sunlight focussed by the at least one lens element. The second chamber may be at least partially transparent. The second chamber may include a transparent wall portion. The transparent wall portion may be located on a side portion of the oven. The transparent wall portion may be located on a lower side portion of the oven. The

transparent wall portion may be made from glass. The glass may be a glass pate. The glass may be borosilicate glass. The glass plate may be made from borosilicate glass. The second chamber may be configured to allow sunlight focussed by the at least one element to enter the second chamber through the transparent wall portion. The oven may include a removable cover member that is arranged to cover the transparent wall portion of the second chamber. The removable cover member may be insulated. The removable cover member may be an insulated plug.

The oven may be at least partially transparent. The oven may include a transparent wall portion. The transparent wall portion may be located on a side portion of the oven. The transparent wall portion may be located on a lower side portion of the oven. The transparent wall portion may be made from glass. The glass may be a glass pate. The glass may be borosilicate glass. The glass plate may be made from borosilicate glass. The oven may be configured to allow sunlight focussed by the at least one lens element to enter the second chamber through the transparent wall portion. The oven may include a removable cover member that is arranged to cover the transparent wall portion of the oven. The removable cover member may be insulated. The removable cover member may be an insulated plug.

The second chamber may include an open portion. The open portion may be an open front portion. That is, the open portion may be open to the front of the oven. The open portion allows entry of the sunlight focussed by the at least one lens element. The second chamber may include a transparent wall portion. The transparent wall portion may be located on an upper portion of the chamber. The transparent wall portion may be made from glass. The glass may be a glass pate. The glass may be borosilicate glass. The glass plate may be made from borosilicate glass. The first chamber and second chamber may be separated by the transparent wall portion. The second chamber may be configured to allow sunlight focussed by the at least one lens element to enter the second chamber through the open portion. The oven may include a removable cover member that is arranged to cover the open portion of the second chamber. The removable cover member may be insulated. The removable cover member may be an insulated plug. The second chamber may include one or more door members that may be used to cover the open portion.

The oven may further comprise an aluminium heat shield that substantially surrounds the transparent wall portion, or open portion.

The walls of the second chamber may be made from metal. The metal may be copper, aluminium or galvanised steel. At least a portion of the inner surface of the second chamber may include wire wool. The wire wool may be metal wire wool. The wire wool may be copper wool. The inner walls of the second chamber around the transparent wall portion may be covered with wire wool. The wire wool may be copper wool.

At least a portion of the inner surface of the second chamber may be coated with a material that has a high electromagnetic absorption coefficient, particularly in the wavelengths of spectral light and near infrared. At least a portion of the inner surface of the second chamber may be coated with a black selective surface. At least a portion of the inner surface of the second chamber may be coated with a black selective material. This may be a black paint. The inner walls of the second chamber around the transparent wall portion may be coated with a material that has a high electromagnetic absorption coefficient, particularly in the wavelengths of spectral light and near infrared and a low thermal emissivity coefficient. The base plate of the first chamber around the transparent wall portion may be coated with a black selective surface.

A lower surface of the second chamber is located adjacent the base portion of the oven. In this arrangement the lower surface of the second chamber is exposed when the base portion of the oven is removed.

The at least one lens element may be arranged such that its focal point is at a point inside the oven or at a point outside the oven. The at least one lens element may be arranged such that the rays of light focussed towards the oven impact upon substantially all of the transparent wall portion of the oven. In this arrangement substantially the entire area of the transparent wall is illuminated by the sunlight from the at least one lens element. In this arrangement the focal point of the at least one lens element may be either inside the oven, or outside the oven. In this arrangement the focal point of the at least one lens element may be either striking the inside of an absorption chamber of the oven or by reflection via a reflecting plate.

The at least one lens element may be arranged such that the rays of light focussed towards the oven impact upon substantially all of the open portion of the oven. In this arrangement substantially the entire area of the open portion is illuminated by the sunlight from the at least one lens element. In this arrangement the focal point of the at least one lens element may be either inside the oven, or outside the oven. In this arrangement the focal point of the at least one lens element may be striking the inside of the second chamber of the oven.

The oven may include a mirror, or a reflector plate. The mirror may be eatable in the second chamber of the oven. The mirror may be removable from the second chamber of the oven. The at least one lens element may be arranged such that the rays of light focussed towards the oven impact upon substantially all of the mirror when located inside the second chamber of the oven. In this arrangement substantially the entire area of the mirror is illuminated by the sunlight from the at least one lens element. In this arrangement the focal point of the at least one lens element may be located outside the oven.

The at least one lens element may be a modular lens element. The at least one lens element may comprise a number of individual lens elements.

The cooking apparatus may comprise two or more lens elements, with each lens element being arranged to focus sunlight towards the oven. The cooking apparatus may comprise two or more lens elements, with each lens element being arranged to focus sunlight either directly on the absorption chamber or via the reflecting plate.

The at least one lens element may be used as a collector. The at least one lens element may be used as solar concentrator.

The at least one lens element may be a Fresnel lens.

The at least one lens element may have a positive focal length. The at least one lens element may be an inverted Fresnel lens. The Fresnel lens may have its facets, or grooves, on the focus side of the lens. The Fresnel lens may have its facets, or grooves, on the underside of the lens. The at least one lens element may be substantially planar on its non-focus side and have light focussing elements, or surfaces, on its focus side. The at least one lens element may be substantially planar on its non-focus side and have light focussing facets on its focus side. The at least one lens element may include a piano side. The at least one lens element may be used to concentrate sunlight and bring it to a focus at its focus point.

The Fresnel lens may be modular. The Fresnel lens may comprise a number of lens elements, wherein each lens element contributes to a complete Fresnel lens. The Fresnel lens may comprise a number of lens elements, wherein each lens element contributes to a complete Fresnel lens of sufficient area to provide the requisite heat energy. The lens includes a centre lens element and a number of lens elements

surrounding the centre lens element. The centre lens element includes the centre of the concentric facets (concentric facet rings), rings, or grooves, of the Fresnel lens and each additional lens element together provides the surrounding concentric facets, rings, or grooves, of the Fresnel lens. The centre lens element is unique, as it contains the centre of the concentric facets, rings, or grooves, of the Fresnel lens, and the surrounding satellite lens elements are identical. The lens elements of the modular Fresnel lens are hexagonal. The lens elements may be made from PMMA (Poly(methyl methacrylate)), or polycarbonate (Lexan). In this arrangement the modular Fresnel lens includes one central hexagonal lens element and six surrounding hexagonal lens elements. Together the seven lens elements make up a Fresnel lens. The Fresnel lens modules may be supported on a modular framework. The modular framework may be made from lightweight metal. The metal may be aluminium. The at least one lens element may be configured to provide focussed sunlight directly to the oven. In this arrangement the at least one lens element may focus sunlight towards the oven. In this arrangement the at least one lens element may focus sunlight directly into the reflection chamber, or second chamber, of the oven. The at least one lens element may be configured to provide focussed sunlight indirectly to the oven. In this arrangement the cooking apparatus may further comprise a reflector plate configured to reflect sunlight from the at least one lens element towards the oven. In this arrangement the cooking apparatus may further comprise a reflector plate configured to reflect sunlight from the at least one lens element towards the absorption chamber of the oven. In this arrangement the at least one lens element directs focussed sunlight towards the reflector plate, and the reflector plate then reflects the sunlight towards the oven. In this arrangement the at least one lens element directs focussed sunlight towards the base

(absorption) plate of the oven. In this arrangement the at least one lens element directs focussed sunlight towards the reflector plate, and the reflector plate then reflects the sunlight towards the absorption chamber of the oven.

The at least one lens element may be configured to provide focussed sunlight indirectly to the oven. In this arrangement the cooking apparatus may further comprise a mirror configured to reflect sunlight from the at least one lens element towards the first chamber of the oven. In this arrangement the cooking apparatus may further comprise a mirror configured to reflect sunlight from the at least one lens element towards the first chamber of the oven. In this arrangement the at least one lens element directs focussed sunlight towards the mirror, and the mirror then reflects the sunlight towards the oven. In this arrangement the at least one lens element directs focussed sunlight towards the mirror, and the mirror then reflects the sunlight towards the first chamber of the oven. In this arrangement the at least one lens element directs focussed sunlight towards the mirror, and the mirror then reflects the sunlight through the glass plate that separates the first and second chambers towards the first chamber of the oven. The reflector plate may be planar. The reflector plate may be curved. The reflecting surface of the reflector plate may be convex. The reflecting surface of the reflector plate may be polished aluminium.

The reflector plate may be mountable to the oven. The reflector plate may be mountable to a lower portion of the oven. The reflector plate may be adjustable relative to the oven.

The mirror may be a high temperature borosilicate glass mirror or polished aluminium planar surface.

The at least one lens element, oven, frame member and reflector plate may be arranged to allow the focussed sunlight from the at least one lens element to be reflected from the reflector plate to the oven. The at least one lens element, oven, frame member and reflector plate may be arranged to allow the focussed sunlight from the at least one lens element to be reflected by the reflector plate into the absorption chamber of the oven. In this arrangement the sunlight is directed towards the transparent wall portion of the oven. In this arrangement the sunlight focussed by the at least one lens element illuminates substantially the entire area of the reflecting surface of the reflector plate and substantially the entire area of the transparent wall portion of the oven. In this arrangement the sunlight focussed by the at least one lens element is reflected via the reflecting plate into the absorption chamber.

The at least one lens element, oven, frame member and mirror may be arranged to allow the focussed sunlight from the at least one lens element to be reflected from the mirror to the oven. The at least one lens element, oven, frame member and mirror may be arranged to allow the focussed sunlight from the at least one lens element to be reflected by the mirror into the first chamber of the oven. The at least one lens element, oven, frame member and mirror may be arranged to allow the focussed sunlight from the at least one lens element to be reflected by the mirror onto the absorber plate of the first chamber of the oven. In this arrangement the sunlight is directed towards the borosilicate wall portion of the oven. In this arrangement the sunlight focussed by the at least one lens element illuminates substantially the entire area of the open portion of the oven and substantially the entire area of the mirror. In this arrangement the sunlight focussed by the at least one lens element is reflected via the mirror into the first chamber. In this arrangement the sunlight focussed by the at least one lens element is reflected via the mirror onto the absorber plate of the first chamber. This may be through the glass plate that separates the first and second chambers.

The cooking apparatus may further comprise an oven rotating device. The oven rotating device may be an automatic oven rotating device. The oven rotating device may be configured to rotate the oven between the first position and the second position about the first axis of rotation. The oven rotating device may be configured to rotate the oven between the second position and the first position about the first axis of rotation. The oven rotating device may be configured to pull the oven from the first position to the second position. The oven rotating device may be configured to pull the oven from the second position to the first position.

The oven rotating device may be configured to apply a torque to the oven to rotate the oven between the first position and the second position. The oven rotating device may be configured to apply a torque to the oven to rotate the oven between the second position and the first position.

The oven rotating device may comprise a wire having a first end that is attached to the oven and a second end that is attached to a pulling mechanism. Operation of the pulling mechanism causes a force to be applied to the wire and a torque to be applied to the oven via the first end of the wire. In this arrangement the pulling mechanism pulls the second end of the wire.

The pulling mechanism may include a water-operated pulling system. The water-operated pulling system may comprise a pipe member, a float and a water transfer device. The pipe member may be sealed at one end thereof and open at the other. The pipe member is arranged to be in a vertical position with the sealed end at the bottom thereof. The pipe member may include two chambers, an upper chamber and a lower chamber. The water transfer device may be arranged to allow water to be transferred from the upper chamber to the lower chamber. The water transfer device may be arranged to allow water to be transferred between the first and second chambers at a very low rate. The water may be transferred by dripping the water into the second chamber from the first chamber. In this

arrangement the transfer of water from the first chamber to the second chamber may take several hours, for example, up to eight hours.

The float may be located in the second chamber of the pipe and may be arranged such that it can move freely between the bottom of the pipe towards the top of the pipe, or towards the top of the pipe. Attached to the float is the second end of the wire. The pulling mechanism also includes a number of pulleys. A first pulley may be located at the bottom of the pipe and a second pulley may be located towards the middle of the pipe. The wire is connected to the oven (at the first end), and the first and, optionally, second pulleys.

The pulling mechanism may be arranged such that, in use, water held in the first chamber is transferred to the second chamber via the water transfer device. As the water is transferred to the second chamber the second chamber begins to fill with water. As the second chamber fills up with water, the float begins to rise up the second chamber. As the float rises up the second chamber a force is applied to the second end of the wire, i.e. the wire is put under tension. This tension is transmitted through the wire via the first and second pulleys to the oven. The wire then applies a torque to the oven to rotate the oven from either the first position to the second position, or the second position to the first position, depending on the starting conditions.

According to a second aspect of the invention there is provided a modular lens comprising at least two lens elements, the at least two lens elements combining to produce a lens having a plurality of concentric facets, rings, or ridges, on at least one surface thereof.

The modular lens may be a Fresnel lens.

The at least one lens element may have a positive focal length. The at least one lens element may be an inverted Fresnel lens. The Fresnel lens may have its facets, or grooves, on the focus side of the lens. The Fresnel lens may have its facets, or grooves, on the underside of the lens. The at least one lens element may be substantially planar on its non-focus side and have light focussing elements, or surfaces, on its focus side. The at least one lens element may include a piano side. The at least one lens element may be used to concentrate sunlight and bring it to a focus at its focus point.

The modular lens may comprise a number of lens elements, wherein each lens element contributes to a complete Fresnel lens. The modular lens may comprise a number of lens elements, wherein each lens element contributes to a complete Fresnel lens of appropriate surface area to provide the requisite quantity of heat for cooking utility. The modular lens may include a centre lens element and a number of lens elements surrounding the centre lens element. The centre lens element may include the centre of the concentric facets (concentric facet rings), rings, or grooves, of the Fresnel lens and each additional lens element together provide the surrounding concentric facets, rings, or grooves, of the Fresnel lens. The centre lens element is unique, as it contains the centre of the concentric facets, rings, or grooves, of the Fresnel lens, and the

surrounding additional lens elements are identical. The lens elements of the modular lens may be hexagonal. In this arrangement the modular lens includes one centre hexagonal lens element and six surrounding hexagonal lens elements. Together the seven lens elements make up a Fresnel lens. The lens elements of the modular Fresnel lens are hexagonal. The lens elements may be made from PMMA (Poly(methyl methacrylate)), or polycarbonate (Lexan). In this arrangement the modular Fresnel lens includes one centre hexagonal lens element and six surrounding hexagonal lens elements. Together the seven lens elements make up a Fresnel lens. The Fresnel lens modules may be supported on a modular frame. The modular frame may be hexagonal. The modular frame may be made from lightweight metal. The metal may be aluminium.

According to a third aspect of the present invention there is provided an apparatus for cooking comprising:

a frame member;

an oven mountable to the frame member; and

at least one lens element mountable to the oven or the frame member;

wherein the frame member is configured to permit the oven to at least partially rotate relative to the frame member about at least one axis of rotation, and

wherein, in use, the at least one lens element is arranged to provide focussed sunlight to the oven.

According to a fourth aspect of the present invention there is provided an oven for a solar cooking apparatus, the oven comprising:

a hollow body portion, wherein the hollow body portion is configured to receive food to be cooked therein, and wherein at least a portion of a wall of the body portion is transparent.

The oven may be substantially cylindrical. The hollow body portion may be substantially cylindrical. The oven may include at least one removable end portion. The oven may include a removable lid. The oven may include two removable end portions. The oven may include a removable base portion.

The walls of the oven may be insulated. The walls of the oven may be insulated with foam. The foam may be phenolic foam. The insulation may be cellular glass. The insulation may be rock wool. The insulation may be a combination of any of phenolic foam, cellular glass, rock wool, or mineral wool. At least a portion of the oven may be made from metal. The metal may be copper, aluminium or galvanised steel. The internal walls of the oven may be made from copper, aluminium or galvanised steel. The outer wall may be made from a polymer material. The outer wall may be made from polypropylene.

The oven may include a first chamber and a second chamber. The first chamber may be a cooking chamber and the second chamber may be a reflector chamber The first chamber may be configured to receive cooking utensils, such as pots and the like. The first chamber may include a base plate located towards a lower end of the first chamber. The base plate may be made from stone. The first chamber may include a cooking plate located towards an upper end of the first chamber. The cooking plate may be a frying plate or a pizza plate. The cooking plate may be positioned closely to the underside of the lid of the oven, such that an upper facing surface of the cooking plate is exposed when the lid of the oven is removed. The cooking plate is removable from the oven. The cooking plate may be made from stone, Teflon (TM) coated steel or fired clay.

transparent wall portion may be made from glass. The glass may be a glass pate. The glass may be borosilicate glass. The glass plate may be made from borosilicate glass. The second chamber may be configured to allow sunlight focussed by the at least one lens element to enter the second chamber through the transparent wall portion. The oven may include a removable cover member that is arranged to cover the

transparent wall portion of the second chamber. The removable cover member may be insulated. The removable cover member may be an insulated plug.

The second chamber may include an open portion. The open portion may be an open front portion. The open portion allows entry of the sunlight focussed by the at least one lens element. The second chamber may include a transparent wall portion. The transparent wall portion may be located on an upper portion of the chamber. The transparent wall portion may be made from glass. The glass may be a glass pate. The glass may be borosilicate glass. The glass plate may be made from borosilicate glass. The first chamber and second chamber may be separated by the transparent wall portion. The second chamber may be configured to allow sunlight focussed by the at least one lens element to enter the second chamber through the open portion. The oven may include a removable cover member that is arranged to cover the open portion of the second chamber. The removable cover member may be insulated. The removable cover member may be an insulated plug. The second chamber may include one or more door members that may be used to cover the open portion.

The oven may further comprise an aluminium heat shield which

substantially surrounds the transparent wall portion, or the open portion.

The walls of the second chamber may be made from metal. The metal may be copper, aluminium or galvanised steel.

At least a portion of the inner surface of the second chamber may include wire wool. The wire wool may be metal wire wool. The wire wool may be copper wool. The inner walls of the second chamber around the transparent wall portion may be covered with wire wool. The wire wool may be copper wool.

At least a portion of the inner surface of the second chamber may be coated with a material that has a high electromagnetic absorption coefficient, particularly in the wavelengths of spectral light and near and infrared. At least a portion of the inner surface of the second chamber may be coated with a black selective surface. At least a portion of the inner surface of the second chamber may be coated with a black selective material. The inner walls of the second chamber around the transparent wall portion may be coated with a material that has a high electromagnetic absorption coefficient, particularly in the wavelengths of spectral light and near infrared and a low thermal emissivity coefficient.

According to a fifth aspect of the present invention there is provided an apparatus for cooking comprising:

a frame member;

an oven mountable to the frame member, wherein the oven comprises:

a hollow body portion, wherein the hollow body portion is configured to receive food to be cooked therein, and wherein at least a portion of a wall of the body portion is transparent; and

at least one lens element mountable to the oven or the frame member;

wherein, in use, the at least one lens element is arranged to provide focussed sunlight to the transparent body portion of the oven.

According to a sixth aspect of the present invention there is provided an apparatus for cooking comprising:

a frame member; an oven mountable to the frame member, wherein the oven comprises:

a hollow body portion, wherein the hollow body portion is configured to receive food to be cooked therein, and wherein at least a portion of a wall of the body portion is open; and at least one lens element mountable to the oven or the frame member;

wherein, in use, the at least one lens element is arranged to provide focussed sunlight to the open portion of the wall of the oven.

The alternative features and different embodiments as described apply to each and every aspect and each and every embodiment thereof mutatis mutandis. Embodiments of the invention will now be described, by way of example only, with reference to the following drawings, in which:-

Figure 1 is side view of an apparatus for cooking according to the present invention;

Figure 2 is a partial cross-sectional view of the cooking apparatus of the present invention;

Figure 3 is a plan view of the cooking apparatus of figure 1 ;

Figure 4 is a plan view of the cooking apparatus of figure 1 without the lens element;

Figure 5 is a cross-sectional view of the oven rotation device of the cooking apparatus; Figure 6 is a side view of an apparatus for cooking according to an alternate embodiment of the present invention; Figure 7 is partial cut away view of the cooking apparatus of figure 6; Figure 8 is a plan view of the cooking apparatus of figure 6; Figure 9 is a further side view of the cooking apparatus of figure 6;

Figure 10 is a front view of the cooking apparatus of figure 9;

Figure 1 1 is a plan view of the cooking apparatus of figure 9; Figure 12 is a plan view of the lens element of the cooking apparatus;

Figures 13a and 13b are cross-sectional views of the lens element of the cooking apparatus. As illustrated in figures 1 to 4, the cooking apparatus 10 includes a frame member 12, an oven 14 mounted to the frame member 12, a lens 16 mounted to the oven 14, a reflector plate 18 mounted to the frame member 12 and an oven rotating device 20. The frame member 12 is a free-standing structure which is designed to be placed on the ground. The frame member 12 includes a ground-engaging base portion 12a. The ground-engaging base portion 12a is a triangular- shaped member (see figure 3). The cooking apparatus 10 is configured such that the oven 14 and lens 16 substantially lie within an area defined by the footprint that the ground-engaging base portion 12a makes on the ground. This ensures that the cooking apparatus 10 remains stable during use and is not easy to tip over.

The frame member 12 is configured to provide support to the oven 14. As explained further below, the frame member 12 is configured to allow the oven 14 to partially rotate relative to the frame member 12 about a first axis of rotation 22 and a second axis of rotation 24. The first axis of rotation 22 and the second axis of rotation 24 are orthogonal. The frame member 12 is configured to permit the oven 14 to rotate between a first position and a second position about the first axis of rotation 22 and to rotate between a first position and a second position about the second axis of rotation 24. As illustrated in figures 1 and 3, the frame member 12 includes oven support arms 12b. The oven support arms 12b are attached to, or formed with, the ground engaging base portion 12a of the frame member 12. The oven support arms 12b are arranged such that the oven 14 is located there between. As explained further below, the oven support arms 12b are configured to pivotably support the oven 14. The oven 14 may pivot about a pivot point A, as illustrated in figure 1 .

The frame member 12 includes an oven receiving member 26, which is configured to provide support to the oven 14 when mounted therein. In the embodiment illustrated and described here, the oven receiving member 26 is a ring-shaped member that defines an aperture 26a through which the oven 14 is placed.

As illustrated in figures 1 and 3, the oven receiving member 26 is pivotably mounted to the oven support arms 12b of the frame member 12. The oven receiving member 26 and the oven 14, when located therein, may thus pivot with respect to the oven support arms 12b of the frame member 12. In addition to the oven 14 being able to pivot about pivot point A relative to the frame member 12 about the second axis of rotation 24, the oven 14 can also rotate relative to the frame member 12 about the first axis of rotation 22. In order to achieve this the oven 14 is configured to be rotatably engageable with the oven receiving member 26.

As illustrated in figures 1 and 3, the oven 14 includes caster rollers 28 (an example of one or more rolling members) attached to the side wall 14a thereof. The caster rollers 28 are pivotably connected to the oven, such that the wheels 28a of the caster rollers 28 automatically align to the direction of travel. When the oven 14 is located in the oven receiving member 26, the caster rollers 28 engage with the upper facing surface 26b of the oven receiving member 26. In this arrangement the upper facing surface 26b of the oven receiving member 26 provides a track on which the caster rollers 28 may run as the oven 14 rotates relative thereto.

The frame member 12 further comprises an oven support plate 30. The oven support plate 30 is configured to provide support to the lower portion of the oven 14 as the oven rotates about the first axis of rotation 22. As illustrated in figures 1 and 2, the oven support plate 30 is pivotably connected to the frame member 12 and is pivotable between a first position and a second position relative to the ground engaging member ground-engaging base portion 12a of the frame member 12. As explained further below, the oven support plate 30 may be releasably fixed in the first pivot position, the second pivot position, or at any position there between. The frame member 12 further comprises a tilt support member 32, which is configured to support the oven 14 when in tilted position relative to the frame member 12. The tilt support member 32 is operable to provide support to the oven support plate 30. As explained below, the oven support plate 30 is fixedly engageable with the tilt support member 32. The oven support plate 30 is adjustably engageable with the tilt support member 32, such that the pivot position may be adjusted as required during use, as explained below. As illustrated in figures 1 and 2, the tilt support member 32 includes a slot 32a. The slot 32a is configured to be engageable with a slot engagement portion 30a of the oven support plate 30. The slot 32a allows the oven support plate 30 to move between the first position and the second position relative to the frame member 12. In the embodiment illustrated and described here the slot 32a is curved. However, it should be appreciated that the slot 32a may straight, or any other shape that allows the slot to provide support to the oven support plate 30 in the manner described above.

The frame member 12 further comprises a releasable fixing member 34 that is configured to hold the slot engagement portion 30a of the oven support plate 30 in a fixed engagement with the slot 32a of the tilt support member 32a. The releasable fixing member is a thumbscrew and washer. However, it should be appreciated that other releasable fixing members could be used. The angle of tilt of the oven support plate 30 is set depending on the latitude and time of year.

The oven 14 also includes a further caster roller 36 (an example of a rolling member) attached to a lower portion thereof. In the embodiment illustrated and described here the caster roller 36 is mounted to a supporting arm 38 connected to the base portion 14b of the oven 14. However, it should be appreciated that the further caster roller 36 may be connected directly to the base portion 14b of the oven 14.

The further caster roller 36 is configured such that it is pivotably connected to the supporting arm 38 of the oven 14, such that the wheel 36a the caster roller 36 automatically aligns to the direction of travel. When the oven 14 is located in the oven receiving member 26, the further caster roller 36 engages with an upper facing surface 30b of the oven support plate 30. In this arrangement the upper facing surface 30b of the oven support plate 30 provides a track on which the caster roller 36 runs as the oven 14 rotates relative thereto.

The lens 16 is adjustably mountable to the oven 14 (or frame member 12). The lens 16 is mountable to the oven 14 such that the lens 16 may pivot relative to the oven 14 and the frame member 12. As best illustrated in figure 1 , the oven 14 further comprises support arms 40 for supporting the lens 16. The support arms 40 are arranged such that the lens 16 is connectable to one end of each support arm 40. The lens 16 is adjustably connectable to the support arms 40 such that the lens 16 may pivot with respect to the support arms 40. The lens 16 may pivot about pivot point B. The support arms 40 are located towards the top of the oven 14. The support arms 40 are fixedly attachable to the oven 14. The support arms 40 are also arranged such that a counterweight 42 is attached to the arms 40 at the opposite end of the lens 16. The counterweight 42 is pivotably connectable to the support arms 40 of the oven 14 and serves to provide balance to the weight of the lens 16.

As best illustrated in figure 2, the oven 14 is substantially cylindrical. The oven has a lid 14c and a removable base 14d. The walls 14e of the oven 14 are insulated with an insulating material 14f. The insulating material 14f is phenolic foam. However, it should be appreciated that other types of high temperature resisting insulation could be used.

In the embodiment illustrated and described here the internal walls 14g of the oven 14 are made from copper and the outer walls 14h are made from polypropylene. However, it should be appreciated that other types of material could be used, metal or otherwise.

The oven 14 includes a first chamber 14i and a second chamber 14j (an example of an absorption chamber). The first chamber 14i is configured to receive cooking utensils, such as pots (not illustrated) and the like. The first chamber 14i includes a base plate 14k located towards a lower end of the first chamber 14i. The base plate 14k may be made from stone or fired clay. The first chamber 14i also includes a cooking plate 141 located towards an upper end of the first chamber 14i. The cooking plate 141 is positioned closely to the underside of the lid 14c, such that an upper facing surface of the cooking plate 141 is exposed when the lid 14c of the oven 14 is removed. The cooking plate 141 may be removable from the oven 14. The cooking plate 141 may be made from stone or fired clay. As described above, the walls 14g of the first chamber 14i could be made from copper, aluminium or galvanised steel.

The second chamber 14j is configured to receive the sunlight from the lens 16. As described further below, the second chamber 14j absorbs and captures the focussed light from the lens 16 to provide a heat source for the oven 14. As best illustrated in figures 1 and 2, a portion of the side wall 14a of the oven 14 includes a glass plate 44. The glass plate 44 allows the second chamber 14j to be transparent to the focussed sunlight from the lens 16. In the embodiment illustrated and described here the glass plate 44 is made from borosilicate glass. However, it should be appreciated that other suitable types of materials could be used.

As illustrated in figure 2, the oven 14 also includes an insulated cover member 46. The insulated cover member 46 may be used to cover the glass plate 44 when the oven 14 is not in use, or once the oven has reached its highest temperature. The insulated cover member 46 has the same construction as the walls 14e of the oven 14. That is, the insulated cover member 46 has an internal copper wall and phenolic foam insulation between the inner wall and the outer wall. The cover member 46 may have aluminium foil wrapped around phenolic foam insulation.

As illustrated in figure 1 , the oven 14 also comprises an aluminium heat shield 48 which substantially surrounds the transparent wall portion. The heat shield protects the outer walls 14e from accidental light beam spillage.

As described above, the walls 14g of the second chamber 14j are made from copper, aluminium or galvanised steel.

The base plate 14k of the first chamber 14i is coated with a material that has a high electromagnetic absorption coefficient and low thermal emissivity. The material used in the embodiment illustrated and described here is Solkote, available from SOLEC-Solar Energy Corp. 129 Walters Ave. Ewing, NJ 08638-1829, USA. However, it should be appreciated that other suitable types of materials with high electromagnetic absorption and low thermal emissivity coefficients in the appropriate wavelengths could be used. A lower surface 14m of the second chamber 14j is located adjacent the base portion 14b of the oven 14. In this arrangement the lower surface 14m of the second chamber 14j is exposed when the base portion 14b of the oven 14 is removed. This allows a metal plate to be inserted to protect the selective surface and a heat source to be applied to the oven, such as a flame, if the lens 16 is not being used, e.g. due to lack of sunlight.

As described above, the cooking apparatus 10 further comprises a reflector plate 18 that is configured to reflect sunlight from the lens 16 to the oven 14. The reflector plate 18 has either a borosilicate glass mirror or a polished aluminium surface. In this arrangement the lens 16 focuses sunlight towards the reflector plate 18 and the reflector plate 18 reflects this sunlight through the glass plate 44 and onto the base plate 14k of the first chamber 14i. The reflector plate 18 is mounted to the supporting arm 38 of the oven 14. The reflector plate 18 may be adjustably connected to the supporting arm 38, such that the angle of reflection may be adjusted in use.

The lens 16 has a focus point F1 , and the reflector plate 18 is positioned between the focus point F and the lens 16, i.e. within the focal length of the lens 16. This arrangement ensures that the reflecting surface of the reflector plate 18 is illuminated by the focussed sunlight from the lens 16. This also ensures that the reflector plate 18 is not subjected to the very high temperatures possible at the focus point F1 of the lens 16, which could damage the reflector plate 18. Similarly, the focus point F2 of the reflector plate is positioned such that it lies within the oven 14. Again, this arrangement ensures that the entire surface area of the glass plate 44 is illuminated by the reflected sunlight from the reflector plate 18. This ensures that as much sunlight as possible enters the second chamber 14j. This also ensures that the glass plate 44 is not subjected to the very high temperatures possible at the focus point F2 of the reflector plate 18, which could damage the glass plate 44.

As illustrated in figures 1 to 3, the lens 16 is a modular Fresnel lens. As best illustrated in figure 3, the lens 16 comprises a number of lens elements 16a, 16b. Each lens element 16a, 16b contributes to a complete Fresnel lens. The lens 16 has a centre lens element 16b and six surrounding lens elements 16a. The centre lens element 16b includes the centre portion of the Fresnel lens, i.e. the centre ring of the concentric rings, and each additional lens element 16a together provide the surrounding concentric rings of the Fresnel lens. As illustrated in figure 3, the lens elements 16a, 16b are hexagonal, which allows the lenses 16a, 16b to fit together to provide the known concentric ring Fresnel lens arrangement. The lens elements 16a, 16b are connected together by a lightweight aluminium framework (not illustrated). The lens 16 can be made from PMMA Poly(methyl methacrylate), or polycarbonate (Lexan). The lens 16 may be manufactured by injection moulding. However, it should be appreciated that the lens 16 could be manufactured by other suitable methods.

The lens 16 has its facets 15, or grooves, on the focus side of the lens 16. As illustrated, the lens 16 is substantially planar on its non-focus side and has light focussing elements 15, or surfaces, on its focus side. The lens element 16 thus includes a piano side 19 and a light focussing side 21 . The facets 15 of the lens 16 are 1 mm wide and the height of the facets 15 range from 0mm at the centre of the lens 16 to around 0.75mm at the edge of the lens 16. In the embodiment illustrated and described here the lens 16 has a refractive index of 1 .59 and a focal length of 850mm. In this arrangement it should be appreciated that the lens elements 16a are identical and the centre lens element 16b is unique. This means that only two moulds are required to manufacture the lens 16. The hexagonal arrangement also means that the lens 16 can be packaged very

compactly, with the lens elements 16a, 16b being stacked on top of one another.

As described above, the cooking apparatus 10 further comprises an oven rotating device 20. In the embodiment illustrated and described here the oven rotating device 20 is a water-operated, float pulley device, that automatically rotates the oven 14 between the first position and the second position about the first axis of rotation 22. The oven rotating device 20 is configured to pull the oven 14 from the first position to the second position. As described further below, the oven rotating device 20 is configured to pull the oven from the second position to the first position. The oven rotating device 20 achieves this by applying a torque to the oven 14 to rotate the oven 14 between the first position and the second position.

The oven rotating device 20 comprises a wire 56 having a first end 56a that is attached to the oven 14 and a second end 56b that is attached to a pulling mechanism 58. Operation of the pulling mechanism 58 causes a tension on the wire 56 and a torque to be applied to either the oven 14 or the counterbalancing legs via the first end 56a of the wire 56. In this arrangement the pulling mechanism 58 pulls the second end 56b of the wire 56.

In the embodiment illustrated and described here the pulling mechanism 58 is a water-operated pulling system. The water-operated pulling system comprises a pipe member 60, a float 61 and two water transfer devices 62, 64 (Note: only one water transfer device is illustrated in figure 5). The pipe member 60 is a cylindrical member that is sealed at one end thereof and open at the other. The pipe member 60 is arranged to be in a vertical position with the sealed end at the bottom thereof. The pipe member include two chambers, an upper chamber 60a and a lower chamber 60b. The water transfer devices 62, 64 are arranged to allow water to be transferred from the upper chamber 60a to the lower chamber 60b. The water transfer devices 62, 64 are arranged to allow water to be transferred between the first and second chambers 60a, 60b at a very low rate, e.g. by dripping the water into the second chamber 60b from the first chamber 60a. The water drips are illustrated at C in figure 5. In this arrangement the transfer of water from the first chamber 60a to the second chamber 60b may take several hours. The flow rate of water between the first and second chambers 60a, 60b may adjusted by the water transfer devices 62, 64 as required by the use of the cooking apparatus 10.

Inside the second chamber 60b of the pipe 60 there is provided the float 61 . The float is located in the second chamber 60b of the pipe 60 and may be arranged such that it can move freely between the bottom of the pipe towards the top of the pipe. Attached to the lower end of the float is the second end 56b of the wire 56.

The pulling mechanism 58 also includes a number of pulleys through which the wire 56 may pass. A first pulley 63 may be located inside the pipe at the bottom end thereof and second pulleys 58a are located on an outer surface of the pipe 60 towards the middle portion thereof and the frame member 12. The wire 56 is connected to the oven 14 (at the first end 56a), and the first and second pulleys 63, 58a. As described further below, the pulling mechanism 58 is arranged such that, in use, water held in the first chamber 60a is transferred to the second chamber 60b via the water transfer devices 62, 64. As the water is transferred to the second chamber 60b the second chamber 60b begins to fill with water. As the second chamber 60b fills up with water, the float begins to rise up the second chamber 60b. As the float rises up the second chamber 60b a tension is applied to the second end 56b of the wire 56. This tension is transmitted through the wire 56 via the first and second pulleys 58a to the oven 14. The wire 56 then applies a torque to the oven 14 to rotate the oven 14 from either the first position to the second position, or the second position to the first position, depending on the starting conditions.

The oven support plate 30 includes ridges 30c on the upper facing surface 30b. The ridges 30c are located on the side of the oven support plate 30 that the oven 14 moves on from its highest position to the lowest position. The ridges 30c prevents the oven 14 simply rolling down the oven support plate 30 by the effect of gravity thereon. The pulling mechanism 58 of the oven rotating device 20 pulls the oven 14 over the ridges 30c as it operates.

With reference to figures 1 to 4, the operation of the cooking apparatus 10 will now be described. Figure 2 illustrates the starting position of the oven 14. In this position the oven 14 is in the "first position", as referred to above. The food to be cooked is placed in the first chamber 14i. Typically, the food to be cooked will be held in cooking pots, or the like. The pots will rest on the stone base plate 14k. The pipe member 60 of the oven rotating device 20 is filled with water. That is, the first chamber 60a is filled with the required amount of water. Once the first chamber 60a is filled with water, the water transfer devices 62, 64 are set to the desired flow rates. As described further below, two thirds of the water in the first chamber 60a is required to move the oven 14 to the highest position on the oven support plate 30. Water transfer device 62 is set to ensure that enough water is available, at the correct flow rate, to allow the oven 14 to reach the highest position on the oven support plate 30. Once the oven 14 reaches its highest position on the oven support plate 30, one third of the water in the first chamber 60a is required to move the oven 14 back to the lowest position on the oven support plate 30, i.e. to move the oven 14 to its "second position", as described above.

The oven support plate 30 and the tilt support member 32 are then arranged to set the angle of inclination of the oven 14 to angle required for the location of the oven 14 with respect to the path of the Sun during the day. Figure 1 illustrates the oven 14 in the tilted position. The

arrangement of the oven 14 is carried out manually by a user of the cooking apparatus 10. The position of the lens 16 and the reflector plate 18 relative to the oven 14 are then set to ensure that the sunlight passes through the lens 16 to the second chamber 14j, via the reflector plate 18. As described above, the lens 16, reflector plate 18 and second chamber 14j are arranged such that the entire surface area of both the reflector plate 18 and the glass plate 44 of the second chamber 14j are illuminated by the sunlight from the lens 16. This ensures that as much sunlight as possible is transferred into the second chamber 14j during use.

Once the cooking apparatus 10 is set up as described above, sunlight from the Sun passes through the lens 16 and is reflected by the reflector plate 18 into the second chamber 14j of the oven 14. This causes the second chamber 14j to heat up. As described above, the highly absorbent coating on the inner surface of the second chamber 14j ensures that as much electromagnetic radiation is captured as possible; the selective surface ensures that the second chamber 14j heats up quickly. The borosilicate glass plate 44 also ensures that as little convective heat as possible is transferred out of the first chamber 14i.

This arrangement ensures that sufficient heat is generated to heat the first chamber 14i and to cook the food therein. The temperature and/or thermal storage of the first chamber 14i may be controlled using, for example, using stone discs in the first chamber 14i. The number of stone discs chosen can be adjusted to the specific requirements of the cooking apparatus 10. The stone discs may be placed on the base plate 14k and used as mobile hot plates when the food is served.

In order to ensure that sunlight continues to enter the oven 14, it is necessary to move the oven 14 with respect to the frame member 12 as the Sun moves relative to the Earth. As described above, the oven rotation device 20 ensures that the oven moves between the first position and the second position, i.e. the starting position and the finishing position. The starting position may correspond to a "sunrise" position, and the finishing position may correspond to a "sunset" position. The configuration of the pulling mechanism 58 of the oven rotation device 20, and in particular, the flow rate of the water between the first and second chambers 60a, 60b of the pipe 60, ensures that the oven 14 follows the Sun as the Earth orbits the Sun, such that sunlight is continuously passed into the second chamber during the course of the day. Part of this tracking and continuous transfer of sunlight into the oven 14 is the movement of the oven 14 on the oven support plate 30. As illustrated in figures 1 and 2, as the oven rotation device 20 pulls the oven 14 from the first position to the second position, the oven 14 rotates about the first axis of rotation 22 and rolls via caster rollers 28 and 36 on the oven receiving member 26 and oven support plate 30. In moving between the first position and the second position, the oven firstly travels up the oven support plate 30 until it reaches its maximum height, as illustrated in figure 1 , and then travels down the oven support plate 30 as the oven continues to rotate until it reaches a minimum height at the bottom of the oven support plate 30. The path that the oven 14 moves through in this arrangement mimics the path of the Sun relative to the Earth. This ensures that the sunlight passes into the oven 14 throughout the course of the day.

Figures 6 to 1 1 illustrate an alternate embodiment of the cooking apparatus 10'. The cooking apparatus 10' includes three support members 12a', 12b', 12c' (together an example of a frame member), an oven 14' mounted on the support members 12a', 12b', 12c', a lens 16' mounted to the oven 14' and a reflector mirror 18' mounted inside the oven 14'.

The three support members 12a', 12b', 12c' are support legs. The apparatus 10' includes an upper support leg 12a' that is attached towards an upper portion of the oven 14' and two lower support legs 12b' and 12c'. The upper support leg 12a' is pivotably connected to the oven 14' such that the upper support leg 12a' may pivot with respect to the oven 14' about a pivot point 1 1 '. The upper support leg 12a' is telescopic such that the overall length of the upper support leg 12a' may be adjusted. The upper support leg 12a' also includes a ground engaging member 12d'. The ground engaging member 12d' is pivotably connected to the lower portion of the upper support leg 12a'. The lower support legs 12b' are connected to the lower portion of the oven 14'. The lower support legs 12b' also include ground engaging members 12d'. Again, the ground engaging members 12d' are pivotably connected to the lower portion of the lower support legs 12b' and are arranged to pivot about a pivot point 13'. In this arrangement the three support members 12a', 12b', 12c' allow the oven 14' to pivot between a tilted position and an upright position. That is, the three support members 12a', 12b', 12c' allow the oven 14' to at least partially rotate about at least one axis of rotation.

The lens 16' is adjustably mountable to the oven 14'. The lens 16' is mountable to the oven 14' such that the lens 16' may pivot relative to the oven 14'. As illustrated, the apparatus 10' includes support arms 40' for supporting the lens 16'. The support arms 40' are arranged such that the lens 16' is connectable to one end of each support arm 40'. The lens 16' is adjustably connectable to the support arms 40' such that the lens 16' may pivot with respect to the support arms 40'. The lens 16' may pivot about pivot point B'. The support arms 40' are located towards the bottom of the oven 14'. The support arms 40' are fixedly attachable to the oven 14'. The support arms 40' also extend away from the oven 14' on the opposite side to that of the lens 16'. As illustrated, the support arms 40' are substantially L-shaped. The support arms 40' are also arranged such that a counterweight 42' is attached to the arms 40' at the opposite end of the lens 16'. The counterweight 42' is pivotably connectable to the support arms 40' of the oven 14' and serves to provide balance to the weight of the lens 16'. In the embodiment illustrated here the support arms 40' are formed in two parts. However, it should be appreciated that the support arms 40' may be formed from a single member. As illustrated, the oven 14' is substantially cylindrical. The oven 14' has a lid 14c'. The walls 14e' of the oven 14' are insulated with an insulating material 14f, as illustrated in figure 7. The insulating material 14f is phenolic foam and mineral wool. However, it should be appreciated that other types of insulation could be used.

In the embodiment illustrated and described here the internal walls 14g' of the oven 14' are made from copper and the outer walls 14h' are made from polypropylene. However, it should be appreciated that other types of material could be used, metal or otherwise.

The oven 14' includes a first chamber 14i' (cooking chamber) and a second chamber 14j' (reflection chamber) (an example of an absorption chamber). The first chamber 14i' is configured to receive cooking utensils, such as pots (not illustrated) and the like. The first chamber 14i' includes a base plate 14k' located towards the lower end of the first chamber 14i'. The base plate 14k' may be made from copper, aluminium or galvanised steel. As described above, the walls 14g' of the first chamber 14i' are made from copper, aluminium or galvanised steel.

The first chamber 14i' and the second chamber 14j' are separated by a borosilicate glass plate 14n' (an example of a transparent wall portion).

The second chamber 14j' is configured to receive the sunlight from the lens 16'. As described further below, the second chamber 14j' absorbs and captures the focussed light from the lens 16' to provide a heat source for the oven 14'. As best illustrated in figures 7 and 8, a portion of the side wall 14a' of the oven 14' includes an open portion 44'. The open portion 44' allows the second chamber 14j' to receive focussed sunlight from the lens 16'. As illustrated in figure 7, the oven 14' also includes an insulated cover member 46' (plug). The insulated cover member 46' may be used to cover the open portion 44' when the oven 14' is not in use, or once the oven has reached its highest temperature. The insulated cover member 46' has the same construction as the walls 14e' of the oven 14'. That is, the insulated cover member 46' has phenolic foam insulation wrapped in aluminium foil and is positioned in the second chamber 14j'. The oven 14' also includes doors 47' that may cover the open portion 44' and the cover member 46'.

As illustrated in figure 6, the oven 14' also comprises an aluminium heat shield 48' which substantially surrounds the open portion 44'. The heat shield 48' protects the outer walls 14e' from accidental light beam spillage. As described above, the walls 14g' of the second chamber 14j' are made from copper, aluminium or galvanised steel.

The inner surface of the second chamber 14j' is also coated with a selective surface that has a high electromagnetic absorption coefficient and low thermal emissivity. The material used in the embodiment illustrated and described here is Solkote, available from SOLEC-Solar Energy Corp. 129 Walters Ave. Ewing, NJ 08638-1829, USA. However, it should be appreciated that other suitable types of selective surfaces with high electromagnetic absorption and low thermal emissivity coefficients in the appropriate wavelengths could be used.

As described above, the cooking apparatus 10 further comprises a reflector mirror 18' that is configured to reflect sunlight from the lens 16' to the oven 14', and the first chamber 14i'. The reflector mirror 18' may be mounted to a support 23' that is attached to the oven 14'. The reflector mirror 18' is removably attachable to the oven 14'. That is, the reflector mirror 18' may be placed inside the second chamber 14j' when the lens 16' is being used to provide heat to the oven 14' and removed when the oven 14' is up to temperature. In this arrangement the lens 16' focuses sunlight towards the reflector mirror 18' and the reflector mirror 18' reflects this sunlight towards the glass plate 14n' and the first chamber 14i'.

The lens 16' has a focus point F1 , and the reflector mirror 18' is positioned between the focus point F1 and the lens 16', i.e. within the focal length of the lens 16'. This arrangement ensures that the reflecting surface of the reflector mirror 18' is illuminated by the focussed sunlight from the lens 16'. This also ensures that the reflector mirror 18' is not subjected to the very high temperatures possible at the focus point F1 of the lens 16', which could damage the reflector mirror 18'. Similarly, the focus point F2 of the reflector mirror 18' is positioned such that it lies within the second chamber 14j' of the oven 14'. Again, this arrangement ensures that the entire surface area of the glass plate 14n' is illuminated by the reflected sunlight from the reflector mirror 18'. This ensures that as much sunlight as possible hits the absorber plate 14k' of the first chamber 14i'. This also ensures that the reflector mirror 18' is not subjected to the very high temperatures possible at the focus point F2, which could damage the reflector mirror 18'.

As illustrated in figures 8, 1 1 and 12, the lens 16' is a modular Fresnel lens. As best illustrated in figure 12, the lens 16' comprises a number of lens elements 16a', 16b'. Each lens element 16a', 16b' contributes to a complete Fresnel lens. The lens 16' has a centre lens element 16b' and six surrounding lens elements 16a'. The centre lens element 16b' includes the centre portion of the Fresnel lens, i.e. the centre ring of the concentric rings, and each additional lens element 16a' together provide the surrounding concentric rings of the Fresnel lens. As illustrated in figure 12, the lens elements 16a', 16b' are hexagonal, which allows the lenses 16a', 16b to fit together to provide the known concentric ring Fresnel lens arrangement. The lens elements 16a', 16b' are connected together by a lightweight aluminium framework 17'. The lens 16' can be made from PMMA (Poly(methyl methacrylate)) or polycarbonate (Lexan). The lens 16' may be manufactured by injection moulding. However, it should be appreciated that the lens 16' could be manufactured by other suitable methods.

The lens 16' is being used as a solar concentrator and has a positive focal length.

Figure 13a illustrates the profile of the lens 16'. The left side of figure 13a is the centre point of the lens 16' and the right side of figure 13b is the edge of the lens 16'. The profile of the lens 16' has been split over two figures for clarity. As illustrated, the lens 16' is an inverted Fresnel lens.

With reference to figures 13a and 13b, the lens 16' is an inverted Fresnel lens. The lens 16' has its facets 15', or grooves, on the focus side of the lens 16'. As illustrated, the lens 16' is substantially planar on its non-focus side and has light focussing elements 15', or surfaces, on its focus side. The lens element 16' thus includes a piano side 19' and a light focussing side 21 '. The facets 15' of the lens 16' are 1 mm wide and the height of the facets 15' range from 0mm at the centre of the lens 16' to around 0.75mm at the edge of the lens 16'. In the embodiment illustrated and described here the lens 16' has a refractive index of 1.59 and a focal length of 850mm. In this arrangement it should be appreciated that the lens elements 16a' are identical and the centre lens element 16b' is unique. This means that only two moulds are required to manufacture the lens 16'. The hexagonal arrangement also means that the lens 16' can be packaged very compactly, with the lens elements 16a', 16b' being stacked on top of one another.

Although not illustrated, it should be appreciated that the cooking apparatus 10' may further comprise an oven rotating device that rotates the oven 14' between a first position and a second position about an axis of rotation.

In operation the cooking apparatus 10' is arranged such that the direction and angle of inclination of the oven 14' is set to the position and angle required for the location of the oven 14' with respect to the Sun during the day. In the embodiment illustrated and described here the position of the oven 14' with the respect to the Sun must be manually adjusted during the course of the day. As described above, the oven 14' may be positioned using the support members 12a', 12b', 12c' and the lens 16' is also adjustable to ensure that sunlight enters the oven 14'. The food to be cooked is placed in the first chamber 14i'. This can be done before the oven 14' is up to temperature or once the oven 14' has reached a high enough temperature to start cooking. The position of the lens 16' and the reflector mirror 18' relative to the oven 14' are then set to ensure that the sunlight passes through the lens 16' to the second chamber 14j' and on to the first chamber 14i' via the reflector mirror 18'. As described above, the lens 16', reflector mirror 18' and second chamber 14j' are arranged such that the entire surface area of both the reflector mirror 18' and the glass plate 14n' are illuminated by the sunlight from the lens 16'. This ensures that as much sunlight as possible is transferred onto the absorber plate 14k' of the first chamber 14i'.

Once the cooking apparatus 10' is set up as described above, sunlight from the Sun passes through the lens 16' and is reflected by the reflector mirror 18' onto the base plate 14k' of the first chamber 14i' of the oven 14'. This causes the first chamber 14i' to heat up. As described above, the highly absorbent coating on the inner surface of the second chamber 14j' ensures that as much electromagnetic radiation is captured as possible.

This arrangement ensures that sufficient heat is generated to heat the first chamber 14i' and to cook the food therein.

In order to ensure that sunlight continues to enter the oven 14', it is necessary to move the oven 14' as the Sun moves relative to the Earth. The starting position may correspond to a "sunrise" position, and the finishing position may correspond to a "sunset" position.

The cooking apparatus 10, 10' collects and stores solar energy during the day (up to circa 6kWh). As described above, the cooking apparatus 10, 10' can be used to cook the food throughout the day. Alternatively, or additionally, the food can be cooked in the oven 14, 14' after the Sun has set, as the oven 14, 14' can maintain a temperature of 100°C for around 90 minutes after sunset. The oven 14, 14' can reach temperatures in excess of 300°C during the course of the day, allowing flatbreads, or the like, to be fried on the cooking plate 141. The oven 14, 14' may further comprise a temperature indication device that indicates both the current and maximum temperature reached during operation. This device may be a "dead" needle on a simple thermocouple temperature gauge or a battery operated digital device. The ability of the oven 14, 14' to maintain high temperatures after sunset is a particular advantage of the cooking apparatus 10, 10'. The cooking plate 141, which may be exposed by removal of the lid 14c of the oven 14, can also be used to fry food upon.

Additionally, the oven 14 can be converted to burn liquid petroleum gas or wood during seasons where solar gain is limited. In this arrangement, the second chamber 14j of the oven 14 may be removed to expose the lower surface 14m of the second chamber 14j. A steel plate will then be inserted to protect the selective surface 14m form direct flames. A liquid petroleum gas (LPG) burner of wood fire can then be lit below this plate. The ability of the frame member 12 to permit the oven 14 to rotate about the first axis of rotation 22 allows the oven 14 to be moved relative to frame member 12 to track the Sun. The ability of the frame member 12 to permit the oven 14 to be pivoted about the second axis of rotation 24 also allows the oven 14 to tilt and again follow the path of the Sun.

The fact that solar energy is applied to the lower portion of the oven 14, 14' increases the efficiency of the energy storage, as the heat rises through the oven 14, 14'. This minimises heat losses from the cooking apparatus 10, 10'. The cooking apparatus 10, 10' typically has higher efficiency as heat will always rise. This means that the cooking apparatus 10 can cook approximately 3 to 4 times more volume of food than known apparatuses with the same solar input.

The cooking apparatus 10, 10' is capable of serving up to 10kg of food hot to taste (80°C) up to 4 hours after sunset. The cooking apparatus 10, 10' incorporates a hot plate (141) for occasional frying needs. The cooking apparatus 10, 10' allows "slow cooking" of food, which better maintains nutritional value of the food. The cooking apparatus 10, 10' requires minimal supervision and minimal maintenance. Due to the modular design, particularly of the lens 16, 16', the cooking apparatus 10, 10' is easily demountable and transportable. The cooking apparatus 10, 10' is safer than other forms of cooking, as it does not incorporate an open flame or use a concentrated combustible fuel source negating any risk of explosion or toxic gas leakage. Furthermore, the cooking apparatus 10, 10' produces no carbon emissions.

Also, arranging the facets 15', 15', or grooves, on the focus side of the lens 16, 16' means that it is less likely that sand or dirt will get into the facets 15, 15', or grooves, which will eventually reduce the acuity of the lens 16, 16'. In this arrangement the piano side 19, 19' may be simply wiped clean.

Modifications and improvements may be made to the above without departing from the scope of the present invention. For example, although the sunlight has been described above as being reflected into the oven 14 via the reflector plate 18, it should be appreciated that the lens 16 may focus the sunlight directly towards the glass plate 44 of the second chamber 14j of the oven 14. In this instance the focus point of the lens 16 may be spaced from the glass plate 44, or located at some point inside the oven 14, so that the entire surface area of the glass plate 44 is illuminated with sunlight.

Furthermore, although the frame member 12 has been described above as being configured to allow the oven 14 to pivot about the second axis of rotation 24 and rotate about the first axis of rotation 22, it should be appreciated that, depending on where the cooking apparatus 10 is used, i.e. the latitude and time of year, it may not be necessary for the oven 14 to pivot about the second axis of rotation 24. In this case it may be sufficient for the oven 14 to simply rotate about the first axis of rotation 22.

Also, although a modular Fresnel lens 16, 16' has been illustrated and described above, it should be appreciated that other suitable lenses could also be used.

Claims

1 . An apparatus for cooking comprising:

a frame member;

an oven mountable to the frame member; and

at least one lens element mountable to the oven;

wherein, in use, the at least one lens element is arranged to provide focused sunlight to the oven.

2. An apparatus for cooking according to claim 1 , wherein the at least one lens element comprises a plurality of concentric facets on at least one surface thereof.

3. An apparatus for cooking according to claim 1 or claim 2, wherein the at least one lens element comprises a plurality of concentric facets on the focus side of the lens element.

4. An apparatus for cooking according to any preceding claim, wherein the at least one lens element comprises a number of lens elements, wherein each lens element contributes to a complete Fresnel lens.

5. An apparatus for cooking according to claim 4, wherein the at least one lens element includes a centre lens element and a number of lens elements surrounding the centre lens element, wherein the centre lens element includes the centre of the concentric facets of the lens and each additional lens element together provide the surrounding concentric facets of the lens.

6. An apparatus for cooking according to claim 5, wherein the lens elements of the at least one lens element are hexagonal.

7. An apparatus for cooking according to any preceding claim, wherein the frame member provides support to the oven and the at least one lens element.

8. An apparatus for cooking according to any preceding claim, wherein the frame member is configured to permit the oven to at least partially rotate about at least one axis of rotation.

9. An apparatus for cooking according to any preceding claim, wherein the frame member is configured to permit the oven to at least partially rotate relative to the frame member about two axes of rotation.

10. An apparatus for cooking according to claim 9, wherein the two axes of rotation are orthogonal to each other.

1 1 . An apparatus for cooking according to claim 9 or claim 10, wherein the frame member is configured to permit the oven to rotate between a first position and a second position about the first axis of rotation and a first position and a second position about the second axis of rotation.

12. An apparatus for cooking according to any preceding claim, wherein the apparatus includes oven support arms arranged to pivotably support the oven, or the at least one lens element.

13. An apparatus for cooking according to any of claims 1 to 1 1 , wherein the frame member includes oven support arms arranged to pivotably support the oven.

14. An apparatus for cooking according to any preceding claim, wherein the frame member includes an oven receiving member, the oven receiving member being configured to receive the oven in an aperture, or opening, therein.

15. An apparatus for cooking according to claim 14, wherein the oven receiving member is pivotably attached to the oven support arms of the frame member.

16. An apparatus for cooking according to claim 14 or claim 15, wherein the oven is configured to rotatably engage with the oven receiving member.

17. An apparatus for cooking according to any preceding claim, wherein the oven includes one or more rolling members, the one or more rolling members being mounted to an outer surface of the oven.

18. An apparatus for cooking according to claim 17, wherein the one or more rolling members of the oven are configured to engage with an upper facing surface of the oven receiving member, such that the one or more rolling members of the oven run on the oven receiving member as the oven rotates during use.

19. An apparatus for cooking according to any preceding claim, wherein the frame member further comprises an oven support plate, the oven support plate being configured to provide support to a lower portion of the oven and being pivotably connected to the frame member.

20. An apparatus for cooking according to claim 19, wherein the frame member includes a tilt support member, the tilt support member being configured to support the oven support plate in a tilted position relative to the frame member.

21 . An apparatus for cooking according to claim 20, wherein the oven support plate is fixedly engageable with the tilt support member.

22. An apparatus for cooking according to any of claims 19 to 21 , wherein the oven includes at least one further rolling member, the at least one further rolling member being attached to a lower portion of the oven and configured to be engageable with the oven support plate, such that the at least one further rolling member runs on an upper facing surface of the oven support plate as the oven rotates.

23. An apparatus for cooking according to any preceding claim, wherein the oven includes a removable lid and/or a removable base.

24. An apparatus for cooking according to any preceding claim, wherein the walls of the oven are insulated.

25. An apparatus for cooking according to any preceding claim, wherein the internal walls of the oven are made from copper, aluminium or galvanised steel.

26. An apparatus for cooking according to any preceding claim, wherein the oven includes a first chamber and a second chamber, wherein the first chamber is configured to receive cooking utensils and the second chamber is configured to receive the sunlight focused by the at least one lens element.

27. An apparatus for cooking according to claim 26, wherein the first chamber and the second chamber are separated by a transparent wall portion.

28. An apparatus for cooking according to claim 26 or claim 27, wherein the second chamber is at least partially transparent.

29. An apparatus for cooking according to claim 28, wherein the second chamber includes a transparent wall portion located on a lower side portion of the oven.

30. An apparatus for cooking according to claim 29, wherein the transparent wall portion is made from glass.

31 . An apparatus for cooking according to claim 30, wherein the transparent wall portion is a borosilicate glass plate.

32. An apparatus for cooking according to any of claims 26 to 28, wherein the second chamber includes an open portion located on a lower side portion of the oven.

33. An apparatus for cooking according to claim 32, wherein the oven includes an insulated removable cover member that is arranged to cover the transparent wall portion, or the open portion, of the second chamber.

34. An apparatus for cooking according to any of claims 26 to 33, wherein at least a portion of the inner surface of the second chamber includes wire wool.

35. An apparatus for cooking according to claim 34, wherein the wire wool is copper wool.

36. An apparatus for cooking according to any of claims 26 to 35, wherein at least a portion of the inner surface of the second chamber is coated with a material that has a high electromagnetic absorption coefficient and/or a low emissivity coefficient.

37. An apparatus for cooking according to any of claims 26 to 36, wherein a lower surface of the second chamber is located adjacent the base portion of the oven, such that the lower surface of the second chamber is exposed when the base portion of the oven is removed.

38. An apparatus for cooking according to any preceding claim, wherein the at least one lens element is arranged such that its focus point is at a point inside the oven or at a point outside the oven.

39. An apparatus for cooking according to any of claims 29 to 38, wherein the at least one lens element is arranged such that the rays of light focused towards the oven impact upon substantially all of the transparent wall portion of the oven.

40. An apparatus for cooking according to any of claims 32 to 38, wherein the at least one lens element is arranged such that the rays of light focused towards the oven impact upon substantially all of the open portion of the oven.

41 . An apparatus for cooking according to any preceding claim, wherein the cooking apparatus further comprises a reflector mirror configured to reflect sunlight from the at least one lens element towards the oven.

42. An apparatus for cooking according claim 41 , wherein the at least one lens element, oven, frame member and reflector mirror are arranged to allow the focused sunlight from the at least one lens element to be reflected from the reflector mirror to the oven.

43. An apparatus for cooking according to any of claims 1 to 40, wherein the cooking apparatus further comprises a reflector plate configured to reflect sunlight from the at least one lens element towards the oven.

44. An apparatus for cooking according to claim 43, wherein the reflector plate has a convex-shaped reflecting surface.

45. An apparatus for cooking according to any claim 43 or claim 44, wherein the reflecting surface of the reflector plate is polished aluminium or a borosilicate glass mirror.

46. An apparatus for cooking according to any of claims 43 to 45, wherein the at least one lens element, oven, frame member and reflector plate or mirror are arranged to allow the focused sunlight from the at least one lens element to be reflected from the reflector plate to the oven.

47. An apparatus for cooking according to any of claims 8 to 46, wherein the cooking apparatus further comprises an oven rotating device, the oven rotating device being configured to rotate the oven between the first position and the second position about the first axis of rotation.

48. An apparatus for cooking according to claim 47, wherein the oven rotating device is configured to pull the oven from the first position to the second position.

49. An apparatus for cooking according to any claim 47 or claim 48, wherein the oven rotating device comprises a wire having a first end that is attached to the oven and a second end that is attached to a pulling mechanism, the pulling mechanism being operable to put the wire under tension.

50. An apparatus for cooking according to claim 49, wherein the pulling mechanism includes a water-operated pulling system, the water-operated pulling system comprising:

a pipe member;

a float; and

a water transfer device,

wherein the pipe member is arranged to be in a vertical position with a sealed end at the bottom thereof,

wherein the pipe member includes an upper chamber and a lower chamber,

wherein the water transfer device is arranged to allow water to be transferred from the upper chamber to the lower chamber,

wherein the float is located in the second chamber of the pipe and is arranged such that it can move freely in the pipe,

wherein the second end of the wire is attached to the float, and

wherein, in use, as the second chamber fills with water from the first chamber, the float rises and puts the wire under tension.

51 . A modular lens comprising at least two lens elements, the at least two lens elements combining to produce a lens having a plurality of concentric facets on at least one surface thereof.

52. A modular lens according to claim 51 , wherein the at least one lens element comprises a plurality of concentric facets on the focus side thereof.

53. A modular lens according to claim 51 or claim 52, wherein the at least one lens element comprises a number of lens elements, wherein each lens element contributes to a complete Fresnel lens.

54. A modular lens according to any of claims 51 to 53, wherein the at least one lens element includes a centre lens element and a number of lens elements surrounding the centre lens element, wherein the centre lens element includes the centre of the concentric facets of the lens and each additional lens element together provide the surrounding concentric facets of the lens.

55. A modular lens according to claim 54, wherein the lens elements of the at least one lens element are hexagonal.

56. An apparatus for cooking comprising:

a frame member;

an oven mountable to the frame member; and

at least one lens element mountable to the oven or the frame member; wherein the frame member is configured to permit the oven to at least partially rotate relative to the frame member about at least one axis of rotation, and

57. An oven for a solar cooking apparatus, the oven comprising:

58. An oven for a solar cooking apparatus according to claim 57, wherein the oven includes a removable lid and/or a removable base.

59. An oven for a solar cooking apparatus according to claim 57 or claim 58, wherein the walls of the oven are insulated.

60. An oven for a solar cooking apparatus according to any of claims 57 to 59, wherein the internal walls of the oven are made from copper, aluminium or galvanised steel.

61 . An oven for a solar cooking apparatus according to any of claims 57 to 60, wherein the oven includes a first chamber and a second chamber, wherein the first chamber is configured to receive cooking utensils and the second chamber is configured to receive the sunlight focused by the at least one lens element.

62. An oven for a solar cooking apparatus according to claim 61 , wherein the second chamber is at least partially transparent.

63. An oven for a solar cooking apparatus according to claim 61 or claim 62, wherein the second chamber includes an open portion located on a lower side portion of the oven.

64. An oven for a solar cooking apparatus according to claim 61 or claim 62, wherein the second chamber includes a transparent wall portion located on a lower side portion of the oven.

65. An oven for a solar cooking apparatus according to claim 64, wherein the transparent wall portion is made from glass.

66. An oven for a solar cooking apparatus according to claim 65, wherein the transparent wall portion is a borosilicate glass plate.

67. An oven for a solar cooking apparatus according to any of claims 63 to 66, wherein the oven includes a removable cover member that is arranged to cover the open portion of the second chamber.

68. An oven for a solar cooking apparatus according to any of claims 59 to 61 , wherein the oven includes a removable cover member that is arranged to cover the transparent wall portion of the second chamber.

69. An oven for a solar cooking apparatus according to any of claims 61 to 68, wherein at least a portion of the inner surface of the second chamber includes wire wool.

70. An oven for a solar cooking apparatus according to claim 69, wherein the wire wool is copper wool.

71 . An oven for a solar cooking apparatus according to any of claims 61 to 70, wherein at least a portion of the inner surface of the second chamber is coated with a material that has a high electromagnetic absorption coefficient and/or a low thermal emissivity coefficient.

72. An oven for a solar cooking apparatus according to any of claims 61 to 71 , wherein a lower surface of the second chamber is located adjacent the base portion of the oven and the lower surface of the second chamber is exposed when the base portion of the oven is removed.

73. An apparatus for cooking comprising:

a frame member;

an oven mountable to the frame member, wherein the oven comprises:

at least one lens element mountable to the oven or the frame member;

wherein, in use, the at least one lens element is arranged to provide focused sunlight to the transparent body portion of the oven.

74. An apparatus for cooking comprising:

a frame member;

an oven mountable to the frame member; and

at least one lens element mountable to the oven or the frame member;

wherein the at least one lens element is a modular lens element comprising a plurality of lens elements, and wherein, in use, the at least one lens element is arranged to provide focused sunlight to the oven.