GB2463347A

GB2463347A - A skylight assembly with incorporated solar cell

Info

Publication number: GB2463347A
Application number: GB0913466A
Authority: GB
Inventors: Chris John Avery; Robin Adrian Rexworthy Jeffery
Original assignee: Hambleside Danelaw Ltd
Current assignee: Hambleside Danelaw Ltd
Priority date: 2008-08-01
Filing date: 2009-08-03
Publication date: 2010-03-17
Also published as: GB0814093D0; GB0913466D0

Abstract

A rooflight assembly 10 comprising a solar cell 4, whereby the solar cell 4 has a smaller width and/or length than the overall assembly 10 such that at a window along at least one edge of the solar panel 4 is defined and allows natural light to pass through the assembly 10. The assembly 10 preferably comprises an upper translucent or transparent panel 20a which has a greater width and/or length than the solar panel 4. The assembly 10 and/or the solar panels 4 may be optimally angled to best receive incident light from the sun. The solar panel 4 may be of the form of a photovoltaic cell and may be coupled to a light intensity sensing element, a chargeable power supply and a wireless transmitting device, such that power can be supplied to any artificial lighting when the incident light drops below a set threshold.

Description

IMPROVEMENTS IN BUftDINGS

FIELD OF THE INVENTION

The present invention relates to improvements in rooffights for the internal lighting of buildings.

More specifically, the invention relates to the incorporation of solar energy conversion panels within rooflight units. Furthermore, the invention relates to the optimisation of the generation of electrical energy from sunlight using such rooflight units. Even more particularly, but not exdusively, the invention relates to a system appended to and/or integrally formed within such a roofUght unit for contro'ling light levels of a building. Such a system checks internal light evels of a building and is capable of adapting artificial light levels such that the overall light level is satisfactory to those within the building.

BACKGROUND OF THE INVENTION

Efficient use of energy and reduction of waste of energy is of paramount importance in terms of protecting the environment and saving costs. By minimising the amount of artificial light and hence electricity that is used, harmful effects on the environment can be reduced and cost savings can be made.

It is known to position solar panes on the tops of buildings in order to utilise the energy from natura sunlight which can be converted by the solar panels into electrical energy. Solar panels as currently known can be of two principal categories: those which are free-standing and those which are attached to a building. Panels of the later type are generally mountable on a roof, where most light is normally incident upon a building.

Whereas solar panels mounted on top of roofs provide a useful source of "green" energy, the use of such solar panels on roofs can restrict the beneficial use of rooflights that coud allow for the transmission of natural light directly into the building. Further disadvantages of solar panels include the requirement for a connection between the roof-mounted panel and any batteries, which are commonly stored in a cellar or other suitable underground storage, Utilising rooflights in buildings to increase the quantity of natural light transmitted into a building is known. In GB 2399380 and GB237897B to the applicant of the present application, a thermally efficient rooflight is disdosed having additional benefits in terms of the amount of natural ight that can be transmitted into a building and in terms of the spread of such natural light. These benefits are obtained primarily because of the structure of the rooflight core. These rooflights have sufficient thermal efficiency and structural rigidity that a rooflight area of 20% for industrial buildings is a feasible, realistic and cost effective proposition for improving levels of natural daylight and reducing the daytime need for artificial lighting.

ft is desirable to provide a means by which natural light can be utilised as a source of direct light to illuminate a building and as a source of energy that can be converted to electrical energy.

Where natural light provides sufficient lighting within a building the use of artificial lighting and hence electricity can be reduced or dispensed with. However, the amount of natural light varies during the day and with the seasons and sufficient natural light is not always transmitted into a building. At these times it is required to use artificial lighting. Preferably the use of artificial lighting is minimised and therefore it is desirable to balance the amount of natural light that is available within a building with the additional artificial light required. Control systems that employ photo-sensors to detect internal light levels are known. These control products are coupled to the artificial light sources and can switch artificial light sources on and off in response to the measured amount of natural light within a room.

ft is from a consideration of existing solar panels, rooflights and artificial light control systems and their attendant disadvantages that the present invention has been developed.

SUMMARY OF INVENTION

In accordance with a first aspect of the present invention there is provided a solar panel of the type suitable for incorporation into a building structure, the solar panel being incorporated in a rooflight assembly of greater length and/or width leaving at least one space between an edge of the rooflight and an edge of the solar panel, through which space light can pass from the top of the rooflight to its base.

In accordance with a further aspect of the invention there is provided a rooflight assembly incorporating a solar panel, the rooflight assembly comprising an upper translucent or transparent panel, said panel having greater width and/or length than the solar panel such that there is at east one space between an edge of the rooflight panel and an edge of the solar panel through which light can pass.

Preferably the rooflight assembly further comprises a plurality of light transmitting formations located within the rooflight assembly between its base and the solar panel.

Preferably the formation components have partially reflective walls to enhance light transmission.

Preferably the solar panel covers some 50% to 70%, of the surface area of the upper panel of the rooflight assembly.

Preferably the rooflight assembly panel can be about 1500 mm long by about 995 mm wide and the solar panel may be about 1420 mm long by about 630 mm wide.

Preferably the solar panel is so fitted to the rooflight to form part of the top of the rooflight assembly. The solar panel may be fitted on a covering sheet within an insulated rooflight or it may be fitted adjacent the under surface of the upper panel. Alternatively the solar panel can be disposed elsewhere within the rooflight assembly between its upper panel and its lower most base.

Almost any standard solar photovoltaic panel may be used as the solar panel component. Preferably the rooflight assembly is associated with at least one gel-pack battery.

According to a further aspect, the invention provides a rooflight assembly incorporating a photo-voltaic cell, a light intensity sensing element, a chargeable power supply and a wireless transmitting device said photo-voltaic cell being disposed within the rooflight such that it is operable to generate electricity from light incident thereon and being couplable to the chargeable power supply for charging that power supply, the power supply being couptable to the light intensity sensing element for powering that light intensity sensing element, the light intensity sensing element being couplable to the wireless transmitting device the wireless transmitting device being operable to transmit an information signal to a remote receiver for relaying to that receiver information regarding light intensity.

According to yet a further aspect the invention provides a light control system comprising a rooflight assembly according to the preceding paragraph wherein a remote receiver is coupled to a control unit for automaticaUy controlling an artificial lighting circuit in response to the intensity of light detected by the light intensity sensing element. According to yet a further aspect the invention provides a light control system comprising a rooflight assembly according to the preceding paragraph wherein a remote receiver is coupled to a control unit for automatically controlling movement of a blind or screen disposed relative to said rooflight such that in response to the intensity of light detected by the light intensity sensing element the blind or screen is moveable to adjust the amount of natural light transmitted internally of a building in which the system is installed and/or to adjust the amount of artificial light transmitted externally of the building.

According to yet a further aspect of the invention, a light control system is provided which comprises a rooflight assembly as described above wherein a remote receiver is coupled to a control unit for automatically controlling an artificial lighting circuit in response to the intensity of light detected by the light intensity sensing element and wherein a second remote receiver is coupled to a control unit for automatically controlling movement of a blind or screen disposed relative to said rooflight such that in response to the intensity of light detected by the light intensity sensing element the blind or screen is moveable to adjust the amount of natural light transmitted internally of a building in which the system is installed and/or to adjust the amount of artificial light transmitted externally of the building.

Preferably) the afore described rooflight assembly comprises more than one solar panel or photovoltaic cell and wherein each solar panel or photovoltaic cell is angled relative to the plane of a bottom wall of the rooflight assembly. More preferably, said angle of the solar panel or photovoltaic cell is between 15° and 45°, even more preferably between 17° and 30°. Even more preferably an 1800mm rooflight assembly comprises four solar panels or photovoltaic cells of about 176mm length each spaced by about 245mm or more and each angled at about 18° relative to the bottom panel of the rooflight assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

n order that the present invention may be illustrated, more easily understood and readily carried into effect by a skilled addressee, reference will now be made to the accompanying drawings depicting schematic embodiments purely by way of non-limiting examples, wherein: Fig. 1 shows an external view of a factory or warehouse having a roofing system comprising known rooflights; Fig. 2 shows an internal view of a factory or warehouse showing natural light being transmitted by the known rooflights into the building; Fig. 3 is a schematic representation of a rooflight assembly modified to incorporate a solar panel in accordance with a first embodiment of the invention; Fig. 4 is a cross-sectional illustration of a rooflight incorporating a solar panel according to the first embodiment of the invention; Fig. 5 is a schematic representation of the changing angles of sunlight at different times of the year; Fig. 6 is a cross-sectional illustration of a rooflight incorporating inclined solar panels according to a second embodiment of the invention; Fig. 7 is a cross-sectional illustration of a rooflight incorporating inclined solar panels according to a third embodiment of the invention; Fig. 8 is a schematic illustration of a light control system according to a fourth embodiment of the present invention; and Fig. 9 is a schematic illustration of a light control system according to a fifth embodiment of the present invention.

Figure 1 shows an example of a large building 100 such as a warehouse, factory or supermarket wherein, a high proportion approximately 20%) of the roof comprises rooflights. Figure 2 shows an internal view of a similar building to that of Figure 2, in which it can be seen that the internal space is sufficiently illuminated by the incoming natural light transmitted through the rooflights. Sunlight incident upon those rooflights is substantially transmittable to the factory or shop floor i.e. there are no ceilings preventing natural light from being transmitted through the rooflights and from illuminating the room below. In such and other similar buildings, natural sunlight can provide sufficient illumination for the occupants of the building as they carry out their work.

Referring to Figure 3, a translucent Glass-Reinforced Plastics GRP) rooflight assembly 10 is shown which comprises a pair of translucent panels 20 secured together and shaped to define an air pocket cavity between the panels 20. In the foregoing description, the uppermost translucent panel is referred to as 20a, whereas the lowermost or bottom translucent panel is referred to as 20b.

Oriented within the same plane as the panels 20, and located within the cavity optionay as part of the top panel 20a, is a known photovoltaic solar panel 4. It can be seen that there is a light-transmissible space between each edge of the solar panel 4 and the respective edge of the panels 20 of the rooflight assembly 10. The advantage of such an arrangement is that sufficient daylight can still pass through the rooflight assembly 10 to illuminate the nterior of the building below (not shown).

The rooflight assembly 10 preferably includes a plurality of insulating formations 6 (only a few formations are illustrated) constructed of transparent plastics material such as cellulose acetate. It can be seen in Figure 3 that the insulating formations 6 in this embodiment are located below the solar panel 4 and vertically disposed with respect to the panels 20a, 20b and the solar panel 4.

The insulating formations 6 are preferably light transmitting and may act to increase the effective amount of light being transmitted through the rooflight assembly 10. In such embodiments, the formations 6 may reflect or deflect light behind the solar panel 4 to reduce its visible foot print and overcome to some extent any undesired light-blocking effect. Where the solar panel 4 is to be positioned adjacent the top layer 20a, the top layer 20a can be constructed with an increased thickness in order to confer greater rigidity.

A cross-sectional view of the rooflight assembly 10 of Figure 3 is shown in Figure 4. Here the insulating formations or core 6 can be seen immediately disposed as a layer below the photovoltaic cells 4. The illustrated rooflight assembly 10 of figure 3 is optionally 80mm in the X direction and approximately 114mm in the Y direction.

It is envisaged that a solar panel some 1420 mm high and some 64 mm wide could generate up to 14 Watts per hour at 12 Volts direct current. In practice a panel of the photovoltaic type when installed in a GRP rooflight adjacent the under surface of the upper (outer) panel 20a was found to generate some 16V even in overcast daylight conditions. Given more sunlight, it is anticipated that some iSV to 20V per panel may be an achievable target voltage. Electricity thus generated can be stored in a gel-pack battery (not shown). When incorporated into a building, the solar panel 4 can be connected to a lighting system to provide, e.g. overnight or emergency lighting. This application of the invention is described further below with reference to Figures 8 and 9.

in Figure 5, it is shown schernaticay how the angle of incidence of sunlight (relative to the earth's surface) can change in relation to the time of year. The angle of incidence of the sunlight onto the photovoltaic cell(s) 4 in the rooflight assembly 10 is, among other things, dependent upon the pitch of the roof; the ocation of the roof, whether the roof is north or south facing; and the angle of the photovoltaic cells 4. Three exemplary positions that the sun takes during a year are shown in Figure 5. High position 51 corresponds to the summer solstice in June; mid-position 52 corresponds to the equinox and low position 53 corresponds to the winter solstice in December. At high-position 51, the angle of incidence a1 is about 63.5°; at mid-position 52 the angle of incidence a2 is about 40° and at low position 53 the angle of incidence a5 is about 16.5°. As the sun moves thoughout the year the angle of incidence of that sunlight upon a roof, rooflight and/or solar panel may change by as much as, or more than 47°.

Optimum performance of the PV cells 4 will be achieved when sunlight is incident upon the PV cells 4 at an angle approaching or equal to Normal (i.e 90°). To optimise the amount of sunlight that is incident upon the PV cells 4 (and hence the amount of electrical energy created), the PV cells 4 are disposed within the rooflight assembly 10 at an angle inclined relative to the plane of the bottom panel 20b. A supporting member is provided to support the PV cells 4 in the inclined position. Any suitable mechanical fixing can be used to hold the PV cells 4 in the inclined position. in Figure 6, angle a, is the angle of inclination of each of the PV cells 4 relative to the bottom panel 20b of the rooflight assembly. in the illustrated example of Figure 6, the angle a, is 18.4°.

Domestic and commercial roof pitches vary significantly from substantially flat with only a shallow fall to allow for water drainage to angles of 30° or more. The present invention has particularly beneficial application for large buildings such as that shown in Figures 1 and 2, where the roof pitch is often between 4° and 8° and most often about 5°. The roof pitch ct, in the illustrated example is 6° and is added to the angle of inclination a, of each of the PV cells 4, to give the total angle of inclination of the solar PV cells a, of 24.4° ( O + The effective angle of incidence of the sunlight in this example can be calculated as 180°-al-aT and so on for each of the exemplary sunlight angles shown. The effective angle of incidence of the sunlight at the various sunlight positions shown 51, 52, 53 is therefore: 92.1°, 115.6° and 139.1° respectively.

in a preferred arrangement of the invention the total angle a is required to be about 35° for optimisation of the amount of sunlight that will be incident upon the PV cells 4 across the year. For optimum performance, it is also necessary to consider the effects that shadowing from one inclined PV ce can have on an adjacent PV ce 4. The ength of the PV ce 4 also needs to be taken into account for calculation of the geometric arrangement of most benefit.

The angle of the PV cells 4 within the rooflight assembly 10 is dependent upon a number of things. n theory, any angle of PV cell can be accommodated within a rooflight assembly 10. However, to obtain a certain amount of electricity generation, a PV ce 4 needs to be of a certain size; furthermore, specifications of standard sized rooflights 10 mean that the length, width and depth of the individual roof light assemblies 10 are fixed. Whereas any sized PV cell 4 could therefore be housed within a rooflight assembly 10 and it is envisaged that in certain embodiments of the invention, this will be the case, a specific embodiment of the invention, which is shown in Figure 7, provides an optimum arrangement of PV cells 4 which are of a certain standard size and which are accommodated within a rooflight assembly 10 of a certain standard size. In the arrangement shown in Figure 7, each PV cell 4 has a length Z of 175.9mm; this is equivalent to a linear length R of 172mm. The spacings W1, W2 and W, between adjacent PV cells 4 are approximately equal and are approximately 246.2mm. The spacing W4 between the last PV cell 4 and the front or low end of the rooflight assembly 10 is longer and is approximately 345mm. In the embodiment illustrated in Figure 7, the length V of the rooflight assembly 10 is 1800mm. This rooflight assembly section 10 can accommodate four such PV cells 4 arranged successively adjacent to one another each at an angle as of 18°. (It is envisaged that 3600mm rooflight assemblies will accommodate eight PV cells 4 in a similar manner to that described; 1800mm and 3600mm are two of the most common lengths for the rooflight assemblies 10). The pitch of the roof ap in the example shown is 5° thus giving a total angle of the PV cells 4 as aT = 23°. The angle as of the PV cells 4 is determined by the length of the PV cells and the depth within the rooflight assembly that can be used to accommodate the PV cells 4.

It is necessary to consider the effect of possible shadowing that one PV cell 4 may have on an adjacent PV cell at various sunlight angles such as those indicated by 51, 52 and 53. In Figure 7, a variety of sunlight angles are illustrated. Not only are the PV cells 4 disposed such that at any of these angles one or more or all PV cells 4 will receive a good amount of sunlight, but also the carefully selected spacing Wa, W2, W3, W4 between the PV cells 4 ensures that one PV cell 4 does not put an adjacent and successive PV cell in shadow or shade (which would otherwise render the shadowed PV cell ineffective).

In alternative embodiments of the invention, the thermally insulating and light spreading honeycomb core 6 is omitted. In this way the standard (80mm) depth rooflight 10 can accommodate PV ces of a similar ength to that shown, albeit disposed at a more inclined angle a5. As a further afternative, shorter PV cells 4 are used in order to enable a greater angle of inclination a, to be achieved. n other envisaged embodiments, the angle a5 and/or ength of each PV cell 4 within the rooflight assembly 10 is not equal. n such arrangements, the rearmost PV cell 4 may be of shorter length in order that it can be disposed at a more inclined angle a5 relative to the other PV cells 4 disposed nearer to the front of the rooflight assembly 10 and vice versa. In yet further embodiments of the inevntion, an optional jacking mechanism is embedded within the rooflight assembly 10. The jacking mechanism is optionally electrically powered and optionally the electricity is provided by the PV cells and stored in appropriately connected batteries. The jacking mechanism provides a means by which the angle of the PV cell 4 may be altered.

Fourth and fifth embodiments of the rooflight assembly 10 are illustrated in Figures S and 9. A rooflight assembly 10 (such as those described in connection with Figures 3, 4, 6 and 7) can incorporate a sensor linked between a lighting system and the photovoltaic panel 4, arranged to control artificial lighting according to the ambient brightness naturally transmitted through the rooflight and so reduce electricity supply costs. Such a sensor may be battery powered and also incorporated in the rooflight. Such an exemplary application of a rooflight assembly 10 is illustrated in Figure 8. A lighting system and control system for use in buildings such as those shown in Figures 1 and 2 (as non-limiting examples) is provided which utilises rooflights 10 and optionally other light transmitting structures in which a photovoltaic cell 4 and photo-sensor 1 is incorporated.

Photo-sensors convert photons of light that are incident upon them and create an electrical signal.

The intensity of the generated signal is directly proportional to the intensity of the photons incident upon the photo-sensor. These and other devices capable of sensing light and generating a signal indicative of the intensity of light are known in the art. Typically, such sensors 1 are disposed within a building at appropriate locations, typically at ceiling level or in the brightest areas within a room.

The signal generated by the photo-sensors is transmitted to a control system coupled to electric lighting circuits. In this way when the signal transmitted by the photo-sensors indicates that the lighting level is below a set threshold, the control system causes the electric lights to be deployed.

In the present aspect of the invention a rooflight is provided wherein a photo-sensor 1 is incorporated into, for example built into or formed as part of, a rooflight assembly 10. The incorporated sensor 1 is operable to detect the quantity of light being transmitted through the rooflight 10. The transmitted light is substantially proportional to the illumination of the internal space of the building.

Optionally the photo-sensor 1 or similar light detection device 1 is powered by means of a solar generator for example solar panel 4 described above or similar photovoltaic (PV) cell unit 4 of smaller dimension and hence of a lower power output. Preferably the photovoltaic (PV) cell unit 4 is incorporated into the same rooflight assembly 10 or alternatively disposed on said rooflight 10. n this way the light control system can be powered by solar energy converted by the system and thus further increasing the environmental benefit and cost saving capability of the system.

n one embodiment where a solar generator 4, is used to power at least a portion of the light control system including the sensor 1 incorporated into the rooflight 10, the solar generator 4 and light sensor 1 are formed as an integral, unitary component that is manufactured within the rooflight assembly 10. Such an arrangement is illustrated schematically in Figures 8 and 9 wherein two light control system are shown.

In both Figures 8 and 9, a photo-electric cell-sensor 1 which measures the natural light levels within a building is disposed within the core 6 of a rooflight unit 10. Optionally the core 6 comprises a honeycomb structure such as that further described below. A battery 2 is also installed within the core 6 of the rooflight unit 10, which battery 2 is charged by electricity generated by a photo-voltaic cell 4. The photo-voltaic cell 4 is disposed immediately beneath a top sheet 20a of the rooflight 10.

In another embodiment (not illustrated) the photo-voltaic cell 4 is disposed immediately beneath the core 6 comprising honeycomb or other light-collecting or light-focussing mechanism which can serve to enhance the intensity of light incident upon the photo-voltaic cell 4 and provide for efficient and enhanced performance of the PV cell 4.

A wireless transmitter 3 is also provided within the rooflight 10 and is optionally constructed within the same housing as the battery 2 such that the two components can be handled as an integral unit.

For coupling to the wireless transmitter 3, a wireless receiver 5 is provided which wireless receiver 5 is mounted internally within the building 100 (not shown in Fig. 5a and Fig 5b). The wireless receiver works in conjunction with a control system (not shown) for an artificial lighting system, or indeed other appliance such as blind or screen mechanism (see below).

To provide access to the installations mounted within the rooflight an access point 7 is provided. This may be secured in place by means of screws as shown or any other suitable mechanical or other removable fixing. Beneficially a gasket or other sealing component S' is used to seal the access point 7 closed in order to maintain an insulation of the rooflight core 6. In this way an air tight seal is ensured and the thermal efficiency of the rooflight insulating core is maintained.

By incorporating at least the light-sensing element 1 of the light control system and optionally a solar generator 4 for that component, any need to replace batteries 2 for powering the light sensing-element 1 is avoided. This is especially beneficial in buildings 100 of the kind where the present invention is optimally applicable such as warehouses and factories for example which have high roof levels.

In a preferable embodiment of the invention, the light sensing element of the light control system is incorporated into a rooflight or other light transmitting structure having a core 6 such as that described in GB 2399380 and/or GB237897B. The core 6 is structured to provide for increased thermal efficiency and increased transmission or spread of light through the rooflight. Compared to rooflights having only an inner and outer skin 20a, 2Gb; rooflight assemblies which have a honeycomb type core provide for increased transmission of light into a building. A core 6 which can collect light from a rooflight surface and using total-internal-reflection (TlR or other means, cause that light to be transmitted through the rooflight core rather than being reflected away from the surface of the rooflight provides for increased transmission of light. Additionally, such a core 6 can create a more even spread of light through the rooflight. (This is also due to the nature of the core and the manner in which light is reflected through the individual tubesu of the honeycomb core.).

Rooflights and other structures such as windows, curtain and ribbon walling that allow for light transmission and comprising such a core, provide a relatively high transmission of light into a building and an even spread of that light. This means that larger buildings such as warehouses, factories and supermarkets (as non-limiting examples) can be illuminated to sufficient levels using natural light. In addition, a photo-sensor and br light control system wholly or partially pre-installed within the light transmitting structure is able to accurately measure the light intensity or illumination levels within a building an provide for automatic alteration of those light levels by adjusting (increasing or decreasing) the amount of artificial electric light.

It is envisaged that in certain embodiments of light control systems of the present invention a number of rooflights or other light transmitting structures will be deployed; in addition a plurality of photo sensors 1 will be used. These photo-sensors 1 being integrally formed, only within some rooflights and not necessarily all of the rooflights of a building 100. Additionally, it is envisaged that the control circuitry of the system is adaptable so that the photo-sensors are positioned in spatial zones and are linked to the artificial lighting in only that zone. In this way as the incidence of natural sunlight on a large building changes during the day, artificial lighting levels within portions of a building are adjustable independently of the artificial lighting levels in other portions or zones of that building.

In a further aspect of the invention, the solar panel 4 formed within the roof light assembly 10, wall light or other light transmitting structure is used to power a different appliance to the aforementioned light-sensor 1 and transmitter 3. it is envisaged that the photo-voltaic cell 4 could be used to directly power low-power lighting such as security lighting or other types of night-lights.

In a further embodiment of the invention the photo-voltaic cell 4 is coupled to a light-sensor 1 disposed such that the amount of artificial light being transmitted externally of the building can be measured. This application of the invention is beneficial in buildings such as warehouses which make use of a significant proportion of rooflights in the roof and which buildings are in use at night. At night artificial lighting is required to illuminate the working space within the warehouse. At night however, such artificial light can be transmitted externally of the building, through those rooflights and cause light pollution of the local area. This aspect of the invention utilises a photo sensor 1, preferably installed within a rooflight such as that shown in Figures 4A and 4B that measures the amount of artificial light being transmitted externally of the building, which is coupled (by wireless transmitter 3 and receiver 5) to a control mechanism for operating a mechanism that can cause one or more sets of blinds or other suitable screen to be manoeuvred relative to the rooflights (or other light transmitting structure) thereby to reduce the amount of artificial light being transmitted and thus alleviating or at least reducing the light pollution problem.

It can be appreciated that various changes may be made within the scope of the present invention, for example, the size, shape and position of the PV-cells 4, photo-electric cell sensor 1, battery 2, and wireless transmitter 3 within the rooflight may be adjusted to accommodate rooflights and components of differing size or shape.

Optionally one or more photo-sensors 1 may be provided and one or more may be disposed below a liner sheet (preferably formed of GRE') and/or within the core 6 of the rooflight which core may or may not comprise a honeycomb structure. As a further option, one or more photo-sensors 1 may be incorporated integrally with the photo-voltaic cell which may itself then be directly coupled to the wireless transmitter.

Though it is envisaged that the wireless transmitter and receiver can operate using nfra-red in other embodiments of the invention it is envisaged that other known methods of wireless communication such as Bluetooth, radio, Wi-Fi as unlimiting examples could be utilised so that information gathered regarding light intensity from the photo-sensor 1 can be communicated to a control unit of an artificial light system, blind or screen mechanism, or other appliance.

ft will be understood from reading the foregoing that the photo-sensor 1 could comprise one or more or a combination of a CCD-cell or photo-diode as non-limiting examples. The battery 2 could be any charge storage device.

As used herein the term solar panel means any panel suitable for collecting energy emitted by the sun for converting that energy into electrical energy. The term photo-voltaic cell is used to refer to one or more PV cells of a solar panel and may refer to either a single cell or a number of cells forming a solar panel or indeed a complete solar panel.

Claims

Claims 1. A solar panel of the type suitable for incorporation into a building structure, the solar panel being incorporated in a rooflight assembly of greater length and/or width leaving at east one space between an edge of the rooflight and an edge of the solar panel, through which space light can pass from the top of the rooflight to its base.
2. A rooflight assembly incorporating a solar panel, the rooflight assembly comprising an upper translucent or transparent panel, said translucent panel having greater width and/or length than the solar panel such that there is at least one space between an edge of the rooflight panel and an edge of the solar panel through which light can pass.
3. A rooflight assembly according to claim 1 or 2 further comprises a plurality of light transmitting formations located within the rooflight assembly between its base and the solar panel or between its top and the solar panel.
4. A rooflight assembly according to claim 4 wherein the formation components have reflective walls to enhance light transmission.
5. A rooflight assembly according to any of claims 2 to 4 wherein the solar panel covers some 50% to 70%, of the surface area of the upper panel of the rooflight assembly.
6. A rooflight assembly according to any of claims 2 to 5 wherein the rooflight assembly panel is about 1500 mm long by 995 mm wide and the solar panel is about 1420 mm long by 6304 mm wide.
7. A rooflight assembly according to any of claims 2 to 6 wherein the rooflight assembly is associated with at least one gel-pack battery.
S. A rooflight assembly according to any of claims ito 7 comprising more than one solar panel or photovoltaic cell and wherein each solar panel or photovoltaic cell is angled relative to the plane of a bottom wall of the rooflight assembly.
9. A rooflight assembly according to claim 8 wherein said angle of the solar panel or photovoltaic cell is between about 15° and about 45°.
10, A rooflight assembly according to claim 8 wherein said angle of the solar panel or photovoltaic cell is between about 17° and about 30°.
11. A rooflight assembly according to claim 8 wherein said angle of the solar panel or photovoltaic cell is about 30°.
12. A rooflight assembly according to any of claims 8 to 10 wherein the rooflight assembly has a length of about 1800mm and the rooflight assembly comprises four solar panels or photovoltaic cells of about 176mm in length, each of said solar panels or photovoltaic cells being spaced apart by about 245mm or more and each solar panel or photovoltaic cell being angled at about 18° relative to the bottom panel of the rooflight assembly.
13. A rooflight assembly incorporating a photo-voltaic cell, a light intensity sensing element, a chargeable power supply and a wireless transmitting device said photo-voltaic cell being disposed within the rooflight such that it is operable to generate electricity from light incident thereon and being couplable to the chargeable power supply for charging that power supply, the power supply being couplable to the light intensity sensing element for powering that light intensity sensing element, the light intensity sensing element being couplable to the wireless transmitting device the wireless transmitting device being operable to transmit an information signal to a remote receiver for relaying to that receiver information regarding light intensity.
14. A Light control system comprising a rooflight assembly according to claim 13 wherein a remote receiver is coupled to a control unit for automatically controlling an artificial lighting circuit in response to the intensity of light detected by the light intensity sensing element.
15. A Light control system comprising a rooflight assembly according to claim 13 wherein a remote receiver is coupled to a control unit for automatically controlling movement of a blind or screen disposed relative to said rooflight such that in response to the intensity of light detected by the light intensity sensing element the blind or screen is moveable to adjust the amount of natural light transmitted internally of a building in which the system is installed and/or to adjust the amount of artificial light transmitted externally of the building.
16, A Light control system comprising a rooflight assembly according to daim 13 wherein a remote receiver is coupled to a control unit for automatically controlling an artificial lighting circuit in response to the intensity of light detected by the light intensity sensing element and wherein a second remote receiver is coupled to a control unit for automatically controlling movement of a blind or screen disposed relative to said rooflight such that in response to the intensity of light detected by the light intensity sensing element the blind or screen is moveable to adjust the amount of natural light transmitted internally of a building in which the system is installed and/or to adjust the amount of artificial light transmitted externally of the building.
17. A light control system according to any of claims 14 to 16 comprising a rooflight assembly comprising more than one solar panel or photovoltaic cell and wherein each solar panel or photovoltaic cell is angled relative to the plane of a bottom wall of the rooflight assembly.
18. A rooflight assembly substantially as herein described with reference to and/or as illustrated by the accompanying drawings.
19. A roof comprising one or more rooflight assemblies according to any of claims 2 to 12 or 18.
20. A building comprising a roof according to claim 19.