GB2586003A

GB2586003A - Solar pipe

Info

Publication number: GB2586003A
Application number: GB1905278.6A
Authority: GB
Inventors: Pravinchandra Budhdeo Shamir
Original assignee: Engen House F Z C
Current assignee: Engen House F Z C
Priority date: 2019-04-15
Filing date: 2019-04-15
Publication date: 2021-02-03
Anticipated expiration: 2039-04-15
Also published as: GB201905278D0; GB2586003B

Abstract

A solar pipe 10 (figure 2) that has a layer of a photovoltaic material 14 on its inner surface and an aperture 18 to allow light to pass through. The solar pipe has a first end 12a and a second end 12b where the first end (top) may have a convex refractor 20 or a dome. The second end may be a mirrored convex reflector 24. The inner surface of the tube may have a coating of a reflective mirrored material 16 under the PV layer. The solar pipe may be used with a light pipe or a fibre optic cable 46 (figure 13) that concentrates and directs light into the first end of the tube. The cable may be the same diameter as the first end of the tube. The solar pipe may have a heat recovery pipe 34 (figure 2, 3) around the outside of the tube that carries a heat exchange medium such as CO2 or propylene glycol and water. The solar pipe may be placed in an aluminium casing 30 with other solar pipes and heat pipes to form an array as shown in figures 2 and 3.

Description

SOLAR PIPE

FIELD OF THE INVENTION

The present invention relates to a solar pipe for the generation of solar power. It is particularly applicable to a solar pipe for the generation of solar power where the rate of photonic absorption is increased which in turn increases the generation of electricity and thermal energy.

BACKGROUND OF THE INVENTION

Conventionally the majority of photovoltaic (PV) systems incorporate silicon as a semi-conductor base. This is normally found in two forms, polycrystalline and monocrystalline. The latter having slightly higher efficiencies due to its structure. Although silicon is abundant in nature, vapour deposition manufacturing processes mean that PV panel costs have still remained relatively high compared to non-silicon based PV system.

Copper-indium-gallium-selenide (GIGS) PV systems are lightweight and flexible modules with no-penetration-installation and enable solar power generation in a wide variety of non-roofing applications. These new flexible GIGS modules offer the benefits of being lightweight, flexible, and can have a "peel-and-stick application" -all at a much higher power efficiency exceeding 16%. Because these modules can be formed in a thin film and can weigh as little as 7-oz per sq. feet, they can be installed over low-load-capacity roofs that prove challenging for conventional crystalline panels and rack systems because the roofs cannot support the additional weight. Today's flexible modules use a factory-applied butyl-based self-adhesive with a 30-year proven performance history. Installed with this simple peel-and-stick adhesive, these flexible modules become an integrated part of the roof system and have the same wind uplift and seismic performance characteristics of the roof system itself. From an installer perspective, without racks to assemble, ballast to carry and place, or leak-causing roof penetrations, these peel-and-stick thin-film modules are the simplest, fastest and lowest labour cost rooftop solar solution.

The use of any PV system is limited by the amount of surface area and the total quantum of photons it can absorb. The thin film PV systems, described above, unlike silicon PV systems are more flexible and are cheaper than silicon PV systems. However, thin film PV systems have a lower efficiency than their equivalent silicon counterparts. When surface area is a premium, most people will opt for a greater production using silicon cells as the total cost of a system is measured in £ per watt generated. Hence thin film technology has not displaced their more expensive silicon counterparts.

In current PV panels, be they thin film or silicon solar cells, electricity production is heavily influenced by the orientation of the PV panel to the incidence of light. In the UK, the best production is achieved on the SW orientation with a 30-40 degree elevation to the horizontal.

The amount of light at the correct wavelength hitting the PV panel is critical. Too shallow and the light does not enter the glass or PV covering and reflects out. There is an optimal angel of incidence.

Silicon doped semi-conductor panels are by far the most popular PV panel in the market. Silicon has a valence shell of 4 electrons. This atomic configuration increases the quantum probability of a photon of the correct wavelength displacing an electron from its valence shell.

On a quantum level, light moves in waves and the overall production of electrons is a function of its overall probability of hitting an electron in a substance at the right wavelength and the right time to cause an electron to be displaced. It is not just a function of the 'work function' which is the energy of light required for a particular substance to release an electron. This is the 'photon flux' or the amount of photons hitting a surface at any given time per unit of light and this is influenced heavily by the material coating the PV material, its reflectiveness and the angle of incidence.

New silicon based PV and new organic thin film PV films work on multi-junction technology, using layers of materials underneath each other with different work functions to release electrons and absorb more of the electromagnetic energy. The theoretical maximum energy that can be converted from a single p-n junction cell is 33.7% according to the Shockley Queisser Efficiency Limit (SQ limit). The theoretical SQ limit for a silicon based solar cell is about 32% but commonly used monocrystalline solar cells only achieve about 24% due to light reflection caused by the embedded wires and the glass surface of the panel.

SQ limits only apply to single p-n junction cells. More recent developments use multi-layer multiple p-n layers. The theoretical limit of these cells is about 88.7%. However the cost of these cells is prohibitive. Each material in a multi-junction cell utilizes a different wavelength and a 'different work function' allowing a greater quantum of the electromagnetic spectrum to be captured, typically, still within the UV spectrum.

This limit is calculated having regard to various factors such as recombination of electrons and holes and the impact of blackbody radiation amongst others and the EV bandwidth of a material. The above is common to all PV substances.

Increasingly PV manufacturers are overcoming this theoretical limit by using multi-junction cells. However, in all instances the amount of energy created is a function of the photon flux and principally the amount of photons a PV material can absorb.

Equally, current PV systems struggle with the absorption of longer wavelength IR electromagnetic radiation. This radiation causes atomic oscillation and decreases the efficiency of PV cells. There are hybrid systems which use cooling water pipes under the panels to remove heat and cool the panels. Again, the amount of heat absorbed is a function of the total absorption of photons which is a function of the angle of incidence and the amount of radiation reflected from the panel, atmospheric coating of dust and pollutants.

More heat could be created by increasing the amount of photons absorbed.

Another major issue with current PV systems is that the amount of photonic absorption is limited to the surface area of the solar material and the resultant mounting. Solar PV systems are mainly installed on rooftops and their design can be aesthetically challenging. The amount of energy that can be created is a function of the surface area.

Reflection of incident light is a key issue in PV systems worldwide. The angle of incidence is pivotal in PV systems. If a panel is vertical to the sun (on a wall for example), the angle of incidence is so shallow that the efficiency of the panel is reduced by 60% from nominal. If it is horizontal to the plane in terms of angle of incidence, the electromagnetic rays are reflected by the glazing covering from the panel covering. The efficiency of the panel (as opposed to the solar cell) is reduced by 40% or more. Hence, the usage of PV is limited considerably by orientation as well as solar cell efficiency.

The issues detailed above relate equally to thin film PV cells and panels. Thin film systems have a lower conversion efficiency due to the availability of free electrons but this allows for differing materials to be used for thin film. Thin films work better with low level diffuse light but their overall efficiency is lower than silicon based panels. Surface area is a major issue on embedded building generation and as such solar silicon panels are the preferred choice for embedded generation.

SUMMARY OF THE INVENTION

According to the first aspect of the present invention there is provided a solar pipe comprising a tube having a first end and a second end, an internal surface and an external surface wherein the internal surface is provided with a layer of a photovoltaic (PV) material and the first end is provided with an aperture to allow light to pass there through.

In one alternative the tube is cylindrical, in another alternative the tube is conical, in another alternative the tube is part conical and part cylindrical, in a further alternative the tube is spherical.

Preferably the first end of the tube is provided with a convex refractor. In one alternative the convex reflector comprises a dome, in another alternative the convex reflector comprises a lens, in a further alternative the convex reflector comprises a lens and a dome.

Preferably the second end of the tube is provided with a convex reflector.

The present invention creates a three-dimensional tube into which light introduced which leads to a greater absorption of photons. A sphere is the ideal container but current PV materials and manufacturing does not allow for this. However, with the advent of solar ink and photoelectric pigments, this may be possible.

There are two objectives to the invention: to mitigate orientation and to capture reflected photons which are currently discarded by current PV systems. The light hitting a current PV system is either absorbed by the solar cell/panel or reflected. Of the light that is absorbed, only the UV has any useful function with the remaining electromagnetic spectrum adds to the inefficiency of the panel as it increases the heat and molecular oscillation and resistance within the PV panel.

Light entering the first end of the tube will either hit the internal surface of the tube which is provided with the layer of PV material or will travel straight through the tube to the bottom. At the bottom of the tube the convex reflector, such as a mirror will cause light to be reflected back onto the internal surface of the tube which is provided with the layer of PV material.

Preferably the internal surface of the tube is provided with a layer of reflective material, preferably the layer of reflective material is provided under the layer of PV material, preferably the layer of reflective material is a mirror coating.

Preferably the tube is formed from a plastics material.

Preferably the present invention utilises thin film photovoltaic solar pipes which work using the principles of total internal photonic absorption (TI PA).

To increase the quantum of radiation absorbed, the invention seeks to utilize large refracting domes or focal lenses to capture differing incidences of light and refract them into the tube. The tube in one alternative contains a bi-concave lens. This causes the incident light to become divergent towards the thin film on the walls of the pipe or cylinder/sphere. This can also be achieved by using fibre optic cables attached to a lensing system.

Therefore, unlike current PV panels, the light (in the form of photons) entering the tube will be absorbed by the layer of PV material. Any photon that does not hit the layer of PV material at the correct angle such that it is not absorbed, will be reflected by the layer of PV material or the layer of reflective material under the layer of PV material, if provided, and hit another part of the internal surface of the tube or hit the concave reflector or refractor to be reflected back onto another part of the internal surface of the tube. Photons entering the tube will have no escape other than the entry aperture of the solar pipe.

The angle of incidence is addressed as the repeated reflection will cause the light to be reflected repeatedly such that the angle of incidence will become optimal.

From a quantum mechanics perspective, the ability of a photon of light to displace another quantum particle (electron) is a function of quantum probability which includes the angle of incidence. In a typical silicon or flat panel, the light hitting the panel has a single opportunity to displace an electron. If it does not happen on the first instance, the photon absorbed by the panel is reflected and continues as a photon. In the solar pipe, the photon is trapped and continues along its journey inside the pipe and will be absorbed on the next incidence. The invention increases the probability of quantum electron displacement and therefore increases the efficiency of the thin film inside simply by increasing the number of times a photon can interact with the photovoltaic substance.

Surface area is a rate limiting issue for standard PV system whether thermal or photovoltaic. Hence the overall quantum of energy that can be converted is directly related to the surface area. The surface area of a cylinder, sphere, cone etc is far greater than a flat surface. Moreover, the surface area of smaller solar pipes in aggregate is greater than a large diameter solar pipe. A cylinder is 3.14 x length x diameter. The optimal production of energy is determined by the amount length to diameter of the tube. The efficiency is also affected by the number of reflections and the aperture of the tube and photons can escape from the aperture. The combination of refractive dome, divergent lens and convex mirror at the base is optimal for ensuring that photons are directed towards the layer of PV material.

In order to limit the possible of escape of photons through entry aperture, preferably the solar pipe is provided with a large internal surface area such that as much of the light as possible is reflected to the internal surfaces of the sides of the tube that are provide with the layer of PV material such that the amount of light exiting the entry aperture is minimal.

The more photons that hit the internal surface of the sides of the pipe which are provided with the layer of PV material the greater the probability of a photon being absorbed. One way of achieving this is by directing the light as it enters into the solar pipe through the first end onto the internal surface of the tube which is provided with the layer of PV material.

The overall principle is to get light into the tube and cause multiple reflections and opportunities for photonic absorption.

In one alternative the solar pipe is further provided with a plurality of vents, each vent comprising an aperture, preferably each of the vents is provided with a convex refractor.

In one alternative the convex reflector comprises a dome, in another alternative the convex reflector comprises a lens, in a further alternative the convex reflector comprises a lens and a dome.

In such a solar pipe when placed particularly in a horizontal profile, the plurality of vents can be in the form of micro lenses which cover a large surface area that is exposed to the light. Once the light is trapped within the solar pipe, the object of the invention is to trap photons within the solar pipe and to reflect them within the tube until as many as possible are absorbed. That is the fundamental basis if total photonic absorption. UV light of the correct frequency is converted to electricity and other wavelengths excite the trapped air to create heat which can be recovered.

Preferably the solar pipe further comprises a fibre optic pipe, preferably the fibre optic pipe concentrates and directs light into the first end of the tube, preferably the diameter of the opening of the first end of the tube is the same as the dimeter or the fibre optic pipe. By using the smallest possible aperture this would reduce the exit area or waste area for photons to bounce into and exit the solar pipe.

Fibre optic pipes would also allow the solar pipe to be embedded under roof tiles or in basements or in other areas which are less commercially valuable in a dwelling or other development and are not necessarily open to natural light.

The invention can work with silicon insofar as the silicon vapor deposition process is adjusted to allow deposition on a curvature. Polycrystalline silicon would also be suitable.

Heat obtained through solar gain is a function of the Infra-Red (IR) radiation (and other wavelengths) being absorbed, such that an increase in photonic absorption results in greater heat capture. This is a good thing insofar as the energy absorbed is utilized. To this end the solar pipe is preferably provided with a heat exchange system comprising a pipe extending around the outside of the cylindrical tube which carries a heat exchange medium. Preferably the pipe of the heat exchange system comprises a small bore polyethylene (PE) pipe and preferably the heat exchange medium is a cooling fluid which may be a mixture of propylene glycol and water or alternatively carbon dioxide (CO2).

The pipe absorbs the entire electromagnetic radiation spectrum and the electromagnetic radiation that is not converted to electricity, results in atomic vibration of the PV material, resulting in an increase in heat within the solar pipe.

Preferably the small bore PE pipe comprises a loop. Preferably the heat exchange system reduces the temperature of the solar pipe to about 2°C. Preferably the cooling liquid that circulates through the pipe of the heat exchange system is passed to a heat exchanger where the energy could be extracted and concentrated to provide energy to run a carbon dioxide turbine. In one alternative a standard heat pump could be used to simply concentrate the amount of heat to make it usable. The issue of condensation within the tube would be addressed by drying the air in the tube at the point of construction. One of the advantage of active cooling is the positive feedback loop that ensues. All heating is a function of thermodynamic equilibrium. A body at a certain temperature is emitting heat at the same level as it is absorbing heat. Hence a cool solar pipe system would absorb more heat as it is cooled.

The total electrical conversion of the system would increase as the reduction in temperature of the semi-conductor would reduce electrical resistance and also the amount of recombination of electron and holes from the conduction layer to the valence layer.

The overall efficiency is obtained by increasing the field of absorption via refractive domes, lensing devices or fibre optic sun pipes. The divergent lens ensures the light is directed towards the layer of PV material. The convex base reflector which may be a convex lens or a convex mirror, ensures light is reflected onto the internal surfaces of the tube. The surface area is increased greatly due to the diameter of the tube in comparison to a flat panel.

The solar pipes of the present invention increase the absorption of photons which initial experiments indicate increase the total electrical production of thin films by almost 250% per given area reducing the cost of solar electricity generation and the total surface area is up to 2000% higher (based on the diameter on the solar pipe) allowing the solar pipes of the present invention to provide up to 100% of the total electrical usage of a building.

The increased heat energy also allows the solar pipes of the present invention to provide extra electrical energy by using the increased heat absorption to provide energy to heat a building or power a turbine generator.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

Figure 1 illustrates a first embodiment of a solar pipe; Figure 2 illustrates a second embodiment of a solar pipe including a heat exchanger; Figure 3 illustrates a top view of the second embodiment of a solar pipe including a heat exchanger; Figure 4 illustrates a third embodiment of a solar pipe with additional light entry points; Figures 5a and 5b illustrate a fourth embodiment of the solar pipe with additional light entry points grouped together in arrays; Figure 6a and 6b illustrate the fourth embodiment of the solar pipe installed onto a roof top; Figure 7a illustrates the use of an existing PV panel on mounted on a horizontal ledge; and as a comparison; Figure 7b illustrates the use of a plurality of solar pipes of the present invention in the same space; Figures 8 and 9a and 9b illustrates solar pipes of the present invention arranged for mounting on horizontal ledges on buildings; Figure 10 illustrates a fifth embodiment of the solar pipe; Figures lla and llb illustrate a cluster of solar pipes according to the fifth embodiment; Figure 12 illustrates a sixth embodiment of the solar pipe; and Figure 13 illustrates the installation of the sixth embodiment of the solar pipe on a building.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The Basic Solar Pipe Figure 1 illustrates a basic solar pipe 10 of the present invention. The solar pipe 10 comprises a cylindrical tube 12 having a first end 12a and a second end 12b and is formed from a waterproof material such as a plastics material. A PV layer 14 is provided on the internal surface of the cylindrical tube 12 which may be a thin film PV or vapour deposited silicon for example. The PV layer 14 is provided with a backing of a reflective coating material 16 such as a layer silver acetate which acts as a mirror. The first end 12a of the cylindrical tube 12 is provided with an aperture 18 to allow light to pass there through. The first end 12a of the cylindrical tube 12 is provided with a convex refractor in the form of dome 20 and also an optional refracting lens 22. The second end 12b of the cylindrical tube 12 in the embodiment illustrated is closed to the passage of light and is provided with a convex reflector 24 which may be a lens or a mirror.

As illustrated in Figure 1, light 26 is introduced into the cylindrical tube 12 through dome 20 via refracting lens 22 via aperture 18. Light 26 will hit the PV layer 14 and generate electrons, and the excess light will then pass through the PV layer 14 and reflect back from the reflective coating material 16. This light 26 will then pass back through the PV layer 14 possibly exciting some more electrons and then reflect onto the PV layer 14 on the opposite side of incidence. In other words, the light will bounce back and forth within the cylindrical tube 12 until as much useful light energy as possible is absorbed.

As light 26 keeps coming in through the dome 20 and the number of light photons increase and hit the PV layer 14, the number of electrons that are excited increases. The convex reflector 24 located at the second end of the cylindrical tube 12 increases the reflective capacity of the solar pipe 10 as the reflective surface of the convex reflector 24 which may be a mirror or a lens bulges towards the light source. The only light ingress will be through the first end 12a of the cylindrical tube 12. Light egress is also only possible from the first end 12a of the cylindrical tube 12, however, there would a negligible amount of light that would travel back upwards. It is anticipated that any short wavelength light if not used by PV layer 14 (as in multifunction cells or compound PV films) would increase the air temperature inside the cylindrical tube 12 of the solar pipe 10 which could be collected as described in later embodiments.

Regardless of any impact of the total internal reflection to increase the efficiency of the PV layer 14, the provision of a PV layer 14 inside cylindrical tube 12 has a greater density of coverage than if the film was laid out flat. The dome 20 of the solar pipe 10 passively tracks the sun throughout the day, so no mechanical tracking device is required. This allows optimum surface area exposure from 7am to 5pm which covers the majority of the solar radiation each day. The solar pipe 10 receives >20% more solar exposure compared to a flat absorber, allowing more solar energy conversion each day.

Operating outside means that all the components of the solar pipe 10 must be able to withstand all weather conditions from freezing conditions, to the extreme heat and UV radiation of desert locations. A good example is the use of silicone rubber instead of plastics for any tube caps, rubber header seals and manifold covers. Silicone rubber is extremely durable, staying flexible in a wide temperature range. It can withstand over 200 degrees Celsius / 392 degrees Fahrenheit and is extremely resistant to damage from UV light.

Once the cylindrical tube 12 is provided with the PV layer 14, the solar pipe 10 can be placed in an external aluminium casing in an array with other solar pipes 10 and would be then connected with connectors to create an electrical circuit. The generated power will be transferred through the generation meter connected to the circuit. This power will then be used for consumption.

Surface Area Calculations Diameter of Pipe -200mm Depth of Pipe -300mm Total area using single 200mm tube is 0.1884m2 Typical Silicon Solar Panel is 1.6m x 1m or 1.6m2 How many 200mm diameter tubes in 1.6m2 = 40 tubes Total surface area using single 200mm configuration = 0.314 x 40 = 7.53m2 or 4.7 x surface area of a standard PV panel.

Diameter of Pipe -50mm Depth of Pipe 300mm Total surface area -0.0471m2 Number of tubes 50mm pipes in 1.6m2 = 640 tubes Total surface area using single 50mm tubes = 30.14m2 or 18.84 times the surface area of a standard PV panel.

Diameter of Pipe -20mm Depth of Pipe 300mm Total Surface Area of 20mm x 200mm tubes is 0.01884m2 Number of tubes of 20mm x 200mm depth in 1.6m2 = 4000 tubes Total surface area using 20mm tubes is 75.3 x the surface area of a standard PV panel.

Even if we assume that the efficiency of the PV layer 14 does not increase with total internal photonic absorption, the net increase in area is so high that the overall production of electricity using solar pipe 10 even at 6% efficiency (low) is more efficient than standard panels. Thin film PV materials are cheaper than silicon cell based panels and as such the peak production in the examples used would still be 20 times higher per given area.

The photon flux or the number of photon absorbed would logically have to be higher as the photons have a greater probability of being absorbed through Total Internal Photonic Absorption which would increase the efficiency of standard thin film by at least 200%.

Consider the following example. Simple mathematics details that the circumference of a circle is the diameter times Pi. So 1m x 2m monocrystalline panel of 360W with a cell efficiency of 20% is normally used and costs £220 per panel. Using simple mathematics, a similar area of thin film would occupy 0.34m (including pipe thickness). So, we could get three pipes each with a 1m circumference in each pipe. This would allow three solar pipes in the same area. Thin film are typically 50% of the efficiency of solar PV. However with the solar pipe (ignoring total internal reflection), we have a 25% increase in electricity generation over standard PV panels (the extra 1m has 50% of the efficiency of a silicon panel). Given that thin film is 90% cheaper than rigid fixed panels, the solar pipes offer an overall 60% saving per watt of electricity.

Solar Pipe as a Heat Collector Figures 2 and 3 illustrate a plurality of the solar pipes 10 connected together in parallel in an array, enclosed within a solar pipe housing 28 of much larger diameter. The solar pipe housing 28 having an outer tube 30 having a fist end 30a and a second end 30b. The first end 30a of the outer tube 30 is provided with an aperture 36 to allow light to pass there through. The first end 30a of the outer tube 30 is provided with a convex refractor in the form of dome 32. The second end 30b of the outer tube 30 in the embodiment illustrated is closed to the passage of light which will prevent any remaining light rays from escaping thereby ensuring no wastage of sunlight. The solar pipe housing 28 acts to trap the heat generated by the individual solar pipes 10 during the process of electricity generation and the infra-red heat from sunlight. Over the course of the day, the solar pipes 10 will build up heat which can be put to use. Using heat recovery pipes 34 or another heat exchanger system, this energy can be channelled into any suitable medium such as water for general heating and other requirements.

Solar Pipe with an Additional Light Source Figure 4 illustrates a further embodiment of the present invention where in the solar pipe 110 is provided with vents 138 each provided with a convex refractor in the form of dome 140 along the length of the solar pipe 110. The solar pipe 110 comprises a cylindrical tube 112 having a first end 112a and a second end (not shown) and is formed from a waterproof material such as a plastics material. The first end 112a of the cylindrical tube 112 is provided with an aperture 118 to allow light to pass there through. The first end 112a of the cylindrical tube 112 is provided with a convex refractor in the form of dome 120. In one alternative the second end of the cylindrical tube 112 is closed to the passage of light and is provided with a convex reflector 24. In an alternative the second end of the cylindrical tube of solar pipe may also be provided with an aperture to allow light to pass there through and a convex refractor in the form of dome. The vents 138 will allow more light to enter into the solar pipe 110 and compensate for any losses, and also provide continuous illumination along the length of the solar pipe 110 in case the light coming in from the dome gets completely absorbed.

In the alternative illustrated in Figure 5a and 5b the second end of the cylindrical tube of solar pipe 220 is also provided with an aperture to allow light to pass there through and a convex refractor in the form of dome 242, and the solar pipes 220 have been arranged in an array.

Figures 6a and 6b depict an array of solar pipes 220, which are placed in different orientations and have replaced what would otherwise have been conventional solar panels on the roof of a house.

Solar pipe as a replacement for solar panels Figures 7a, 7b, 8, 9a and 9b shows examples of a building where a solar panel 50 has replaced by an array of solar pipes 310 on a horizontal ledge on the side of the building.

Solar Dandelions Figure 10 illustrates another embodiment of a solar pipe 410 wherein instead of a cylindrical tube a tube 412 having a first end 412a and a second end 412b wherein the tube is tapered from the first end 412a to the second end 412b so that it forms a cone shape. The first end 412a of the tube 412 is provided with an aperture 418 to allow light to pass there through. The first end 412a of the tube 412 is provided with a convex refractor in the form of dome 420. These solar pipes 410 can be arranged in spherical fashion to form a structure resembling a dandelion as illustrated in Figures 10 and 11 which display the arrangement of the solar pipes 410 in a hemi-sphere and how the Solar Dandelion looks from side and top view respectively. These dandelions can be placed outdoors or on rooftops or they can be attached to sides of a building and be exposed to the sun.

Solar Funnel Figure 12 illustrates another embodiment of a solar pipe 510 which is a combination of the first and fifth embodiments wherein instead of a cylindrical tube a tube 512 is provided having a first end 512a and a second end 512b and a mid-point 512c wherein the tube 512 is tapered or conical from the first end 512a to the mid-point 512b and is then cylindrical from the mid-point to the second end 512b but of reduced diameter to the first end 512a so that it forms a shape rather like a torch. The first end 512a of the tube 512 is provided with an aperture 518 to allow light to pass there through. The first end 512a of the tube 512 is provided with a convex refractor in the form of dome 520. In one alternative the second end 512b of the tube 512 is closed to the passage of light and is provided with a convex reflector. In an alternative the second end of the tube of solar pipe may also be provided with an aperture to allow light to pass there through and a convex refractor in the form of dome. In a further alternative as illustrated the second end 512b of the tube 512 is open for the passage of light such that it acts as a funnel. In this alternative the solar pipe 510 may be used to collect light from the roof and concentrate it and send it through light pipes 46 such a fibre optic cables via total internal reflection to other areas in the building where larger arrays of solar pipes 28 may be located. In this alternative the inner surface of the tube 512 may or may not be provided with the layer of PV material.

Claims

CLAIMS1. A solar pipe comprising a tube having a first end and a second end, an internal surface and an external surface wherein the internal surface is provided with a layer of a photovoltaic (PV) material, the first end is provided with an aperture to allow light to pass there through.
2. A solar pipe as claimed in claim 1 wherein the tube is cylindrical, conical, part conical and part cylindrical or spherical.
3. A solar pipe as claimed in claim 1 or claim 2 wherein the first end of the tube is provided with a convex refractor.
4. A solar pipe as claimed in any preceding claim wherein the second end of the tube is provided with a convex reflector.
5. A solar pipe as claimed in any preceding claim wherein the internal surface of the tube is provided with a layer of reflective material.
6. A solar pipe as claimed in claim 5 wherein the layer of reflective material is provided under the layer of PV material.
7. A solar pipe as claimed in claim 5 or claim 6 wherein the layer of reflective material is a mirror coating.
8. A solar pipe as claimed in any preceding claim wherein the tube is formed from a plastics material.
9. A solar pipe as claimed in any preceding claim wherein the layer of a photovoltaic PV material is selected from a thin film PV material, silicon vapor deposition and polycrystalline silicon.
10. A solar pipe as claimed in any preceding claim further comprising a fibre optic pipe.
11. A solar pipe as claimed in claim 10 wherein the fibre optic pipe concentrates and directs light into the first end of the tube.
12. A solar pipe as claimed in claim 10 wherein the diameter of the opening of the first end of the tube is the same as the dimeter or the fibre optic pipe.
13. A solar pipe as claimed in any preceding claim further comprising a heat exchange system comprising a pipe extending around the outside of the tube which carries a heat exchange medium.
14. A solar pipe as claimed in claim 13 wherein the pipe of the heat exchange system comprises a small bore polyethylene (PE) pipe.
15. A solar pipe as claimed in claim 13 or claim 14 wherein the heat exchange medium is a cooling fluid which may be a mixture of propylene glycol and water or alternatively carbon dioxide (CO2).
16. A solar pipe as claimed in claim 15 wherein the heat exchange system reduces the temperature of the solar pipe to about 2°C. 20
17. A solar pipe as claimed in claim 15 or claim 16 wherein the cooling liquid that circulates through the pipe of the heat exchange system is passed to a heat exchanger where the energy is extracted and concentrated to provide energy to run a carbon dioxide turbine.
18. A solar pipe as claimed in any preceding claim further provided with a plurality of vents, each vent comprising an aperture.
19. A solar pipe as claimed in claim 18 wherein each of the vents is provided with a convex refractor.