WO2021143675A1

WO2021143675A1 - Method of enhancing heat dissipation from solar panel, and device therefor

Info

Publication number: WO2021143675A1
Application number: PCT/CN2021/071282
Authority: WO
Inventors: Hock Yew Winston LOW
Original assignee: Low Hock Yew Winston
Priority date: 2020-01-13
Filing date: 2021-01-12
Publication date: 2021-07-22
Also published as: CN219677269U; AU2021207960A1; JP3241939U; AU2021107542A4

Abstract

A water jacket( 401) for cooling a solar panel (101), and aluminium strips (501) for attaching to the back sheet (311) of the solar pane l(101). The aluminium strips (501) effectively increase the surface area of the back sheet (311) of the solar panel (101) which allows better emanation or radiation of heat. The water jacket (401) is placed over the back sheet (311) and the aluminium strips (501), such that water running inside the water jacket (401) is able to absorb heat dispelled from the back sheet (311) and from the aluminium strips (501).

Description

[Title established by the ISA under Rule 37.2] METHOD OF ENHANCING HEAT DISSIPATION FROM SOLAR PANEL, AND DEVICE THEREFOR

Field of Invention

This invention relates to solar panels for converting sunlight into electricity. In particular, the invention relates to methods and devices for improving dissipation of heat from solar panels.

Background of Invention

A solar panel that is rated by its manufacturer to be capable of producing a certain amount of electricity at optimum performance may actually be producing significant less power due to high operating temperature. This is because of the unrealistic Standard Testing Conditions (STC) under which manufacturers are required to characterise solar panels. Imposition of the Standard Testing Conditions (STC) allows solar panel performance to be compared. However, the STC include a requirement of a testing temperature of 25℃ (for completeness, it may be noted that the other test conditions include an irradiance of sunlight at 1000 W/m ² through an air mass of 1.5 units) . When deployed in real life application, photovoltaic cells in a solar panel are quickly heated to above 25℃ by direct sunlight. It is estimated that there is a yield drop of 5%for every increase of 10℃. This means that the STC data is only good for comparing solar panels at standard temperature but not for characterising their actual performance.

In temperate European regions, it is estimated that sunlight produces approximately 1000W/m ² of electricity in a standard solar panel under STC. The standard solar panel has about 2m ² of operational surface area, and should therefore produce about 2000W. Typically, only 20%of sunlight that irradiates onto a solar panel is converted to electricity. 25%of sunlight reaching a solar panel is simply reflected away. The remaining 55%, however, is lost as heat dissipated into the surroundings. This 55%of unharnessed sunlight could have produced another 1100W in the standard solar panel.

The problem of yield loss as heat is self-aggravating. Hot photovoltaic cells convert sunlight into energy poorly. Hence, the higher the temperature of a solar panel, the poorer the photovoltaic cells in the solar panel convert sunlight into electricity, and this in turn causes more loss of sunlight as heat, which heats up the photovoltaic cells even more.

Photovoltaics cells are prone to heating up because they are arranged into a singular layer that is encapsulated between two layers of transparent plastic, all of which are overlaid with a layer of tempered glass. These transparent layers allow the passage of sunlight to reach the photovoltaic cells. However, heat produced in the photovoltaic cells is incapable of escaping through the transparent layers as radiation. Hence, heat in a solar panel is dissipated only by conduction into the surrounding air, which is a relatively slow process.

Attempts have been made to provide self-cooling solar panels that are integrated with stainless steel tubes. The tubes are laid beneath photovoltaic cells inside the solar panel. Water is supplied into the metal tube continually by a pump. Heat is thereby transferred into the tube, and carried away by the water inside the tube. However, this method is unsatisfactory as stainless steel is expensive. Therefore, traversal of stainless steel tube across the plane of the solar panel is sparse and not dense enough to cool the solar panel efficiently. Furthermore, solar panels become heavier with a stainless steel tube inside, and this adds to the cost of transportation and installation. In addition, existing rooftop solar panels have to be replaced prematurely with such self-cooling solar panels if homeowners wish to enjoy better electricity yield.

Accordingly, it is desirable to provide one or more methods to which could possibly improve cooling of existing, installed solar panels, and which could possibly mitigate the problems found in the prior art.

Summary of the Invention

In a first aspect, the invention proposes a solar panel comprising: a back sheet; the back sheet having a protrusion. In particular, the protrusion is suitable for conducting heat away from the back sheet

On one hand, the protrusion embellishes the outer surface of the back sheet and breaks the evenness of the back sheet. This creates a profiled surface on the back sheet, which increases the surface area of the back sheet. An increase in surface area allows heat to be irradiated or conducted away more quickly than a flat surface area. This is because a flat surface has the smallest area compared to an uneven or profiled, or even a curved surface of the same perimeter and two-dimensional size.

On the other hand, the protrusion conducts heat away from the back sheet into the direction in which the protrusion extends. Where the protrusion points downwardly from an installed solar panel, heat from the solar panel is conducted downwardly along the protrusion. Although heat is conducted in every direction inside a solid, ambient convection often urges heat to move upwardly. For example, air pockets trapped in the solar panel urge heat in the solar panel to transfer upwardly. Furthermore, if the solar panel is mounted in an angle to the ground, heat gathered in the higher end of the solar panel is likely to be dissipated more easily by movement of ambient air. This causes an upward movement of heat.

The downward-facing back sheet on the back of an installed solar panel would be the most convenient location for applying any cooling measure; the back sheet has no particular use except to be a support for the solar panel, and has a flat and wide surface without any embellishment. However, removing heat from the back sheet is simply inefficient as heat movement is not urged from the other parts of the solar panel down into the back sheet. The protrusion mitigates this inefficiency, as the protrusion extends downwardly from the back sheet is therefore capable of conducting heat away from the back sheet, causing more heat to move into the back sheet. This also allows a coolant to be placed beneath the back sheet to absorb heat from the protrusion. Consequently, efficient removal of heat from a protrusion on the back sheet encourages movement of heat from the solar panel into the back sheet.

Typically, the protrusion is made of a good heat conductor, such as a metallic material. More preferably, the material is aluminium, as aluminium is lightweight enough to be secured to the back sheet, is a good heat conductor and is not prone to oxidation.

It should be clear to the skilled reader that the protrusion does not need to be an integral extension from the back sheet itself, but any embellishment added to the surface of the back sheet.

In some embodiments, the protrusion is in the form of strip, i.e. a thin planar layer that may be laid flat onto the back sheet. Even if thin, such a planer layer provides a possibility of sufficient heat dissipation merely by increasing the surface area on the back sheet, and by directing heat away from the back sheet.

Alternatively, the protrusion is a radiation fin, which also improves heat dissipation by providing dramatically increased surface area.

Preferably, a coolant jacket is mounted onto the back sheet, such that the protrusion is held between the coolant jacket and the back sheet. A coolant jacket is any device which can be placed against the back sheet and which absorbs heat from the back sheet. Typically, a coolant fluid is supplied to flow inside the coolant jacket, absorbing and carrying away heat from the coolant jacket.

The coolant jacket and the protrusion work together to improve heat removal more effectively than either of them working alone; the coolant jacket is capable of absorbing heat from the solar panel more efficiently due to improved emanation of heat from the profiled back sheet by the protrusion.

Typically, the coolant jacket comprises at least one depression into which the at least one protrusion may be inserted. Hence, the protrusion directs heat into the depression. This improves the efficiency of heat transfer into the water jacket as it forces the heat to interact with the surfaces surrounding the sides of the protrusion.

Typically, the coolant jacket comprises a channel suitable for supplying a flow of coolant fluid. Preferably, the coolant fluid is water. Water is a good heat conductor at ambient conditions and is plentiful in residential areas where small solar panels are often used. Alternatively, the coolant fluid is air or any compressed inert gas. Air is a good alternative in locations where water or other coolant fluid is not easily available.

In a second aspect, the invention proposes a heat conductive protrusion for placing onto the back sheet of a solar panel. Typically, the protrusion is suitable for to direct heat away from the back sheet. Therefore, the protrusion provides a possibility of providing a cooling system to existing, installed solar panels, as it can be bought and placed onto any solar panel back sheet. This could allow existing solar panels to be augmented and improved, instead of replaced.

Preferably, the heat conductive protrusion has dimensions to fit into a corresponding depression in a heat absorbent layer laid onto the back sheet, wherein directing heat away from the back sheet includes directing heat into the heat absorbent layer. A coolant jacket is an example of heat absorbent layer. Typically, the depression envelopes the protrusion, with as much surface contact between the depression and the protrusion as possible.

In a further aspect, the invention proposes a method of enhancing heat dissipation from a solar panel comprising the steps of: placing a protrusion in contact with the back sheet of a solar panel for conducting heat away from the back sheet, particularly in the direction in which the protrusion extends.

Preferably, the protrusion is provided in the form of a planar piece of metal, such as a flat piece of metal strip. More preferably, the protrusion is an aluminium strip. Typically, the metal strip is suitable for fitting into a corresponding depression in a heat absorbent layer, to be enveloped by the depression. The envelopment of the protrusion by the depression ensures heat emanating from the protrusion is directed into the surfaces of the enveloping heat absorbent layer as much as possible.

In a further aspect, the invention proposes a coolant jacket for a solar panel, comprising: at least one conduit for a coolant; wherein the coolant jacket is capable of being placed onto the back sheet of the solar panel to cause transfer of heat from the back sheet into the coolant. The coolant jacket provides the possibility that existing solar panels can be cooled effectively as they are heated by sunlight, such that the performance and lifespan of these existing solar panels may be improved. The coolant jacket may be made of light weight plastic suitable for being attached to depend from a solar panel back sheet.

Alternatively, new solar panels may be produced already integrated with a coolant jacket. Hence, a new generation of solar panel may be produced without need of securing a separate coolant jacket thereto.

Preferably, the surface of the coolant jacket to be laid onto the back sheet further comprises a depression for containing a protrusion extending from the back sheet of the solar panel. The protrusion transfers heat from the back sheet into the coolant jacket.

Optionally, the depression is pre-inserted with the protrusion, such that the protrusion is capable of being placed into contact with the back sheet to become a protrusion extending from the back sheet when the coolant jacket is laid onto the back sheet. This relieves the user from having to arrange protrusions such as aluminium strips to embellish solar panels.

In yet a further aspect, the invention proposes a water heater, comprising the aforementioned water jacket for absorbing heat from a solar panel, wherein the heat from the water jacket is supplied to a source of water. Typically, the water heater is useable to heat up portable water.

Preferably, the water jacket contains a coolant for absorbing heat from the solar panel, the coolant useable to supply heat to a heat exchange to heat up the supply of portable water.

Optionally, the coolant jacket has a generally rectangular shape; and the conduit has an inlet and an outlet; the inlet being positioned near a first corner of the rectangular coolant jacket; and the outlet being positioned near a corner diagonally opposition the first corner. In contrast to coolant jackets where the inlet and outlet are not located at diagonally opposed corners, this configuration allows many rectangular coolant jacket to be connected together, wherein the outlet of one coolant jacket may be connected to the inlet of a next coolant jacket, using relatively shorter lengths of coolant tubings.

Brief Description of the Drawings

It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention, in which like integers refer to like parts. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

Figure 1 shows a solar panel to which an embodiment of the present invention may be applied;

Figure 2 shows the solar panel of Figure 1 in the back view;

Figure 3 is an exploded view of a plurality of layers in a typical solar panel, such as the solar panel shown in Figure 1;

Figure 4 shows a water jacket which is used on the back of a solar panel such as that shown in Figure 1;

Figure 5 shows an aluminium strip with is used with the water jacket of Figure 4;

Figure 6 shows how the water jacket of Figure 4 and the aluminium strip of Figure 5 are used in accordance to the embodiment;

Figure 7 is another illustration of the water jacket of Figure 4;

Figure 8 is another illustration of the water jacket of Figure 4;

Figure 8a is a photograph of a prototype corresponding to Figure 8;

Figure 9 is another illustration of the water jacket of Figure 4;

Figure 9aa is a photograph of a prototype corresponding to Figure 9;

Figure 9a illustrates how to arrange three water jackets of Figure 7 together;

Figure 9b illustrates a variation of the arrangement shown in Figure 9a;

Figure 9c illustrates a variation of the water jacket of Figure 7;

Figure 9d illustrates how to arrange three water jacket of Figure 9c together;

Figure 9e further illustrates how to arrange three water jacket of Figure 9c together;

Figure 9f illustrates how to exploit heat obtained by the water jacket of Figure 7;

Figure 9g is a side view of a water jacket of Figure 4 and aluminium strips of Figure 5 assembled onto the back sheet of a solar panel of Figure 1;

Figure 10 shows an embodiment which is a variation of the embodiment of Figure 4, Figure 5 and Figure 6;

Figure 11 shows another embodiment of the invention;

Figure 12 shows an embodiment which is a variation of the embodiment of Figure 11;

Figure 13 shows another embodiment of the invention;

Figure 14 shows yet another embodiment of the invention; and

Figure 15 shows yet another embodiment of the invention.

Description of Embodiments

Figure 1 illustrates a typical solar panel 101. The solar panel 101 is shown mounted on a support structure 103. The support structure 103 can be replaced by any other forms of mounting for solar panel 101, and this does not require further elaboration here. Figure 2 shows the corresponding back view or bottom view of the solar panel 101 of Figure 1.

The top view, which is also the front view, of the solar panel 101 is labelled with the letter ‘A’ in the drawings, while the back view or bottom view of the solar panel 101 is labelled with the letter ‘B’ .

Figure 3 is an exploded view of different layers making up the solar panel 101 (without the support structure 103) . The topmost of the layers shown is an aluminium frame 301 that holds the other layers together by the edges of these other layers.

These other layers below the aluminium frame 301 comprise the following: a layer of tempered glass 303, a top layer of plastic 305, a layer of photovoltaic cells 307 for converting sunlight into electricity, a further layer of plastic 309 beneath the photovoltaic cells 307, and a back sheet 311 which is the lowest most layer. Beneath the back sheet 311 is a set of connectors 313 for supplying electricity produced by the photovoltaic cells into a battery (not shown) . All these other layers are stacked one onto another, and inserted into groove in the aluminium frame 301 to be held, thereby assembled into becoming the solar panel 101. The aluminium frame 301 protects the edges of the layers and also provides a solid structure for mounting the solar panel 101, such as mounting onto the support structure 103 shown in Figure 1.

The tempered glass 303 and the top layer of plastic 305 have a level of transparency that gives passage to wavelengths of sunlight to which the photovoltaic cells respond to produce electricity. Typically, the two layers of

plastic

305, 309 are made of ‘ethylene vinyl acetate’ (EVA) , which is highly transparent. These two layers of

plastic

305, 309 encapsulate or wrap around the layer of photovoltaic cells 307 to protect the photovoltaic cells 307 from dust and contaminants.

One of the causes of high temperature in photovoltaic cells 307 is heat converted from sunlight, and this heat is unable to escape from the entrapment of the enveloping

plastic layers

305, 309 and the tempered glass 303. Hence, the photovoltaic cells 307 tend to become very hot under the sun.

The layer of photovoltaic cells 307 is a planar arrangement of a plurality of photovoltaic cells. A photovoltaic cell is a crystal of pure silicon "doped" with different elements that provide electrons free to move as electric current, on being excited by light. Typically, each cell is very thin and measures approximately 100mm across its width and length. A number of these photovoltaic cells may be wired together to form the layer of photovoltaic cells 307. Electrical connecting strips are attached from the bottom of one cell to the top of the next cell. In this way, the cells are connected in series. The working of a photovoltaic cell is known to the skilled man, and further details are not necessary here.

The back sheet 311 is the rear most or bottom most layer of the solar panel 101 and faces in the direction opposite to that of the tempered glass 303. The back sheet 311 acts as a further layer of protection for the solar panel 101, being a moisture barrier, a mechanical protection layer and an electrical insulation. The back sheet 311 can be made of glass of plastic such as PP (polypropylene) , PET (polyethylene terephthalate) and PVF (polyvinyl fluoride) .

Figure 4 shows a coolant jacket for absorbing heat from a solar panel 101. In this example, the coolant jacket is a water jacket 401. The water jacket 401 is typically made of a polymer material such as high density polyethylene (HDPE) . A hollow water channel 403, or conduit, is provided inside the water jacket 401 for a flow of water to assist in cooling any surface to which the water jacket 401 is attached. In other embodiments, air or other fluids may be used in place of water as the coolant.

The drawing on the left side of Figure 4 shows the front of the water jacket 401 and is labelled ‘C’ in the drawings. The water channel 403 can be seen in the front of the water jacket 401, rising from the bed of the water jacket 401. The water channel 403 runs back and forth across the water jacket 401 to traverse as much of the water jacket 401 as possible. The denser the meanderings of the transversal path in an area of the coolant jacket, the higher the resolution of the flow of the coolant over the area.

The drawing on the right side of Figure 4 shows the back of the water jacket 401, which is labelled ‘D’ in the drawings. In use, the back of the water jacket 401 is placed flatly against the back sheet 311 of the solar panel 101 to absorb heat from the back sheet 311. Water flowing in the water channel 403 is guided thereby to flow and meander over as much of the water jacket 401 as possible, absorbing heat that has transferred from the back sheet 311 into the walls of the water jacket 401. As the water carries away heat from the water jacket 401, this increases the rate of heat transfer away from the back sheet 311 into the water jacket 401, which in turn increases the rate of heat transfer from the rest of the solar panel 101, including the photovoltaic cells, to the back sheet 301. The resultant reduction of the temperature of photovoltaic cells provides the possibility of more efficient sunlight-to-electricity conversion. In this way, the water jacket 401 can possibly be applied to existing solar panels to improve electricity production yield.

Figure 5 shows an optional feature of the embodiment, which is an aluminium strip 501 useable to improve heat transfer into the water jacket. The aluminium strip is simply an elongate and planar layer of aluminium, having a surface area that covers only a part of the back sheet 311. Hence, a plurality of aluminium strips 501 may be placed onto the back sheet 311, as shown in Figure 6. When the water jacket 401 is laid onto the back sheet 311, the aluminium strips 501 are sandwiched between the back sheet 311 and the water jacket 401.

As shown in Figure 4 and in Figure 6, the back of the water jacket 401 is provided with a series of depressions 405. Each of the depressions 405 is shaped to be fitted snugly with an aluminium strip 501 that is in a corresponding location on the back sheet 311. In this way, the water jacket 401 is able to lie flat against the back sheet 311 while accommodating the protruding aluminium strips 501 in the depressions 405. Preferably, the aluminium strips 501 are sized to be capable of being embedded into the depressions 405 by interference fit, such as snap-fitting.

In an actual product, the width and length of each aluminium strip 501 may depend on the size of the solar panel 101 which the aluminium strip 501 is intended to be used on. For use with the typical solar panel 101 most commonly seen, the aluminium strip 501 is preferably 30 mm wide and 500 mm long, and 1.5 mm thick. This thickness of the aluminium strip is effective in directing heat from the back sheet 311 into the water jacket 401, while not making the aluminium strip 501 too heavy to be held by adhesive onto the back sheet 311. The depressions 405 on the back of the water jacket 401 have similar internal dimensions in order to hold corresponding aluminium strips 501 firmly.

When placed on the back sheet 311, the aluminium strips 501 effectively become part of the solar panel 101 by contact, and act as protrusions extending from surface of the back sheet 311. In this way, the aluminium strips 501 embellish the back sheet 311 and create an uneven surface profile on the otherwise flat back sheet 311. This enlarges the overall surface area of the back sheet 311 for improved heat dissipation. As the skilled man knows, the greater a surface area, the more heat is able to emanate from the area.

As the aluminium strip 501 and the back sheet 311 are all covered over tightly by the water jacket 401, this leads to more efficient transfer of heat from the back sheet 311 into the water jacket 401. Where the back sheet 311 is laid with an aluminium strip 501, heat is transferred from the back sheet 311 into the aluminium strip 501, and then from the aluminium strip 501 into the water jacket 401. On a spot where there is no aluminium strip 501 on the back sheet 311, heat is transferred directly from the back sheet 311 into the water jacket 401. The running water in the water jacket 401 remains cooler than the temperature in the solar panel 101, which creates a temperature difference attracting heat from the back sheet 311 and aluminium strips 501 into the cooler water.

Factors influencing contact conductance between two materials include contact pressure. As contact pressure increases, true contact area increases and contact conductance becomes greater. Hence, the water jacket 401 is dimensioned to be capable of being stretch over and onto the back sheet 311 in a taut fashion, in order to urge the aluminium strips 501 inside the depressions 405 against the back sheet 311. Possibly, contact between the aluminium strip 501 and the back of the solar panel 101 is direct, without any adhesive between the aluminium strip 501 and the back sheet 311. This provides the possibility of easy installation, as there is no need to apply adhesive between the aluminium strip 501 and the back sheet 311. However, other factors that affect heat conductance between two materials include interstitial materials that fill in microscopic air gaps between the two materials. If there are a lot of air gaps between the two materials on a microscopic level, this could retard conductance of heat. Hence, it is preferable to apply an adhesive between the aluminium strip 501 and the back sheet 311. The use of adhesive also secures the positions of the aluminium strips 501 in the back sheet 311. There are many adhesive types in the market and it is preferable to select one which has a good heat conducting properties to facilitate transfer of heat from the back sheet 311 to the aluminium strips 501, such as Thermo Glue ^TM or other thermal glues.

Figure 7 is a technical drawing of the water jacket 401, showing the front of the water jacket 401 where the water channel 403 can be seen. Figure 7 shows an inlet 701 for introducing running water into the water jacket. The inlet 701 is provided at the starting end of the water channel 403. An outlet 703 is provided at the other end of the water channel 403 for expulsion of water from the water channel 403. The inlet 701 and outlet 703 are the typical nipple which can be used to connect to water tubing.

The inlet 701 of the water channel 403 may be supplied with water from the tap, or from a reservoir and directed by a simple motor pump, and the outlet 703 of the water channel 403 is possibly connected to a warm water reservoir (not illustrated) . As the flow of coolant water is directed to traverse back and forth across the back sheet 311 of the solar panel 101 in the water channel 403, heat from the solar panel 101 moves across the walls of the water jacket 401 and into the relatively colder water. The running water is warmed up by the heat emanating from the back sheet as a result.

Any unit of warm water expelled from the water jacket may be left to cool in the warm water reservoir before being sucked in by the pump again to be recycled through the water jacket. Optionally, water dispelled from the water jacket is disposed directly into the drain.

In countries where temperature may drop below 0℃, anti-freeze may be added into a reservoir of water specifically intended for recycling use in the water jacket 401.

Figure 8 is a corresponding perspective drawing of the water jacket 401 from the front view. Figure 8a is a photograph of a water jacket prototype where the water channel 403 is clearly seen rising from a flat plastic bed. The inlet and outlet is also clearly visible in Figure 8a.

Figure 9 is a perspective drawing showing the back view of the water jacket 401, where the depressions 405 for containing the aluminium strips 501 can be seen. The raised water channel 403 on the other side of the water jacket 401 can be seen peering over the bottom edge of the water jacket 401 in Figure 9. Figure 9aa is a corresponding photograph of the flip side of the water jacket prototype shown in Figure 8a. The shallow depressions 405 for the placement of aluminium strips 501 can be seen in Figure 9aa.

A typical solar panel seen in domestic use has a dimension of 1900mm x 960mm. However, a preferred size for the water jacket 401 is about 900mm x 600mm for easy handling. Hence, the typical solar panel 101 requires three water jackets 401 assembled together to cover over most of the entire back sheet 311 of the solar panel 101. Figure 9a shows how three water jackets 401 of Figure 7 are laid side by side to make up the area of the back sheet 311. The white arrows in Figure 9a illustrates how the inlet 701 on each water jacket 401 is independently supplied by a separate source of coolant water, and the outlet 703 of each water jacket 401 expels heated water separately.

The water jackets 401 may be secured to the back sheet 311 by securing mechanisms such as clips all around the edges of the solar panel 101 and the edges of the water jackets 401, as well as by application of Thermo Glue ^TM.

Figure 9b shows an alternative arrangement to that of Figure 9a, in which coolant water is supplied into the inlet 701 of the water jacket 401 illustrated leftmost. The expelled water from the outlet 703 of this leftmost water jacket 401 is supplied into the inlet 701 of the water jacket 401 in the middle position, and water expelled from the outlet 703 of this middle-placed water jacket 401 is supplied to the inlet 701 of the water jacket 401 placed rightmost. Heated water is finally expelled from the outlet 703 of the rightmost water jacket 401. Movements of the water inside the three water jackets are indicated by white arrows.

As Figure 9b shows three water jackets 401 of Figure 7 connected in series, and as the outlet 703 and inlet 701 of the water jacket 401 in Figure 7 are arranged on the same side of the water jacket 401, a connection tubing (drawn as a thick black line) which is almost as long as the width of the water jacket 401 is required to connect the outlet 703 of the leftmost water jacket 401 to the inlet 701 of the middle-placed water jacket 401. Similarly, a connection tubing as long as the width of the water jacket 401 is required to connect the outlet 703 of the middle-placed water jacket 401 to the inlet 701 of the rightmost water jacket 401.

Figure 9c shows a variation of the water jacket 401 of Figure 7, wherein the water inlet 701 is positioned near one corner of the water jacket 401 and the water outlet 703 is positioned near the diagonally opposite corner.

Figure 9d and Figure 9e shows how this configuration of the water jacket 401 allows shorter connection tubing to be used to connect three of the water jackets 401. Figure 9d shows how the outlet 703 of each water jacket 401 may be positioned adjacent the inlet 701 of the next water jacket 401 in the series. Figure 9e is simply Figure 9d shown with the connection tubing. Hence, placing the water inlet 701 and water outlet 703 in diagonally opposite corners provides the possibility to use the shortest lengths of connection tubing to connect an odd number of water jackets 401 in a series.

As schematically illustrated in Figure 9f, the heat in warm water expelled from the series of water jackets 401 may be used to warm up portable water in regular plumping, via a heat exchanger 901. The skilled reader should note that in Figure 9f, the solar panel 101 faces into the page and is blocked from view by the water jackets 401. Specifically, Figure 9f shows how water from a cool water reservoir 903 is moved by a pump 905 into the inlet 701 of the first water jacket 401 of the series of water jackets 401. The water flows inside the water channels 403 in the three water jackets 401 until the water emerges heated from the outlet 703 of the last one of the water jackets 401. Inside the heat exchanger 901, the connection tubing is interlaced (not illustrated) with pipes 907 of domestic plumbing carrying portable water. Heat is thereby transferred from the connection tubing into the pipes, warming up portable water which may then be stored in a warm portable water reservoir 909 for bathing or consumption.

In cold climate regions such as that of many European countries, more than 50%of household energy use is for heating of water. Accordingly, the embodiment provides the possibility of reducing energy consumption by exploiting waste heat expelled from solar panel 101 to heat up portable water for domestic use. In other words, the embodiment provides a possibility to collect electrical energy and heat energy at the same time. That is, hot water is produced at the same time as a heated solar panel 101 is being cooled down.

More importantly, providing the possibility of operating the solar panel 101 at a lower temperature allows the lifespan of the solar panel 101 to be increased, possibly by even ten years or more.

Figure 9g is a schematic cross-sectional side view of a solar panel 101 assembled with a water jacket 401. In a line of sight which looks from left side of the drawing towards the right, one would see the front of the solar panel 101, i.e. the view ‘A’ . The solar panel 101 hides the back of the water jacket 401, which otherwise could be visible as view ‘D’ . The back of the water jacket 401 is placed against the back sheet 311. In a line of sight looking from the right side of the drawing towards the left, one would see the front of the water jacket 401, i.e. the view ‘C’ . The water jacket 401 hides most of the back sheet 311 of the solar panel 101, which could otherwise be visible as view ‘B’ . Figure 9g shows the cross-sections of three aluminium strips 501, which are fitted snugly into corresponding depressions 405 on the back of the water jacket 401, and these aluminium strips 501 are sandwiched in between the water jacket 401 and the back sheet 311 of the solar panel 101. The inlet 701 and outlet 703 can be seen connected to the water channel 403 which traverses across the plane of the water jacket 401. Water may be supplied by the inlet 701 to flow through the water channel 403 and be expelled from the water jacket 401 by the outlet 703 (illustrated by white arrows) .

As the water flows in the water jackets 401 traverses the back sheet 311 of the solar panel 101, the aluminium strips 501 placed against the back sheet 311 absorb heat from the back sheet 311 only to emanate some of the heat into the depressions 405 in the water jacket 401. This heats up the walls of the water jacket 401 surrounding the aluminium strips 501, and the heat is eventually transferred from the walls of the water jacket 401 into water flowing inside the water channel 403. Therefore, in an installed solar panel 101 where the back sheet 311 faces the ground, the aluminium strips 501 are able to direct heat to move downwardly of the back sheet 311, and into the water jacket 401 to be absorbed by the running water.

In other words, use of the aluminium strips 501 on the back sheet 311 of a solar panel 101 not only provides a greater surface area on the back sheet 311 from which heat may emanate, the aluminium strips 501 also direct the heat from the back sheet 311 into depressions 405 in the water jacket 401, more effectively forcing heat to flow into the water jacket 401. In contrast, without the aluminium strips 501, heat may move laterally along the back sheet 311 without transferring much into the water jacket 401.

Figure 10 shows a variation of the embodiment of Figure 4, which is a water jacket 401 the back of which is pre-embedded with aluminium strips 501 in the depressions 405. The advantage of pre-embedding aluminium strips 501 in the water jacket 401 is that the user does not need to take the trouble of arranging aluminium strips 501 onto the back sheet 311 or into the water jacket 401. The user only needs to lay and secure the water jacket 401 over back sheet 311.

Figure 11 shows yet another embodiment, in which the aluminium is not provided in the form of strips. Instead, the aluminium is provided as studs 1101 on the back sheet 311. The studs 1101 are in contact with the back sheet 311 by the base of each stud 1101. Heat is dissipated from back sheet through the studs 1101 into a corresponding water jacket 401. The studs 1101 effectively increase the surface area of the back sheet 311 by giving the back sheet 311 an uneven surface profile. The depressions 405 on the water jacket 401 shown in Figure 4 are now replaced by receiving holes 1103 into which the studs 1101 may be snugly and tightly inserted into. The positions of the studs 1101 correspond to the positions of receiving holes 1103 in the water jacket 401. An adhesive or grease may be provided between the studs 1101 and the back sheet 311. Alternatively, the studs 1101 may be held to be in direct contact with the back sheet 311 by the tautness of the water jacket 401. As water flows in the water channel 403, heat dissipated from the back sheet 311 with modified surface area is absorbed and carried away by the water flowing in the water channel 403.

Figure 12 shows a variation of the embodiment of Figure 11, which is a water jacket 401 pre-embedded with aluminium studs 1101 in the holes provided in the water jacket 401. This embodiment may be sold in this way to users, so that the users do not need to take the trouble to arrange the aluminium studs 1101 onto the back sheet 311.

Figure 13 shows yet another embodiment in which, instead of aluminium strips 501 or aluminium studs 1101, aluminium radiation fins 1301 are placed onto the back sheet 311 instead. When the solar panel 101 is deployed, the back sheet 311 faces downward and the aluminium radiation fins 1301 extend toward the ground. The fins 1301 provide an enlarged surface area for dissipation of the solar panel heat downwardly as radiation, into the shadow of the solar panel. In this embodiment, there is no water jacket 401 to apply over the fins 1301, as the large surface area of the fins 1301 allow the fins to be cooled by wind. This embodiment is more suitable for deployment in warm, dry but windy areas such as in the deserts.

Figure 14 shows yet another embodiment in which elongate aluminium protrusions 1401 are added to the back sheet 311, to allow heat to emanate from the elongate protrusions 1401 and to be dissipated in the wind. A variation of this embodiment is to use long, thin protrusions in the form of aluminium bristles.

Figure 15 shows yet a further example, in which a larger piece of planar aluminium sheet 1501 than those shown in the aforementioned embodiments is used instead of a plurality of smaller aluminium strips 501. As a convenient figure of speech, “sheet” is used here to differentiate aluminium sheets with larger surface area from “strips” of planar aluminium with a smaller surface area. The larger piece of aluminium sheet 1501 singularly covers over most of the area of the back sheet 311. The corresponding depression on the back of the water jacket is also singular and enlarged. This configuration, however, is not the preferred as a single, large aluminium sheet 1501 suitable to cover over a typical solar panel 101 or the aforementioned size of the water jacket 401 is more expensive than the smaller separate strips 501 used in the embodiment of Figure 4 and Figure 6. Furthermore, the larger piece of aluminium sheet 1501 is heavier and more difficult to secure to the back sheet 311 and to be laid over with the water jacket 401. Use of the smaller pieces of aluminium strips 501 allows less weight to hang from the back sheet 311 while effectively transferring heat from the back sheet 311. This reduces the likelihood of aluminium strips 501 peeling away from the back sheet.

In general, the described embodiments are examples showing that there are many ways of increasing the surface area of the back sheet 311 of an existing solar panel 101, by adding suitably shaped solid objects to change the surface profile.

In some embodiments, the back sheets 311 can be produced in the factory already provided with an uneven surface. The corresponding water jacket 401 is provided with suitable depressions 405 for fitting snugly over uneven surface, in order for the water jacket 401 to be laid in direct contact with the back sheet 311.

Accordingly, the embodiments include a solar panel 101 comprising: a back sheet 311; the back sheet having a protrusion, such as the aluminium strip 501. Furthermore, the embodiments include a heat conductive protrusion, such as the aluminium strip 501, for placing onto the back sheet 311 of a solar panel 101 to direct heat away from the back sheet 311

Also, the embodiments include a method of enhancing heat dissipation from a solar panel 101 comprising the steps of: placing a protrusion, such as the aluminium strip 501, in contact with the back sheet 311 of a solar panel 101, to conduct heat from the back sheet 311 in the direction which the protrusion extends from the back sheet 311.

Also, the embodiments include a coolant jacket for a solar panel 101, such as the aforementioned water jacket 401, comprising: at least one conduit 501 for a coolant; wherein the coolant jacket 401 is capable of being laid over the back sheet 311 of the solar panel 101 to cause transfer of heat from the back sheet 311 into the coolant.

While there has been described in the foregoing description preferred embodiments of the present invention, it will be understood by those skilled in the technology concerned that many variations or modifications in details of design, construction or operation may be made without departing from the scope of the present invention as claimed.

For example, although aluminium strips 501 have been described for providing a surface profile to the back sheet 311, alternative shapes and forms of material for changing the surface profile of the back sheet 311 is possible. For example, steel, iron, bronze or any other material which his capable of conducting heat sufficiently efficiently for any given location of deployment of the solar panel 101 may be used. The material should preferably be stable and not prone to oxidising. Copper and cast iron, for example, are not the most suitable materials.

Claims

A solar panel comprising:

a back sheet; wherein

the back sheet has at least one protrusion for conducting heat away from the back sheet.
A solar panel as claimed in claim 1, wherein

the protrusion is metallic.
A solar panel as claimed in claim 1 or claim 2, wherein

the protrusion is a planar layer.
A solar panel as claimed in claim 3, wherein

the protrusion is a radiation fin.
A solar panel as claimed in anyone of the preceding claims wherein,

a coolant jacket is mounted on the back sheet, such that

the protrusion is held between the coolant jacket and the back sheet.
A solar panel as claimed in claim 5, wherein,

the coolant jacket comprises at least one depression into which the at least one protrusion is inserted.
A solar panel as claimed claim 6, wherein,

the coolant jacket comprises a channel suitable for supplying a flow of coolant fluid.
A solar panel as claimed claim 7, wherein,

the coolant fluid is water.
A solar panel as claimed claim 7, wherein,

the coolant fluid is air.
A heat conductive protrusion for placing on the back sheet of a solar panel and for directing heat away from the back sheet.
A heat conductive protrusion for placing onto the back sheet of a solar panel as claimed in claim 10, wherein

the heat conductive protrusion has dimensions to allow the heat conductive protrusion to fit into a corresponding depression in a heat absorbent layer laid onto the back sheet; wherein

directing heat away from the back sheet includes directing heat into the heat absorbent layer.
A heat conductive protrusion for placing onto the back sheet of a solar panel as claimed in claim 11, wherein

the heat absorbent layer contains a conduit capable of containing a coolant.
A method of enhancing heat dissipation from a solar panel comprising the steps of:

placing a protrusion in contact with the back sheet of a solar panel for conducting heat away from the back sheet.
A method of enhancing heat dissipation from a solar panel as claimed in claim 13, wherein:

the protrusion is a planar piece of metal.
A method of enhancing heat dissipation from a solar panel as claimed in claim 13 or claim 14, wherein:

the protrusion is suitable for fitting into a corresponding depression in a heat absorbent layer.
A coolant jacket for a solar panel, comprising:

at least one conduit for a coolant; wherein

the coolant jacket is capable of being placed onto the back sheet of the solar panel to cause transfer of heat from the back sheet into the coolant.
A coolant jacket for a solar panel as claimed in claim 16, further comprising a depression for containing a protrusion extending from the back sheet of the solar panel.
A coolant jacket for a solar panel as claimed in claim 16, wherein

the depression is pre-inserted with the protrusion, such that the protrusion is capable of being placed into contact with the back sheet to become a protrusion extending from the back sheet when the coolant jacket is laid onto the back sheet.
A coolant jacket for a solar panel as claimed in claim 16, claim 17 or claim 18, wherein

the coolant jacket has a generally rectangular shape;

the conduit has an inlet and an outlet;

the inlet being positioned near a first corner of the rectangular coolant jacket; and

the outlet being positioned near a corner diagonally opposition the first corner.
A solar panel substantially as described in the description or illustrated in the drawings.
A coolant jacket substantially as described in the description or illustrated in the drawings.
A heat conductive protrusion substantially as described in the description or illustrated in the drawings.
A method of enhancing heat dissipation from a solar panel substantially as described in the description or illustrated in the drawings.