WO2015188226A1

WO2015188226A1 - System and apparatus for generating electricity

Info

Publication number: WO2015188226A1
Application number: PCT/AU2015/050309
Authority: WO
Inventors: Roger Webb; Maria Webb
Original assignee: Geiger Trading Gmbh
Priority date: 2014-06-10
Filing date: 2015-06-05
Publication date: 2015-12-17

Abstract

An apparatus for generating electricity comprises a solar panel having a plurality of photovoltaic cells, a plurality of heat sink tiles and a heat exchanger. The heat sink tiles are disposed between the solar panel and the heat exchanger. The heat exchanger is connected to a circulation system which allows coolant fluid to flow through the heat exchanger. Each of the heat sink tiles having a first side in direct thermal contact with a respective one of the photovoltaic cells and an opposite second side in contact with the heat exchanger. The heat exchanger having a plurality of coolant chambers disposed adjacent to the heat sink tiles.

Description

SYSTEM AND APPARATUS FOR GENERATING ELECTRICITY TECHNICAL FIELD

The present invention relates to an apparatus for generating electricity. In particular, this invention is firstly directed towards a photovoltaic solar panel in combination with heat sink tiles and a heat exchanger having coolant chambers, the latter cooling the solar panel to assist in improving its efficiency. Secondly this invention is described with reference to a modular unit for attachment to a solar panel.

BACKGROUND

A "solar panel" is a set of solar photovoltaic modules electrically connected and mounted on a supporting structure. A photovoltaic module is a packaged, connected assembly of solar cells. The solar module can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications, and as such solar panels are widely used throughout the world.

A photovoltaic system typically includes a panel or an array of photovoltaic modules, an inverter, and sometimes a battery and or solar tracker and interconnection wiring.

Each photovoltaic module is rated by its DC output power under standard test conditions, and these typically range from 100 to 320 watts.

One disadvantage of a solar panel is that as the temperature of the collecting surface increases, the efficiency of the solar panel significantly decreases. A conservative estimate by manufacturers (and used by some researchers) is that every 1°C of temperature rise corresponds to a drop in efficiency by 0.5%. Based on our testing, with standard 100W solar panels, a more realistic estimate is that for every 1°C of temperature rise above 25°C in cell temperature, there is a reduction between 0.5% and 1.5% of peak output. As the cell temperature increases further, there is a larger reduction in efficiency.

Field experiments in hotter climatic conditions have also revealed that the photovoltaic cell temperature can also be over three times that of ambient temperature. This means, that at an ambient temperature of 20°C, the cell temperature of a photovoltaic panel surface may already be over 60°C. This would give a possible reduction of over 50% of the output of the solar panel. The output of solar panel systems varies with intensity of sunshine. The more sun, the more power a solar cell will initially generate. However, the more sun, the more heat builds up in the photovoltaic cell, thereby reducing its efficiency to generate power.

There have been many attempts over the years to reduce the heat in solar panels to make them efficient by cooling same. For example US4361717 (Gilmore et al.) dating back to 1982 discloses a fluid cooled photovoltaic device.

In recent years researchers throughout the world have tried to address the heat problem in photovoltaic cells, and the best results so far have a 30% increase in power output. However, the mechanisms and systems developed to achieve this 30% improvement are very expensive, and therefore have not been placed in widespread service.

There is also an oversupply of conventional solar panels on the world market, primarily because of the massive amount of stock produced in China in recent years, and the waning solar subsidies in major markets such as Europe. As such it is desirable to provide a unit that can be attached to or otherwise be used with conventional solar panels, which will improve the efficiency of generating electricity.

Some attempts have been made to propose simple cooling solutions to improve the power output of solar panels. Whilst cooling attempts have been made using both water and air, the more effective cooling method is by using water. One simple arrangement using a heat exchanger is discussed in "Experimental Investigation of Solar Panel Cooling by a Novel Micro Heat Pipe Array" (Tang, Xiao et al. - Energy and Power Engineering, 2010, 2, 171-174). In the heat pipe cooling arrangement disclosed therein, a micro heat pipe array as proposed in Chinese Patent Publication No. 102506597 (Zhao, Yaohua et al.) is used. This heat pipe array is provided in a "flat plate" configuration, thereby providing a good contact between the heat exchanger and the underside of the solar panel. Tang's experimental arrangement using water cooling was able to achieve an average increase of output power of 9% from the solar panel, and a maximum output of power of nearly 14%. Whilst such energy efficiency increase is possible, and the heated water could be used for heating, such as in domestic applications, the water has to be circulated using a pump that consumes power. When contemplating the application of such heat pipe cooling, the net energy gain must be considered against the initial cost of the heat pipe assembly and other equipment.

Because simple cooling arrangements are not efficient, attempts have been made to minimize the amount of water and the amount of energy used in such arrangements, as discussed in "Enhancing the performance of photovoltaic panels by water cooling" (Moharram K.A. et al.) Ain Shams Engineering Journal (2013) 4 869-877. However, the proposed enhancements do not significantly improve the overall output, but rather identify when it is best to provide the heat exchanger cooling in order to find a compromise between the output energy of the solar panels and the energy needed for cooling.

It also has been proposed to utilize the "thermoelectric effect" or "Seebeck effect" for cooling a photovoltaic module. Such arrangements utilise thermoelectric modules, sometimes referred to as "Peltier modules", as described in US5197291 (Levinson) dating back to 1993, and in

DE102008009979 (Perez) where a system is proposed for both cooling and generating electrical energy. Another arrangement is proposed in US2011/0155214 (Lam) where a Peltier module is affixed thereto. Many of these arrangements are actually inefficient and therefore have not been employed. DEI 02008009979 whilst proposing to improve efficiency would actually have the opposite effect, as the fans employed to cool the rear of the Peltier modules would consume more power than the additional output. US2011/0155214 discloses very inefficient air cooling of the panel.

A temperature differential of at least 10°C is required for Peltier modules to make any useful electrical energy output. The abovementioned prior art Peltier module arrangements could not provide a temperature differential of this magnitude, and therefore are not of practical use.

IEEE Transactions on energy conversion Vol 26, No. 2 June 2011 pp662-670 "Energy conversion efficiency of a hybrid solar system for photovoltaic, thermoelectric, and heat utilization" (Yang, D. et al.) discloses a hybrid solar panel comprising a photovoltaic layer (PL), a thermoelectric layer, and a hot water layer containing water tubes. The various layers are attached to each other by adhesives. In this arrangement the hot water tubes are made of copper and are embedded in moulded fibreglass. This arrangement claims to have 30% higher electrical output over traditional photovoltaic systems, and those employing simpler cooling solutions. However, by the cost analysis as discussed in Section D of that paper, the hybrid panel, and in particular the

thermoelectric layer, is quite expensive. Due to the high cost of this hybrid arrangement, it is not commercially viable.

Another issue with much of the prior art, is that when connecting heat sinks and heat exchanger materials by adhesives to solar panels, you have the problem that dissimilar materials will expand and contract at different rates. Expansion and contraction of a single layer of metallic heat sink extending over and adhered to the entire length of a "glass" solar panel will cause the solar panel to fatigue and crack. This will degrade the efficiency of the solar panel over time, and cause

"hotspots" to worsen and/or develop. Hotspots and their detrimental effect are discussed later.

An improved arrangement by the present inventors is described in International Patent Publication No. WO2015/039185 (Webb et al.). Heat exchangers in combination with thermoelectric modules are used to make solar panels more efficient. In particular a modular unit capable of being fitted to a conventional solar panel is described. One of the advantages in this arrangement is the use of a plurality of heat sink tiles that minimize effects of the expansion and contraction problem of dissimilar materials. However, the use of thermo electric modules whilst improving the efficiency of solar panels, still add cost to the system.

A single photovoltaic cell, affected by shadow or dirt or by "hot spot", will be negatively influenced up to thirty six times its affected area throughout the panel or string of cells. In most instances the output of a solar panel is determined by the weakest photovoltaic cell, and the output of a photovoltaic system is determined by the weakest panel.

"Hot spots" are a common problem in conventionally mass produced solar panels, and can become significant as the panel ages and becomes exposed to the environment. Hot spot heating occurs in a module when its operating current exceeds the reduced short-circuit current of a shadowed cell or group of cells within it. There are a variety of causes, including local shadowing, cell degradation due to cracking, or loss of a series-parallel circuit due to individual interconnect open circuits. Hot spots can also occur at the periphery of the cells.

Reverting now to the earlier mentioned Tang prior art, its inability to produce no more than an average increase of output power of 9% from the solar panel, is because of the limitation of the "flat plate" heat exchanger employed. The flat plate heat exchanger, as shown in CN102506597 is abutted against the back of the solar panel (made up of an array of cells), and water passing there through is used to transfer heat away from the solar panel. Most simple heat exchangers, whether they be heat pipe arrays as in CN102506597 with straight pipes, or instead pipes following tortuous paths, will have a pipe with a water inlet at one end of a solar panel and an outlet at the opposite end. This means that the coolant water provided at the inlet end is more effective in cooling the photovoltaic cells at or near the inlet end, but as the temperature of the coolant water increases within the pipe as it moves across the panel past a row of cells, its ability to cool the photovoltaic cells near the outlet is considerably reduced. One of the problems associated with this is that the area/region having the most heat, say from a hotspot may be a photovoltaic cell near the water inlet of the heat exchanger. Coolant (water) passing that "hotspot" cell, will have its coolant temperature considerably rise due to heat transfer. This "coolant water" whose temperature has considerably risen may cause a number of heat transfer issues. Firstly, this water now may actually be so warm that it actually spreads the heat to other parts of the solar panel, and secondly because its temperature has risen it is not effective in cooling any other "hot spot" regions it may encounter during its path through the heat exchanger. Furthermore because the "hot spot" may affect a significant area of the panel, the cooling effect provided by such a heat exchanger is limited.

Because of the "hotspot" problem, which is encountered in many of the mass produced low cost solar panels, this and other prior art simple heat exchanger arrangements cannot under typical operating conditions achieve substantially uniform removal of heat across a row of photovoltaic cells. This then impacts on the ability to significantly increase the power output of the solar panel.

It is desirable to have an improved cooling arrangement and system that could be used with existing conventional solar panels, as a retrofit or during manufacture, with or without the use of thermoelectric modules, and which reduces heating due to hot spots by providing more uniform cooling. It is also desirable to provide a heat exchange assembly as a modular unit, which is not costly to make, easy to attach, and capable of significantly increasing the output of a conventional solar panel by effectively cooling all of the cells in the solar panel.

The present invention seeks to provide an apparatus for generating electricity that will ameliorate or overcome at least one of the deficiencies of the prior art.

SUMMARY OF INVENTION

According to a first aspect the present invention consists in an apparatus for generating electricity comprising:

at least one solar panel having a plurality of photovoltaic cells;

a plurality of heat sink tiles; and

a first heat exchanger; wherein said heat sink tiles are disposed between said solar panel and said first heat exchanger, and said first heat exchanger is connected to a circulation system which is adapted to allow coolant fluid to flow through said first heat exchanger, and each of said heat sink tiles having a first side in direct thermal contact with a respective one of said photovoltaic cells and an opposite second side in contact with said first heat exchanger, and said first heat exchanger having a plurality of first coolant chambers disposed adjacent to said heat sink tiles.

Preferably said heat exchanger has a plurality of inlet galleries and outlet galleries for delivering and removing said coolant fluid to and from said first coolant chambers, and said inlet galleries and said outlet galleries are spaced apart from said heat tiles.

Preferably each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith.

Preferably said inlet galleries are for delivering said coolant fluid from an inlet manifold such that coolant entering said respective first coolant chambers of adjacent heat sink tiles are at substantially the same temperature to each other.

Preferably said inlet galleries are for delivering said coolant fluid from an inlet manifold in parallel at substantially the same temperature to said respective first coolant chambers of adjacent heat sink tiles.

Preferably each heat sink tile is substantially square and has four of said first coolant chambers associated therewith.

Preferably an expansion gap is disposed between two adjacent said heat sink tiles.

Preferably said plurality of heat sink tiles are provided in a grid array with expansion gaps there between.

Preferably said grid array of said plurality of heat sink tiles is formed from a single thin sheet of metal, with each of said heat sink tiles connected to each other by a minimal connection.

Preferably said minimal connection is a perforation or tab.

Preferably said heat sink tiles are bonded to said photovoltaic cells of said solar panel.

Preferably an electronic control unit is electrically connected to said solar panel, and said electronic control unit is used for distribution and storage of electrical charge.

Preferably a pump disposed in said circulation system operably circulates said coolant fluid through said first heat exchanger. Preferably a surface temperature sensor is disposed on said solar panel and operably connected to said electronic control unit, so that said pump is operated above a predetermined temperature sensed by said sensor.

Preferably said coolant fluid exiting said first heat exchanger is circulated through a second heat exchanger disposed within a storage tank containing water.

Preferably said heat energy within said coolant is transferred to said water contained within said storage tank.

Preferably said first heat exchanger has at least one second coolant chamber, and said second coolant chamber is disposed adjacent to a box housing the electrical connections of said solar panel.

Preferably at least one thermoelectric module is disposed between said first heat exchanger and at least one of said respective heat sink tiles, so that said opposite second side of said respective heat sink tile is in direct contact with said thermoelectric module, and at least one first coolant chamber of said first heat exchanger is adjacent said thermoelectric module so that heat transfer can occur between said coolant fluid passing through said first coolant chamber and said thermoelectric module.

Preferably a heat differential between a first side of said thermoelectric module and an opposed second side thereof generates at least a portion of said electrical charge.

Preferably said plurality of heat sink tiles and said first heat exchanger are formed in a modular unit attachable to said solar panel.

According to a second aspect the present invention consists in an apparatus for generating electricity comprising:

at least one solar panel having a plurality of photovoltaic cells; and

a first heat exchanger;

wherein said apparatus further comprising a plurality of heat sink tiles disposed between said solar panel and said first heat exchanger, and said first heat exchanger is connected to a circulation system which is adapted to allow coolant fluid to flow through said first heat exchanger, and each of said heat sink tiles having a first side in direct thermal contact with a respective one of said photovoltaic cells and an opposite second side in contact with said first heat exchanger, and said first heat exchanger having a plurality of first coolant chambers and a plurality of inlet galleries and outlet galleries delivering and removing coolant fluid to and from said first coolant chambers, each coolant chamber having an open end disposed adjacent to one of said heat sink tiles and an opposed closed end, and said inlet galleries and said outlet galleries are spaced apart from said heat sink tiles.

Preferably the inlet and outlet galleries are disposed at or near the closed end of said coolant chambers.

According to a third aspect the present invention consists in an apparatus for generating electricity comprising:

at least one solar panel having a plurality of photovoltaic cells; and

a first heat exchanger;

wherein said apparatus further comprising a plurality of heat sink tiles disposed between said solar panel and said first heat exchanger, and said first heat exchanger is connected to a circulation system which is adapted to allow coolant fluid to flow through said first heat exchanger, and each of said heat sink tiles having a first side in direct thermal contact with a respective one of said photovoltaic cells and an opposite second side in contact with said first heat exchanger, and said first heat exchanger having a plurality of first coolant chambers and a plurality of inlet galleries and outlet galleries for delivering and removing coolant fluid to and from said first coolant chambers, each coolant chamber having an open end disposed adjacent to one of said heat sink tiles and an opposed closed end, and said inlet galleries and said outlet galleries are spaced apart from said heat sink tiles.

According to a fourth aspect the present invention consists in an apparatus for cooling a solar panel having a plurality of photovoltaic cells, said apparatus comprising a plurality of heat sink tiles and a heat exchanger; said heat sink tiles arranged in a grid array with each heat sink tile having a first side adapted to contact a respective photovoltaic cell, each heat sink tile disposed within the peripheral boundary of its respective photovoltaic cell, and said first heat exchanger having a plurality of first coolant chambers and a plurality of inlet galleries and outlet galleries which are adapted for delivering and removing a coolant fluid to and from said first coolant chambers, each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith, each coolant chamber having an open end disposed adjacent its respective heat sink tile and an opposed closed end, and said inlet galleries and said outlet galleries are spaced apart from said heat sink tiles.

Preferably at least one expansion gap is disposed between two adjacent said heat sink tiles.

Preferably said heat sink tiles are formed from a single thin sheet of metal and are minimally connected to each other.

According to a fifth aspect the present invention consists in a modular unit for attachment to a solar panel having a plurality of photovoltaic cells, said modular unit comprising:

a heat exchanger having an inlet manifold and an outlet manifold; and

a plurality of heat sink tiles arranged in a grid array with expansion gaps there between;

wherein each of said heat sink tiles having a coolant side in contact with said first heat exchanger and an opposed bonding side for contact with a respective one of said photovoltaic cells, and said first heat exchanger having a plurality of first coolant chambers disposed adjacent to said heat sink tiles, and each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith.

Preferably said heat exchanger has a plurality of inlet galleries and outlet galleries in fluid communication between said first coolant chambers and said inlet manifold and outlet manifold, and said inlet galleries and said outlet galleries are spaced apart from said heat tiles.

Preferably said minimal connection is a perforation or tab.

Preferably said inlet galleries are adapted to deliver a coolant fluid to said coolant chambers from an inlet manifold in parallel at substantially the same temperature.

Preferably said modular unit is connected to a circulation system, and a pump disposed in said circulation system is operably adapted to circulate said coolant fluid through said first heat exchanger. According to a sixth aspect the present invention is a heat exchanger assembly for cooling a solar panel having a plurality of photovoltaic cells, said assembly comprising a plurality of cooling groups, each cooling group adapted for independent transfer of heat from a respective photovoltaic cell;

each cooling group comprising a heat sink tile, at least one first coolant chamber having an open end and an opposed closed end, and at least one inlet gallery and outlet gallery in fluid communication with said first coolant chamber, said heat sink tile having a first side adapted to thermally contact said respective photovoltaic cell, and an opposite second side facing and abutted against said open end of said first coolant chamber, and said inlet gallery and said outlet gallery are spaced apart from said heat sink tile.

Preferably said each of said heat sink tiles is arranged in a grid array with expansion gaps there between.

Preferably said grid array of said heat sink tiles is formed from a single thin sheet of metal, with each of said heat sink tiles connected to each other by a minimal connection.

Preferably said minimal connection is a perforation or tab connection.

Preferably each of said cooling groups are adapted to deliver a coolant fluid from an inlet manifold via their respective inlet galleries in parallel at substantially the same temperature.

Preferably each of said cooling groups have outlet galleries for delivering said coolant fluid to an outlet manifold in parallel.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 shows a schematic view of a system for generating electricity in accordance with a first embodiment of the present invention;

Fig. 2 is a schematic view of the array of heat sink tiles used in the system depicted in fig 1 ;

Fig. 3 is a schematic view of the first heat exchanger and its coolant chambers connected thereto of the embodiment shown in Fig. 1.

Fig. 4 is a schematic view of a conventional prior art solar panel used in a system for generating electricity in accordance with the embodiment of Fig. 1 ; Fig. 5 a is an enlarged cross sectional detail of the first heat exchanger assembly and its coolant chambers in accordance with the embodiment of Fig 1.

Fig. 5b is an enlarged cross sectional detail of a first heat exchanger assembly and its coolant chambers in accordance with an alternative second embodiment utilising thermoelectric modules.

Fig. 6 is an enlarged schematic view of cooling arrangement at the solar panel junction box region of the embodiment shown in Fig. 1.

Fig. 7a depicts an enlarged schematic view of some of the heat sink tiles shown in Fig. 2.

Fig. 7b depicts an enlarged schematic view of the adhesive detail of the centre of a heat sink tile shown in Fig. 7a, attached to the photovoltaic layer of the embodiment shown in Fig. 1

Fig. 7c depicts an enlarged schematic view of the adhesive detail of two adjacent heat sink tiles shown in Fig. 7a attached to the photovoltaic layer of the embodiment shown in Fig. 1.

Fig. 8 depicts an enlarged schematic view of a single heat sink tile from the array of tiles shown in Fig. 2, with the location of the coolant fluid contact areas.

Fig. 9 is an exploded perspective view of an alternative embodiment of a heat exchanger (coolant gallery unit) and array of heat sink tile forming a modular unit that can be attached to a solar panel and used in the system of Fig. 1.

Fig. 10 depicts an exploded segment of first and second production parts that can be assembled to form a coolant gallery unit forming part of the modular unit depicted in Fig. 9.

Fig. 11 depicts a top perspective view of the two assembled production parts of Fig. 10.

Fig. 12 depicts a bottom perspective view of the two assembled production parts of Fig. 10.

Fig. 13a depicts an enlarged plan view of the segment of the coolant gallery unit shown in Fig. 10.

Fig. 13b depicts a cross section of the segment of the coolant gallery unit through A- A in Fig. 13 a.

Fig. 13c depicts a cross section of the segment of the coolant gallery unit through B-B in Fig. 13a.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figs. 1 to 5 a and 6 to 7c depict a system 50 for generating electricity comprising a solar panel 100 and an array 30 of heat sink tiles 29 with heat exchanger 26 fixed thereto. Heat sink tiles 29 are arranged in a "grid array" as best seen in Fig. 2 and are spaced apart such that expansion gaps 41 exist there between. A "cut out" space 151 is disposed in two of tiles 29, so that they may be fitted around electrical junction box 150 of solar panel 100.

Solar panel 100 is a conventional set of solar photovoltaic modules, represented by photovoltaic layer 200 which contains twenty four photovoltaic cells 38, a backing layer 39 adhered thereto and a glass protection layer 40. In this embodiment, the photovoltaic cells 38 are of a common size used, namely 156 mm x 156 mm. Backing layer 39 is typically a thin plastic sheet or paint, whose purpose is to protect photovoltaic cells 38 from UV, moisture and weather. However, layer 39 is intentionally thin so as to not provide any substantive thermal insulation to cells 38.

Each heat sink tile 29, preferably made of thin sheet aluminium (of about 1mm thickness) is fixed to and therefore associated to a respective photovoltaic cell 38 via thin layer 39, of the

photovoltaic layer 200.

Solar panel 100 is electrically connected and mounted on a supporting structure, and operably connected to an electronic control unit (ECU) 8 via leads 6. Solar panel 100 has a panel frame 101, as shown in Fig. 4. A battery (or bank of batteries) 12 is also operably connected to ECU 8 via leads 10.

System 50 also comprises a circulation system including a first heat exchanger (water gallery exchanger) 26, circulation pipe network 24, 25, circulation pump 17 and second heat exchanger 18 disposed within water storage tank 19. Water, or some other coolant, is able to be pumped through circulation pipe network 24, 25 between first heat exchanger 26 and second heat exchanger 18.

First heat exchanger 26 has an inlet manifold 21 and outlet manifold 22, and a plurality of galleries 23 extending there between. In Fig. 3, water is shown entering inlet manifold 21 via inlet 31 as arrow 21a, and exiting outlet manifold 22 via outlet 32 as arrow 22a.

In addition to inlet manifold 21 and outlet manifold 22, heat exchanger 26 has a plurality of galleries, namely cold water gallery 222 and warm water gallery 333, connected to coolant chambers 55 extending there between. Each coolant chamber 55 has an "open end" disposed adjacent a tile 29 and an opposed closed end. Each gallery 222,333 of heat exchanger 26 comprises a "tubular member", best seen in Fig 5a. The "tubular member" of gallery 222, 333 is the conduit through which coolant fluid passes there through when heat exchanger 26 is in use. Galleries 222,333 fluidally connect to chambers 55 at or near the "closed end" thereof. By disposing the galleries 222,333 at a location away, or spaced apart from heat sink tiles 29, there is minimal transfer of heat between tiles 29 and coolant in galleries 222,333. This minimal transfer of heat between tiles 29 and coolant in galleries 222,333 can be improved by choosing a suitable grade and thickness of plastic from which heat exchanger 26 is made that provides certain level of thermal insulation.

As best seen in Fig. 5a each coolant chamber 55 is fixed at the rear of the photovoltaic layer 200 of solar panel 100 via the heat sink tiles assembly 29. In this embodiment a conventional

commercially photovoltaic solar panel 100 is used, and heat sink tiles 29 made of aluminium, are disposed between coolant chambers 55 and cells 38 of photovoltaic layer 200, and in "direct thermal contact" therewith.

In this specification "direct thermal contact" between a heat sink tile 29 and a respective photovoltaic cell 38, means that tile 29 is bonded to photovoltaic cell 38 or its thin adjacent layer 39, via an adhesive 58, which may for example be an epoxy resin or thermal plaster. The layer 39 and adhesive 58 are so thin that they do not prevent substantive heat transfer between tile 29 and its respective photovoltaic cell 38.

In this embodiment four coolant chambers 55, their associated galleries 222,333 and the respective heat sink tile 29 is referred to as a "cooling group". However, it should be understood that the invention in other embodiments may utilise a different number of coolant chambers in each "cooling group" with its respective heat sink tile 29.

In this embodiment solar panel 100 is rated at 100 watts. Each heat sink tile 29 with its "cooling group' of four coolant chambers 55 of heat exchanger 26, has its "bonding side" correspondingly fixed and aligned with a respective photovoltaic cell 38 via adjacent layer 39 on the rear layer 200 of panel 100. The other side of each heat sink tile 29, i.e. its "cooling side" is in communication with the coolant chambers 55, i.e. it is in contact with heat exchanger 26.

The cold water gallery 222 ensures that water (coolant) of substantially the same temperature from inlet manifold 21 is entering each "cooling group" of coolant chambers 55 associated with each heat sink tile 29, and the water (coolant) with elevated temperature that exits chambers 55 via outlet galleries 333 are delivered to outlet manifold 22. This ensures substantially "linear removal heat". It should be noted that coolant chambers 55 are cavities that are substantially larger in size than the galleries 222,333 extending from them. For instance in this embodiment, coolant chambers 55 are about 40mm x 40mm x 5mm, whereas galleries 222,333 have a internal diameter of about 4mm. Chambers 55 which are open to heat sink tiles 29, ensures that water passing through chambers 55 is in direct contact with tiles 29 and an efficient heat transfer occurs there between.

Fig. 8 schematically depicts a square heat sink tile 29, typically about 155mm x 155 mm. In use it would be laid over a respective photovoltaic cell 38 that makes up layer 200. Four areas 29 CA are shown, one of which is shaded, each of which is disposed centrally in a respective quadrant of heat sink tile 29. Each of these areas 29CA is about 40mm x 40mm, namely about 1600 mm . Each area 29ca represents both the "open end" of the coolant chamber 55 and the "contact area" on heat sink tile 29 being directly contacted by the coolant fluid passing through the respective coolant chamber 55. Each area 29 CA comprises at least one quarter of the surface area of the quadrant of the heat sink tile 29 it is disposed on. Contact areas of this size are effective in ensuring the cooling effect extends to all areas of the "tile quadrant", where the internal cavity height of each cooling chamber 55 is about 5mm.

By ensuring that heat sink tiles 29 are slightly smaller than the respective photovoltaic cells 38 they are associated with and thermally contacted to, a "gap" can be provided between each heat sink tile 29 in the "grid array". As heat sink tiles 29 have gaps between them, then heat transfer from one heat sink tile 29 to another is minimised, and expansion and contraction of each tile 29 is possible, substantially independent of the surrounding tiles 29. Preferably, a continuous gap at the periphery boundary of tiles 29 would be desirable, however, if heat sink tiles 29 are "minimally connected" to each other by perforations or tabs 49, heat transfer between heat sink tiles 29 is still minimized, and tiles 29 are still able to individually expand and contract. In this specification "minimally connected" means that length of gaps 41 between adjacent tiles 29 are substantially larger than the length of any tabs 49 or other connection that would interconnect them.

As seen in Fig. 7a the "grid array" 30 of heat tiles 29 is for ease of manufacture made from as single sheet of aluminium. Each heat sink tile 29 has a very small opening 401 at its centre. At the time of bonding heat sink tile 29 over a respective photovoltaic cell 38 via layer 39 using adhesive 58, opening 401 allows for excess adhesive 58a to pass there through, as shown in Fig. 7b. In the single sheet "grid array" 30, tabs 49 are used to minimally connect heat sink tiles 29 at the periphery boundary between heat sink tiles. At gap 41 adjacent to tab 49, excess adhesive 58b may pass there through, as shown in Fig 7c. Tab 49 is shown as bent or creased, but it should be understood that tab 49 could be shaped otherwise.

Adhesive 304 is used to bond heat exchanger (water gallery exchanger) 26 via coolant chambers 55, to tile assembly 29. Heat sink tiles 29 should preferably be a maximum size of about 155mm x 155mm, to avoid damage or failure to their respective slightly larger photovoltaic cells 38 they are associated with. This is because the different materials of the photovoltaic cells 38 and tiles 29 expand and contract at different rates. Gaps 41 between tiles 29 are needed but may be filled with adhesive to allow for expansion and shrinkage. In this embodiment, as a tile 29 is slightly smaller than the respective photovoltaic cell 38 it is bonded to, the periphery of each tile 29 lies within the circuit boundary lines of the respective twenty four photovoltaic cells 38 on the opposing front side of layer 200.

As can be seen in Fig. 5A, coolant chamber 55 is formed by chamber housing members 305 being bonded to galleries 222,333 of heat exchanger 26 and also positioned and bonded against the rear side of heat sink tile 29, via adhesive (bonding agent) 304. A cooling gallery chassis 303 interconnects the gallery structure. In use coolant flowing through heat exchanger 26 enters a coolant chamber 55 via cold water gallery 222 and exits via warm water gallery 333. Heat transfer occurs between heat sink tile 29 and the coolant passing through coolant chamber 55.

Surface temperature sensor 5 disposed on solar panel 200, senses change in temperature of the "photovoltaic operational surface" of panel layer 200. Sensor 5 is operably connected to ECU 8. Pump 17 is operably connected to ECU 8 via power cable 9 such that its operation can be controlled thereby.

In use when a predetermined temperature has been reached, say about 28°C, ECU 8 switches water circulating pump 17 to "on", causing coolant to flow through pipe 24 into first heat exchanger 26 across the rear of panel layer 200 and circulating through galleries 222,333, coolant chambers 55 and pipe 25 and heat exchanger 18 in water tank 19. The " coolant " in heat exchanger 26 causes a heat differential to occur throughout the array of heat sink tiles 29 and drawing the heat across from the heat on the front "panel" facing side and cold on rear "exchanger" side. In addition, remotely positioned secondary coolant chambers 56 in the electrical connection box 150 are fluidly connected via 222A and 333A. Secondary coolant chambers 56 reduce the localised heat within the box 150 which houses electrical connections of said solar panel.

The resulting heat is removed from the rear of solar panel via first heat exchanger 26 and pipe network 24, 25, and circulated by pump 17, such that it is pumped through second heat exchanger unit 18, whereby the "heat energy" of the circulating coolant is transferred into stored water 20, in tank 19, thereby elevating its temperature for future use.

Coolant is delivered throughout first heat exchanger 26 through inlet manifold 21 and is further delivered individually to each "cooling group" of coolant chambers 55 via cold water gallery 222 and exits coolant chambers 55 via warm water galleries 333 and outlet manifold 22. A substantially even linear removal of heat is obtained throughout the photovoltaic layer 200 and first heat exchanger 26. This is because each "cooling group" with its heat sink tile 29 is in most part "independently" cooling its respective photovoltaic cell 38. This substantially independent cooling in combination with minimal heat transfer between adjacent heat sink tiles 29, and therefore adjacent "cooling groups" ensures that heat from a "hotspot" in one photovoltaic cell 38 is not spread to other photovoltaic cells 38 in layer 200. This contributes significantly to improved efficiency of the output power of panel 100. Furthermore, the substantially independent expansion and contraction of each of heat sink tiles 29 means that less stress is placed on the photovoltaic cells 38 they are associated with, therefore minimising the likelihood of cracking and fatigue of photovoltaic cells 38.

It must also be understood the system 50 is specifically designed to eliminate hotspots throughout solar panel 200, resulting in a greatly elevated electrical output within a solar radiation

environment, and providing a photovoltaic panel with an improved electrical output.

In the abovementioned embodiment the "coolant" is preferably water, but may include

conventional coolant additives such as ethylene glycol or other heat transfer agents, such as those commonly used in air conditioners or car engine cooling. The coolant but may be substituted for a commercially available gas. In the abovementioned embodiment the gallery assembly components of the heat exchanger 26, including galleries 222,333 and chamber members 305 are preferably manufactured from plastic, but may in other embodiments be made of other suitable materials.

A heat exchange system similar to system 50 using coolant chambers 55 and heat sink tiles 29 was prototyped and trialled to ascertain the improvement in efficiency of solar panel output that direct contact of coolant on the heat sink tiles could achieve. A monocrystalline 100W solar panel by SOLRAISER™ model no. SPM-ST100W having an array of twenty four photovoltaic cells was first trialled outdoors during daylight without any heat exchanger arrangement. Without any cooling and at an ambient temperature of about 26°C, the photovoltaic cell temperature typically was about 73°C, and only produced about 25W. When the heat exchange system similar to system 50 was fitted to this panel, and the panel was cooled, at an ambient temperature of about 26°C, the photovoltaic cell temperature was typically reduced to 23°C and the panel produced in excess of 70W.

Figs. 9 to 13c depict a second embodiment which allows the important components of the earlier described first embodiment, namely coolant galleries 222,333 including coolant chambers 55 of heat exchanger 26 and heat sink tiles 29 to be constructed as a modular unit 123 which can be readily constructed alone and attached to a solar panel 100 to be utilised in a system similar to the first embodiment.

This modular unit 123 has its primary components provided in two integrated production parts, namely coolant gallery unit (CGU) 126 and heat sink tile array (HSTA) 130.

For ease of reference, the assembly of the first primary production part is shown in Figs 10 to 13c, showing just a segment of CGU 126 that would make up a single "cooling group" made up of four coolant chambers 55m, their associated galleries 222m,333m and the respective heat sink tile of array 129.

CGU 126 is preferably formed as an assembly of two plastic components, first component 126a and second component 126b which together form coolant chambers 55m and inlet and outlet galleries 222m, 333m and other interconnecting galleries 223. Not only does CGU 126 contain coolant galleries 222m, 333m, 223and coolant chambers 55m, it also includes the electrical junction box housing 150m for a solar panel 100 of the earlier embodiment.

The second primary production part, namely HSTA 130 is preferably a single sheet of thin gauge aluminium. It may be formed, stamped, pressed, perforated and cut-out in single operation, or possibly chemically etched. HSTA 130 comprises the array of heat sink tiles 29 which are "minimally connected" to each other by perforations or tabs.

CGU 126 and HSTA 130 are permanently bonded together to form a complete unit, namely modular unit 123. This modular unit 123 can be made and packaged separately for remote, additional fitment to solar panel 100, whether at manufacturing end product level or as an addition to panels 100 already in service.

The marked improvement in efficiency of power output of the present invention, whether employing the arrangement shown in the first or second embodiments, is because of a number of reasons. Firstly, using heat sink tiles 29 that are spaced apart from each other with "minimal connection" or no connection ensures that very little heat transfer occurs between them. This means that "hotspot" heat on one photovoltaic cell 38 is not readily transferred to an adjoining cell 38 via adjacent heat sink tiles 29. Secondly, the heat transfer from each photovoltaic cell 38 by a "cooling group" is occurring substantially independently from heat transfer of adjoining photovoltaic cells 38, with the primary heat transfer occurring between cooling chambers 55 and a respective heat sink tile 29 in any one cooling group. Thirdly, as inlet and outlet galleries 222,333 are disposed away, or spaced apart from the surface of heat sink tiles 29, very little heat transfer occurs between tiles 29 and galleries 222,333.

In the abovementioned first embodiment as shown in Fig. 5 a, tile 29 is disposed between a cell 38 of solar panel 100 and coolant chambers 55. However, in an alternative embodiment as depicted in Fig. 5b, the use of a thermoelectric module 1 and heat sink pad 27 is added to the structure of the embodiment shown in Fig 5a. In the Fig 5b embodiment thermoelectric modules 1 have a first side thereof in direct contact with heat sink tile 29 and an opposed side is abutted (in direct contact) with heat sink pad 27. Opposed edges of thermoelectric module 1 and heat sink pad 27, sit under the stepped regions 42 of chamber members 305. In this embodiment the coolant passing through coolant chamber 55 passes over heat sink pad 27. Where the arrangement of Fig 5b is used in system 50 of the first embodiment, thermoelectric modules 1 are operably connected to ECU 8 via leads (not shown). The heat differential between a first side of thermoelectric modules (against heat sink tiles 29) and opposed second sides thereof generates an electrical charge, which is delivered to battery 12 via the abovementioned not shown leads. This generation of electrical charge is similar to that generated in the embodiments described in International patent publication No. WO2015/039185 (Webb et al.). However, in this embodiment shown in Fig. 5b, the coolant flowing through coolant chambers 55 provides improved cooling when compared to the prior art, thus providing a potentially increased heat differential, and therefore a greater amount of electrical charge generated by thermoelectric modules 1.

In the abovementioned embodiments, the heat exchanger assembly components and heat sink tiles could be attached to solar panels either at the manufacturing stage, or retrofitted to existing solar panels. The heat exchanger assembly components and heat sink tiles could be provided in

"modular unit" form.

The terms "comprising" and "including" (and their grammatical variations) as used herein are used in inclusive sense and not in the exclusive sense of "consisting only of.

Claims

CLAIMS:

1. An apparatus for generating electricity comprising:

at least one solar panel having a plurality of photovoltaic cells;

a plurality of heat sink tiles; and

a first heat exchanger;

wherein said heat sink tiles are disposed between said solar panel and said first heat exchanger, and said first heat exchanger is connected to a circulation system which is adapted to allow coolant fluid to flow through said first heat exchanger, and each of said heat sink tiles having a first side in direct thermal contact with a respective one of said photovoltaic cells and an opposite second side in contact with said first heat exchanger, and said first heat exchanger having a plurality of first coolant chambers disposed adjacent to said heat sink tiles.

2. An apparatus as claimed in claim 1, wherein in said heat exchanger has a plurality of inlet galleries and outlet galleries for delivering and removing said coolant fluid to and from said first coolant chambers, and said inlet galleries and said outlet galleries are spaced apart from said heat tiles.

3. An apparatus as claimed in claim 2, wherein each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith.

4. An apparatus as claimed in claim 3, wherein said inlet galleries are for delivering said

coolant fluid from an inlet manifold such that coolant entering said respective first coolant chambers of adjacent heat sink tiles are at substantially the same temperature to each other.

5. An apparatus as claimed in claim 3, wherein said inlet galleries are for delivering said coolant fluid from an inlet manifold in parallel at substantially the same temperature to said respective first coolant chambers of adjacent heat sink tiles.

6. An apparatus as claimed in claim 1, wherein each heat sink tile is substantially square and has four of said first coolant chambers associated therewith.

7. An apparatus as claimed in claim 1, wherein an expansion gap is disposed between two adjacent said heat sink tiles.

8. An apparatus as claimed in claim 1, wherein said plurality of heat sink tiles are provided in a grid array with expansion gaps there between.

9. An apparatus as claimed in claim 8, wherein said grid array of said plurality of heat sink tiles is formed from a single thin sheet of metal, with each of said heat sink tiles connected to each other by a minimal connection.

10. An apparatus as claimed in claim 9, wherein said minimal connection is a perforation or tab.

11. An apparatus as claimed in claim 1 , wherein said heat sink tiles are bonded to said

photovoltaic cells of said solar panel.

12. An apparatus as claimed in claim 1, wherein an electronic control unit is electrically

connected to said solar panel, and said electronic control unit is used for distribution and storage of electrical charge.

13. An apparatus as claimed in claim 12, wherein a pump disposed in said circulation system operably circulates coolant through said first heat exchanger.

14. An apparatus as claimed in claim 13, wherein a surface temperature sensor is disposed on said solar panel and operably connected to said electronic control unit, so that said pump is operated above a predetermined temperature sensed by said sensor.

15. An apparatus as claimed in claim 13, wherein said coolant fluid exiting said first heat

exchanger is circulated through a second heat exchanger disposed within a storage tank containing water.

16. An apparatus as claimed in 15, wherein said heat energy within said coolant is transferred to said water contained within said storage tank.

17. An apparatus as claimed in claim 1, wherein said first heat exchanger has at least one

second coolant chamber, and said second coolant chamber is disposed adjacent to a box housing the electrical connections of said solar panel.

18. An apparatus as claimed in claim 12, wherein at least one thermoelectric module is

disposed between said first heat exchanger and at least one of said respective heat sink tiles, so that said opposite second side of said respective heat sink tile is in direct contact with said thermoelectric module, and at least one first coolant chamber of said first heat exchanger is adjacent said thermoelectric module so that heat transfer can occur between said coolant fluid passing through said first coolant chamber and said thermoelectric module.

19. An apparatus as claimed in claim 18, wherein a heat differential between a first side of said thermoelectric module and an opposed second side thereof generates at least a portion of said electrical charge.

20. An apparatus as claimed in claim 1 wherein said plurality of heat sink tiles and said first heat exchanger are formed in a modular unit attachable to said solar panel.

21. An apparatus for generating electricity comprising:

at least one solar panel having a plurality of photovoltaic cells; and

a first heat exchanger;

wherein said apparatus further comprising a plurality of heat sink tiles disposed between said solar panel and said first heat exchanger, and said first heat exchanger is connected to a circulation system which is adapted to allow a coolant fluid to flow through said first heat exchanger, and each of said heat sink tiles having a first side in direct thermal contact with a respective one of said photovoltaic cells and an opposite second side in contact with said first heat exchanger, and said first heat exchanger having a plurality of first coolant chambers and a plurality of inlet galleries and outlet galleries delivering and removing coolant fluid to and from said first coolant chambers, each coolant chamber having an open end disposed adjacent to one of said heat sink tiles and an opposed closed end, and said inlet galleries and said outlet galleries are spaced apart from said heat sink tiles.

22. An apparatus as claimed in claim 21 wherein each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith.

23. An apparatus as claimed in claim 21, wherein the inlet and outlet galleries are disposed at or near the closed end of said coolant chambers.

24. An apparatus for generating electricity comprising:

at least one solar panel having a plurality of photovoltaic cells; and

a first heat exchanger;

25. An apparatus for cooling a solar panel having a plurality of photovoltaic cells, said

apparatus comprising a plurality of heat sink tiles and a heat exchanger; said heat sink tiles arranged in a grid array with each heat sink tile having a first side adapted to contact a respective photovoltaic cell, each heat sink tile disposed within the peripheral boundary of its respective photovoltaic cell, and said first heat exchanger having a plurality of first coolant chambers and a plurality of inlet galleries and outlet galleries which are adapted for delivering and removing a coolant fluid to and from said first coolant chambers, each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith, each coolant chamber having an open end disposed adjacent its respective heat sink tile and an opposed closed end, and said inlet galleries and said outlet galleries are spaced apart from said heat sink tiles.

26. An apparatus as claimed in claim 25 wherein at least one expansion gap is disposed

between two adjacent said heat sink tiles.

27. An apparatus as claimed in claim 26, wherein said heat sink tiles are formed from a single thin sheet of metal and are minimally connected to each other.

28. An apparatus as claimed in claim 25 wherein said inlet galleries are for delivering said coolant fluid from an inlet manifold in parallel at substantially the same temperature to said respective first coolant chambers of adjacent heat sink tiles.

29. A modular unit for attachment to a solar panel having a plurality of photovoltaic cells, said modular unit comprising:

a heat exchanger having an inlet manifold and an outlet manifold; and

a plurality of heat sink tiles arranged in a grid array with expansion gaps there between; wherein each of said heat sink tiles having a coolant side in contact with said first heat exchanger and an opposed bonding side for direct thermal contact with a respective one of said photovoltaic cells, and said first heat exchanger having a plurality of first coolant chambers disposed adjacent to said heat sink tiles, and each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith.

30. A modular unit as claimed in claim 29, wherein said heat exchanger has a plurality of inlet galleries and outlet galleries in fluid communication between said first coolant chambers and said inlet manifold and outlet manifold, and said inlet galleries and said outlet galleries are spaced apart from said heat tiles.

31. A modular unit as claimed in claim 29, wherein said grid array of said plurality of heat sink tiles is formed from a single thin sheet of metal, with each of said heat sink tiles connected to each other by a minimal connection.

32. A modular unit as claimed in claim 31, wherein said minimal connection is a perforation or tab.

33. A modular unit as claimed in claim 29, wherein said inlet galleries are adapted to deliver a coolant fluid to said coolant chambers from an inlet manifold in parallel at substantially the same temperature.

34. A modular unit as claimed in claim 33, wherein said modular unit is connected to a

circulation system, and a pump disposed in said circulation system is operably adapted to circulate said coolant fluid through said first heat exchanger.

35. A heat exchanger assembly for cooling a solar panel having a plurality of photovoltaic cells, said assembly comprising a plurality of cooling groups, each cooling group adapted for substantially independent transfer of heat from a respective photovoltaic cell;

36. A heat exchanger assembly as claimed in claim 35 wherein said each of said heat sink tiles is arranged in a grid array with expansion gaps there between.

37. A heat exchanger assembly as claimed in claim 36, wherein said grid array of said heat sink tiles is formed from a single thin sheet of metal, with each of said heat sink tiles connected to each other by a minimal connection.

38. A heat exchanger assembly as claimed in claim 37, wherein said minimal connection is a perforation or tab connection.

39. A heat exchanger assembly as claimed in claim 37, wherein each of said of cooling groups are adapted to deliver a coolant fluid from an inlet manifold via their respective inlet galleries in parallel at substantially the same temperature.

40. A heat exchanger assembly as claimed in claim 39, wherein each of said cooling groups have outlet galleries for delivering said coolant fluid to an outlet manifold in parallel.