WO2018148796A1

WO2018148796A1 - Apparatus and system for generating electricity with interfaced heat exchange

Info

Publication number: WO2018148796A1
Application number: PCT/AU2018/050119
Authority: WO
Inventors: Roger Clyde Webb; Maria Anna Webb
Original assignee: Qingdao Austech Solar Technology Co. Ltd.
Priority date: 2017-02-15
Filing date: 2018-02-15
Publication date: 2018-08-23

Abstract

An apparatus for generating electricity comprises a solar panel having a plurality of photovoltaic cells, a plurality of heat sink tiles and a first heat exchanger in a first low pressure circulation system having a first low pressure pump for circulating a first coolant. The low pressure circulation interfaces with an interface heat exchanger in order to transfer heat to second coolant in second circulation system having a third heat exchanger disposed in a water storage tank. A second pump circulates the second coolant. A plurality of valves in the first heat exchanger may be opened or closed to allow variability in the flow path.

Description

APPARATUS AND SYSTEM FOR GENERATING ELECTRICITY WITH INTERFACED

HEAT EXCHANGE

TECHNICAL FIELD

The present invention relates to an apparatus and system for generating electricity. In particular, this invention is firstly directed towards a photovoltaic solar panel in combination with heat sink tiles and a first heat exchanger having coolant chambers, the latter cooling the solar panel to assist in improving its efficiency. The first heat exchanger is in a first low pressure cooling circuit interfaced with a second heat exchanger in a second cooling circuit operating at a high pressure. The apparatus is described with coolant zoning and variable coolant distribution, which in addition to improving the efficiency of the solar panel provides a dual purpose of using heat drawn away by the heat exchanger to heat water.

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 "hot spot" 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.

International Patent Publication No. WO 2015/188226 (Webb et al.) discloses an apparatus and system that attempts to provide cooling to a solar panel having an array of photovoltaic cells to address the "hot spot" problem. However, the arrangement is prone to suffer from non-linear coolant circulation and distribution and over pressurisation of coolant fluid. In this arrangement certain photovoltaic cells would be cooled effectively avoiding hot spots in such cells. However, the non-linear cooling circulation resulted in other photovoltaic cells within the array to have elevated hot spot zones. In a typical embodiment the solar panel and its associated heat exchanger are elevated relative to the water tank containing the second heat exchanger, and the height difference typically would be about 3 to 3.5 metres as the solar panel is typically mounted on a roof and the water tank at a nearby location there below. In order to circulate the coolant fluid the system had to be substantially pressurised say to about 80-100 psi (about 550-690 kPa) by a pump so that the coolant fluid could be moved the height (vertical distance) between the heat exchangers. The elevated hot spots and the pressurised fluid may lead to mechanical deformation, damage and failure of the photovoltaic cells, and therefore disruption of the electrical conductivity of the solar panel.

It is desirable to have an improved cooling arrangement that could be used with existing conventional solar panels, as a retrofit or during manufacture, which reduces heating due to hot spots by providing more uniform cooling. This arrangement preferably provides a dual purpose of using heat drawn away by the heat exchanger from the solar panel to heat water.

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 cooling at least one solar panel having a plurality of photovoltaic cells, said apparatus comprising a plurality of heat sink tiles and a first heat exchanger; said heat sink tiles arranged in a grid array with expansion gaps there between, and 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, said first heat exchanger having an inlet manifold and an outlet manifold and plurality of spaced apart galleries extending there between, each gallery having a plurality of first coolant chambers connected in series through which a first coolant fluid flows, each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith, and wherein said first heat exchanger is fluidally connected to a second interface heat exchanger via a first low pressure circulation system, a first low pressure pump disposed in said first circulation system for circulating said first coolant fluid through said first heat exchanger and said second interface heat exchanger, and a second circulation system through which a second coolant fluid flows is thermally interfaced with said second interface heat exchanger to transfer heat away from said first circulation system, said second circulation system comprising a third heat exchanger disposed within a storage tank containing water.

Preferably said first heat exchanger having a plurality of valves which when open allows for said first coolant fluid from said inlet manifold to pass through all said galleries to said outlet manifold in a first flow configuration, and by closing said valves allows for coolant fluid to alter the flow path of said first coolant fluid through said galleries to a second flow configuration. Preferably said first flow configuration is a linear flow path through the galleries between the inlet manifold and outlet manifold, and wherein said second flow configuration is a tortuous flow path through the galleries between the inlet manifold and outlet manifold.

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 in at least one battery, and a plurality of temperature sensors are disposed on said solar panel and operably connected to said electronic control unit, each of said rows of photovoltaic cells having at least one of said sensors disposed thereon, and said valves operably connected to said electronic control unit.

Preferably said valves are selectively opened and closed in response to changes in sensed temperature measured by said sensors.

Preferably said valves are selectively opened and closed in response to sensed variables.

Preferably said variables comprising one or more of sensed temperature measured by said sensors, status of charge in said battery , the demand of heated water from said tank, and the temperature of water in said tank.

Preferably said low pressure of said first coolant fluid in said first circulation system when circulated by said low pressure pump is less than 25 psi.

Preferably said low pressure of said first coolant fluid in said first circulation system when circulated by said low pressure pump is about 5 psi.

Preferably said inlet manifold and/or outlet manifold have a flow restrictor therein.

Preferably at least one thermoelectric module is disposed between said first circulation system and said second circulation system within said second interface heat exchanger, and a heat differential between a first side of said thermoelectric module and an opposed second side thereof generates an electrical charge.

Preferably heating element is disposed within said storage tank and operably connected to said electronic control unit.

According to a second aspect the present invention consists in an apparatus for the dual purpose for cooling at least one solar panel having a plurality of photovoltaic cells and for heating water disposed in a storage tank, wherein said apparatus comprising a first low pressure circulation system independent from second circulation system, said first low pressure circulation system comprising a plurality of heat sink tiles and a first heat exchanger; said heat sink tiles arranged in a grid array with expansion gaps there between, and with each heat sink tile having a first side adapted to contact a respective photovoltaic cell of said solar panel, each heat sink tile disposed within the peripheral boundary of its respective photovoltaic cell, said heat exchanger having an inlet manifold and an outlet manifold and plurality of spaced apart galleries extending there between, each gallery having a plurality of first coolant chambers connected in series through which a first coolant fluid flows, each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith, and said first heat exchanger is fluidally connected to a second interface heat exchanger , a first low pressure pump disposed in said first circulation system for circulating said first coolant fluid through said first heat exchanger and said second interface heat exchanger, and a second coolant fluid flows through said second interface heat exchanger, and said first low pressure circulation system is thermally interfaced with said second circulation system within said second interface heat exchanger for transferring heat away from said first circulation system to said second circulation system, and said second circulation system

comprising a third heat exchanger disposed within a storage tank containing water.

Preferably said first heat exchanger having a plurality of valves which when open allows for said first coolant fluid from said inlet manifold to pass through all said galleries to said outlet manifold in a first flow configuration, and by closing said valves allows for coolant fluid to alter the flow path of said first coolant fluid through said galleries to a different second flow configuration.

Preferably said first flow configuration is a linear flow path through the galleries between the inlet manifold and outlet manifold, and wherein said second flow configuration is a tortuous flow path through the galleries between the inlet manifold and outlet manifold.

Preferably said valves are selectively opened and closed in response to sensed variables. Preferably said variables comprising one or more of sensed temperature measured by said sensors, status of charge in said battery , the demand of heated water from said tank, and the temperature of Preferably said low pressure of said first coolant fluid in said first circulation system when circulated by said low pressure pump is less than 25 psi.

Preferably a heating element is disposed within said storage tank and operably connected to said electronic control unit.

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 a conventional prior art solar panel used in a system for generating electricity in accordance with the embodiment of Fig. 1 ;

Fig. 4 is a schematic enlarged partial view of the interface heat exchanger and bottom row of the first heat exchanger/photovoltaic cells of the first low pressure circulation system shown in Fig. 1 , with flow detail.

Fig. 5 a is a schematic representation of the tortuous flow through the first heat exchanger when the valves are closed in accordance with the embodiment of Fig 1.

Fig. 5b is a schematic representation of the linear flow through the first heat exchanger when the valves are open in accordance with the embodiment of Fig 1. Fig. 6 shows a schematic view of a system for generating electricity in accordance with a second embodiment of the present invention, where three solar panels (and associated heat exchangers) are in a low pressure circulation system which interfaces with single interface heat exhanger;.

Fig. 7 depicts a schematic view of a third embodiment solar panel with forty photovoltaic cells showing the tortuous flow through the associated heat exchanger when the valves are closed.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figs. 1 to 5b depict a system 50 for generating electricity and for heating water. The system 50 comprises two distinct circulation systems, namely first (solar panel) circulation system 50s and second (water tank) circulation system 50χ which interface with each other at an interface heat exchanger 80.

First circulation system 50s comprises 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. These heat sink tiles 29 and the expansion gaps are similar to those found in the admitted prior art International Patent Publication No. WO 2015/188226 (Webb et al.). In similar fashion to this prior art there is "direct thermal contact" between a heat sink tile 29 and a respective photovoltaic cell 38. This means that tile 29 is bonded to photovoltaic cell 38 or its thin adjacent layer via an adhesive. The thin adjacent layer and adhesive are so thin that they do not prevent substantive heat transfer between tile 29 and its respective photovoltaic cell 38.

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 rated at 100 watts and is a conventional set of solar photovoltaic modules, represented by photovoltaic layer 200, see Fig. 3, which contains twenty four photovoltaic cells 38, a backing layer (not shown) adhered thereto and a glass protection layer (not shown). In this embodiment, the photovoltaic cells 38 are of a common size used, namely 156 mm x 156 mm. The abovementioned backing layer_ is typically a thin plastic sheet or paint, whose purpose is to protect photovoltaic cells 38 from UV, moisture and weather. However, backing layer 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 0.6 mm thickness) is fixed to and therefore associated to a respective photovoltaic cell 38 via the thin backing layer 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. The battery 12 is connected to a DC to AC converter 13.

First circulation system 50s is a "sealed low pressure system" through which a "first coolant" flows. This first coolant preferably has a high percentage of a heat transfer agent such as ethylene glycol. Other heat transfer agents, such as those commonly used in air conditioners or car engine cooling may be used. The first coolant but may be substituted for a commercially available gas.

First circulation system 50s comprises a tortuous conduit 75 passing through interface heat exchanger 80. The inlet 81 and outlet 82 of heat exchanger 80 is connected to heat exchanger 26. Downstream of outlet 82 a low pressure circulation pump 17L is disposed. This low pressure pump 17L is rated to ensure a low pressure of about 5 psi (about 35kPa) is imparted to the first coolant being circulated through system 50s-

Whilst the low pressure in this embodiment as referred above is about 5 psi, it should be understood that in this specification the term "low pressure" means a pressure of 25 psi or less.

Heat exchanger 26 has an inlet manifold 21 and outlet manifold 22, and a plurality of galleries 23, extending there between. The galleries 23 are identified as galleries 23a, 23b, 23c, 23d, 23e and 23f with each of these galleries gallery associated with row of four heat sink tiles 29 and therefore four photovoltaic cells 38. These rows are identified as A, B, C, D, E and F.

First coolant is shown entering inlet manifold 21 via inlet 31 downstream of low pressure circulation pump 17L, and exiting outlet manifold 22 via outlet 32 as A first valve 91 is disposed on inlet manifold 21 side of heat exchanger 26 near row B. A second valve 92 is disposed on outlet manifold 22 near row E. There is also a plurality of restrictors 93 in the inlet and outlet manifolds 21 , 22 to regulate the flow of first coolant through heat exchanger 26. This assists in maintaining regulated low pressure within heat exchanger 26 and system 50s- The galleries 23 have a plurality of coolant chambers (pockets) 55. In this embodiment each coolant chamber (pocket) 55 is associated with a respective heat sink tile 29 and photovoltaic cell 38. As such there are four coolant chambers 55 for each row A, B, C, D, E and F. As such there are twenty four coolant chambers 55 in this embodiment.

Three temperature sensors 94 are disposed on heat sink tiles at rows B, D and F respectively. These sensors 94 are operably connected to control unit 8.

In use the first coolant flows through heat exchanger 26 so that it passes through galleries 23 and coolant chambers 55, thus removing the heat energy from the photovoltaic cells 38 via heat sink tiles 29. The link galleries 23i exit the first coolant, now heated into outlet manifold 22.

The first coolant when exiting outlet manifold 22 then flows into the second closely mounted interface heat exchanger 80 via inlet 81. The first coolant then passes through interface heat exchanger 80 via a first tortuous gallery 75 exchanging heat with a "second coolant" passing through a second tortuous gallery 85 of the second circulation system 50_t. The first coolant is returned to the inlet manifold 21 of heat exchanger 26 via low pressure circulation pump 17L.

The flow path of first coolant passing through the coolant chambers 55 of row A, is shown in the schematic in Fig. 4.

As first circulation system 50s is limited to the heat exchanger 26 and the tortuous path 84 passing through the closely mounted interface heat exchanger 80, it is possible to easily maintain the small volume of first coolant in a sealed low pressure system.

Second tortuous gallery 85 (of interface heat exchanger 80) of second circulation system 50τ is interconnected with a third water tank heat exchanger 18 via pipe network 24, 25. Pipe 24 takes second coolant from outlet 86 of interface heat exchanger 80 to inlet 87 of heat exchanger 18, whilst outlet 88 of heat exchanger 18 delivers second coolant to inlet 89 of interface heat exchanger 80. Second coolant is circulated by pump 17H through second circulation system 50χ, whereby the "heat energy" of the circulating second coolant, gained by heat transfer in interface heat changer 80 from the first circulation system 50s is transferred into stored water 20 in tank 19, thereby elevating its temperature for future use. The pump 17nis designed to pressurise the second coolant in second circulation system 50_tto a pressure of about 80-500 psi (about 170-3447 kPa), which is

substantially higher to the pressure in low pressure first circulation system 50s. The second coolant may also have a heat transfer agent such as ethylene glycol however its composition/percentages does necessarily have to identical to that of the first coolant.

Water 20 inside tank 19, may also be heated by heating element 95 controlled by control unit 8. This may for example be activated when the battery 12 is full, or to assist in increasing the temperature of water 20 when hot water demand is high.

In use the electricity generated by the solar panel is stored in battery 12. The cooling provided by heat exchanger 26 improves the output efficiency of solar panel 100. The heat transfer away from the solar panel 100 firstly to the first coolant, and then through interface heat exchanger 80 to the second coolant ensures, that heat is put to use in heating water 20 in tank 19.

The use of valves 91 and 92 means that flow of first coolant through the heat exchanger 26 may be varied, preferably to optimise either output of the solar panel or the waste heat being harvested to heat water 20 in tank 19 and/or to achieve a reasonable balance there between.

The first valve 91 and second valve 92 are able by their opening and closing to vary the path characteristics (nature of flow) through heat exchanger 26. If both valves 91 and 92 are closed the first coolant passing through rows A and B are then forced to "tortuously pass" through the remaining rows. This is best seen in Fig 5a where the arrows depict tortuous flow firstly in one direction as shown in rows A,B and then in the opposite direction in rows C,D, and then finally in rows E,F in the same direction as in rows A,B.

However, if both valves 91 , 92 are opened then the flow through the heat exchanger 26 is linear. This is best seen in Fig 5b where all the arrows depict linear flow in all the rows A to E from the inlet manifold 21 to the outlet manifold 22.

Where both valves 91 ,92 are closed thus causing tortuous flow, this will under typical conditions optimise the heat being harvested for heating the water 20 in tank 19. However, when both valves 91 ,92 are opened this will under typical conditions optimise the cooling and therefore the output of solar panel 100.

Preferably, valves 91, 92 are electromagnetic and operably connected to control unit 8. As such, whether the intent is to optimise the output of solar panel 100 or the heating water 20 in tank 19, the valves may be operably both opened or both closed depending on various variables, such as the status of charge in battery 12, the demand of heated water from tank 19, and the temperature sensed by sensors 94 to name a few. An advantage of the present embodiment over the prior art is that firstly the separation of two separate circulation systems, namely a low pressure system to be used with the solar panel cooling separate from the higher pressure system for use with the hot water tank, means that the likelihood of a coolant pressure causing damage to the photovoltaic cells as they are cooled is eliminated or significantly reduced. Secondly, the use of the valves 91 , 92 can be used to vary between optimising for solar panel output efficiency and heating of hot water, or for achieving a balance therbetween.

The present embodiment could in a not shown embodiment be further enhanced by providing thermoelectric (Peltier) modules to be disposed within interface heat exchanger 80, so that the temperature differential between the first circulation system 50s at tortuous path 84 and the second circulation system 50t at tortuous path 85 generates additional power output.

It should be understood that a plurality of solar panels 100 each having associated heat exchangers 26 of the type described in the abovementioned first embodiment could be fluidally connected to a single interface heat exchanger 80. Such a second embodiment is schematically shown in Fig. 6, where three solar panels 100 with associated heat exchangers 26 are fluidally connected to a single interface heat exchanger 80 to form a circulation system 50p, and utilise a single low pressure pump 17_L to circulate coolant there through. The interface heat exchanger 80 of this second embodiment interfaces with a second circulation system 50τ having a pump 17H and water tank 19 containing water 20 in similar fashion to the first embodiment. In such an arrangement, circulation system 50p IS "sealed low pressure system"similar to the first embodiment, and low pressure pump 17L is rated to ensure a low pressure of about 5 psi (about 35kPa) is imparted to the coolant being circulated through system 50p.

Fig. 7 shows a schematic of second embodiment of a larger solar panel 100a, say rated at 200 watts and containing forty photovoltaic cells 38, arranged in ten rows of four. Like that of the first embodiment it has a heat exchanger 26a, containing galleries have a plurality of coolant chambers (pockets) 55a. Like in the first embodiment each coolant chamber (pocket) 55a is associated with a respective photovoltaic cell 38 (and associated heat sink tile), so that there are forty coolant chambers. In this embodiment there are two first valves 91a disposed on inlet manifold 21a side of heat exchanger 26a, and two second valves 92a is disposed on outlet manifold 22a side. The inlet manifold 21a also comprises a number of restrictors 93a in the inlet manifiold 21a to regulate flow. The heat exchanger 26a would be part of low pressure sealed circulation system (not shown) and fluidally connected to an interface heat exchanger (not shown) in a similar fashion to the earlier embodiments. Like that of the first embodiment valves 91a and 92a are able to be opened and closed to change the flow path of coolant there through.

In this embodiment each "pair of adjacent rows" are identified by G, H, I, J and K, and the valves 91a and 92a are all closed. This cause the flow to follow a tortuous path through the row pairs G, H, I, J and K, which would be advantageous for optimising the heat being harvested. However, if the valves 91a and 92a were to be opened, then the flow path would revert to linear (not shown but similar to Fig 5b), thus optimising the cooling effect to the solar panel 100a.

It should be understood that whilst in all of the abovementioned embodiments there is single coolant chamber 55,55a associated with each photovoltaic cell 38 and the adjacent heat sink tile 29. However, it should be understood that in not shown embodiments of the present invention a plurality of "coolant chambers" could be associated with each photovoltaic cell 38 in a similar fashion to that described in International Patent Publication No. WO 2015/188226 (Webb et al.).

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 sink tiles could be provided in a sheet form "heat sink array" (depicted as 30 in Fig. 2) and provided with expansion gaps 41 and minimal connection as described in International Patent Publication No. WO 2015/188226 (Webb et al.), or as individual tiles 29 adhered to each photovoltaic cell 38.

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 cooling at least one solar panel having a plurality of photovoltaic cells, said apparatus comprising a plurality of heat sink tiles and a first heat exchanger; said heat sink tiles arranged in a grid array with expansion gaps there between, and 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, said first heat exchanger having an inlet manifold and an outlet manifold and plurality of spaced apart galleries extending there between, each gallery having a plurality of first coolant chambers connected in series through which a first coolant fluid flows, each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith, and wherein said first heat exchanger is fluidally connected to a second interface heat exchanger via a first low pressure circulation system, a first low pressure pump disposed in said first circulation system for circulating said first coolant fluid through said first heat exchanger and said second interface heat exchanger, and a second circulation system through which a second coolant fluid flows is thermally interfaced with said second interface heat exchanger to transfer heat away from said first circulation system, said second circulation system comprising a third heat exchanger disposed within a storage tank containing water.

2. An apparatus as claimed in claim 1, wherein said first heat exchanger having a plurality of valves which when open allows for said first coolant fluid from said inlet manifold to pass through all said galleries to said outlet manifold in a first flow configuration, and by closing said valves allows for coolant fluid to alter the flow path of said first coolant fluid through said galleries to a second flow configuration.

3. An apparatus as claimed in claim 2, wherein said first flow configuration is a linear flow path through the galleries between the inlet manifold and outlet manifold, and wherein said second flow configuration is a tortuous flow path through the galleries between the inlet manifold and outlet manifold.

4. An apparatus as claimed in claim 2, 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 in at least one battery, and a plurality of temperature sensors are disposed on said solar panel and operably connected to said electronic control unit, each of said rows of photovoltaic cells having at least one of said sensors disposed thereon, and said valves operably connected to said electronic control unit.

5. An apparatus as claimed in claim 4, wherein said valves are selectively opened and closed in response to changes in sensed temperature measured by said sensors.

6. An apparatus as claimed in claim 4, wherein said valves are selectively opened and closed in response to sensed variables.

7. An apparatus as claimed in claim 6, wherein said variables comprising one or more of sensed temperature measured by said sensors, status of charge in said battery , the demand of heated water from said tank, and the temperature of water in said tank.

8. An apparatus as claimed in claim 1, wherein said low pressure of said first coolant fluid in said first circulation system when circulated by said low pressure pump is less than 25 psi.

9. An apparatus as claimed in claim 8, wherein said low pressure of said first coolant fluid in said first circulation system when circulated by said low pressure pump is about 5 psi.

10. An apparatus as claimed in claim 1, wherein said inlet manifold and/or outlet manifold have a flow restrictor therein.

11. An apparatus as claimed in claim 1 , wherein at least one thermoelectric module is disposed between said first circulation system and said second circulation system within said second interface heat exchanger, and a heat differential between a first side of said thermoelectric module and an opposed second side thereof generates an electrical charge.

12. An apparatus as claimed in claim 4, wherein a heating element is disposed within said storage tank and operably connected to said electronic control unit.

13. An apparatus for the dual purpose for cooling at least one solar panel having a plurality of photovoltaic cells and for heating water disposed in a storage tank, wherein said apparatus comprising a first low pressure circulation system independent from second circulation system, said first low pressure circulation system comprising a plurality of heat sink tiles and a first heat exchanger; said heat sink tiles arranged in a grid array with expansion gaps there between, and with each heat sink tile having a first side adapted to contact a respective photovoltaic cell of said solar panel, each heat sink tile disposed within the peripheral boundary of its respective photovoltaic cell, said heat exchanger having an inlet manifold and an outlet manifold and plurality of spaced apart galleries extending there between, each gallery having a plurality of first coolant chambers connected in series through which a first coolant fluid flows, each heat sink tile has at least one of said plurality of first coolant chambers respectively associated therewith, and said first heat exchanger is fluidally connected to a second interface heat exchanger , a first low pressure pump disposed in said first circulation system for circulating said first coolant fluid through said first heat exchanger and said second interface heat exchanger, and a second coolant fluid flows through said second interface heat exchanger, and said first low pressure circulation system is thermally interfaced with said second circulation system within said second interface heat exchanger for transferring heat away from said first circulation system to said second circulation system, and said second circulation system comprising a third heat exchanger disposed within a storage tank containing water.

14. An apparatus as claimed in claim 13, wherein said first heat exchanger having a plurality of valves which when open allows for said first coolant fluid from said inlet manifold to pass through all said galleries to said outlet manifold in a first flow configuration, and by closing said valves allows for coolant fluid to alter the flow path of said first coolant fluid through said galleries to a different second flow configuration.

15. An apparatus as claimed in claim 14, wherein said first flow configuration is a linear flow path through the galleries between the inlet manifold and outlet manifold, and wherein said second flow configuration is a tortuous flow path through the galleries between the inlet manifold and outlet manifold.

16. An apparatus as claimed in claim 14, wherein an electronic control unit is electrically

17. An apparatus as claimed in claim 16, wherein said valves are selectively opened and closed in response to changes in sensed temperature measured by said sensors.

18. An apparatus as claimed in claim 16, wherein said valves are selectively opened and closed in response to sensed variables.

19. An apparatus as claimed in claim 18, wherein said variables comprising one or more of sensed temperature measured by said sensors, status of charge in said battery , the demand of heated water from said tank, and the temperature of water in said tank.

20. An apparatus as claimed in claim 13, wherein said low pressure of said first coolant fluid in said first circulation system when circulated by said low pressure pump is less than 25 psi.

21. An apparatus as claimed in claim 20, wherein said low pressure of said first coolant fluid in said first circulation system when circulated by said low pressure pump is about 5 psi.

22. An apparatus as claimed in claim 13, wherein said inlet manifold and/or outlet manifold have a flow restrictor therein.

23. An apparatus as claimed in claim 13, wherein at least one thermoelectric module is

disposed between said first circulation system and said second circulation system within said second interface heat exchanger, and a heat differential between a first side of said thermoelectric module and an opposed second side thereof generates an electrical charge.

24. An apparatus as claimed in claim 16, wherein a heating element is disposed within said storage tank and operably connected to said electronic control unit.