WO2005003643A1

WO2005003643A1 - Solar heater system

Info

Publication number: WO2005003643A1
Application number: PCT/AU2004/000924
Authority: WO
Inventors: John Wayne Craft
Original assignee: John Wayne Craft
Priority date: 2003-07-08
Filing date: 2004-07-08
Publication date: 2005-01-13
Also published as: AU2003903512A0

Abstract

A solar heater system (10) comprises a dome shaped solar energy collector (12) that has a transparent dome shaped outer member (14) and a reflective dome-shaped inner member (16). The dome shape means that in use of the solar collector (12) and over a substantial portion of a day, some portion or other of the surface of the collector will generally face towards the sun. An enclosed space (18) between the outer and inner members (14, 16) contains heat absorbing conduits (20) of a primary fluid flow circuit for passage of a fluid to be heated. The conduits (20) extend uprightly between a lower manifold (22) and an upper manifold (24). The primary fluid flow circuit includes a reservoir (26) within the inner member for collection of the heated fluid. A second, closed, fluid flow circut for a pressurized low boiling point liquid may also be provided. This has upright heat absorbing conduits (40) between upper and lower manifolds (44 and 46) and a heat exchange coil (42) within the reservoir (26). A solar cell array (50) may also be provided in the top of the dome for providing power for pumps (36, 48) in the primary and second fluid flow circuits and/or for an electrical heating element (70) within the reservoir (26). The solar heater system (10) has a high efficiency because of the integration of two fluid heating systems and an electric heating system. Also the shape of the solar energy collector allows for a higher efficiency than known flat panel solar collectors.

Description

SOLAR HEATER SYSTEM

Technical Field The present invention relates to a solar heater system for heating a fluid. The fluid will typically be water, however other fluids are possible, for example an ethylene glycol/water mixture.

Background The discussion below of the background to the invention is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge in Australia as at the priority date of any of the claims.

Solar heater systems typically include a flat panel type solar energy collector through which tubes conveying the fluid to be heated pass. The tubes absorb heat and this is transferred to the fluid as it passes through the tubes.

The fluid can be water, in which case the solar heater system may be such as to directly heat a potable water supply. Typically the heated water is stored in a tank and re-cycled through the solar collector panel. Alternatively the solar heater system can indirectly heat a potable water supply. In this case the fluid to be heated (which may be other than water for example an ethylene glycol/water mixture) flows in a loop circuit through the solar panel and a heat exchanger associated with a storage tank containing the potable water. Solar heater systems have many uses including, for example, heating swimming pools, distilling water, power generation and room heating.

The efficiency of a solar heater system depends upon many factors including the hours of sunshine and the orientation of a panel at a given location. Another important factor is the efficiency of the solar energy collector, which should be as high as possible.

Disclosure of the Invention The present invention provides a solar heater system for heating a fluid, the system including a shaped solar energy collector that includes at least one heat absorbing conduit for passage of a fluid for the fluid to be heated, the shaped solar energy collector having a three-dimensional curvilinear or rectilinear surface area for exposure to solar energy, the shape of the surface area being such that in use and over a substantial portion of a day, some portion or other of the surface thereof will generally face towards the sun, the solar energy collector including an outer member providing said surface area for exposure to solar energy and an inner member of substantially similar but smaller shape having a reflective surface, whereby the outer and inner members define therebetween an enclosed space which contains the at least one conduit, a heat insulated reservoir for the fluid, and a primary fluid flow circuit between a fluid inlet to the solar energy collector and a fluid outlet from the reservoir, the fluid flow circuit including the at least one conduit and the reservoir wherein fluid entering through the inlet is heated as it passes through the at least one conduit and is collected in the reservoir for delivery of heated fluid through the outlet.

By providing a shaped solar energy collector as defined, which is preferably dome shaped, for example, hemispherical, the collector can be mounted such that over a substantial portion of a day some portion or other of the collector will generally face towards the sun thereby giving a longer exposure time of the collector to the sun compared to that which is generally available with a prior art flat panel solar collector. Additionally, for a given "footprint" size for a solar collector, a shaped solar collector as defined provides a greater surface area for exposure to the sun compared to a flat panel collector. It also allows a greater length of the heat absorbing conduit to be provided within the solar heated enclosed space between the outer and inner members. All of these factors contribute to the shaped solar energy collector component of a system according to the invention being able to achieve a higher efficiency compared to a flat panel collector.

Preferably the inner member of the shaped solar energy collector encloses the heat insulated reservoir. This also assists to increase the efficiency of the system because the length of the fluid flow circuit between the solar energy collector and the reservoir can be minimized thereby reducing losses. According to an embodiment, the inner member contains an insulation material that surrounds the reservoir, thereby heat insulating the reservoir. With this structure the reservoir can be supported by the filler insulating material, which allows for reduced production costs.

With the reservoir within the inner member, it may not have a large enough capacity to operate, for example as a storage tank for a domestic or commercial potable hot water supply. In cases such as this, the reservoir of the solar heater system may feed hot water to a larger capacity storage tank, or may feed to a heat exchanger in a larger capacity storage tank.

The at least one heat absorbing conduit may be a continuous convoluted or coiled conduit within the enclosed space between the outer and inner members. Preferably for increased efficiency of heat transfer, the primary fluid flow circuit includes a first manifold to which the inlet is connected and a second manifold having a feed pipe into the reservoir, wherein there are a plurality of heat absorbing conduits which are connected between the first and second manifolds. The first manifold may be located peripherally around the inner member of the solar energy collector at a lower region thereof and the second manifold may be located at an upper region thereof, with the heat absorbing conduits spaced around the inner member and extending upwardly between the first and the second manifolds. This structure assists an increase in efficiency because the system can include an overall greater length of the fluid carrying heat absorbing conduit than is typically the case in conventional flat panel solar collectors. Also in an embodiment where the reservoir is within the inner member, the upright conduits allow for the thermo-siphon effect to encourage fluid flow from the inlet and ultimately into the reservoir. The primary fluid flow circuit may also include a pump for pumping the fluid through the circuit.

Preferably a solar heater system according to the invention includes a second, closed, fluid flow circuit for a pressurized low boiling point liquid, the second fluid flow circuit including a heat absorbing portion within the enclosed space between the outer and inner members of the solar energy collector and a second portion within the reservoir, wherein when a pressurized low boiling point liquid is contained in the second, closed, fluid flow circuit, it absorbs heat from the solar heat absorbing portion and releases heat via the second portion to a fluid in the reservoir.

The incorporation of the second, closed, fluid flow circuit into the shaped solar energy collector to provide additional heating for the fluid in the reservoir allows for further improvement in the efficiency of the solar heater system. Preferably the second, closed, fluid flow circuit includes a plurality of heat absorbing conduits spaced between the heat absorbing conduits of the primary fluid flow circuit. More preferably the heat absorbing conduits of the primary fluid flow circuit and the second, closed, fluid flow circuit extend generally upwardly between a lower region and an upper region of the inner member of the shaped solar energy collector.

The second portion of the second, closed, fluid flow circuit that is located within the reservoir preferably includes a heat exchange coil for providing an increased surface area for contact with a fluid in the reservoir. The second, closed, fluid flow circuit may also include a pump for pumping the pressurized low boiling point liquid around the second fluid flow circuit.

Preferably a solar heater system according to the invention includes an array of photovoltaic solar cells on a top surface portion of the outer member of the shaped solar energy collector, and further includes an electrical circuit for the solar heater system, wherein the array of solar cells provides electrical power to the electrical circuit.

The electrical circuit may include a rechargeable battery for supplementing the power supplied by the array of solar cells. The electrical circuit may function to operate an electrical heating element within the reservoir or to operate pumps in the primary and secondary fluid flow circuits, or both. This feature thus allows for further improvement in the efficiency of the solar heater system. It also allows for a typically mains powered booster system that a conventional solar heater system would generally incorporate to be omitted. Such a booster system is usually operated when the solar energy and thus heating is low or at night and adds to the running costs of a conventional system. Such extra running costs can be reduced with a solar heating system according to the invention incorporating an array of solar cells as above described, thereby allowing for further improvements in efficiency.

Preferably the electrical circuit provides for the rechargeable battery to be charged, when required, from the power supplied by the array of solar cells. The electrical circuit preferably includes a microprocessor which is programmed for the various circuit functions to occur according to predetermined criteria. Such predetermined criteria may include providing a lower temperature threshold and an upper temperature threshold for the fluid within the reservoir and providing temperature sensing devices, for example thermistors, for providing signals to the microprocessor from appropriate locations within the fluid flow circuits indicative of temperature . The microprocessor may operate to ensure power is supplied to the heating element only between the temperature thresholds. The electrical circuit may also include an invertor for inverting the DC power from the array of solar cells and battery to provide AC power for the heating element and/or for electric motors for driving pumps in the primary and secondary fluid flow circuits.

For a better understanding of the invention and to show how it may be carried into effect, preferred embodiments thereof will now be described, by way of non-limiting example only, with reference to the accompanying drawings.

Brief Description of Drawings. Fig. 1 is a perspective view of a solar heater system according to a preferred embodiment of the invention. Fig. 2 is a cross-sectional view of the solar heater system of Fig. 1. Fig. 3 is a block diagram of an electrical circuit of the solar heater system of Fig. 1. Detailed Description of Embodiments A solar heater system 10 according to an embodiment of the invention includes a shaped solar energy collector 12 having a three-dimensional curvilinear surface area, in this embodiment hemispherical, for exposure to solar energy. The surface may have other three-dimensional curvilinear shapes, eg. semi-ellipsoidal, catenoidal, paraboloidal or like dome shapes. It may alternatively have a three-dimensional rectilinear shape, eg. a truncated prismatic or semi-hedral (eg. semi-hexahedral, semi-octahedral) or the like shape. The dome shape of the solar energy collecting surface is such that in use and over a substantial portion of a day, some portion or other of the surface thereof will generally face towards the sun. Effectively, the solar energy collector 12 has a 180° aperture.

The shaped solar energy collector 12 includes a hemispherical outer member 14, which provides a cover for the solar collector, and a hemispherical inner member 16. The outer member 14 and inner member 16 are mounted on a base 17 and define therebetween an enclosed, relatively narrow, space 18. The outer member 14 is transparent to solar radiation and may be made of a suitable plastics glazing material, eg. heat stabilized polycarbonate or polyvinylchloride (PVC). The inner member 16, which may be made of fibreglass, is provided with a reflective outer surface.

The space 18 includes a heat absorber component in the form of fluid carrying conduits 20 connected between a lower manifold 22 and an upper manifold 24. Thus the conduits 20 extend generally upwardly between the manifolds 22 and 24. They are also spaced around the inner member 16. The conduits 20 may be made of, for example, a high performance plastics material suitable for heat exchanger usage, which has a high thermal conductivity. Suitable materials for the conduits 20 are, for example, polyphenylene sulphide (PPS), polytetrafluoroethylene (PTFE) and polyurethane (PUR). They may be treated to have a selective outer surface to reduce the emission of heat energy therefrom so that more energy is available to heat the fluid flowing through the conduits 20. Selective surface coatings giving an emissivity as low as 10 to 12% are known. Generally the conduits 20 should have at least a matt black surface. Generally a selective solar absorber surface for the conduits 20 can be highly absorptive of short wavelength solar radiation and have low emittance of long wavelength infrared radiation from the surface. Solar radiation passing through the outer member 14 impinges on at least some of the heat absorbing conduits 20 which absorb the heat transmitted by the radiation, and the conduits 20 in turn transfer a large portion of this absorbed heat to a fluid as it flows through the conduits 20. The solar radiation also heats the enclosed space 18, which heating is enhanced by reflection of radiation from the reflective surface of the inner member 16. This heating of the enclosed space 18 adds to the heat that is available to be absorbed by the conduits 20.

The solar heater system 10 also includes a reservoir 26 (see Fig. 2) which is preferably located within the inner member 16. A reservoir 26 not located within the inner member 16 is preferably located nearby the solar energy collector 12. A reservoir 26 within the inner member 16 may be provided by a tank, eg. of a suitable metal, or a suitable plastics material able to withstand the expected temperature of the heated fluid it is to contain. A reservoir 26 within the inner member 16 allows for relatively ready assembly concomitantly with appropriately heat insulating the reservoir 26. Thus with the inner member 16 inverted, a tank for providing the reservoir 26 can be temporarily held in position therein and a suitable insulating material 28, eg. polystyrene, then added into the inner member 16 to surround the tank. The. insulating material 28, when set, both structurally supports the tank of reservoir

26 in position and provides its heat insulation.

The solar heater collector 12 includes a fluid inlet 30 into the lower manifold 22. The upper manifold 24 includes a feed pipe 32 into the reservoir 26 and the reservoir 26 has a fluid outlet 34. Thus a primary fluid flow circuit extends from the fluid inlet 30 into the lower manifold 22, through the heat absorbing conduits 20 into the upper manifold 24, from the upper manifold 24 through the feed pipe 32 into the reservoir 26, and from the reservoir 26 through the outlet 34. Fluid, typically water, entering through the inlet 30 is heated as it passes through the conduits 20. The heated fluid is collected in the reservoir 26 for delivery through the outlet 34.

The primary fluid flow circuit 30-22-20-24-32-26-34 preferably includes an electrically driven pump 36, also located within the inner member 16, for pumping the fluid through the circuit. An electrical circuit for providing power to operate the pump 36 is described below. With or without the pump 36, the heating of fluid within the conduits 20 will induce a thermo-siphon effect which will cause some fluid flow through the circuit from inlet 30 to outlet 34.

The solar heater system 10 also preferably includes a second, closed, fluid flow circuit 38 for a pressurized low boiling point liquid. This second circuit 38 includes a heat absorbing portion in the form of conduits 40 within the enclosed space 18 and a second portion in the form of a heat exchange coil 42 within the reservoir 26. The heat absorbing conduits 40 are connected between a lower manifold 44 and an upper manifold 46 with the coil 42 connected between the upper and lower manifolds 44 and 46 as indicated by reference 47. The coil 44 fluid flow path 47 of the circuit 38 includes an electrically driven pump 48, located within the inner member 16, for ensuring circulation of the fluid within the second, closed, fluid flow circuit 38. An electrical circuit for providing power to operate the pump 48 is described below.

The conduits 40 of the second fluid flow circuit 38 extend generally uprightly between the manifolds 44 and 46 and also are spaced around the inner member 16, with each conduit 40 of the second fluid flow circuit 38 being located between and radially outwardly of two of the conduits 20 of the primary fluid flow circuit.

The conduits 40 may be made of the same plastics material (or other suitable plastics material) and have the same surface treatment as the conduits

20, provided such material can withstand the intended pressuhzation and operating conditions of the second fluid flow circuit 38. Alternatively for higher pressure applications, a metal, such as copper or an aluminium/nickel alloy having high thermal conductivity and suitably treated for the conduits 40 to have an appropriate selective surface, can be used.

The liquid for the second fluid flow circuit 38 may be a glycol or ammonium based liquid and its pressuhzation may be such as to give an operating pressure up to, for example, about 500 kPa. A pressure relief valve (not shown) may be included in the second, closed, fluid flow circuit 38 for safety. This liquid absorbs heat as it is pumped through the conduits 40 and releases this heat into a fluid within the reservoir 26 via the heat exchange coil 42. Thus the circuit 38 provides additional heating for a fluid in the reservoir 26.

The solar heater system 10 also preferably includes an array 50 of photovoltaic solar cells on a top surface portion of the outer member 14. It also includes additional electrical circuitry (shown as a block 52 in Fig. 2 and described in more detail below with reference to Fig. 3. Note that electrical connections between block 52 and other components of the circuit are not shown in Fig. 2). The array 50 of solar cells provides electrical power to the electrical circuit 52 to operate, among other things, the two pumps 36 and 48. With reference to Fig. 3, the electrical circuit 52 includes a microprocessor controller 54 and an inverter 56. DC power is supplied to the inverter 56 from the solar cell array 50 as indicated by circuit connection 58. A rechargeable battery 60 is also provided which, through a switch 62 controlled by microprocessor 54, can also supply DC power to the inverter 56 as indicated by circuit connection 64. The AC output of the inverter 56 operates the pumps 36 and 48, as indicated respectively by circuit connections 66 and 68. The reservoir 26 may include a heating element 70 to which AC power can be supplied by the electrical circuit 52, as indicated by circuit connection 72, under the control of the microprocessor 54. Thus the microprocessor 54 controls the inverter 56 as indicated by the signal line 74 and in response to predetermined criteria (described below) to invert the DC power supplied from the solar array 50 and/or the battery 60 to operate, as required, the pumps 36 and 48 and the heating element 70. The electrical circuit 52 also includes temperature sensing devices, one of which 76 is located in the feed pipe 32 from the upper manifold 24 into the reservoir 26 and is in front of and adjacent the pump 36. Another temperature sensing device 78 is in the outlet side of the coil 44 fluid flow path 47 of the second, closed, fluid flow circuit 38 and is adjacent and in front of the pump 48. The temperature sensing devices 76 and 78 may be thermistors. Each thermistor 76 and 78 provides a signal input into the microprocessor 54 as indicated by, respectively, signal lines 80 and 82. The thermistor 76 provides a signal representative of the temperature of the heated fluid from conduits 20 that is entering the reservoir 26 and thus can be associated via appropriate programming of the microprocessor 54 with an upper temperature threshold for the fluid in the reservoir 26. The thermistor 78 provides a signal representative of the temperature of the pressurized fluid in the second, closed, fluid flow path 38 after it has passed through the heat exchanger coil 42 and thus can be associated, via appropriate programming of the microprocessor 54, with a lower temperature threshold. Thus the microprocessor 54 can be programmed for the inverter 56 to supply AC power to the heating element 70 when the lower temperature threshold is sensed and to cease supply of that power when the upper temperature threshold is sensed. It may simultaneously be programmed for the inverter 56 to operate the pumps 36 and 48. Alternatively, if it is a high solar radiation day (a sensor for which may also be provided to supply a signal to the microprocessor 54) only the pumps 36 and 48 may be operated. If an over-temperature condition for the fluid in reservoir 26 is sensed, then the programming of the microprocessor 54 may be such as to cause the inverter 56 to operate the pumps 36 and 48 to rapidly circulate fluid through both of the fluid flow circuits to achieve a cooling effect to thereby reduce the heat content. The microprocessor 54 is also programmed to operate the switch 62, via a signal line 84, for a charging current (indicated by reference 86) to flow into the battery 60 from the DC power from the solar cell array 50. This charging can also be in response to a predetermined criterion programmed into microprocessor 54. For example, at any time when excess power is available from the solar cell array 50 for the circuit 52 functions, a trickle charge can be supplied into the battery 62.

The solar cell array 50 may supply about 15 to 30 watts of power, which is readily achievable by connecting an appropriate number of known solar cells in series. For example, a known "Solarex" array of 36 solar cells can deliver a current of about 1.2A at about 17V at peak power. The rechargeable battery 62 may be a 12V battery. It may also comprise a plurality, for example two batteries, connected in parallel to increase the VA rating.

The insulation 28 within the inner member 16 includes a cavity 88 (see Fig. 2) that is accessible through the base 17. The cavity 88 includes most of the electrical circuit 52 components (apart from the heating element 70 and thermistors 76 and 78) and the pumps 36 and 48. Thus these electrical circuit components and the pumps are accessible for maintenance. Alternatively, access to this componentry may be provided through a removable/replaceable portion of the inner member 16, which would require removal of the outer member 14 and the heat absorbing structures of the primary and the second fluid flow circuits. A person skilled in the art will readily realise suitable structures that would allow access for maintenance.

A prototype solar heater system 10 that has been constructed has a hemispherical outer member 14 of outside radius 800mm and a space 18 that is 80mm between the facing surfaces of the inner and outer members 16 and 14. The outer member 14 is made of a heat stabilized polycarbonate and the inner member is made of fibreglass and its reflective coating is an automotive chrome paint. A reflective mirror film could alternatively be applied to the fibreglass shell for the inner member. The conduits 20 of the primary fluid flow circuit are of nylon of 8mm ID and have a matt black surface finish. The lower and upper manifolds 22 and 24 of the primary fluid flow circuit are of copper of 30mm diameter and also have a matt black finish (copper instead of plastic was used for ease of manufacture of the prototype). The conduits 40, lower and upper manifolds 44 and 46 and other piping of the second, closed, fluid flow circuit 38 are made of copper. The conduits 40 are 12mm diameter and the manifolds 44 and 46 are 20mm diameter and have a matt black surface finish. There are 82 of each of the conduits 20 and 40. The second fluid flow circuit 38 is manufactured from copper instead of a plastic to enable different pressurizations of its liquid for testing purposes.

The conduits and manifolds of the primary and secondary fluid flow circuits could each be integrally formed from a suitable synthetic material, such as for example an EDPM rubber. Thus each could be moulded as a domed cage-like structure for placement over the inner member and then suitably connected to the incoming and outgoing pipework to complete each fluid flow circuit. Also the number of the conduits 20 and 40 may be less than or greater than 82, depending upon their diameters and the diameter of the inner member 16. Generally for maximum heat collection, as many conduits as practical should be provided.

The capacity of the reservoir 26 may be as large as possible consistent with fitting into the inner member 16 and being adequately heat-insulated. Generally, for the solar heater system 10 to supply hot water, the capacity of reservoir 26 can be as large as possible. Alternatively, if a steam output is required, the reservoir 26 can have a small capacity. A person skilled in the art will realise that appropriate safety devices, for example a pressure relief valve (not shown) will be included.

The diameter of the solar cell array 50 is about 600mm.

It is to be understood that other embodiments of the invention may include any number of and any combination of the features of the above described embodiment 10. For example, most broadly the invention may comprise only the solar energy collector 12 and the primary fluid flow circuit (as defined by the appended claim 1 ). Another embodiment may additionally include the second, closed, fluid flow circuit 38. Another embodiment may include the solar cell array 50 and the electrical circuit 52 without the second, closed, fluid flow circuit 38 (with the electrical circuit 52 modified as appropriate). Also an electrical circuit 52 may provide for only the heating element 70 to be heated by a solar cell array 50 (as defined by the appended claim 16), or for operation of only one pump 36 (when the second, closed, fluid flow circuit 38 is omitted) or both pumps 36 and 48. A person skilled in the art of electrical circuitry will realise that many circuit constructs are possible that will provide the desired functions.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the scope of the following claims.

Claims

1. A solar heater system for heating a fluid, the system including a shaped solar energy collector that includes at least one heat absorbing conduit for passage of a fluid for the fluid to be heated, the shaped solar energy collector having a three-dimensional curvilinear or rectilinear surface area for exposure to solar energy, the shape of the surface area being such that in use and over a substantial portion of a day, some portion or other of the surface thereof will generally face towards the sun, the solar energy collector including an outer member providing said surface area for exposure to solar energy and an inner member of substantially similar but smaller shape having a reflective surface, whereby the outer and inner members define therebetween an enclosed space which contains the at least one conduit, a heat insulated reservoir for the fluid, and a primary fluid flow circuit between a fluid inlet to the solar energy collector and a fluid outlet from the reservoir, the primary fluid flow circuit including the at least one conduit and the reservoir wherein fluid entering through the inlet is heated as it passes through the at least one conduit and is collected in the reservoir for delivery of heated fluid through the outlet.

2. A solar heater system as claimed in claim 1 wherein the inner member encloses the reservoir.

3. A solar heater system as claimed in claim 2 wherein the inner member contains an insulation material that surrounds the reservoir, thereby heat insulating the reservoir and supporting it within the inner member.

4. A solar heater system as claimed in any one of claims 1 to 3 wherein the shaped solar energy collector is substantially hemispherical.

5. A solar heater system as claimed in any one of claims 1 to 4 wherein the primary fluid flow circuit includes a first manifold to which the inlet is connected and a second manifold having an outlet into the reservoir, wherein there are a plurality of heat absorbing conduits which are connected between the first and second manifolds.

6. A solar heater system as claimed in claim 5 wherein the first manifold is located peripherally around the inner member of the solar energy collector at a lower region thereof and the second manifold is located at an upper region thereof, and the heat absorbing conduits are spaced around the inner member and extend upwardly between the first and the second manifolds.

7. A solar heater system as claimed in any one of claims 1 to 6 wherein the primary fluid flow circuit includes a pump for pumping the fluid through the circuit.

8. A solar heater system as claimed in claim 7 wherein the pump is contained within the inner member externally of the reservoir.

9. A solar heater system as claimed in any one of claims 1 to 8 wherein the shaped solar energy collector includes a second, closed, fluid flow circuit for a pressurized low boiling point liquid, the second fluid flow circuit including a heat absorbing portion within the enclosed space between the outer and inner members of the solar energy collector and a second portion within the reservoir, wherein when a pressurized low boiling point liquid is contained in the second fluid flow circuit, it absorbs solar heat from the heat absorbing portion and releases heat via said second portion to a fluid in the reservoir.

10. A solar heater system as claimed in claim 9 wherein the second, closed, fluid flow circuit includes a pump for pumping a pressurized low boiling point liquid around the second fluid flow circuit.

11. A solar heater system as claimed in claim 10 wherein the pump of the second, closed, fluid flow circuit is contained within the inner member externally of the reservoir.

12. A solar heater system as claimed in any one of claims 9 to 11 , the primary fluid flow circuit including a first manifold to which the inlet is connected and a second manifold having an outlet into the reservoir, wherein there are a plurality of heat absorbing conduits which are connected between the first and second manifolds, and wherein the heat absorbing portion of the second, closed, fluid flow circuit includes a plurality of heat absorbing conduits spaced between the heat absorbing conduits of the primary fluid flow circuit.

13. A solar heater system as claimed in claim 12 wherein the heat absorbing conduits of the primary fluid flow circuit and the second, closed, fluid flow circuit extend generally upwardly between a lower region and an upper region of the inner member of the shaped solar energy collector.

14. A solar heater system as claimed in any one of claims 9 to 13 wherein the second portion of the second, closed, fluid flow circuit that is located within the reservoir includes a heat exchange coil for providing an increased surface area for contact with a fluid in the reservoir.

15. A solar heater system as claimed in any one of claims 1 to 14 including an array of photovoltaic solar cells on a top surface portion of the outer member of the shaped solar energy collector, and further including an electrical circuit for the solar heater system, wherein the array of solar cells provides electrical power to the electrical circuit.

16. A solar heater system as claimed in claim 15 wherein the electrical circuit includes an electrical heating element within the reservoir, wherein the electrical circuit utilizes electrical power from the array of solar cells to supply an electrical current to the electrical heating element for heating a fluid in the reservoir.

17. A solar heater system as claimed in claim 16 wherein the electrical circuit includes temperature sensing devices associated with at least the primary fluid flow circuit and operable such that when the temperature of a fluid in the reservoir reaches a lower threshold, the electrical circuit supplies an electrical current to the heating element, and when the temperature reaches an upper threshold, the electrical circuit stops the supply of an electrical current to the heating element.

18. A solar heater system as claimed in claim 15 having a primary fluid flow circuit that includes a pump and a second, closed, fluid flow circuit that includes a pump, wherein the electrical circuit utilizes the electrical power from the array of solar cells to supply electrical power to drive the pump of the primary fluid flow circuit and/or to drive the pump of the second, closed, fluid flow circuit.

19. A solar heater system as claimed in any one of claims 15 to 18 wherein the electrical circuit includes a rechargeable battery for providing extra electrical power when insufficient electrical power is available from the array of solar cells.

20. A solar heater system as claimed in claim 19 wherein the electrical circuit provides for a charging current to flow to the battery from the electrical power supplied by the array of solar cells.

21. A solar heater system as claimed in claim 15 wherein the electrical circuit includes an electrical heating element within the reservoir for heating a fluid in the reservoir, temperature sensing devices associated with at least the primary fluid flow circuit for providing a signal, respectively, for determining lower temperature threshold and an upper temperature threshold for a fluid in the reservoir, a microprocessor and an inverter, wherein the microprocessor is programmed to set the upper and lower temperature thresholds and to operate the invertor to invert the DC power from the array of solar cells to provide AC power to the electrical heating element in response to a signal indicative of the lower temperature threshold to thereby heat a fluid in the reservoir, and to cease such provision of AC power in response to a signal indicative of the upper temperature threshold.

22. A solar heater system as claimed in claim 21 wherein the electrical circuit further includes an electric motor for driving a pump which is included in the primary fluid flow circuit for pumping a fluid through the circuit, and the microprocessor is programmed such that in response to indicative signals from the temperature sensing devices, the invertor is operated to also supply AC power to the electric motor of the pump of the primary fluid flow circuit to pump a fluid through the circuit.

23. A solar heater system as claimed in claim 22 wherein the electrical circuit further includes a re-chargeable battery for providing extra electric power when insufficient electric power is available from the array of solar cells, and the microprocessor is programmed to operate the electrical circuit to provide a DC charging current to the battery according to a predetermined criterion.

24. A solar heater system as claimed in any one of claims 1 to 23 wherein the primary fluid flow circuit contains water.

25. A solar heater system as claimed in claim 9 wherein the primary fluid flow circuit contains water and the second, closed, fluid flow circuit contains a pressurized low boiling point liquid.