GB2437843A

GB2437843A - Renewable energy apparatus

Info

Publication number: GB2437843A
Application number: GB0708696A
Authority: GB
Inventors: Raymond J Hudson
Original assignee: Ray Hudson Ltd
Current assignee: Ray Hudson Ltd
Priority date: 2006-05-04
Filing date: 2007-05-04
Publication date: 2007-11-07
Also published as: GB0608852D0; GB0708696D0

Abstract

Electrical power generating apparatus comprises a solar powered electrical power generating device, preferably a photovoltaic solar panel 12, in combination with a device which interacts with a fluid flow. In a first aspect of the invention the solar panel 12 is combined with an airflow driven electrical power generating device 34, 38, preferably a turbine, wherein an airflow is caused to flow, at least in part, towards the airflow driven electrical power generating device 34, 38, by the solar panel 12. In a second aspect of the invention the solar panel is combined with an airflow driven electrical power generating device 34, 38, wherein the airflow driven electrical power generating device 34, 38 can be selectively driven by electricity generated by the electrical power generating apparatus. In a third aspect of the invention the solar panel 12 is combined with on air moving device 34, 38 which is driven by electricity generated by the electrical power generating apparatus, the air moving device being used to cool the solar panel 12.

Description

* * 2437843

APPARATUS FOR GENERATING ELECTRICAL POWER FROM RENEWABLE

ENERGY SOURCES

Field of the Invention

The invention relates to power generating apparatus for generating electrical power from renewable energy sources and particularly, but not exclusively, to the use of such apparatus to power ventilation equipment.

Background to the Invention

Photovoltaic power generation by means of so-called solar panels is becoming increasingly attractive as power generation fuelled by non-renewable energy resources becomes more expensive and governments increase the pressure to move to power generation using renewable energy resources. However, although the running cost of photovoltaic power generation apparatus is low, the capital cost of the apparatus is presently very high, which makes it less attractive to potential users.

Photovoltaic power generation is also limited in its application by the size of solar panel(s) needed to produce a given amount of power and, for many countries, the seasonal variations in the number of hours during which solar energy is available to produce such power It is known to supplement the power output of a photovoltaic power generation apparatus by means of a wind driven generator.

Summary of the Invention

The invention provides power generating apparatus for generating electrical power from renewable energy sources, said apparatus comprising a solar powered electrical power generating device and an airflow driven electrical power generating S...

device arranged to be driven by at least one airflow that is at least in part caused to : ** 30 flow towards said airflow driven electrical power generating device by said solar powered electrical power generating device.

The invention also includes power generating apparatus for generating electrical power from renewable energy sources, said apparatus comprising a solar powered * 35 electrical power generating device and an airflow driven electrical power generating device arranged for generating electrical power from airflow in the region of said solar * 2 powered electrical power generating device that is at least partially generated by heat from said solar powered electrical power generating device.

The invention also includes power generating apparatus for generating electrical power from renewable energy sources, said apparatus comprising a solar powered electrical power generating device and an airflow driven electrical power generating device arranged for generating electrical power from airflow, said airflow driven electrical power generating device being arranged to receive airflow deflected by said solar powered electrical power generating device. I0

One use of the power generating apparatus is to power a ventilation system, which may be a ventilation system for ventilating a space, such as a bathroom or kitchen, in a domestic environment. The ventilation system can comprise an extraction and input fan, positive pressure fan, air heat recovery system using simultaneous intake and extract of air, or any system or device suitable to effect a change to the condition of the air in a defined area.

The invention also includes a method of generating electrical power from renewable sources comprising providing a solar powered electrical power generating device and a wind powered electrical power generating device and arranging said power generating devices such that at least one airflow is at least in part caused to flow towards said airflow driven electrical power generating device by said solar powered electrical power generating device.

The invention also includes power generating apparatus for generating electrical power from renewable sources, said apparatus comprising a solar powered electrical power generating device and an airflow driven electrical power generating device and : a control, wherein said control is arranged to selectively cause said airflow driven S...

electrical power generating device to be driven by electricity from the power generating apparatus. *5I

* The invention also includes a method of sinking electrical energy produced by a power generating apparatus that generates electrical power from renewable energy :: : sources, said power generating apparatus comprising a solar powered electrical * 35 power generating device and an airflow driven electrical power generating device, and the method comprising selectively causing said airflow driven electrical power generating device to be driven by electricity from the power generating apparatus.

The invention also includes a method of cooling a solar powered electrical power generating device of a power generating apparatus that generates electrical power from renewable energy sources and comprises a solar powered electrical power generating device and an airflow driven electrical power generating device, the method comprising selectively switching said airflow driven electrical power generating device to be driven by electricity from the power generating apparatus to provide a cooling airflow directed at the solar powered electrical power generating device.

The invention also includes a power generating apparatus for generating electrical power from renewable energy sources, said apparatus comprising a solar powered electrical power generating device and an airflow driven electrical power generating device arranged to be driven by at least one airflow that is at least in part caused to flow towards said airflow driven electrical power generating device by said solar powered electrical power generating device.

The invention also includes a method of cooling a solar powered electrical power generating device comprising powering an air mover to provide an airflow for cooling said solar powered electrical power generating device with electricity generated by said solar powered electrical power generating device when a load connected to said solar powered electrical power generating device is below a predetermined level and/or an accumulator connected to said solar powered electrical power generating device is charged above a predetermined level.

Brief Description of the Drawings

In order that the invention may be well understood, an embodiment thereof, which is : **. given by way of example only, will now be described with reference to the drawings a..

in which: * *. 30 Figure 1 is a schematic side view of power generating apparatus for generating **.

* electrical power from renewable energy sources; I... * I *

Figure 2 is a perspective view of the power generating apparatus of Figure 1; and * S 35 Figure 3 is a schematic illustration of the power generating apparatus of Figures 1 and 2 connected to a ventilation system.

Detailed Description of the Preferred Embodiment

Referring to Figures 1 and 2, a power generating apparatus 10 for generating electrical power from renewable energy sources comprises a solar powered electrical power generating device comprising a flat photovoltaic power generating device, or solar panel 12. The solar panel 12 is supported by a housing 14. Support for the solar panel 12 may take any convenient form and is indicated schematically at 16 (the indication of the support 16 is omitted from Figure 2 for the sake of clarity).

The housing 14 comprises a base member 18 that has a generally planar midsection and a first upstanding end portion 20 at one end and a second upstanding end portion 22 at the opposite end. The housing 14 additionally comprises opposed sidewalls 24, only one of which is shown. The sidewalls 24 extend upwardly from the base member 18 and from the first upstanding end portion 20 to the second upstanding end portion 22 such that the housing 14 comprises an enclosure that is open on one side (the top side as viewed in the drawings).

The solar panel 12 is positioned intermediate the upstanding end portions 20, 22 such that it closes the open side of the side of the housing 14, except for respective openings 26, 28 that are defined between opposite ends of the solar panel 12 and the respective facing end portions 20, 22. The openings 26, 28 each form a portion of an enclosed channel 30 defined between the internal surfaces of the housing 14 and the rear face 32 of the solar panel 12.

The respective inner surfaces of the upstanding end portions 20, 22 of the housing 14 that face towards the front (outer) face 33 of the solar panel 12, or portions of those surfaces, may be made reflective so as to reflect sunlight onto the face 33 of the solar panel. *... * * *.*

* * 30 A first cylindrical wind driven turbine 34 is mounted in the channel 30 at a location :*** nearer to the opening 26 than to the opening 28. The turbine 34 is mounted on supports 36 located at opposite sides of the channel 30 such that its axis of rotation extends perpendicular to the lengthways direction of the channel 30 and across the * width of the channel. * * S

* .. 35 A second cylindrical wind driven turbine 38 is mounted in the channel 30 at a location nearer to the opening 28 than to the opening 26. The turbine 38 is mounted on supports 40 located at opposite sides of the channel 30 such that its axis of rotation extends perpendicular to the lengthways direction of the channel 30 and across the width of the channel. In the embodiment, the turbines 34, 38 are mounted such that their respective axes of rotation are mutually parallel.

The turbines 34, 38 are connected to respective electrical generators 42. The generators 42 are mounted within the housing 14 and may be of any form suitable for generating electricity when the turbines 34, 38 are rotated by the flow of air through the channel 30.

Referring to Figure 3, the power generating apparatus 10 is provided with a control system that is integrated with the control system of a ventilation system 100, which is suitable for ventilating a space in a domestic environment. The integrated control system 102 comprises charging and conditioning circuitry 104, which is connected to the solar panel 12 and the generators 42 for receiving electrical power output by the power generating apparatus 10. The power generating apparatus 10 includes an accumulator 106, which in this embodiment takes the form of a series of AH NiMH batteries, but can be any convenient means for storing electrical energy. The accumulator 106 is connected with the charging and conditioning circuitry 102 so that it can be charged with electricity generated by the solar panel 12 and generators 42 and provide electrical power to the ventilation system 100 under control of the integrated control system 102. The charging and conditioning circuitry 104 comprises rectifiers (not shown) for converting ac output from the generators 42 into a dc input to the accumulator 106.

The integrated control system 102 further comprises a processor 108 that is :. connected to the charging and conditioning circuitry 104. The processor 108 is * programmed to control the operation of the power generating apparatus 10. ***. * S S...

The ventilation system 100 comprises one or more fans 110. The ventilation system may be for ventilating a domestic bathroom. In that case, there would typically I..

be one fan 110 rated at, for example, 1.6W. Alternatively, the ventilation system 100 *:::: might be used for ventilating a kitchen, in which case, there would preferably be two fans 110 each rated at 3.2W. For ease of reference, in the description that follows * 5: 35 mention will be made of a single fan. However, this is not to be taken as limiting. The fan 110 is preferably a low power brushless dc ventilator fan.

The processor 108 is also programmed to control the operation of the ventilation system 100 and, in particular, the fan 110. Preferably the processor 108 controls the ventilation system using control software comprising the Autostat IV program produced by Ray Hudson Ltd of Stuarts Lane, Greys Road, Henley-on-Thames, RG9 1PB. The Autostat IV program utilises data derived from signals indicative of temperature and humidity that are provided by a temperature sensor 112 and humidity sensor 114. The temperature sensor 112 and humidity sensor 114 are each connected with the processor 108 by suitable circuitry, which may include an AiD converter (not shown).

Control features incorporated in, or driven by, the Autostat IV program are described in W098/07083, the content of which is incorporated herein by reference.

The ventilation system 100 preferably includes an override switch 116 and circuitry 118 for receiving a trickle charge from a mains electricity source (not shown). The override switch 116 allows a user to bypass the normal control of the ventilation system 100 and run the fan 110 manually. Preferably, the processor 108 is programmed to detect manual operation of the fan 110 and cause the fan to be switched off after a set period of operation. The override switch 116 may be configured to allow the user to programme a period of operation for the fan 110.

Alternatively, a keypad (not shown) may be provided in conjunction with the override switch 116 for the same purpose.

In use, the power generating apparatus 10 would typically be mounted on the roof 120 (Figure 1) of a building, although it could be mounted to an upright wall of a building. Suitable wiring would be provided for connecting the generators 42 to the integrated control system 102, which would typically be mounted in or adjacent to a : space that is to be ventilated. It will be appreciated that the precise location of certain components of the ventilation system 100 and integrated control system 102 * *. 30 is a matter of convenience as suitable connections may be made by wireless transmission or hardwiring. However, the temperature sensor 112 and humidity sensor 114 should be located in the space to be ventilated and the fan 110 should be located such that it can draw air from that space. ** *

*. .: 35 As illustrated in Figure 1, the opening 26 is located lower than the opening 28. In operation, when there is sufficient sunlight, the solar panel 12 generates electricity, which is fed to the charging and conditioning circuitry 104 from where it may be fed directly to the fan 110, if the fan is in use, or to the accumulator 106. In these conditions, in addition to the solar energy used to generate the electricity, the solar panel 12 absorbs heat from the sun. This results in an increase in temperature of the solar panel 12. The heat radiated from the solar panel 12 generates convection currents that induce a flow of relatively cooler air through the channel 30 with the opening 26 serving as an inlet and the opening 28 serving as an outlet. This thermally induced airflow causes the turbine 34 to rotate, which in turn causes the moving parts of the associated generator 42 to rotate and thereby generate of electricity that is fed to the charging and conditioning circuitry 104. The turbine 34 is configured such that it can be caused to rotate by the relatively gentle thermally induced airflow through the channel 30 and the first upstanding end portion 20 is arranged to guide the thermally induced air flow into the channel via the opening 26.

On days when there is some wind blowing, the solar panel 12 will tend to be cooled by that wind and so, if there is any thermally induced airflow, it is may be negligible.

However, the second upstanding end portion 22 is arranged to direct wind, including wind that has been deflected by the outer face 33 of the solar panel 12, into the opening 28. In this case, the opening 28 serves as an inlet to the channel 30, so that there is wind flow through the channel. This flow of wind from the opening 28 to the opening 26 turns the turbine 38, which rotates the associated generator 42 resulting in generation of electricity that is fed to the charging and conditioning circuitry 104.

As mentioned above, the turbine 34 that is driven by the thermally induced airflow is configured to be driven by a relatively gentle airflow. Accordingly, the turbine should have a relatively low inertia and to this end would be made relatively light. To further reduce that inertia, it is preferred that the generator coupled to the turbine is configured to have a low magnetic resistance, as compared with the generator : coupled to the wind driven turbine. S... * S S...

* .. 30 It will be appreciated that the power generating apparatus 10 has the advantage that a more consistent level of power generation can be obtained than would be the case *.S if a solar panel or wind driven turbine was used alone. For example, in countries :. where there are considerable variations in the daylight hours available to provide energy for the solar panel, the wind driven turbine has the potential to provide power * 35 generation during periods when the solar panel provides little, or no, power output.

Furthermore, by providing deflecting surfaces for directing wind onto the wind driven turbine, including the outer face 33 of the solar panel, improved harnessing of the available wind can be obtained, which may be particularly advantageous during periods when the available wind is relatively light.

It will be understood these advantages are useful when the power generating apparatus 10 is used to power ventilation equipment for condensation control. It will be appreciated that condensation and the need to remove moist laden air from buildings is a problem during cooler seasons when the inner surfaces of buildings are cooled to the dew point and that during such seasons there is typically insufficient solar gain to provide the power needed for the ventilation equipment without installing an unduly large and expensive solar panel installation. The power generated by the wind turbine can compensate for the low solar gain allowing the use of smaller economically viable solar power panel installations.

By arranging for convention currents generated by heat radiating from the solar panel to provide an airflow directed onto a turbine, additional power may be generated when there is daylight, but relatively little wind. This provides the possibility of obtaining adequate power generation for a particular application while using a smaller solar panel than would be required when using a solar panel alone. This is beneficial because solar panels are expensive and cost is linked to size.

Furthermore for aesthetic reasons, it is often desirable to minimise the size of the solar panel, or panels, used.

A further advantage provided by combining solar and wind powered power generation in the power generating apparatus is that it provides for better utilisation of space and, in particular, a greater potential generating capacity for a finite space.

A further feature of the use a dual source for power generation is that it may make possible the use of power generating apparatus relying on renewable energy sources in situations in which solar gain by itself would not be practical because of the size : ** 30 and/or cost of the solar panels that would otherwise be required. *S. *

S S..

* It will be appreciated that while it is preferable to have respective turbines for generating electricity from the wind and airflow generated by heat radiating from the *. : solar panel, advantage can be obtained by having just one turbine arranged to make * 35 use of one or the other source of airflow. Alternatively, a single wind driven turbine might be used and a suitable arrangement of guide surfaces provided for directing both the thermally induced airflow and wind to the turbine.

It will also be appreciated that it is not essential for the turbines to be connected to dedicated generators as in the embodiment. Although not preferred, a suitable drive arrangement may be provided for transmitting the rotation of each turbine to a common generator.

It will also be appreciated that there while it may be advantageous to have an integrated control system for controlling the power generating apparatus and the apparatus that is to be powered by the output of the power generating apparatus, this is not essential. The power generating apparatus may have a dedicated control system, which can be arranged to interact with the control systems of other apparatus when required. Typically, this will be the case when the power generating apparatus is for general use, rather than configured for a particular application.

It will be appreciated that whHe in the embodiment there is just one solar panel, the power generating apparatus may comprise one or an array of solar panels as required. The number of panels selected is simply a matter of convenience and the choice will typically depend on the power output required, cost and the space available for housing the panel(s).

It will be understood that while in the embodiment, the power generating apparatus is used to power a domestic ventilation system, it is not limited to such use. In principle, the power generating apparatus could be used to provide power for any sort of apparatus, either as the sole source of power, or as an auxiliary to other power sources, such as mains electricity.

One or both of the generators may be switchable between a generating mode and a motor mode. With such an arrangement, a generator could be switched to motor mode and draw power from the power generating apparatus to drive the turbine(s) * *. 30 connected to it to act as a fan. Motor mode would preferably be made operative when there is little or no demand from the apparatus powered by the power *..

generating apparatus and the accumulator(s) is/are fully charged, or at least charged to a relatively high level. When driven by its associated generator, a turbine would :: : act as a power sink and provide a cooling airflow for the solar panel, thereby * 35 protecting the integrity of the solar panel.

A mechanical take-off drive arrangement may be used to connect a wind driven turbine of the power generating apparatus to the apparatus to be driven. Thus, in the embodiment, a ventilation fan 110 might be connected to the wind driven turbine 38 such that rotation of the turbine would directly drive the fan.

In the embodiment, the upstanding end portions 20, 22 are integral parts of the base member 18. However, it will be appreciated that this is not essential and that the housing 14 can be fabricated from a number of panels, including the sidewalls 24. It will also be understood that in addition to making the surfaces of the end portions 20, 22 that face the front face 33 of the solar panel 12 reflective, the housing may be provided with additional reflective surfaces, or have reflective surfaces fixed thereto, for further enhancing the operating efficiency of the solar panel. Any such additional surfaces may be arranged to assist in directing airflow to the airflow driven power generating apparatus.

It may be desirable to provide one or more wind deflecting surfaces for deflecting wind into the opening 28 that are movable relative to the opening to take account of changes in the wind direction.

It will be appreciated that while it is preferred that the power generating apparatus is used to provide power to a load that requires de power, it may be used to provide power to equipment driven by ac power. In that case, the charging and conditioning circuitry would be provided with inverters for converting dc power supplied from the accumulator to ac power for supply to the load.

It is currently envisaged that in a power generating apparatus used to power a domestic ventilation system, the solar panel would be rated at approximately 10 watts, although, units with an output up to around 50 watts (that is an output of 50 watts in a twenty four hour period) could be used. The wind driven generators are : ** 30 envisaged as generating a similar output. Overall, it is believed that for a domestic * S. . . . * ventilation unit, an apparatus with a combined output of 25 watts in twenty four hours *..

* would be acceptable, although more powerful apparatus with an output of approximately 200 watts is envisaged. ** *

*. .: 35 In an alternative arrangement shown in Figure 4, a plurality of separately operable turbine impellers (34A, 34B, 34C) are mounted as an array in gaps 43 between a plurality of separate, spaced solar panels (12A, 12B, 12C). In use of the depicted arrangement, thermal differences between the front and back faces of the solar panels cause airflow through the gaps between the spaced panels. Such airflow at least partly induced by the solar panels themselves. Moving air that has been warmed by the arrangement is directed across the turbine impellors situated within said gaps thereby causing impeller motion. Being airflow driven electrical generators, the impeller motion is converted into electrical energy as described above in relation to other embodiments of the invention. Appropriate gearing may be deployed to alter the speed of the driven generators. * * * 1.1 * *** * * * *** * .* * * * *** *

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Claims

CLAIMS

1. Power generating apparatus for generating electrical power from renewable energy sources, said apparatus comprising a solar powered electrical power generating device and an airflow driven electrical power generating device arranged to be driven by at least one airflow that is at least in part caused to flow towards said airflow driven electrical power generating device by said solar powered electrical power generating device.

2. Apparatus as claimed in Claim 1, wherein said at least one airflow comprises an airflow at least partially generated by heat from said solar powered electrical power generating device.

3. Apparatus as claimed in Claim 1 or 2, wherein said airflow driven electrical power generating device is arranged such that said at least one airflow comprises an airflow that is wind deflected by said solar powered electrical power generating device.

4. Apparatus as claimed in Claim 3 when dependent on claim 2, wherein said airflow driven electrical power generating device is arranged to be driven by a said airflow at least partially generated by heat from said solar powered electrical power generating device which flows in a direction different to the direction of said airflow that is wind deflected by said solar powered electrical power generating device.

5. Apparatus as claimed in Claim 4, wherein said airflow driven electrical power generating device comprises respective wind driven turbines for receiving said airfiows. S. * * * *.*

6. Apparatus as claimed in any one of the preceding claims, further comprising at * ** least one deflector for deflecting the at least one airflow towards the airflow driven electrical power generating apparatus. I..

S

7. Apparatus as claimed in Claim 6, wherein said at least one deflector at least * partially supports said solar powered electrical power generating device. * * * * S*

8. Apparatus as claimed in Claim 6 or 7, wherein said at least one deflector comprises a structure defining a channel for channelling said at least one airflow to said airflow driven electrical power generating device.

9. Apparatus as claimed in Claim 8, wherein a first major face of said solar powered electrical power generating device that is disposed opposite a second major face, which second major face, in use, receives solar energy, partially defines said channel.

10. Apparatus as claimed in Claim 8 or 9, wherein said airflow driven electrical power generating device comprises at least one turbine located in said channel.

11. Apparatus as claimed in any one of Claims 6 to 10, wherein the or at least one said deflector is arranged for reflecting light onto the solar powered electrical power generating device.

12. Apparatus as claimed in any one of the preceding claims, wherein said solar powered electrical power generating device comprises at least one photovoltaic device.

13. Apparatus as claimed in Claim 12, wherein said solar powered device comprises one or more photovoltaic panels.

14. Apparatus as claimed in Claim 13, wherein a plurality of such photovoltaic panels are present, mounted such that a gap is provided between at least two such spaced panels.

: 15. Apparatus as claimed in Claim 14, wherein at least one airflow driven electrical :..::: power generating device is provided at least partly located within such gap. s.

16. Apparatus as claimed in Claim 15, wherein at least one support comprising a plurality of said panels, a plurality of said gaps and a plurality of said airflow driven devices. S... * . . *

17. Apparatus as claimed in Claim 15 or 16, wherein said airflow driven device comprises a turbine generator.

18. Apparatus as claimed in any one of the preceding claims, further comprising an accumulator for storing electricity generated by at least one of said solar powered electrical power generating device and said airflow driven power generating device.

19 Apparatus as claimed in Claim 18, further comprising a control arranged to switch said airflow driven power generating device to a driven mode in which electricity generated by said solar powered electrical power generating device is used to drive said airflow driven power generating device.

20. A ventilation system in combination with power generating apparatus as claimed in any one of the preceding claims, in use, the ventilation system being at least in part powered by electricity generated by the power generating apparatus.

21. A combination of a ventilation system and power generating apparatus as claimed in Claim 20, wherein the ventilation system comprises a controller for controlling air moving apparatus with reference to determined humidity levels.

22. A combination of a ventilation system and power generating apparatus as claimed in Claim 21, wherein the ventilation system comprises at least one temperature sensor and at least one humidity sensor and the determined humidity levels are absolute humidity levels determined using signals received from said sensors 23. An installation comprising a ventilation system comprising at least one air mover in combination with power generating apparatus as claimed in any one of Claim 1 to 19, the ventilation system being arranged to ventilate a bathroom or kitchen and, in use, being powered at least in part by the power generating apparatus S. * S :..::: 24. An installation comprising a power generating apparatus as claimed in any one of Claims 8 to 11, wherein said channel has a first end and a second end and the second end is disposed higher than the first end. *.*

25. An installation as claimed in Claim 24, further comprising a ventilation system which, in use, is at least in part powered by the power generating apparatus.

S S *

* 26. An installation as claimed in Claim 23 or 25, wherein said power generating apparatus is roof mounted or mounted to an upright wall of a building.

27. A method of generating electrical power from renewable sources comprising providing a solar powered electrical power generating device and an airflow powered electrical power generating device and arranging said power generating devices such that at least one airflow is at least in part caused to flow towards said airflow driven electrical power generating device by said solar powered electrical power generating device.

28. A method as claimed in Claim 25, comprising arranging said solar powered electrical power generating device and airflow driven power generating device such that convection currents generated by heat radiating from said solar powered electrical power generating device cause a said airflow.

29. A method as claimed in Claim 27 or 28, comprising arranging said solar powered electrical power generating device and airflow driven power generating device such that wind is deflected towards said airflow driven electrical power generating device at least in part by said solar powered electrical power generating device.

30. A method as claimed in Claim 27, 28 or 29, comprising providing airflow deflecting surfaces for deflecting said at least one airflow towards said airflow driven electrical power generating apparatus.

31. A method as claimed in any one of Claims 27 to 31, wherein said deflecting surfaces define a passage and said airflow driven electrical power generating device is disposed in said passage.

32. A method as claimed in any one of Claims 27 to 31, wherein the electrical power :. generated by the solar powered electrical power generating device and the airflow powered electrical power generating device is used to power ventilation equipment arranged to ventilate a space according to determined humidity levels in said : * space.

33. A method as claimed in Claim 32, wherein the determined humidity levels are *:: : : absolute humidity levels. * **

* 34. Power generating apparatus for generating electrical power from renewable sources, said apparatus comprising a solar powered electrical power generating -s--device and an airflow driven electrical power generating device and a control, wherein said control is arranged to selectively cause said airflow driven electrical power generating device to be driven by electricity from the power generating apparatus.

35. Apparatus as claimed in Claim 34, wherein said airflow driven electrical power generating device is arranged such that when driven by electricity from the power generating apparatus, it provides an airflow for cooling said solar powered electrical power generating device.

36 Apparatus as claimed in Claim 34 or 35, further comprising an accumulator for storing electricity generated by said solar powered electrical power generating device and said airflow driven electrical power generating device.

37. Apparatus as claimed in Claim 36, wherein said control is arranged to cause said airflow driven electrical power generating device to be switched from a generating mode to a driven mode in which it is driven by electricity from the power generating apparatus when said accumulator is holding a predetermined charge and a load connected, in use, to the power generating apparatus provides a loading below a predetermined level.

38. A method of sinking electrical energy produced by a power generating apparatus that generates electrical power from renewable energy sources, said power generating apparatus comprising a solar powered electrical power generating device and an airflow driven electrical power generating device, and the method comprising selectively causing said airflow driven electrical power generating device to be driven by electricity from the power generating apparatus. * *

39 A method as claimed in Claim 34, wherein said power generating apparatus comprises an accumulator for storing electricity generated by the solar powered : *. electrical power generating device and the airflow driven electrical power *** * * generating device and said airflow driven electrical power generating device is switched from a generating mode to a mode in which it is driven by electricity from the power generating apparatus when said accumulator is charged to a *.! predetermined level and a load connected to the power generating apparatus provides a loading below a predetermined level.

40. A method as claimed in Claim 38 or 39, comprising arranging said airflow driven electrical power generating device such that when it is driven by electricity from the power generating apparatus it produces a cooling airflow for cooling the solar powered electrical power generating apparatus.

41. A method of cooling a solar powered electrical power generating device of a power generating apparatus that generates electrical power from renewable energy sources and comprises a solar powered electrical power generating device and an airflow driven electrical power generating device, the method comprising selectively switching said airflow driven electrical power generating device to be driven by electricity from the power generating apparatus to provide a cooling airflow directed at the solar powered electrical power generating device.

42. Power generating apparatus for generating electrical power from renewable energy sources, said apparatus comprising a solar powered electrical power generating device, an air mover for cooling said solar powered electrical power generating device and a control, said control being arranged to selectively cause said air mover to be driven by electricity generated by said solar powered electrical power generating device.

43. Apparatus as claimed in Claim 42, further comprising an accumulator for storing electricity generated by said solar powered electrical power generating device wherein said control causes said air mover to be driven by electricity generated by said solar powered electrical power generating device when said accumulator holds a predetermined charge and a load, which in use is connected to the apparatus, is below a predetermined amount.

44. A method of cooling a solar powered electrical power generating device comprising powering an air mover to provide an airflow for cooling said solar powered electrical power generating device with electricity generated by said solar powered electrical power generating device when a load connected to said solar powered electrical power generating device is below a predetermined level and/or an accumulator connected to said solar powered electrical power generating *: device is charged above a predetermined level S * * 45. Power generating apparatus for generating electricity from renewable energy sources substantially as herein described.

46. Power generating apparatus for generating electricity from renewable energy sources substantially as herein illustrated in Figure 1 or Fiture 2 of the accompanying drawings.

47. Power generating apparatus for generating electricity from renewable energy sources substantially as herein illustrated in Figure 4 of the accompanying drawings. * * * *** ***S * * I... * *. * * * *** * * ***

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