GB2025602A

GB2025602A - Solar panel.

Info

Publication number: GB2025602A
Application number: GB7829650A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-07-12
Filing date: 1978-07-12
Publication date: 1980-01-23

Abstract

A solar panel, particularly for use in heating swimming pools and to replace known solar panels which are rigid and bulky, has two flexible layers (10, 11) between which is defined a passageway (15) for the throughflow of water. One flexible outer heat insulating region (18) allows the passage of solar radiation to one of the two flexible layers (10) whilst another flexible outer heat insulating region (22) reduces heat loss by conduction and convection from water in the passageway (15). The panel may be folded or rolled into a compact space when not in use. <IMAGE>

Description

SPECIFICATION Solar panel The invention relates to solar panels and is particularly concerned with the application of such panels to the heating of water for swimming pools.

The use of solar radiation for heating water is well known and solar panels which absorb infra red radiation from the sun and transmit the absorbed energy, in the form of heat, to water flowing within the panel, are becoming increasingly widespread.

Solar heaters of this type are especially useful for heating water in the home and for heating swimming pool water. In the last mentioned application a large volume of water is heated through a relatively small temperature difference so that the water flow type of solar panel is almost ideally suited. However the known solar panels have two serious disadvantages. Firstly the cost is often prohibited since each panel is sturdily built comprising a rigid box, a large quantity of tubing, insulation, glazing and, often, a stand to incline the panel to the sun. Secondly, these known panels take up a large amount of space and may provide a storage problem when the panels are not in use in the winter.

One aim of the present invention is to provide a solar panel which is considerably cheaper to produce than known solar panels.

Another aim of the present invention is to provide a solar panel which takes up less space than known panels and which may be stored within a small space when not in use.

According to the present invention there is provided a solar panel comprising two flexible waterproof sheet portions superposed and joined or formed integrally with one another at their outer peripheries to form a flexible envelope, the sheet portions being also joined to one another at superposed regions within the interior region bounded by the joined peripheries of the sheets in such manner as to provide a continuous passageway between the joined regionsfortheflowofwaterfrom an inlet to an outlet of the envelope.

Preferably at least one of the sheet portions is of a colour and/or texture conducive to the absorption of heat radiation. However one of the sheet portions may be transparent to the passage of infra red radiation to allow such radiation to pass through the 'sheet to be absorbed by the other of the sheet portions.

Advantageously a heat insulating region is provided on a side of the panel which in use is remote from the incident radiation, to reduce heat loss from that side of the solar panel. The region may comprise a layer of plastics foam sandwiched between two thin sheets of a plastics material.

Preferably a translucent region is provided to cover that side of the panel which in use is exposed to the solar radiation, the translucent region being operative to reduce heat loss by ventilation or convection whilst allowing the passage of infra red radiation. This translucent region may be in the form of an inflatable outer envelope such as a clear plastics sheet or may be formed from a dual layer plastics material in which one layer is flat whilst the other layer is pressed to form an array of discrete enclosures in which air is trapped. In this latter case, the flat region of the dual layer material is preferably disposed outermost on the solar panel.Of course, such a translucent heat retaining region may be provided on both sides of the panel, in which case a separate region of heat insulation on one side of the panel will not be required, and further, the panel may then be used with either of its sides presented to the solar radiation or may indeed be arranged such that the side remote from the direct rays of the sun also receives and utilises some indirect radiation by reflection.

In one variation in accordance with the invention a solar panel comprises three flexible waterproof sheet portions which are joined orformed integrally with one another at their outer peripheries and joined to one another at superposed regions within the interior region bounded by their joined peripheries so as to provide at last one respective continuous passageway on each side of a central one of the sheet portions from a respective inlet to a respective outlet on each side of the panel. In this case the central sheet portion may be adapted, by virtue of its colour and/or texture, to absorb heat radiation, whilst the outer sheet portions may be transparent to the passage of heat radiation to enable the solar radiation to reach the central sheet portion where it can be converted to heat and passed to water flowing in the passageways.Here again one or both sides of the panel may be provided with a heat retaining region, in the form of an outer envelope transparent to the passage of infra red radiation, or in the form of a dual layer of plastics material as described hereinbefore.

The material from which the sheet portions are fabricated is preferably a plastics material such as vinyl of sufficient thickness to provide good durability and resistance to tear. Vinyl of thickness 0.5 mm has been found adequate in this respect and commercially produced sheet black vinyl has been found to have the required heat radiation absorption properties. A translucent or transparent plastics material may be used for sheet portions which are to allow the passage of heat radiation through to a heat absorbing sheet portion of the panel.

The present invention will hereinafter be further described by way of example with reference to the accompanying drawings in which: Figure lisa plan view of a solar panel constructed in accordance with the invention; Figure 2 is a perspective view of a cutaway portion of the solar panel of Figure 1; and Figure 3 is a cross section along the line Ill-Ill of Figure 1.

The panel 9 comprises a sheet of black vinyl of thickness 0.5 mm which is folded about a central region to provide two overlying sheet portions 10 and 11 (Figure 2) which are welded together around a perimeter 12 to form an envelope or jacket for the passage of water, and leaving, between the folded portion and the perimeter 12, a sleeve 13 by means of which the panel 9 may be suspended when in use.

The two vinyl sheets are also welded together along linear portions 14 disposed so as to provide a respective passageway 15 for the throughflow of water between an inlet orifice 16 and an outlet orifice 17. A layer of transparent heat insulating material 18 is fixed to the sheet portion 10 and consists of an upper planar plastics sheet 19 and a lower plastics sheet 20 attached to the sheet 19 and moulded to form an array of pill-box enclosures 21 which encapsulate a corresponding volume of air. The material 18 may be welded to the vinyl sheet portion 10 at the same places as the two sheet portions 10 and 11 are welded, the operations being performed simultaneously.The enclosures 21 serve to space the upper planar sheet 19 from the sheet portion 10 and also reduce heat loss by convection between the sheet 10 and sheet 19 by reducing convection currents in the space between the two sheets. It will also be appreciated that damage to the material 18 by the bursting of some of the enclosures 21 will not seriously reduce the effectiveness of the material 18 which allows heat radiation incident thereon to reach and be absorbed by the sheet portion 10 whilst at the same time acting as a heat insulator to the loss of heat by conduction and convection.

To the sheet portion 11, which in use is remote from the incident solar radiation, is attached a heat insulating material 22 which consists of a layer 23 of plastics foam between two thin sheets 24 of vinyl, the sheets being welded to one another in crisscross fashion to form a quilted arrangement. The material 22 may, like the material 18, be welded to the vinyl sheet portion 11 in a welding operation simultaneous with the welding together of the sheet portions 10 and 11.

In use the panel 9 is arranged in a vertical position, for example by suspension from a rod extending through the sleeve 13, with that side of the panel bearing the beat insulating material 18 disposed towards the sum. Water is pumped through the panel 9, entering at inlet 16 and leaving at outlet 17.

The water follows a single pathway 15 defined by the vertical linearwelded portions 14andthustakesa long and meandering route through the panel. Of course other forms of passageways for the water may be defined by the welds between the sheets 10 and 11 so that the welds 14 could be disposed horizontally or a series of parallel pathways could be formed afterthe fashion of a motor vehicle radiator.

Solar radiation incident on the material 18 passes through sheets 19 and 20 to the black vinyl sheet portion 10 where it is absorbed. The relatively cool water passing through the passageway 15 is warmed by its contact with the hotter panel 10 so that the water temperature steadily increases during its passage. The insulating material 22 serves to reduce heat loss from the heated water through the sheet portion 11. As an alternative to the insulating material 22, the vinyl sheet portion 11 may be provided with an insulating sheet of material of the same type as the transparent material 18 in which case the panel 9 may be used with either of its sides facing the sum and indeed may be arranged that one side receives solar radiation directly whilst the other side receives scattered or reflected radiation.

Apart from the advantage of low cost, the panel in accordance with the invention has the advantage of physical fiexibilky so that when not in use it may be drained and then folded or rolled into a compact article for storage.

Claims

1. A solar panel comprising two flexible waterproof sheet portions superposed and joined or formed integrally with one another at their outer peripheries to form a flexible envelope, the sheet portions being also joined to one another at superposed regions within the interior region bounded by the joined peripheries of the sheets in such manner as to provide a continuous passageway between the joined regions for the flow of water from an inlet to an outlet of the envelope.

2. A solar panel as claimed in claim 1 in which at least one of the sheet portions is of a colour and/or texture conductive to the absorption of heat radiation.

3. A solar panel as claimed in claim 1 or 2 further comprising a heat insulating region disposed on a side of the panel which in use is remote from the incident radiation.

4. A solar panel as claimed in claim 3 in which the heat insulating material comprises a plastics foam.

5. A solar panel as claimed in claim 4 in which the plastics foam is sandwiched between two thin sheets of a plastics material.

6. A solar panel as claimed in claim 5 in which the plastics material is vinyl.

7. A solar panel as claimed in any preceding claim in which the waterproof sheet portions are vinyl.

8. A solar panel as claimed in any preceding claim in which one side of the panel which in use is exposed to solar radiation is covered at least partially with a translucent region operative to reduce heat loss by ventilation or convection, and transparent to the passage of heat radiation.

9. A solar panel as claimed in claim 8 in which the translucent region is in the form of an inflatable outer envelope.

10. A solar panel as claimed in claim 8 in which the translucent region comprises a duel layer plastics material, one layer being flat and the other layer, attached to the first, providing an array of discrete enclosures in which air is trapped between the layers.

11. A solar panel as claimed in claim 10 in which the layer translucent region is attached to one of the flexible sheet portions such that the flat layer is outermost and furthest from the sheet portion.

12. A solar panel as claimed in any of claims 1 to 3 or in any of claims 7 to 11 when dependent on any of claims 1 to 3 in which the heat insulating region is transparent to the passage of heat radiation.

13. A solar panel as claimed in claim 12 in which the heat insulating region comprises a dual layer plastics material, one layer being flat and the other layer, attached to the first, providing an array of discrete enclosures in which air is trapped between the layers.

14. A solar panel as claimed in claim 14 in which the heat insulating region is attached to one of the flexible sheet portions such that the flat layer is outermost.

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15. A solar panel comprising three flexible waterproof sheet portions which are joined or formed integrally with one another at their outer peripheries and joined to one another at superposed regions within the interior region bounded by their joined peripheries so as to provide at least one respective continuous passageway on each side of a central one of the sheet portions from a respective inlet to a respective outlet on each side of the panel.

16. A solar panel as claimed in claim 15 in which the central sheet portion is adapted to absorb heat radiation and in which the outer sheet portions are transparent to the passage of heat radiation.

17. A solar panel as claimed in claim 15 or 16 in which both sides are provided with a respective heat insulating region operative to allow the passage of heat radiation whilst reducing heat loss by conduction and convection.

18. A solar panel substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.