ZA200104858B

ZA200104858B - Solar module.

Info

Publication number: ZA200104858B
Application number: ZA200104858A
Authority: ZA
Inventors: Martin Kurth
Original assignee: Kurth Glas & Spiegel Ag
Priority date: 1999-02-01
Filing date: 2001-06-14
Publication date: 2002-05-23
Also published as: CZ20012282A3; PL349073A1; EP1153440B1; PL197540B1; CN1327618A; CA2360814A1; CN1189949C; BR0007893A; JP2002536834A; AU2090200A; TR200102207T2; WO2000046860A1; ATE241857T1; HUP0104864A2; HUP0104864A3; EP1153440A1; AU756285B2; DE50002347D1; KR20010108137A

Description

, PCT/CHO00/00054

Solar Module

The present invention relates to a solar module according to the preamble to claim 1.

A solar module is known, e.g. from EP-A-0 525 225, which is based on a glass substrate consisting of hardened solar glass of 4 mm thickness. Onto the glass substrate a stack of layers is laminated consisting of a first synthetic film, electrically interconnected solar cells, a second synthetic film and a composite film as a cover film. Laminating is effected under vacuum at an elevated temperature in which process the synthetic films are welded onto each other and form a solid compound with the substrate.

Furthermore from DE-41 28 766 a solar module is known comprising a number of solar cells interconnected into a solar cell string in which arrangement a transpar- ent substrate pane is provided with a screen printed conductor system. The rear contacts of the solar cells in this arrangement contact the screen printed conductor system within a solar cell string. The front contacts of the solar cells within a solar cell string are connected in parallel or in series mutually and/or to the rear contacts of neighbouring solar cells if required. A transparent cover pane is connected to the substrate pane, in the manner of a composite safety glass, using a connecting compound e.g. based on a plastic film or a cast resin. The cover pane also is provided with a screen printed conductor system which within a solar cell string contacts the front contacts of the solar cells in such a manner that front and/or rear contacts of neighbouring solar cells are electrically interconnected.

In a further design example according to Fig. 4 of the cited document the cover pane and the substrate pane form the individual panes of an insulating glass pane in which arrangement the solar cells are located in the air-filled interspace be- tween the panes. The panes in this arrangement are spaced at the required dis- tance using spacers. Between the solar cell strings and the screen printed con- ductor systems of the cover pane and of the substrate pane electrically conducting

AMENDED SHEET

] 2 PCT/CHO00/00054 hook-shaped or U-shaped spacer elements are arranged in such a manner that the solar cell strings are soldered to the screen print conductor systems not di- rectly but via the spacer elements. Obviously this design example is of secondary importance only as in the patent claims only a solar module with a connecting compound based on a plastic film or on a cast resin is referred to, i.e. the inter- space is filled with a cast resin mass according to the examples described with reference to the Figures 1 through 3.

The example according to Fig. 4 of the patent document cited above will hardly be economically feasible for various reasons as even small tension differences between cover and substrate panes may cause glass breakages of the solar modules. Further the screen print conductor systems applied to both sides of the solar module impair the effectiveness of the solar irradiation which may cause considerable power loss. Due to the wiring of the solar cells on alternating faces a relatively high resistance is generated which further reduces the yield.

The known solar modules in which the solar cells are embedded in a synthetic film or in a cast resin mass are hardly suitable for recycling, since separation and elimination of glass substrates, synthetic films and/or cast resins and conductors is very demanding and thus so expensive that elimination of the elements as hazardous waste rather proves economically feasible. it thus is the objective of the present invention to improve a solar module as men- tioned above in such a manner that a particularly simple arrangement results and that the solar modules, in case of glass breakage or similar damage, may be recy- cled, or re-used, without difficulty.

This objective is met using a solar module presenting the characteristics according to the patent claim 1.

The inventive solar module presents the important advantage that the individual solar cells held therein may be exchanged in relatively simple manner, and that

AMENDED SHEET

PCT/CHO00/00054 the solar cells are nevertheless very effectively protected against weather exposure from solar irradiation, rain and similar influences. Stresses generated in the glass substrates as a result of such influences are not transmitted, or are transmitted to a merely insignificant degree to the solar cells, owing to the connection of the solar cells to one glass substrate only. In addition, owing to the simple lay-out of the inventive solar module, the energy spent in manufacturing the module is considerably lower compared to conventional modules, and thus manufacturing cost may be lowered by one third or more.

Further advantages of the present invention are explained in the dependent patent claims and in the following description in which the present invention is discussed in more detail with reference to a design example illustrated in schematic draw- ings. In the drawings,

Fig. 1 shows a schematic view of the lay-out of a solar module seen in a top view,

Fig. 2 shows a section of the solar module along the line A-A according to Fig. 1,

Fig. 3 shows a first arrangement of the conductors on the glass substrate, and

Fig. 4 shows a second arrangement of the conductors.

In the Figures identical elements are referred to using the same reference signs, and explanations given in respect of an earlier drawing are applicable to later drawings unless otherwise stated.

In Fig. 1 a top view of a solar module 1 is shown in purely schematic manner, with a support pane 2 laid out as a glass substrate and a congruent cover pane 3 laid out as a glass substrate, the two panes being spaced by a predetermined distance using a sealing spacer frame 4, indicated with dashed lines, arranged at their bor- der zones. The glass substrate 2 is provided with conductor leads 6 to which the solar cells 7 are connected via soldered bridges. The conductors 6 are provided

AMENDED SHEET

. . ) PCT/CHO00/00054 with contacting leads 8 and 9 extending to the outside and laid out as positive ports and negative ports, respectively. The solar cells 7 may be known silicon or titanium cells, or photochemical cells, as described e.g. in EP-B-0 525 070.

In Fig. 2 part of the cross-section along the line A-A according to Fig. 1 of the solar module 1 is shown. The solar cells 7 are fastened exclusively to the conductor leads 6 on the support pane 2 using soldering bridges 10 and are spaced at a distance from the two glass substrates 2 and 3. Additional elastic fastening elements, such as binding spots formed by a silicon adhesive (not shown here) may also be provided. The solar cells 7 are arranged more or less freely in the air- filled interspace 11 between the two glass substrates 2 and 3. The support pane 2 as well as the cover pane 3 are made from a silicate glass, preferably a colourless (white) glass, of a thickness of less than 5 mm. Depending on the desired application, a certain quantity of recycled silicate glass maybe used for manufacturing the glass substrates 2 and 3. On the inner faces of both substrates 2 and 3 thin layers, 12 and 13 respectively, of a light reflecting paint presenting a light reflectance value of more than 62% is applied. This paint advantageously is a ceramic paint, of a type also known as so-called glass pastes. For this purpose the ceramic paint is applied to the glass substrates using the screen print method and is baked onto the surface in a tunnel kiln at a temperature exceeding 600 °C.

Further, the conductors 7 are printed onto the glass substrate 2 using an electrically conductive paste, preferably a silver paste, and are baked on at a temperature exceeding 600 °C. Baking of the ceramic paint and of the electrically conductive paste may be effected in the same processing step. Instead of applying a ceramic paint coat, the glass substrates 2 and 3 may be subject to a surface treatment, such as sand blasting or chemical etching, in such a manner that on their outer surfaces they are rendered non-reflecting with a high diffusion effect.

Other types of non-reflecting glass may also be applied in the manufacture of the glass substrates 2 and 3. In order to equalise stresses in the glass substrates 2 and 3, the dimension of which may be e.g. 100 cm by 100 cm, the glass substrates are thermally pre-stressed, i.e. they are heated in a tunnel kiln on

AMENDED SHEET

! ; PCT/CHO00/00054 rollers to a temperature of about 600 °C to 700 °C and then are shock-chilled in a cold air stream.

The spacer frame 4 furthermore contains glass rods of rectangular cross-section serving as a spacer elements, the thickness of which is chosen at between about 6 and 16 mm, preferentially at about 8 mm. At the junctions of the outer corners of the glass rod 15 and the glass substrates 2 and 3 a seal 16 is provided made from butyl rubber. On the outer side of the glass spacer 15 a further seal 17 is provided made from a rubber-elastic material such as silicon rubber, or, for example, a melt adhesive known under the trade mark "Bynel" or "hot melt", to act as a moisture barrier for the solar module 1. However, seal 16 could be omitted and only the further seal 17 could be provided. The spacer 15 may also be made from other materials, e.g. from wooden slats of a hard wood, such as oak or beech wood.

Further, aluminium slats may be provided which are fastened between the glass substrates 2 and 3 using a melt adhesive ("hot melt"). Furthermore, a molecular sieve 19, such as e.g. zeolite, may be provided within the solar module, to act as a drying agent in order to reduce the residual humidity within the interspace 11 and to protect the solar cells 6 against corrosion. Additionally, a humidity gauge 20 may be arranged in the interspace 11 between the glass substrates 2 and 3, electric contacts of which may also be extended to the exterior via conductor leads, which are not shown here. Using this arrangement humidity inside a solar module 1 may be monitored and any leaks in the solar module 1 may be detected.

In Fig. 3 an arrangement of a number of parallel conductor leads 6 is shown, by way of example, each of which is soldered to an oblong solar cell 7 (indicated by means of dashed lines). In the manufacturing process one single large silicon board is soldered onto the conductor leads 6 and subsequently the board is cut, using a laser beam, into the individual oblong solar cells 7. To the left and the right of the glass substrate of the support pane 2 two connecting ports (positive and negative) are indicated. In Fig. 4 a further arrangement of the conductor leads 6 is shown provided for four solar cells 7, indicated by means of dashed lines.

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. . PCT/CHO00/00054

Furthermore, using the spacer frame 4 it is feasible to mount the support pane 2 and the cover pane 3 so that they are not precisely in register above one other but are slightly offset. In this manner a plurality of solar modules 1 may be lined up seamlessly to form a larger array. The solar modules lined up in this manner may form a wall, or a so-called “weather coat’ for building facades, on roofs or on similar parts of a building.

It has been proven that the energy consumed in manufacturing the inventive solar module 1 is in the order of 30 to 50 KWh per m2. the glass substrate thicknesses being chosen between 3.5 and 4.5 mm. This corresponds to about 2.2 kWh per kg of glass.

AMENDED SHEET

Claims

‘oo . PCT/CH00/00054 Claims

1. A solar module with two glass substrates arranged opposite one another which in their border zone are interconnected and spaced by a sealing spacer frame and in which a plurality of solar cells is arranged in an air-filled interspace between the glass substrates and at a distance with respect thereto, the solar cells being electrically interconnected via conductor leads, characterized in that the conductor leads are applied exclusively to one glass substrate and the solar cells are fastened to the said one glass substrate by means of flexible spacer elements.

2. The solar module according to claim 1, characterized in that the solar cells are fastened to the conductor leads of the one glass substrate by means of solder bridges which provide the flexible spacer elements.

3. The solar module according to claim 1 or 2, characterized in that the solar cells are further fastened to the one glass substrate by means of elastic fastening elements.

4. The solar module as claimed in claim 3, characterized in that the elastic fastening elements comprise binding spots formed by a silicon adhesive.

5. The solar module according to one of claims 1 to 4, characterized in that the spacer frame has a spacer element and an elastic seal

6. The solar module according to claim 5, characterized in that the elastic seal is of butyl rubber.

7. The solar module according to claim 5, characterized in that the elastic seal is of a silicon rubber.

8. The solar module according to claim 5, characterized in that the elastic seal is of a hardened melt adhesive.

9. The solar module according to one of claims 1 to 8, characterized in that the glass substrates are made of silicate glass. AMENDED SHEET

CL PCT/CH00/00054

10. The solar module according to claim 9, characterized in that the silicate glass is colourless (white) glass.

11. The solar module according to claim 9 or claim 10, characterized in that the silicate glass has a maximum thickness of 5 mm.

12. The solar module according to any one of claims 9 to 11, characterized in that the glass substrates are coated on an entire surface thereof with a light- reflecting paint presenting a light reflectance value of at least 62%.

13. The solar module according to the claim 12, characterized in that the light reflecting paint is a ceramic paint.

14. The solar module according to any one of claims 9 to 11, characterized in that the glass substrates have a non-reflecting surface with a high diffusion effect.

15. The solar module according to one of claims 1 to 14, characterized in that the conductor leads contain silver.

16. The solar module according to one of claims 1 to 11, characterized in that, within the interspace, molecular sieves are provided in order to reduce the residual humidity within the solar module.

17. The solar module according to claim 16, characterized in that the molecular sieves comprise zeolites.

18. The solar module according to one of claims 1 to 17, characterized in that, within the interspace, a humidity monitoring gauge is provided, by means of which leaks in the solar module may be detected.

19. A solar module substantially as described and illustrated herein with reference to Figures 1 and 2 and incorporating the arrangement of conductors illustrated in Figure 3 of the drawings. AMENDED SHEET a ‘ 4 9 . i Summary A solar module (1) is described the two opposite glass substrates (2, 3) of which are interconnected in their border zones spaced by a sealing spacer frame (4),

and in the air-filled interspace (11) of which a plurality of solar cells (7) are ar- ranged distanced from the glass substrates (2, 3). The solar cells (7) are electri- cally interconnected via conductor leads (6) applied to the glass substrates.

Fur- thermore the conductor leads (6) are applied exclusively to one glass substrate (2) and the solar cells (7) are fastened to the one glass substrate (2) by means of flexible spacer elements. (Fig. 2) KGSp001