Technical field of the invention

This invention relates to a solar panel comprising a number of solar cells. The invention also relates to a solar concentrator comprising at least one solar panel according to this invention.

State of the art

Solar concentrators comprise reflective surfaces that concentrate the incident sunlight on to solar panels

incorporated into the solar concentrator and in turn

comprising solar cells. These known solar concentrators also have a sun tracker function, which is in principle always subject to a certain degree of error, i.e. the area of

concentrated sunlight generated by the reflective surfaces is not perfectly positioned relative to the area of the solar panel. In order to compensate for this, the reflective surfaces generate an area of concentrated sunlight greater than the area of the solar panel, i.e. the reflective surfaces are "oversized" in relation to the area of the solar panel.

Solar cells can be connected in parallel or in series. Series connection is preferred as an arrangement of this kind results in lower system currents and higher voltage. Low currents lead to fewer transmission losses and high voltage facilitates the conversion from direct current to alternating current .

If all of the solar cells in a solar panel are connected in series, the maximum effect is only obtained if all of the solar cells have maximum illumination. In order to compensate for sun tracker error, the area of concentrated sunlight generated by the reflective surfaces must therefore be greater than the area of the solar panel. Aims and features of the invention

A first aim of this invention is to provide a solar panel of the type defined hereinabove, in which the solar cells incorporated into the solar panel are connected together in such a manner that a lower light intensity in the edge regions of the solar panel as a result of defects in the sun tracker function does not have an adverse effect on the efficiency of the solar panel. The area of concentrated sunlight generated by the reflective surface therefore does not have to be "oversized" in relation to the area of the solar panel.

At least the first aim of this invention is achieved by means of devices having the features specified in the

following independent claims. Preferred embodiments of the invention are defined in the dependent claims.

Brief description of the drawings

Preferred embodiments of solar panels according to this invention will now be described with reference to the

accompanying drawings, in which:

Fig. A shows a known solar panel with solar cells connected in series, the box indicated by the solid line symbolising the region of full light intensity incident upon the solar panel;

Fig. B shows the solar panel according to Fig. A, but with the region of full light intensity offset in relation to the position according to Fig. A;

Fig. 1 shows a first embodiment of a solar panel according to this invention;

Fig. 2 shows a circuit diagram for solar cells provided on the solar panel according to Fig. 1;

Fig. 3 shows another embodiment of a solar panel according to this invention;

Fig. 4 shows a circuit diagram for solar cells provided on the solar panel according to Fig. 3;

Fig. 5 shows a solar panel according to this invention in

which a region of full light intensity does not cover the entire solar panel, and

Fig. 6 shows a solar panel according to this invention in

which a region of full light intensity does not cover the entire solar panel and is offset in relation to the position according to Fig. 5. Detailed description of preferred embodiments of the invention

Figures A and B show a solar panel comprising solar cells C connected in series, wherein these solar cells C are symbolised by squares with shading extending diagonally upwards to the right (see the relevant symbol) . The box R indicated by the solid line symbolises the area where the incident light has full intensity.

As will be clear from Figures A and B, the box R indicated by the solid line is offset in relation to the solar cells C of the solar panel. Fig. A shows an offset in the vertical direction, while Fig. B shows an offset in the lateral direction. In the situation shown in Fig. A, the uppermost row of solar cells is not situated entirely within the box R and the box R passes right through this uppermost row of solar cells. In the situation shown in Fig. B, the solar cells situated furthest to the left are not situated entirely within the box R and the box R passes right through the row of solar cells situated furthest to the left.

Fig. 1 is a diagrammatic plan view of a solar panel according to this invention, wherein the solar panel is provided both with first solar cells 1 connected in series and with second solar cells 3 connected in parallel. As will be clear from the relevant symbols, the solar cells 1 connected in series are designated by squares having shading extending diagonally upwards to the right. The second solar cells 3 connected in parallel are symbolised by squares having shading extending diagonally upwards to the left. The first and second solar cells 1 and 3 respectively have an identical area, i.e. the squares are the same size.

In the embodiment of a solar panel according to this invention shown in Fig. 1, the second solar cells 3 situated around the edge portions of the solar panel are connected in parallel, while the first solar cells 1 situated to the inside of these second solar cells 3 are connected in series. The solar cells 1 connected in series will be referred to

hereinafter as central cells, while the solar cells 3

connected in parallel will be referred to as edge cells.

Fig. 1 shows the parallel connection between two edge cells 3, wherein one of these edge cells 3 is situated in an upper row of the solar panel, while the other of these edge cells 3 is situated in a lower row of the solar panel. In principle, according to the invention, the edge cells 3 connected in parallel are situated in opposing rows of edge cells 3, the rows being parallel. This applies both to the edge cells 3 situated along the horizontal edges of the solar panel and to the edge cells 3 situated along the vertical edges of the solar panel. The reason for this will be

explained hereinbelow.

In Fig. 1, the edge strip containing the edge cells 3 has the width Bl and the relationship between the width Bl of the edge strip and the width B or height H of the solar panel is as follows: 0 < Bl < 0,1B/H.

Fig. 2 shows the circuit arrangement for the central cells 1 and the edge cells 3 of the solar panel according to Fig. 1. The edge cells 3 connected in parallel in pairs, e.g. one edge cell 3 from the uppermost row of the solar panel and one edge cell from the lowermost row of the solar panel, are connected together in series, i.e. a first pair of edge cells 3 connected in parallel is connected in series with a second pair of edge cells 3 connected in parallel, wherein the second pair of edge cells 3 connected in parallel is connected in series with a third pair of edge cells 3 connected in

parallel, etc.. The last pair of edge cells 3 connected in parallel is connected in series with the first central cell 1 connected in series, which is in turn connected in series with the next central cell 1 connected in series, etc.. It should be noted in this connection that the circuit arrangement according to Fig. 2 also applies to the edge cells 3 situated on the side according to Fig. 1.

Also in the case of the embodiment of a solar panel according to this invention shown in Fig. 3, the edge cells 103 situated along the edge portions of the solar panel are connected in parallel, while the central cells 101 situated to the inside of these edge cells 103 are connected in series. Fig. 3 shows the parallel connection between two groups of edge cells 103, wherein one group of edge cells 103 is

situated in the uppermost row of the solar panel, while the other group of these edge cells 103 is situated in the lowermost row of the solar panel. In principle, according to the invention, the groups of second solar cells 103 connected in parallel are situated in opposing rows of solar cells 103 situated at the edge, the rows being parallel. This applies both to the edge cells 103 situated along the horizontal edges of the solar panel and to the edge cells 103 situated along the vertical edges of the solar panel. The reason for this will be explained hereinbelow. With respect to the width Bl of the edge strip in relation to the dimensions of the solar panel, reference should be made to the statements made

hereinabove in connection with Fig. 1.

Fig. 4 shows the circuit arrangement for the central cells 101 and the edge cells 103 of the solar panel according to Fig. 3. As will be clear from Fig. 3, the edge cells 103 situated at the top are connected in series and the edge cells 103 situated at the bottom are also connected in series. This results in a group of edge cells 103 situated at the top in which the edge cells forming part of the group are connected in series, as well as a group of edge cells 103 situated at the bottom in which the edge cells 103 forming part of the group are also connected in series. These two groups of edge cells 103 are connected in parallel, wherein each group of edge cells 103 connected in series can be regarded as a solar cell. In a corresponding manner, the two rows of edge cells 103 in the vertical direction H of the solar cell are

connected in series in each row, thereby resulting in two groups of edge cells 103 connected in series situated furthest to the outside in the direction of the width B of the solar panel. These two groups of edge cells can also be connected in parallel, wherein each group of edge cells can be regarded as a solar cell.

Fig. 4 shows how the groups of edge cells 103 connected in series are connected in parallel and how one of these groups connected in parallel is connected in series with a first central cell 101, which is in turn connected in series with the next central cell 101, etc..

Figures 5 and 6 show how the special parallel connection of the edge cells 3 described hereinabove operates when the area of full light intensity does not cover all of the solar cells on the solar panel. The area of full light intensity is thus symbolised by the box R indicated by the solid line.

Fig. 5 shows two edge cells 3 connected in parallel, wherein half of the area of these two edge cells 3 is situated inside the box R indicated by the solid line. As these two edge cells 3 are connected in parallel, they can be regarded as a solar cell with an area that is the sum of the two half areas, i.e. a solar cell/edge cell with an area corresponding to the area of a central cell 1.

Fig. 6 shows how the box R is offset in relation to the position of the box R according to Fig. 5. Only approximately 20% of the left-hand edge cell 103 is thus situated inside the box R, while approximately 80% of the upper edge cell 3 is situated inside the box R. As a result of the fact that the edge cells 3 are connected in parallel, the sum of the areas of the edge cells 3 situated inside the box R can be regarded as a solar cell/edge cell with an area corresponding to that of a central cell 1.

As the edge cells 3 connected in parallel have a total area corresponding to the area of the central cells 1

connected in series, both the edge cells 3 and the central cells 1 produce their full effect in both instances of

illumination of the solar panel according to this invention shown in Figures 5 and 6.

If edge cells are interconnected in series (see Fig. 3 and circuit diagram according to Fig. 4), the edge cells 103 connected in series in Fig. 3, i.e. four at the top and four at the bottom, generate the same amount of energy as four central cells 101 connected in series. The total illuminated area of these eight edge cells 103 then corresponds to the illuminated area of four central cells 101 connected in series 101. When edge cells 103 are connected in series as in

Fig. 3, twice as many edge cells 103 as central cells 101 are thus required to generate the same amount of electrical energy. With reference to the embodiment shown in Fig. 3, it should also be noted that the edge cells 103 situated at the side can also be connected in series in a corresponding manner in order to form groups of edge cells 103 connected in series, the groups then being connected in parallel. Possible modifications of the invention

In the embodiments described hereinabove, the rows of solar cells situated furthest to the outside are referred to as edge cells 3; 103. However, depending on the size of the solar cells, the cells referred to as edge cells may be formed by more than one row of solar cells around the circumference of the solar panel. It should be noted in this connection that the number of solar cells provided on the solar panel according to the embodiments shown in diagrammatic form is specified only by way of example.

Any desired shape is in principle possible for the shape of the solar panel according to this invention in plan view, wherein rectangular, circular or oval can be mentioned by way of non-limiting examples. A parameter relation corresponding to that specified hereinabove applies to the width of the edge portions provided with edge cells, although the width B and the height H are replaced by the relevant dimensions of the shape in question. The parameter relation 0 < Bl ≤ 0,1D thus applies in the case of a circular shape, where D is the diameter of the circle.

With reference to the shape of the solar cells provided on the solar panel in plan view, these solar cells 1, 3; 101, 103 have a square shape in the embodiments described

hereinabove. However, according to this invention, it may also be conceivable for the solar cells to have a shape other than square, wherein rectangular, hexagonal and triangular can be mentioned by way of non-limiting examples. It should be mentioned in this connection that it is also possible for solar cells on the same solar panel to have different shapes.

In the embodiments described hereinabove, all of the solar cells incorporated into a solar panel are the same size. However, according to this invention, the edge cells may have an area that is greater than the area of the central cells. It should be noted in this connection that the area of an edge cell should also be understood to be the sum of parts of edge cells as shown according to Figures 5 and 6.