CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Chinese Patent Application No. 201210086063.4, filed on March 28, 2012, the entire contents of which are hereby incorporated by reference.

FIELD

The present invention relates to a field of solar battery, and more particularly to a solar battery assembly.

BACKGROUND

Since a single crystal silicon solar cell is breakable and with a low power, a plurality of solar cells are connected and packaged as an assembly in practice. For example, a plurality of solar cells are connected as a cell pack, and then a plurality of cell packs are arranged in an array, in which the solar cells in a same row are connected in series and rows of solar cells are connected in parallel. For the serial connection, a back electrode of each solar cell is connected with a front electrode of an adjacent solar cell by a thin welding strip.

A conventional solar battery assembly usually uses welding strips with uniform width, the width of which is equal to or slightly larger than that of an electrode grid line, to connect the adjacent front electrode and back electrode. An internal resistance of the welding strip is depended on the width thereof under a certain thickness. During a normal working process of the solar battery assembly, a current density in the main grid lines of the front electrode of each solar cell is nonuniform, even when the welding strips with uniform width are used. Thus, it is a waste to the welding strip in a region with a small current density and also a waste to a light receiving area, which results in a relatively larger internal resistance and a relatively lower power of the solar cell.

SUMMARY

The present invention is directed to solve at least one of problems in the prior art such as a large internal resistance and a low power of a conventional solar battery assembly.

According to a first aspect of the present invention, a solar battery assembly is provided, comprising: a plurality of solar cells; and a plurality of conductive strips, for connecting the plurality of solar cells with each other and/or for connecting the solar cell with a load, wherein each solar cell comprises a front electrode and a back electrode, the front electrode is connected with a first connecting region of a first conductive strip, the back electrode is connected with a second connecting region of a second conductive strip, and a width of a widest portion of the first connecting region is a, a width of a widest portion of the second connecting region is b, and a<b. In one embodiment, a ratio between a and b satisfies 0.5=¾a/b< 1.

In one embodiment, a difference between b and a satisfies 0<b-a=¾3mm.

In one embodiment, a width of each solar cell is d, 0.6%d ^: ¾;a ^:: 5¾2%d, and 0.6%d<b ^; ¾4%d. In one embodiment, lmm^a^3mm, and lmm<b^6mm.

In one embodiment, each solar cell comprises three front electrodes, each front electrode is connected with one first conductive strip, 1.5 mm^a^2.5mm, and; each solar cell comprises three back electrodes, each back electrode is connected with one second conductive strip, 1.5 mm <b=¾5mm.

In one embodiment, each solar cell comprises two front electrodes, each front electrode is connected with one first conductive strip, 2.0 mm^a^2.5mm; and each solar cell comprises two back electrodes, each back electrode is connected with one second conductive strip, 2.0 mm< ^ 5 mm.

In one embodiment, a ratio c between an area of the first connecting region and an area of the second connecting region satisfies 0.25 =¾c< 1

In one embodiment, the front electrode of the solar cell is electrically connected with the back electrode of an adjacent solar cell via a conductive strip; and the first connecting region of the solar cell and the second connecting region of the adjacent solar cell constitute the conductive strip.

In one embodiment, at least a portion of the first connecting region's width changes with a change of the current density.

In one embodiment, the first connecting region's width changes with a change of the current density. In one embodiment, the first connecting region's width increases with an increase of the current density, and decreases with a decrease of the current density.

In one embodiment, the first connecting region comprises a distal end and an initial end, the distal end extends to the load or the back electrode of an adjacent solar cell, and the initial end is narrower than the distal end. Since a current density increases from the initial end to the distal end, the first conductive strip is widened along a current collecting direction, so that a light shielding area is decreased at a portion with a relatively smaller width, a light receiving area is increased to certain extent, and a resistance of the solar cell is not increased.

In one embodiment, the first connecting region gradually increases in width from the initial end to the distal end with a continuous increase of the current density.

In one embodiment, a width of a widest portion of the first connecting region ranges from 0% to 1.3% of that of the solar cell.

In one embodiment, a width of a narrowest portion of the first connecting region ranges from 0 to 2mm.

In one embodiment, the first connecting region is symmetric about a longitudinal midline, that is, a current is uniformly led out from both sides of the longitudinal midline so as to avoid choosing an orientation when placing the welding strip.

In one embodiment, the first connecting region is a triangle in shape. It is convenient for processing a triangular welding strip in practical applications.

In one embodiment, the first connecting region is an isosceles triangle in shape, which may not only uniformly lead the current out, but also avoid choosing the orientation when placing the welding strip.

In one embodiment, the first connecting region is a right triangle in shape, which is easier to realize and more convenient to process in practical applications.

In one embodiment, the first connecting region is a trapezoid in shape. A top-side of the trapezoid has a certain breadth, so as to facilitate a process of the welding strips and ensure enough strength for an initial welding.

In one embodiment, the first connecting region is an isosceles trapezoid in shape, which may not only uniformly lead the current out, but also avoid choosing the orientation when placing the welding strip.

In one embodiment, the second connecting region is uniform in width.

In one embodiment, the second connecting region is a rectangle in shape. Because the first connecting region is for collecting the current and the second connecting region is for delivering the collected current, the current in the second connecting region does not change obviously. Thus, the second connecting region can be simply designed as the rectangle.

In one embodiment, at least a portion of the second connecting region's width changes with a change of the current density.

In one embodiment, the second connecting region's width changes with a change of the current density.

In one embodiment, the second connecting region's width increases with an increase of the current density, and decreases with a decrease of the current density.

In one embodiment, the second connecting region comprises a distal end and an initial end, the distal end extends to the load or the back electrode of an adjacent solar battery, and the initial end is narrower than the distal end.

In one embodiment, the second connecting region gradually increases in width from the initial end to the distal end.

In one embodiment, a width of a narrowest portion of the second connecting region ranges from 0% to 1.3% of that of the solar cell. In one embodiment, a width of a narrowest portion of the second connecting region ranges from 0 to 3mm.

In one embodiment, the second connecting region is symmetric about a longitudinal midline.

In one embodiment, the second connecting region is a triangle in shape.

In one embodiment, the second connecting region is an isosceles triangle in shape.

In one embodiment, the second connecting region is a right triangle in shape.

In one embodiment, the second conductive strip connecting region is a trapezoid in shape.

In one embodiment, the second connecting region is an isosceles trapezoid in shape.

In one embodiment, the first connecting region is an isosceles triangle in shape; the second connecting region is a rectangle in shape, and a ratio between a length of a bottom-side of the isosceles triangle ranges from 0.6 to 0.85.

In one embodiment, a difference between the width of the rectangle and the length of the bottom-side of the isosceles triangle ranges from 0.5mm to 1.5mm.

In one embodiment, a length of the first connecting region ranges from 80% to 100% of that of the front electrode. The length of the first connecting region may be equal to or less than that of the front electrode. In the later case, a certain length of the front electrode at the initial end is reserved, while a rest length is connected with the first conductive strip. A length of the front electrode is designed according to that of the solar cell, for example, slightly less than that of the solar cell.

In one embodiment, a length of the second connecting region ranges from 50% to 100% of that of the back electrode. The length of the second connecting region may be equal to or less than that of the back electrode. In the later case, a certain length of the back electrode at the initial end is reserved, while a rest length is connected with the second conductive strip. Preferably, the second connecting region may be shorter than the first connecting region. For example, the second connecting region may be 8-segment adapting to an 8-segment back electrode, or may be a whole segment conductive strip.

In one embodiment, the conductive strip is a welding strip, and the welding strip is welded with the front electrode and/or the back electrode.

In one embodiment, the conductive strip is a macro molecular conductive strip, and the macro molecular conductive strip is adhered to the front electrode and/or the back electrode.

According to a second aspect of the present invention, a solar battery assembly is provided, comprising: one solar cell, and two conductive strips for connecting the one solar cell with a load, in which the one solar cell comprises a front electrode and a back electrode, a first connecting region of one conductive strip is connected with the front electrode, a second connecting region of the other conductive strip is connected with the front electrode, both a second connecting region of the one conductive strip and a first connecting region of the other conductive strip are connected with the load, and a width of a widest portion of the first connecting region is a, a width of a widest portion of the second connecting region is b, and a<b.

With the solar battery assembly according to embodiment of the present invention, according to a current density distribution of the main grid line in a front face (i.e., a light receiving face), a wider conductive strip is used where the current density is large to reduce the internal resistance and a power loss, and a narrower conductive strip is used where the current density is small to increase the light receiving area and an actual power. By using the conductive strip with width varying with the current density distribution, a light-receiving efficiency and a photoelectric conversion efficiency of the solar cell is improved, and thus an output power of the solar battery assembly is increased. Moreover, the solar battery assembly is easy to realize.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic structural view of a front face (i.e., a light receiving face) of a solar cell according to an embodiment of the present invention;

Fig. 2 is a schematic structural view of a back face (i.e., a light shading face) of the solar cell according to an embodiment of the present invention;

Fig. 3 is a schematic structural view of a conductive strip according to embodiment 1 of the present invention;

Fig. 4 is a schematic structural view of the front face of one solar cell connected with a conductive strip according to embodiment 1 of the present invention;

Fig. 5 is a schematic structural view of the back face of one solar cell connected with a conductive strip according to embodiment 1 of the present invention;

Fig. 6 is a schematic structural view of two adjacent solar cells according to embodiment 1 of the present invention;

Fig. 7 is a schematic structural view of a conductive strip according to embodiment 3 of the present invention;

Fig. 8 is a schematic structural view of the front face of one solar cell connected with a conductive strip according to embodiment 3 of the present invention;

Fig. 9 is a schematic structural view of a conductive strip according to embodiment 4 of the present invention;

Fig. 10 is a schematic structural view of the front face of one solar cell connected with a conductive strip according to embodiment 4 of the present invention;

Fig. 11 is a schematic structural view of a conductive strip according to embodiment 5 of the present invention; Fig. 12 is a schematic structural view of the front face of one solar cell connected with a conductive strip according to embodiment 5 of the present invention;

Fig. 13 is a schematic structural view of the back face of one solar cell connected with a conductive strip according to embodiment 5 of the present invention;

Fig. 14 is a schematic structural view of a conductive strip according to comparing embodiment 1; and

Fig. 15 is a schematic structural view of a conductive strip according to comparing embodiment 3.

DETAILED DESCRIPTION

The aforementioned features and advantages of the present invention as well as the additional features and advantages thereof will be further clearly understood hereafter as a result of a detailed description of the following embodiments when taken in conjunction with the drawings.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the specification, including definitions, will control.

The present invention relates to a solar battery assembly.

EMBODIMENT 1

A front electrode refers to an electrode (commonly a negative electrode) on a light receiving face (i.e., a front face hereinafter) for leading a current out. As shown in Fig. 1, the front electrode is commonly achieved by several main grid lines 2 printed on the front face of the solar cell 1 (for example, two or three main grid lines). The main grid lines are commonly made by coating and baking a silver conductive paste. The current is collected by a plurality of thin auxiliary grid lines 3 which are connected to the main grid lines 2, and then led out by the main grid lines 2.

A back electrode refers to an electrode (commonly a positive electrode) on a face coating a back electric field (i.e., a back face hereinafter) for leading a current out. As shown in Fig. 2, the back electrode is commonly achieved by several grid lines 4 printed on the back face of the solar cell 1. The grid lines 4 commonly coincide with the main grid lines 2 respectively. The grid lines 4 are commonly made by coating and baking the silver conductive paste. Each grid line 4 may be a whole one or segmented.

In one embodiment, there is one solar cell 1, and the main grid lines 2 and the grid lines 4 are connected with one conductive strip 5 respectively. The current on the solar cell 1 is led out by the conductive strips 5, and then connected with a junction box or likewise to electrically connect with a load. In another embodiment, there are at least two solar cells 1, and two adjacent solar cells are connected with each other by the conductive strip 5, that is, the front electrode of one solar cell 1 and the back electrode of the other solar cell 1 are connected by one conductive strip 5. A solar cell 1 arranged at an outside is connected with a junction box or likewise to electrically connect with a load.

A part of the conductive strip 5 connected to the front electrode is defined as a first connecting region 51. Commonly, the conductive strip 5 totally or partially covers on the main grid line 2 without shading a light receiving area of the solar cell. An overlay region is the first connecting region 51. A part of the conductive strip 5 connected to the back electrode is defined as a second connecting region 52. Commonly, the conductive strip 5 totally or partially covers on the grid line 4. An overlay region is the second connecting region 52. According to an embodiment of the present invention, a width of a widest portion of the first connecting region 51 is less than a width of a widest portion of the second connecting region 52 to enlarge the light receiving face of the solar cell and ensure the internal resistance.

Preferably, when there is one solar cell 1, a width of a widest portion of one end of one conductive strip 5 connecting with a load is greater than a width of a widest portion of the other end of the one conductive strip 5 (i.e., the first connecting region 51) connecting with a main grid line 2. However, there is no limit to a width of one end of the other conductive strip 5 connecting with the load, which may be equal or unequal to the width of the widest portion of the second connecting region 52. When there are at least two solar cells 1, the front electrode of the solar cell is electrically connected with the back electrode of an adjacent solar cell via a conductive strip 5. The first connecting region 51 of the solar cell and the second connecting region 52 of the adjacent solar cell constitute the conductive strip 5. According to a distance between two adjacent solar cells, there may be certain space between the first connecting region 51 and the second connecting region 52, which is a so called inter-part 53. There is no limit to a shape and a width of the inter-part, which may be designed according to practical applications. Commonly, the first connecting region 51, the second connecting region 52 and the inter-part 53 are an integrated conductive strip 5.

In all embodiments of the present invention, provided that a width of a widest portion of the first connecting region is a, and a width of a widest portion of the second connecting region is b. In order to increase a current on a back face of the solar cell, a ration between a and b satisfies 0.5 a/b=¾ l . For a common solar cell and a common electrode grid line, a difference between b and a satisfies 0<b-a=¾3mm, and preferably 0<b-a=¾2.5mm. In one embodiment, a width of each solar cell is d, 0.6%d ^; ¾a ^: ¾2%d, and 0.6%d<b ^; ¾4%d. For a common solar cell and a common electrode grid line, a and b satisfy lmm^a^3mm and lmm<b^6mm respectively.

Further preferably, in one embodiment, each solar cell comprises three front electrodes, each front electrode is connected with one first conductive strip, 1.5 mm^a^2.5mm; and each solar cell comprises three back electrodes, each back electrode is connected with one second conductive strip, 1.5 mm<b=¾5mm. In another embodiment, each solar cell comprises two front electrodes, each front electrode is connected with one first conductive strip, 2.0 mm^a^2.5mm; and each solar cell comprises two back electrodes, each back electrode is connected with one second conductive strip, 2.0 mm<b^5mm.

The conductive strip 5 may be any conventional conductive strip, for example, a metal strip (i.e. a welding strip), which can be a copper strip. The conductive strip 5 may be welded with the front electrode and/or the back electrode such as by tin soldering. Alternatively, the conductive strip 5 may be welded with the front electrode and/or the back electrode by conductive adhesive tape, particularly a macro molecular conductive tape which may be directly stuck on a surface of the main grid line 2 or the grid line 4.

A shape of the first connecting region 51 may be any conventional shape known in the art, such as a rectangle. Preferably, the first connecting region's width changes with a change of a current density. When a current of the front electrode of the solar cell 1 is led out by the conductive strip 5, the current in the grid line 2 is nonuniform, and thus a current density of the conductive strip 5 is different. In this embodiment, at least a portion of the first connecting region's width changes with a change of a current density so as to lead the current out better and improve a light-receiving efficiency and a photoelectric conversion efficiency of the solar battery. Specifically, a width of the first connecting region 51 increases with an increase of the current density, and decreases with a decrease of the current density. A wider conductive strip is used where the current density is large to reduce the internal resistance and a power loss, and a narrower conductive strip is used where the current density is small to increase the light receiving area and an actual power.

As shown in Fig. 3, the first connecting region 51 comprises a distal end 512 and an initial end 511. The distal end 512 extends to the load or the back electrode of an adjacent solar cell. The initial end 511 is narrower than the distal end 512. Commonly, the current density increases gradually along a direction of the current with an accumulation of electrons, thus, preferably, the first connecting region gradually increases in width from the initial end 511 to the distal end 512. Commonly, sizes of the conductive strip 5 and the first connecting region 51 are designed according to sizes of the solar cell 1 and the main grid line 2. Preferably, a length of the first connecting region 51 ranges from 80% to 100% of that of the front electrode. The length of the first connecting region 51 may be equal to or less than that of the front electrode. In the later case, a certain length of the front electrode at the initial end 511 is reserved, while a rest length is connected with the first conductive strip. In one embodiment, the length of the solar cell is 156mm; the length of the main grid line 2 is 153mm; the length of the first connecting region 51 is 153mm, that is, the main grid line 2 is printed at 1.5mm away from an edge of the solar cell, and the conductive strip 5 is welded from the initial end 512 of the main grid line 2, that is, the total length of the main grid line 2 is covered with the conductive strip 5.

Preferably, the first connecting region 51 is symmetric about a longitudinal midline, that is, a current is uniformly led out from both sides of the midline. Usually the first connecting region 51 is symmetric about a longitudinal midline of the main grid line 2 to ensure a uniform current density and decrease the internal resistance. Preferably, the first conductive strip region 51 is a triangle in shape to realize an easy welding and convenient processing in practical applications. Particularly, the first connecting region 51 may be an isosceles triangle in shape as shown in Fig. 4. Taking a solar cell with size of 156mmx l56mmx20(^m for example, the main grid line is 1.5mm in width and 153mm in length. The widest portion of the isosceles triangular first connecting region 51 is a bottom-side of the isosceles triangle, which is 2.5mm in length; and the length of the first connecting region 51 is a height of the isosceles triangle, which is 153mm. The initial end 511 begins from a start end of the main grid line 2.

A shape of the second connecting region 52 may be any conventional shape known in the art. In one embodiment, a width of the second connecting region 52 is uniform. Particularly, the second connecting region 52 is a rectangle in shape as shown in Figs. 5. Taking a solar cell with size of 156mmx l56mmx20(^m for example, the grid line 4 is 1.8mm in width and 136mm in length. The grid line 4 is printed from the edge of the solar cell 1 and may be 8 segmented. The second connecting region 52 may be 3 mm in width and 136mm in length. The conductive strip 5 is welded from the initial end of the grid line 4, that is, the total length of the grid line 4 is covered with the conductive strip 5. The second connecting region 52 may be designed as a whole conductive strip.

A plurality of solar cells are connected in series. Fig. 4 is a schematic structural view of the front face of one solar cell, and Fig. 5 is a schematic structural view of the back face of an adjacent solar cell. As shown in Fig. 4, there are three main grid lines 2 as the front electrodes, i.e. the negative electrodes. Each main grid line 2 is welded with one conductive strip 5. A triangular part of the conductive strip 5 covers the main grid line 2. A vertex of the triangle falls on the main grid lines 2 and is 1.5mm away from the edge of the solar cell. As shown in Fig. 5, there are three grid lines 4 as the back electrodes, i.e. the positive electrodes. Each grid line 4 is welded with one conductive strip 5. A rectangular part of the conductive strip 5 covers the grid line 4 and stops at 10mm away from the edge of the solar cell.

As shown in Fig. 6, two solar cells 11 and 12 connected in series are taken as an example. Firstly, the triangular part of each welding strip is welded onto the front electrode. Then, the other half (i.e., the rectangular part) of each welding strip is welded onto the back electrode of an adjacent solar cell, and thus a plurality of solar cells in one row are connected in series to form a cell pack. Then a plurality of cell packs are connected in series to form a battery array. Alternatively, one end of the triangular part of each welding strip is welded onto the front electrode of each solar cell, and then, each solar cell with the welding strip is over turned and the other half of each welding strip is welded onto the back electrode of an adjacent solar cell. It should be noted that, depending on a requirement, it is also possible to connect the solar packs in parallel to adapt to a desired output current and output voltage. Finally, two welding strips will be remained and output as the positive electrode and negative electrode of the battery array. Subsequent processing steps known to those skilled in the art will be briefly described as follows. For example, a glass plate is provided on an operation stage; a first binding agent layer is formed on the glass plate; the battery array is arranged on the binding agent layer; a second binding agent layer is formed on the battery array; a backing plate is formed on the second binding agent layer; the above layers are laminated in an laminating machine to form the solar battery assembly. Then the solar battery assembly is installed with borders, and the positive electrode and the negative electrode are connected to the junction box to form an ultimate solar battery assembly.

EMBODIMENT 2

The shape, size and the grid lines of the solar cell are same with EMBODIMENT 1 respectively. The conductive strip 5 connects with two adjacent solar cells 1. The size and number of the solar cells 1, the method for forming the solar battery assembly, a total length and a welding position of the conductive strip 5 are same with EMBODIMENT 1 respectively. What is different from EMBODIMENT 1 lies in that the widest portion of the isosceles triangular first connecting region 51 is a bottom-side of the isosceles triangle, which is 2.5mm in length, and the rectangular second connecting region 52 is 4mm in width.

EMBODIMENT 3

As shown in Fig. 7, the first connecting region 51 with the shape of right triangle is described in details in this embodiment. Taking a solar cell with size of 156mm>< 156mm><20(^m as example, the main grid line 2 is 1.5mm in width and 15mm in length. The widest portion of the right triangular first connecting region 51 is a bottom-side of the right triangle, which is 2.5mm in length; and the length of the first connecting region 51 is a height of the right triangle, which is 153mm. The initial end 511 begins from the start end of the main grid line 2. In this embodiment, the second connecting region 52 is a rectangle in shape. The grid line 4 is 1.8mm in width, 136mm in length and 8 segmented. The second connecting region 52 is 4mm in width and 136mm in length. A plurality of solar cells are connected in series. Fig. 8 is a schematic structural view of the front face of one solar cell. As shown in Fig. 8, there are three main grid lines 2 as the front electrodes, i.e. the negative electrodes. Each main grid line 2 is welded with one conductive strip 5 as shown in Fig. 7. A right triangular part of the conductive strip 5 covers the main grid line 2. A vertex of the right triangle falls on a right angle of the main grid lines 2 and 1.5mm away from the edge of the solar cell. There are three grid lines 4 as the back electrodes, i.e. the positive electrodes. Each grid line 4 is welded with one conductive strip 5 as shown in Fig. 7. A rectangular part of the conductive strip 5 covers the grid line 4 and stops at 10mm away from the edge of the solar cell. The battery assembly is formed by the method substantially similar to EMBODIMENT 1.

EMBODIMENT 4

As shown in Fig. 9, the first connecting strip region 51 with the shape of isosceles trapezoid is described in details in this embodiment. Taking a solar cell with size of 156mmx l56mmx20(^m as example, the main grid line 2 is 1.5mm in width and 153mm in length. The widest portion of the isosceles trapeziform first conductive strip region 51 is a bottom-side of the isosceles trapezoid, which is 2.5mm in length; and the narrowest portion of the isosceles trapeziform first conductive strip region 51 is a top-side of the isosceles trapezoid, which is 0.5mm in length. The length of the first connecting region 51 is a height of the isosceles trapezoid, which is 153mm. The initial end 511 begins from the start end of the main grid line 2. In this embodiment, the second connecting region 52 is a rectangle in shape. The grid line 4 is 1.8mm in width, 136mm in length and 8 segmented. The second connecting region 52 is 4mm in width and 136mm in length.

A plurality of solar cells are connected in series. Fig. 10 is a schematic structural view of the front face of one solar cell. As shown in Fig. 10, there are three main grid lines 2 as the front electrodes, i.e. the negative electrodes. Each main grid line 2 is welded with one conductive strip 5 shown in the Fig. 9. An isosceles trapezoid part of the conductive strip 5 covers the main grid line 2. The top-side of the isosceles trapezoid falls on the main grid lines 2 and 1.5mm away from the edge of the solar cell. There are three grid lines 4 as the back electrodes, i.e. the positive electrodes. Each grid line 4 is welded with one conductive strip 5 as shown in Fig. 9. A rectangular part of the conductive strip 5 covers the grid line 4 and stops at 10mm away from the edge of the solar cell. The battery assembly is formed by the method substantially similar to EMBODIMENT 1.

EMBODIMENT 5

When a current of the back electrode of the solar cell 1 is led out by the conductive strip 5, the current in the grid line 4 is also nonuniform, thus a current density of the conductive strip 5 is slightly different. In this embodiment, at least a portion of the second connecting region's width changes with a change of a current density so as to lead the current out better and lower a cost. Specifically, a width of the second connecting region 52 increases with an increase of the current density, and decreases with a decrease of the current density. A wider conductive strip is used where the current density is large to reduce the internal resistance and a power loss, and a narrower conductive strip is used where the current density is small to lower the cost.

As shown in Fig. 11, the conductive strip 5 comprises the second conductive strip region 52 connected to the back electrode of the solar cell. The second conductive strip region 52 comprises a distal end 522 and an initial end 521. The distal end 522 extends to the load or the front electrode of an adjacent solar cell. The initial end 521 is narrower than that of the distal end 522. Commonly, the current density increases gradually along a direction of the current with an accumulation of electrons, thus, preferably, the second connecting region 52 gradually increases in width from the initial end 521 to the distal end 522.

Commonly, sizes of the conductive strip 5 and the second connecting region 52 are designed according to sizes of the solar cell 1 and the grid line 4. Preferably, the width of the widest portion of the second connecting region 52 ranges from 1mm to 3mm, and a width of a narrowest portion of the second connecting region 52 ranges from 0mm to 2mm (that is, the narrowest portion even may be a point). A length of the second connecting region 52 ranges from 50% to 100% of that of the back electrode. The length of the second connecting region 52 may be equal to that of the back electrode, that is, the length of the second connecting region 52 may be equal to that of the solar cell. Alternately, the length of the second connecting region 52 may be less than that of the back electrode, that is, a certain length of the second electrode at the initial end 521 is reserved, while a rest length is connected with the conductive strip 5 to avoid edge short circuit. The second connecting region 52 may be 8 segmented or a whole conductive strip.

Preferably, the second connecting region 52 is symmetric about a longitudinal midline, that is, a current is uniformly led out from both sides of the midline. Usually the second connecting region 52 is symmetric about a longitudinal midline of the grid line 4 to ensure a uniform current density and decrease the internal resistance. The shape of the second connecting region 52 may be a triangle, such as isosceles triangle, or a right triangle.

In this embodiment, the shape of the first connecting region 51 and the second connecting region 52 is an isosceles trapezoid as shown in Figs. 11, 12 and 13. . Taking a solar cell with size of 156ηΐΜΧ 156ηιηΐ ^χ 200μι for example, the main grid line is 1.5mm in width and 153mm in length. The widest portion of the isosceles trapeziform first connecting region 51 is a bottom-side of the isosceles trapezoid, which is 2.5mm in length; the narrowest portion of the isosceles trapeziform first connecting region 51 is a top-side of the isosceles trapezoid, which is 0.5mm in length; and the length of the first connecting region 51 is a height of the isosceles trapezoid, which is 153mm. The initial end 511 begins from a start end of the main grid line 2.

The grid line 4 is 1.8mm in width, 136mm in length, and 8 segmented. The widest portion of the isosceles trapeziform second connecting region 52 is a bottom-side of the isosceles trapezoid, which is 4mm in length; the narrowest portion of the isosceles trapeziform second connecting region 52 is a top-side of the isosceles trapezoid, which is 0.5mm in length; and the length of the second connecting region 52 is a height of the isosceles trapezoid, which is 136mm. The second connecting region 52 covers the main grid line 4 and stops at 10mm away from the edge of the solar cell. The battery assembly is formed by the method substantially similar to EMBODIMENT 1.

COMPARING EMBODIMENT 1

A conventional conductive strip 5 with a rectangular first connecting region 51 and a rectangular second connecting region 52 as shown in Fig. 14 is taken as example for forming the solar battery assembly. The size and number of the solar cells 1, the method for forming the solar battery assembly, a total length and a welding position of the conductive strip 5 are same with EMBODIMENT 1. The rectangle is 1.5mm in width and 300mm in length.

COMPARING EMBODIMENT 2

A conventional conductive strip 5 with a rectangular first connecting region 51 and a rectangular second connecting region 52 as shown in Fig. 14 is taken as example for forming the solar battery assembly. The size and number of the solar cells 1, the method for forming the solar battery assembly, a total length and a welding position of the conductive strip 5 are same with EMBODIMENT 1. The rectangle is 2.5mm in width and 300mm in length.

COMPARING EMBODIMENT 3

As shown in Fig. 15, a diamond-shaped conductive strip 5 with an isosceles triangular first connecting region 51 and an isosceles triangular second connecting region 52 is taken as example for forming the solar battery assembly. A bottom-side of the first connecting region 51 is equal to that of the second connecting region 52, which is 2.5mm in length. The size and number of the solar cells 1, the method for forming the solar battery assembly, a total length and a welding position of the conductive strip 5 are same with EMBODIMENT 1. The total length of the conductive strip 5 is 300mm.

Performance Test

The solar battery assemblies according to EMBODIMENTS 1-5 and COMPARING EMBODIMENTS 1-3 are tested at a same ambient temperature respectively, by using a solar battery assembly test apparatus with simulated AMI .5 sunlight, the spectra of which is in accordance with IEC 60904-9, Level A. A standard solar battery assembly with a same size and a same spectral response is used to calibrate each above solar battery assembly before testing. Results are list in Table 1.

Table 1

maximum power internal resistance (W) Rs ( Q )

EMBODIMENT 1 247.0 0.5018

EMBODIMENT 2 247.1 0.5007

EMBODIMENT 3 247.1 0.4993

EMBODIMENT 4 247.2 0.4976

EMBODIMENT 5 247.1 0.5002

COMPARING 244.8 0.5583

EMBODIMENT 1

COMPARING 245.1 0.4946

EMBODIMENT 2

COMPARING 246.5 0.5097

EMBODIMENT 3

It can be seen from the results that, with the solar battery assembly according to embodiment of the present invention, the internal resistance and the power loss are obviously reduced, and the output power is significantly increased. Meanwhile, the photoelectric conversion efficiency of the solar battery is improved due to an increase of the light-receiving efficiency. Furthermore, by applying the solar battery assembly in a solar power station, the total output power of the solar power station will be significantly increased. Moreover, the solar battery assembly is at low cost and easy to realize.

Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that changes, alternatives, and modifications all falling into the scope of the claims and their equivalents may be made in the embodiments without departing from spirit and principles of the disclosure.