WO2016052041A1

WO2016052041A1 - Reverse-surface-electrode solar battery cell with wiring sheet

Info

Publication number: WO2016052041A1
Application number: PCT/JP2015/074608
Authority: WO
Inventors: 純也嶋田; 康志吉川; 尉絵長野
Original assignee: シャープ株式会社
Priority date: 2014-09-29
Filing date: 2015-08-31
Publication date: 2016-04-07

Abstract

　In the present invention, the wiring provided to a wiring sheet in a reverse-surface-electrode solar battery cell provided with the wiring sheet is substantially in the configuration of a comb having a plurality of comb sections, the width of the base parts of the comb sections being greater than the width of the tip parts of the comb sections.

Description

Back electrode type solar cell with wiring sheet

The present invention relates to a back electrode type solar cell with a wiring sheet.

In recent years, interest in global environmental issues is increasing, and new energy technologies using natural energy are attracting a great deal of attention. As one of them, a system using solar energy is highly interested. In particular, solar power generation that converts light energy into electric energy using a photoelectric conversion effect is widely performed as a means for obtaining clean energy.

There are various types of solar cell elements such as those using compound semiconductors and those using organic materials, but currently, solar cells using silicon crystals are the mainstream.

Currently, the most manufactured and sold solar cells have an n-electrode formed on the surface on which sunlight is incident (light-receiving surface), and a p-electrode on the surface opposite to the light-receiving surface (back surface). It is a double-sided electrode type solar cell having the formed structure. Further, development of a back electrode type solar battery cell in which an electrode is not formed on the light receiving surface of the solar battery cell and an n electrode and a p electrode are formed only on the back surface of the solar battery cell is also under development.

For example, Patent Document 1 discloses a back electrode type solar cell with a wiring sheet. Patent Document 1 includes a wiring sheet in which a back electrode type solar battery cell and a wiring sheet are bonded using a fixing resin placed between at least one electrode of the back electrode type solar battery cell and between wirings of the wiring sheet. A back electrode type solar cell is disclosed. In addition, the step of curing the fixing resin to the first cured state, the step of softening the fixed resin in the first cured state, and the step of curing the softened fixing resin to bring the fixing resin into the second cured state A back electrode type solar cell with a wiring sheet including a process is disclosed. According to the invention disclosed in Patent Document 1, it is possible to improve the stability of the mechanical connection between the solar battery cell and the wiring sheet and improve the stability of the electrical connection.

JP 2012-99569 A

However, Patent Document 1 does not have a detailed disclosure about improving the conversion efficiency of the back electrode type solar cell with a wiring sheet.

There has been a demand for a structure that improves the conversion efficiency while ensuring a stable connection between the back electrode type solar cell and the wiring sheet.

In the back electrode type solar cell with a wiring sheet of the present invention, the wiring sheet has an insulating substrate and wiring provided on the light receiving surface side of the insulating substrate, and the back electrode type solar cell is made of silicon. The substrate has an electrode provided on the back side of the silicon substrate, and the wiring has a substantially comb shape having a plurality of comb parts, and the width of the root part of the comb part is longer than the width of the tip part of the comb part. Features.

According to the present invention, it is possible to provide a structure that improves the conversion efficiency while ensuring a stable connection between the back electrode type solar cell and the wiring sheet.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the 1st Embodiment of this invention and shows a back electrode type photovoltaic cell with a wiring sheet. 1 shows a first embodiment of the present invention and is a schematic view of a back electrode type solar battery cell. FIG. 1 shows a first embodiment of the present invention and is a schematic view of a wiring sheet. FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged schematic diagram illustrating a wiring of a wiring sheet, showing a first embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic diagram which shows the 1st Embodiment of this invention and shows the manufacturing method of a back electrode type photovoltaic cell. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic diagram which shows the 1st Embodiment of this invention and shows the joining method of a back electrode type photovoltaic cell and a wiring sheet. The 2nd Embodiment of this invention is shown, Comprising: It is a schematic diagram which shows the wiring of a wiring sheet. The 3rd Embodiment of this invention is shown and it is a schematic diagram which shows the wiring of a wiring sheet. The 4th Embodiment of this invention is shown and it is a schematic diagram which shows the wiring of a wiring sheet. The 5th Embodiment of this invention is shown, Comprising: It is a schematic diagram which shows the wiring of a wiring sheet. The 6th Embodiment of this invention is shown and it is a schematic diagram which shows the wiring of a wiring sheet.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
The back electrode type solar cell with wiring sheet according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a view of a back electrode type solar cell with a wiring sheet of the present embodiment as viewed from the light receiving surface side. The back electrode type solar cell 100 with the wiring sheet is formed by placing the back electrode type solar cell 2 on the wiring sheet 1. The back electrode type solar cells 2 are placed on the wiring sheet 1 at positions corresponding to the substantially comb-shaped n-type wiring and p-type wiring, respectively, so that the n-type electrode and the p-type electrode correspond to each other. The n-type wiring is electrically connected to the n-type electrode, and the p-type wiring is electrically connected to the p-type electrode. In the present embodiment, the wiring and the electrode are connected via a bonding member.

FIG. 2 is a diagram schematically showing the back electrode type solar battery cell of the present embodiment. FIG. 2A is a view showing a cross section AA ′ of the back electrode type solar cell in FIG. 1, and FIG. 2B is a schematic view when the back electrode type solar cell is viewed from the back side. It is. The back surface in this application is a surface opposite to the light receiving surface of the back electrode type solar cell.

As shown in FIG. 2A, an antireflection film 22 is formed on the light receiving side of the silicon substrate 21 having the concavo-convex shape of the back electrode type solar cell 2, and a passivation film 25 is formed on the back side of the silicon substrate 21. Has been. As the silicon substrate 21, for example, a substrate made of polycrystalline silicon or single crystal silicon having either n-type or p-type conductivity can be used. The thickness of the silicon substrate 21 is preferably about 50 μm or more and 400 μm or less. A film made of silicon nitride was used as the antireflection film 22, and a film made of silicon oxide was used as the passivation film 25. None of these are limited to these. As the passivation film 25, for example, a silicon nitride film or a stacked body of a silicon oxide film and a silicon nitride film can be used.

Further, an n-type impurity diffusion region 23 in which an n-type impurity such as phosphorus is diffused and a p-type impurity diffusion region 24 in which a p-type impurity such as boron is diffused are formed on the back side inside the silicon substrate 21. ing. The n-type impurity diffusion region 23 is a region containing n-type impurities such as phosphorus. The p-type impurity diffusion region 24 is a region containing a p-type impurity such as boron or aluminum.

Inside the silicon substrate 21 having the n-type or p-type conductivity type, a plurality of pn junctions are formed at the interface between the n-type impurity diffusion region 23 or the p-type impurity diffusion region 24 and the silicon substrate 21. Therefore, each of the n-type electrode 26 connected to the n-type impurity diffusion region 23 and the p-type electrode 27 connected to the p-type impurity diffusion region 24 through the contact holes provided in the passivation film 25 is The electrodes respectively correspond to a plurality of pn junctions formed on the back side inside the silicon substrate 21. As the n-type electrode 26 and the p-type electrode 27, for example, electrodes made of a metal such as silver can be used.

As shown in FIG. 2B, the n-type electrode 26 and the p-type electrode 27 each have a plurality of rectangular portions having a longitudinal direction formed at predetermined intervals. The rectangular portion of the n-type electrode 26 and the rectangular portion of the p-type electrode 27 are alternately arranged one by one at a predetermined interval in a direction orthogonal to the longitudinal direction of the rectangular portion. In both the n-type electrode 26 and the p-type electrode 27, the width and pitch of the rectangular portion are substantially constant. The width of the rectangular portion indicates a direction orthogonal to the longitudinal direction of the electrode, that is, a length in the short direction. The pitch of the rectangular portion indicates the distance between the midpoint of the electrodes in the short direction and the midpoint of the adjacent electrodes in the short direction.

Further, the n-type electrode and the p-type electrode may have a shape divided into a plurality in the longitudinal direction.
FIG. 3 is a schematic diagram of the wiring sheet of the present embodiment. 3A is a view as seen from the light receiving surface side, and FIG. 3B is a view showing a BB ′ cross section of FIG. 3A.

The wiring sheet 1 is composed of an insulating base material 11 and wirings 16 formed on one surface of the insulating base material 11. For example, PET is used as the insulating substrate 11. For the wiring 16, for example, a conductive material such as copper is used. In the present embodiment, a resin sheet mainly composed of PET having a thickness of about 75 μm is used as the insulating substrate of the wiring sheet, and a copper wiring having a thickness of about 35 μm is used as the wiring. The main component of the resin sheet is not limited to PET, and PEN or the like may be used.

3 A total of 16 back electrode type solar cells of 4 rows and 4 columns are arranged on the wiring sheet 1 of FIG. 3 to constitute a back electrode type solar cell with a wiring sheet. By the wiring on the wiring sheet 1, the 16 back electrode type solar cells are electrically connected in series. For example, the n-type electrode and the p-type electrode of the back electrode type solar cell disposed in the region C on the wiring sheet 1 are electrically connected to the n-type wire 12 and the p-type wire 13 in the region C, respectively. And physically connected.

Each of the n-type wiring 12 and the p-type wiring 13 has a substantially comb shape, and the portion corresponding to the comb blade has a plurality of isosceles triangular shapes formed at predetermined intervals. ing. The isosceles triangle portion corresponding to the comb blade of the n-type wiring 12 and the isosceles triangle portion corresponding to the comb blade of the p-type wiring 13 have a predetermined interval in a direction orthogonal to the longitudinal direction of the isosceles triangle. Open and arranged alternately one by one. The direction orthogonal to the longitudinal direction of the isosceles triangle corresponds to the base direction.

The

connection wires

14a and 14b extend in a direction orthogonal to the longitudinal direction of the isosceles triangle of the n-type wire 12 and the p-type wire 13, and the isosceles triangle of the n-type wire 12 and the p-type wire 13 The portion is connected to the

connection wiring

14a or 14b.

The p-type wiring 13 in the region C of the wiring sheet 1 is connected to the P-type extraction wiring 13a. Further, the n-type wiring 12 in the region C is connected to the p-type wiring in the region D through the connection wiring 14a. In other words, the adjacent back electrode type solar cells arranged in the column direction are electrically and physically connected via the connection wiring 14 a on the wiring sheet 1. Further, the back electrode type solar cells arranged in the row direction are electrically connected via the connection wiring 14b. Thus, the 16 back electrode type solar cells are electrically connected in series, and the current generated by the photoelectric conversion is taken out from the p-type take-out wiring 13a and the n-type take-out wiring 12a, respectively. . Further, the n-type wiring 12 and the p-type wiring 13 other than the n-type wiring 12a and the p-type wiring 13a, which are located at the end of the wiring sheet 1, are electrically connected by the

connection wiring

14a or 14b. Connected. Further, the connection wiring 14b is provided outside the portion where the back electrode type solar cells are placed.

FIG. 4 is an enlarged view of a portion E in FIG. The substantially comb-like wiring on the wiring sheet 1 has a substantially isosceles triangular shape. The root portion corresponding to the base of the isosceles triangle of each wiring is in physical contact with the connection wiring 14a, and the tip portion corresponding to the apex of the isosceles triangle of the wiring is not in physical contact with the connection wiring 14a. . By making the width L1 of the root portion larger than the width L2 of the tip portion, it becomes possible to improve the output power of the back electrode type solar cell with a wiring sheet. This is because the electrical resistance in the length direction of the wiring could be lowered.

The reason why the output power is improved will be described in more detail as follows.
When heat is applied to the back electrode type solar cell with the wiring sheet, due to the difference in thermal expansion coefficient between the insulating base material 11 constituting the wiring sheet 1 and the silicon substrate 21 constituting the back electrode type solar cell 2, In some cases, the positions of the wiring and the electrode, which should be arranged at opposing positions, are shifted. Due to the misalignment, the P-type wiring and the n-type electrode, or the n-type wiring and the p-type electrode approach each other. Therefore, a short circuit between the electrodes occurs, which may lead to a decrease in output power of the back electrode type solar cell with a wiring sheet. In order to prevent the output power from being lowered due to such positioning, it is desirable that the distance between the wirings be a certain value or more. If the distance between the wires is too small, there is a concern about ion migration. Specifically, about 50 μm to 300 μm is desirable. As an example of the case where heat is applied to the back electrode type solar cell with a wiring sheet, a sealing process in which heating at about 160 degrees can be given.

In this embodiment, the wiring pitch is about 750 μm. Further, the height of the triangle was about 160 mm, and the width at the substantially central portion in the height direction of the triangle was about 650 μm.

The back electrode type solar cell has a substantially rectangular shape. The width in the short direction of the substantially rectangular shape is almost constant. By adopting a substantially rectangular shape, stable high output power can be obtained. This is because the shape is easy to form an accurate electrode pattern.

In this embodiment, the shape of the opposing electrode and the shape of the wiring are different, but the output of the back electrode type solar cell with a wiring sheet due to the difference in shape does not occur. The reason will be described below.

In the back electrode type solar cell with a wiring sheet, the wiring on the wiring sheet and the electrode on the back electrode are arranged at opposite positions. In the electrode provided in the back electrode type solar cell, most of the electrons generated inside the solar cell flow toward the electrode immediately below and further flow toward the wiring immediately below. Therefore, in the back electrode type solar cell, the current density hardly changes depending on the location of the substantially rectangular electrode. On the contrary, in the wiring of the wiring sheet, the current density gradually increases from the tip portion toward the root portion. Therefore, even if the width of the rectangular portion of the electrode is substantially constant and the width of the rectangular portion of the wiring gradually increases toward the root, there is no problem that the resistance loss increases. Therefore, even if an electrode is a substantially rectangular shape, the output electric power of a back surface electrode type photovoltaic cell will not fall.

Below, the manufacturing method of the back electrode solar cell with a wiring sheet of this embodiment is shown.
FIG. 5 is a schematic cross-sectional view showing an example of a method for manufacturing the back electrode type solar battery cell of the present embodiment shown in FIGS. 1 and 2. An example of the manufacturing method of the back surface electrode type photovoltaic cell of this embodiment is demonstrated using FIG.

First, as shown in FIG. 5A, a silicon substrate 21 is first prepared. Since it is sliced from the ingot, slice damage 21 a is formed on the surface of the silicon substrate 21.

Next, as shown in FIG. 5B, the slice damage 21a on the surface of the silicon substrate 21 is removed. Here, the removal of the slice damage 21a can be performed, for example, by etching the surface of the silicon substrate 21 after slicing with a mixed acid of hydrogen fluoride aqueous solution and nitric acid or an alkaline aqueous solution such as sodium hydroxide. .

Next, as shown in FIG. 5C, an n-type impurity diffusion region 23 and a p-type impurity diffusion region 24 are formed on the back surface of the silicon substrate 21, respectively. The n-type impurity diffusion region 23 can be formed, for example, by vapor phase diffusion using a gas containing phosphorus which is an n-type impurity such as POCl3. The p-type impurity diffusion region 24 can be formed by a method such as vapor phase diffusion using a gas containing boron which is a p-type impurity such as BBr3.

Next, as shown in FIG. 5D, a passivation film 25 is formed on the back surface of the silicon substrate 21. Here, the passivation film 25 can be formed by a method such as a thermal oxidation method or a plasma CVD (Chemical Vapor Deposition) method.

Next, as shown in FIG. 5E, an uneven structure such as a texture structure is formed on the entire light receiving surface of the silicon substrate 21, and then an antireflection film 22 is formed on the uneven structure. The texture structure is obtained by etching the light receiving surface of the silicon substrate 21 using an etching solution obtained by heating a solution obtained by adding isopropyl alcohol to an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide to 70 ° C. or more and 80 ° C. or less, for example. Can be formed. The antireflection film 22 can be formed by, for example, a plasma CVD method.

Next, as shown in FIG. 5F, a part of the passivation film 25 on the back surface of the silicon substrate 21 is removed to form a contact hole 25a and a contact hole 25b. Here, the contact hole 25a is formed to expose at least part of the surface of the n-type impurity diffusion region 23, and the contact hole 25b is exposed to at least part of the surface of the p-type impurity diffusion region 24. It is formed.

Each of the

contact holes

25a and 25b is formed, for example, by forming a resist pattern having an opening on a portion corresponding to the contact hole forming portion on the passivation film 25 using a photolithography technique, and then opening the passivation film from the opening of the resist pattern. 25 can be formed by etching or the like.

Next, as shown in FIG. 5G, the n-type electrode 26 and the p-type electrode 27 are formed by screen printing of silver. The n-type electrode 26 is in contact with the n-type impurity diffusion region 23 through the contact hole 25a, and the p-type electrode 27 is in contact with the p-type impurity diffusion region 24 through the contact hole 25b. By making the electrode substantially rectangular, screen printing fading or the like hardly occurs, and the electrode formation process can be further stabilized.

Furthermore, the attachment of the back electrode type solar cell and the wiring sheet of this embodiment will be described with reference to FIG.

First, as shown in FIG. 6A, a back electrode type solar cell 2 including an n type electrode 26 and a p type electrode 27 provided on the back surface of the silicon substrate 21 with a predetermined interval is provided. prepare. Here, only one n-type electrode 26 and one p-type electrode 27 are shown for convenience of explanation, but it goes without saying that there may be a plurality of each.

Next, as shown in FIG. 6B, an uncured fixing resin is interposed between the n-type electrode 26 and the p-type electrode 27 on the back surface of the silicon substrate 21 of the back electrode type solar battery cell 2, respectively. 31a is installed. The fixing resin fixes the back electrode type solar cell and the wiring sheet.

Examples of the method for installing the fixing resin 31a include screen printing, dispenser coating, and inkjet coating. Among these, it is preferable to use screen printing. The fixing resin 31a can be easily installed at low cost and in a short time.

The width of the fixing resin 31a on the silicon substrate 21 side of the back electrode type solar battery cell 2 is preferably a width that does not contact the n-type electrode 26 and the p-type electrode 27. This is because an improvement in the stability of the electrical connection between the electrode of the back electrode type solar cell 2 and the wiring of the wiring sheet 1 can be expected.

In the present embodiment, the case where the fixing resin 31a is installed between the electrodes of the back electrode type solar battery cell 2 will be described. However, the fixing resin 31a may be installed between the wirings of the wiring sheet 1, and the back surface. The fixing resin 31 a may be installed between the electrodes of the electrode type solar battery cell 2 and between the wirings of the wiring sheet 1.

The shape of the fixing resin 31a is preferably a line shape along each of the n-type electrode 26 and the p-type electrode 27 of the back electrode type solar cell 2, but a sealing step into a sealing material to be described later In this case, the gap may be intermittently arranged as long as the gap is provided between the first cured resin and the electrode so as to be sufficiently expanded.

As the fixing resin 31a, it is preferable to use a resin that can be B-staged. The B-stageable resin means that when the liquid uncured fixing resin 31a is heated, the viscosity increases and becomes a cured state (first cured state), and then the viscosity decreases and softens. Thereafter, the viscosity is increased again, and the resin becomes a cured state (second cured state).

Next, as shown in the schematic cross-sectional view of FIG. 6C, the uncured fixing resin 31a is cured to form the first cured fixing resin 31b. The uncured fixing resin 31a is cured by, for example, heating and / or irradiation with light such as ultraviolet rays to be in a first cured state. Thereby, compared with the state of uncured fixed resin 31a, fixed resin 31b in the first cured state with reduced adhesive force and fluidity can be obtained.

In addition, the fixed resin 31b in the first cured state has a higher viscosity than the uncured state at room temperature (about 25 ° C.), has shape retainability (a property that does not deform unless an external force is applied), and Low adhesiveness (adhesiveness to the extent that the fixing resin 31b does not adhere to the back electrode solar cell 2 or the wiring sheet even if the back electrode solar cell 2 or the wiring sheet 1 is brought into contact with the surface of the fixing resin 31b. It is preferable that the In this case, it is possible to employ a printing process with high productivity in the process of installing the joining member described later. Further, in the step of overlapping the back electrode type solar battery cell 2 and the wiring sheet 1 described later, the back electrode type solar battery cell 2 even after the back electrode type solar battery cell 2 and the wiring sheet 1 are overlapped. And the wiring sheet 1 tend to be easily removable. Therefore, it exists in the tendency which can align the electrode of the back surface electrode type photovoltaic cell 2 and the wiring of the wiring sheet 1 easily and with high precision.

When the uncured fixed resin 31a is changed to the first fixed resin 31b in the first cured state by heating, the temperature that becomes the first fixed resin 31b in the first cured state is the first temperature described later. The temperature is preferably lower than the temperature at which the cured first fixing resin 31b is softened and the temperature at which the softened first fixing resin 31c is in the second cured state. Thereby, by controlling the heating temperature, it is possible to prevent the uncured fixed resin 31a from proceeding to the softened state or the second cured state.

Next, as shown in the schematic cross-sectional view of FIG. 6 (d), the bonding member 32 is installed on each surface of the n-type electrode 26 and the p-type electrode 27 of the back electrode type solar battery cell 2. As the joining member 32, for example, a material containing a conductive substance such as solder can be used. The joining member 32 can be installed by methods, such as screen printing, dispenser application | coating, or inkjet application | coating, for example. Among these, it is preferable to use screen printing. This is because the joining member 32 can be easily installed at a low cost and in a short time.

In the present embodiment, the case where the bonding member 32 is installed on the electrode of the back electrode type solar battery cell 2 will be described. However, the bonding member 32 may be installed on the wiring of the wiring sheet. The joining member 32 may be installed on each of the electrodes of the solar cell 2 and the wiring of the wiring sheet. Further, both the fixed resin 31a and the bonding member 32 may not be installed on the back electrode type solar cell 2 or the wiring sheet 1. For example, the fixed resin 31a is interposed between the electrodes of the back electrode type solar cell 2. And the joining member 32 may be installed on the wiring of the wiring sheet.

Next, as shown in FIG. 6 (e), the back electrode type solar cells 2 and the wiring sheet 1 are overlapped. When the back electrode type solar cell 2 and the wiring sheet 1 are overlapped, the n type electrode 26 and the p type electrode 27 of the back electrode type solar cell 2 are respectively placed on the insulating substrate 11 of the wiring sheet 1. The n-type wiring 12 and the p-type wiring 13 provided are opposed to each other through the bonding member 32.

Next, by heating and / or irradiating light while pressurizing the back electrode type solar cell 2 and the wiring sheet 1 that are overlapped as described above, a back electrode type solar cell with a wiring sheet is produced. .

Here, as shown in the schematic cross-sectional view of FIG. 6 (f), the fixed resin 31b in the first cured state is softened due to a decrease in viscosity due to heating and / or irradiation with light such as ultraviolet rays. Fixing resin 32c.

As shown in the schematic cross-sectional view of FIG. 6G, the softened fixing resin 31 c located between the electrodes of the back electrode solar cell 2 is composed of the back electrode solar cell 2, the wiring sheet 1, and the like. Is deformed by the pressurization between the wires and enters between the wirings of the wiring sheet 1. Further, the conductive material in the bonding member 32 is also melted by being heated, and the electrode of the back electrode solar cell 2 and the wiring sheet 1 are pressed by the pressure between the back electrode solar cell 2 and the wiring sheet 1. Deforms between the wires.

Thereafter, as shown in the schematic cross-sectional view of FIG. 6 (h), the fixed resin 31c in the softened state further increases in viscosity by heating and / or irradiation with light such as ultraviolet rays, and is cured again. The fixing resin 31d. Since the second cured state is cured by a crosslinking reaction of the resin, the state of the fixed resin 31d in the second cured state is stabilized without being softened again. That is, the back electrode type solar cell 2 and the wiring sheet 1 can be firmly bonded.

Then, from the light receiving surface side, it is arranged to be a translucent base material, sealing resin, back electrode solar cell with wiring sheet, sealing resin, back surface side protective material, and by heating and pressing Sealed. Glass was used as the translucent substrate. Moreover, EVA (ethylene vinyl acetate resin) was used as the sealing resin. There is no necessity to limit to EVA, and for example, an olefin resin may be used.

The back electrode type solar cell with wiring sheet had p-type extraction wiring and n-type extraction wiring, and each was electrically connected to the terminal box. Furthermore, it was set as the structure which inserts a flame | frame in the side part of the back electrode type solar cell with a wiring sheet | seat with a seal | sticker, and obtains high intensity | strength.

[Embodiment 2]
The back electrode type solar cell with wiring sheet according to Embodiment 2 will be described below with reference to the drawings. The difference from the first embodiment is that the shape of the n-type electrode and the p-type electrode on the wiring sheet is not a triangle but a trapezoid.

FIG. 7 shows a part of the wiring sheet of this embodiment. This corresponds to an enlarged view of a portion E in FIG. 3A used in the description of the first embodiment. The n-type wiring 121 has a shape composed of a plurality of trapezoids. Similarly, the P-type wiring 131 has a plurality of trapezoidal shapes. If there was an acute angle part in the wiring, there was a possibility that the disconnection would occur at a narrow part of the wiring, but it became possible to suppress the disconnection with high accuracy by eliminating the acute angle part.

[Embodiment 3]
The back electrode type solar cell with wiring sheet according to Embodiment 3 will be described below with reference to the drawings. The difference from the second embodiment is the shape of the connection wiring on the wiring sheet.

FIG. 8 shows a part of the wiring sheet of this embodiment. This corresponds to an enlarged view of a portion E in FIG. 3A used in the description of the first embodiment. Each of the n-type wiring 122 and the p-type wiring 132 has a plurality of substantially trapezoidal portions. Further, the root portions of the n-type wiring 122 and the p-type wiring 132 connected to the connection wiring 142a are curved with a curvature. The corner portion of the wiring sometimes becomes a starting point of the crack. When cracks occur in the wiring, the electrical resistance of the wiring increases. By eliminating the corners, cracks are less likely to occur in the wiring, and high conversion efficiency can be secured stably.

[Embodiment 4]
The back electrode type solar cell with wiring sheet according to Embodiment 4 will be described with reference to the drawings. The difference from the third embodiment is that the tip of the wiring is curved.

Fig. 9 shows a part of the comb-shaped electrode of the wiring sheet. This corresponds to an enlarged view of a portion E in FIG. 3A used in the description of the first embodiment. Each of the n-type wiring 123 and the p-type wiring 133 has a plurality of substantially trapezoidal portions, and the tip portion is curved. The tip is a portion corresponding to a short side of a pair of parallel sides of a trapezoid facing each other. Further, the n-type wiring 123 and the p-type wiring 133 are connected to the connection wiring 143a at the roots. By eliminating the corners at the tip of the wiring, it is possible to make it harder for the wiring to crack.

[Embodiment 5]
The back electrode type solar cell with wiring sheet according to Embodiment 5 will be described below with reference to the drawings. The difference from the third embodiment is that a radius is provided at the corner of the tip of the wiring.

Fig. 10 shows a part of the comb-shaped electrode of the wiring sheet. 10A corresponds to an enlarged view of a portion E in FIG. 3A used in the description of the first embodiment, and FIG. 10B is an enlarged view of a portion F in FIG. 10A. . Each of the n-type wiring 124 and the P-type wiring 134 has a plurality of substantially trapezoidal portions, and the root portion is connected to the connection wiring 144a. In this embodiment, the corner portion of the tip has a rounded structure. By providing rounded corners at the tip of the wiring, the wiring is less likely to crack.

Further, in this embodiment, the fixing resin is arranged so that the inflection points of the straight line portion and the curved portion of the wiring are covered with the fixing resin. Inflection points tend to be the starting point of cracks because stress tends to concentrate, but by covering them with a fixing resin, the generation of cracks can be prevented more reliably. This is presumably because the effect of preventing in-plane deformation is obtained by bonding the wiring to the wiring sheet with a fixing resin.

[Embodiment 6]
The back electrode type solar electrolysis cell with wiring sheet according to the sixth embodiment will be described below with reference to the drawings. The difference from the first embodiment is that the connection wiring on the wiring sheet has an opening. It is a point provided.

Fig. 11 shows a part of the comb-shaped electrode of the wiring sheet. FIG. 11 corresponds to an enlarged view of a portion E in FIG. 3A used in the description of the first embodiment. The wiring sheet is provided with an n-type wiring 125, a p-type wiring 135, and a connection wiring 145a. The n-type wiring 125 and the p-type wiring 135 are electrically and physically connected to the n-type electrode and the p-type electrode of the back electrode type solar cell, respectively. The connection wiring 145a is a wiring that connects adjacent back-surface electrode type solar cells arranged in the column direction. In the present embodiment, the opening 17 is provided in the connection wiring 145a. The opening 17 has a circular shape with a diameter of about 500 μm, and is arranged at the root of each n-type wiring and p-type wiring. By providing an opening in the connection wiring, it is possible to make it difficult for the wiring to crack.

The diameter of the opening 17 is preferably about 100 μm to 600 μm. If it is smaller than 100 μm, it is difficult to form a clear pattern on the wiring, and if it is larger than 600 μm, the conversion efficiency is lowered due to an increase in resistance of the connecting wiring. The opening may be an ellipse instead of a circle. Further, in the present embodiment, the connection wiring is arranged so as to open the opening, but may be arranged linearly.

As mentioned above, although Embodiment 1 to Embodiment 6 was specifically described, the present invention is not limited to them. Embodiments obtained by appropriately combining the technical means disclosed in the six embodiments described above are also included in the technical scope of the present invention.

It should be noted that the embodiment disclosed this time is an example in all respects and does not serve as a basis for limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Moreover, all the changes within the meaning and range equivalent to a claim are included.

DESCRIPTION OF SYMBOLS 1 Wiring sheet, 2 Back electrode type photovoltaic cell, 11 Insulating base material, 12 n type wiring, 13 p type wiring, 14 connection wiring, 16 wiring, 17 opening part, 21 silicon substrate, 22 antireflection film , 23 n-type impurity diffusion region, 24 p-type impurity diffusion region, 25 passivation film, 26 n-type electrode, 27 p-type electrode, 31 fixing resin, 32 bonding member, 100 back sheet solar cell with wiring sheet.

Claims

A back electrode type solar cell with a wiring sheet consisting of a wiring sheet and a back electrode type solar cell,
The wiring sheet has an insulating base and wiring provided on the light receiving surface side of the insulating base,
The back electrode type solar cell has a silicon substrate and an electrode provided on the back side of the silicon substrate,
The wiring has a substantially comb shape having a plurality of comb portions,
A back electrode type solar cell with a wiring sheet, wherein a width of a base portion of the comb portion is longer than a width of a tip portion of the comb portion.
The back electrode type solar cell with a wiring sheet according to claim 1, wherein the root portion has a curve.
The back electrode type solar cell with wiring sheet according to claim 1 or 2, wherein the tip has a curve.
A back electrode solar cell with the wiring sheet in which a fixing resin is disposed between the wiring sheet and the back electrode solar cell,
The comb portion of the wiring has a straight line in the longitudinal direction,
The back electrode type solar cell with a wiring sheet according to claim 2 or 3, wherein a fixing resin is arranged so that an inflection point between a straight line and a curve constituting the shape of the wiring is covered with the fixing resin.
The back electrode type solar cell with a wiring sheet according to any one of claims 1 to 4, wherein the electrode has a substantially rectangular shape and a width in a short side direction is substantially constant.