TWI585989B - Solar cell unit, solar cell module, method for manufacturing the solar cell, and method for manufacturing the solar cell module - Google Patents

Description

Solar battery unit, solar battery module, manufacturing method of solar battery unit, and manufacturing method of solar battery module

The present invention relates to a solar cell in which an electrode is formed by screen printing, a solar cell module, a method of manufacturing a solar cell, and a method of manufacturing a solar cell module.

The power generated by the solar cells is collected by a grid electrode and collected by a bus electrode connected to the gate electrode. In addition, by soldering the connection tabs to the bus electrodes, the solar cells can be connected in series to each other to obtain more power. Here, when the gate electrode and the bus electrode are collectively printed, the material of the gate electrode and the bus electrode becomes the same kind of electrode material. On the other hand, the gate electrode and the bus electrode are separately formed by printing, and different kinds of electrode materials can be used for the electrode materials of the gate electrode and the bus electrode. Thereby, there are many options for efficiently collecting the electrode material generated in the solar cell, and the cost of the electrode material can be reduced.

However, when the gate electrode and the bus electrode are separately printed, in order to collect the electric power generated in the solar cell, it is necessary to overlap the gate electrode and the bus electrode in order to electrically connect the gate electrode and the bus electrode. Therefore, uneven portions are formed on the surface of the bus electrode around the overlapping portion of the gate electrode and the bus electrode. Further, in order to connect the plurality of solar battery cells in series to solder the connection leads to the respective solar battery cells, only the connection leads are welded and joined to the convex portions of the uneven portions. Therefore, there is a problem that the welding of the bus electrode and the connecting lead is not stably obtained, and the electric resistance between the bus electrode and the connecting lead is increased, resulting in power loss.

In Patent Document 1, in order to reduce the manufacturing cost of the solar cell and improve the efficiency of the solar cell, the electrode is formed into a laminated structure, and an electrode material is used. Further, when the first collecting portion and the second collecting portion are separately formed by printing, the side faces of the respective collecting portions are connected to each other.

[Previous Technical Literature] (Patent Literature)

(Patent Document 1) Japanese Patent Laid-Open Publication No. 2012-4571

However, according to the technique of Patent Document 1, there are variations in the position of the first power collecting portion and the second power collecting portion, such as the positional accuracy of printing, the dimensional accuracy of printing, and the dimensional accuracy of a print mask. factor. Therefore, if the overlapping portion between the first power collecting portion and the second power collecting portion is not provided, it is difficult to form a connection between the two. Then, the first collector and the second collector are generated. When the overlapping portion of the portion is formed, unevenness is generated on the surface of the electrode. When the connecting wire is welded in the modularization of the solar cell, stable welding is not obtained, and power loss is caused.

The present invention has been made in view of the above problems, and an object thereof is to provide a solar battery cell capable of reducing power loss at the time of current collection.

In order to achieve the object of the present invention, an object of the present invention is to provide an electrode having a pn-bonded semiconductor substrate on one surface thereof, the electrode including an elongated shape in which a first direction is elongated in a surface direction of the semiconductor substrate. a gate electrode and a bus electrode extending in a second direction intersecting the first direction and having a width wider than the gate electrode; and the bus electrode having a side surface extending from the side in the second direction toward the inside in the first direction In the notch portion, the end portion of the gate electrode on the side of the bus electrode is housed in the notch portion without being overlapped with the bus electrode.

According to the present invention, an effect is obtained in which a solar battery unit capable of reducing power loss at the time of current collection can be obtained.

11,11a,11b,11c‧‧‧Solar battery unit

12‧‧‧ Single crystal germanium substrate

12a‧‧‧n type impurity diffusion layer

12b‧‧‧p type single crystal germanium substrate

13‧‧‧Photon side electrode

13a‧‧‧ gate electrode

13b‧‧‧Concurrent electrode

21‧‧‧ gate electrode end

22,44‧‧‧ nicks

23‧‧‧ side

24‧‧‧ gap

25‧‧‧Abutment

26‧‧‧Overlap width

31‧‧‧Connecting leads

32‧‧‧Solder

41‧‧‧ gate electrode end

42‧‧‧ gate electrode width

43‧‧‧ gate electrode end width

45‧‧‧ wide gap

46‧‧‧ Wide gap width

47‧‧‧ notch width

Fig. 1 is a perspective view of the solar battery cell according to the first embodiment of the present invention as seen from the light receiving surface side.

Fig. 2 is a plan view showing a principal part of a shape of a gate electrode of a solar battery cell according to Embodiment 1 of the present invention.

Fig. 3 is a plan view showing a principal part of a shape of a bus electrode of a solar battery cell according to Embodiment 1 of the present invention.

Fig. 4 is a plan view showing a principal part of a light-receiving surface side electrode in a solar battery cell according to Embodiment 1 of the present invention.

Fig. 5 is a cross-sectional view showing the main part of the light-receiving surface side electrode in the solar battery cell according to the first embodiment of the present invention.

Fig. 6 is a cross-sectional view showing the principal part of the light-receiving surface side electrode in the solar battery cell according to the first embodiment of the present invention.

Fig. 7 is a plan view showing a principal part of a light-receiving surface side electrode in a solar battery cell according to Embodiment 1 of the present invention.

Fig. 8 is a perspective view showing a state in which the connecting leads for connecting the solar cell unit welding units according to the first embodiment of the present invention are viewed from the light receiving surface side.

Fig. 9 is a plan view showing a principal part of a state in which the connecting leads for connecting the light-receiving surface side electrode welding units in the solar battery cell according to the first embodiment of the present invention are enlarged.

Fig. 10 is a cross-sectional view showing the main part of a state in which the connecting leads for connecting the solar cell unit between the welding cells of the first embodiment of the present invention are connected.

Fig. 11 is a cross-sectional view showing a principal part of a state in which a connection lead for connecting between light-receiving surface side electrode welding units in a solar battery cell according to Embodiment 1 of the present invention is shown.

Fig. 12 is a view showing a state in which the solar battery cells according to the first embodiment of the present invention are electrically connected in series by connecting the connecting leads for connecting the cells. Sexual perspective.

Fig. 13 is a plan view showing a principal part of a modification of the shape of the light-receiving surface side electrode according to the first embodiment of the present invention.

Fig. 14 is a plan view showing a principal part of another modification of the shape of the light-receiving surface side electrode according to the first embodiment of the present invention.

Fig. 15 is a plan view showing a principal part of a shape of a gate electrode of a solar battery cell according to Embodiment 2 of the present invention.

Fig. 16 is a plan view showing a principal part of a shape of a bus electrode of a solar battery cell according to a second embodiment of the present invention.

Fig. 17 is a plan view showing a principal part of a light-receiving surface side electrode in a solar battery cell according to a second embodiment of the present invention.

Figure 18 is a cross-sectional view showing the principal part of the light-receiving surface side electrode in the solar battery cell of the second embodiment of the present invention.

Fig. 19 is a plan view showing a principal part of the light-receiving surface side electrode when the gate electrode and the bus electrode are in contact with each other in the second embodiment of the present invention.

Fig. 20 is a plan view showing a principal part of another light-receiving surface side electrode in the solar battery cell according to Embodiment 2 of the present invention.

Hereinafter, a solar battery cell, a solar battery module, a method of manufacturing a solar battery cell, and a method of manufacturing a solar battery module according to embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited by the embodiment.

Embodiment 1.

Fig. 1 is a perspective view of the solar battery unit 11 according to the first embodiment of the present invention as seen from the light receiving surface side. The solar battery cell 11 of the first embodiment includes an n-type impurity diffusion layer in which an n-type impurity which is a second conductivity type is diffused on the surface layer of the p-type single crystal germanium substrate 12b which is a semiconductor substrate of the first conductivity type. a single crystal germanium substrate 12 having a pn junction, a comb-shaped light-receiving surface side electrode 13 formed on the surface of the single crystal germanium substrate 12 on the light-receiving surface side, and a side opposite to the light-receiving surface of the single crystal germanium substrate 12; A back side electrode (not shown) having a comb shape on the back side.

The surface of the p-type single crystal germanium substrate 12b, that is, the surface of the n-type impurity diffusion layer 12a is formed so that the solar cell unit 11 can absorb more sunlight, and is surrounded by a (111) plane having, for example, germanium. A texture structure (not shown) formed by the unevenness of the quadrangular pyramid-shaped convex portion. Further, on the surface on the light-receiving surface side of the single crystal germanium substrate 12, an anti-reflection film may be provided in a region where the light-receiving surface side electrode 13 is not formed. The semiconductor substrate is not limited to a p-type single crystal germanium substrate, and a substrate which can be used for a solar cell such as a p-type polycrystalline germanium substrate, an n-type single crystal germanium substrate, or an n-type polycrystalline germanium substrate can be used. When an n-type substrate is used as the semiconductor substrate, the conductivity type of each member of the solar cell unit 11 may be reversed.

The light-receiving side electrode 13 includes a gate electrode 13a having an elongated shape and two bus electrodes 13b having a width wider than that of the gate electrode 13a. The gate electrode 13a is disposed on the light receiving surface of the single crystal germanium substrate 12 having the pn junction, and is elongated in the first direction in the surface direction of the single crystal germanium substrate 12. The bus electrode 13b is elongated and arranged in the second direction crossing the first direction. In the present embodiment, the direction of elongation of the gate electrode 13a and the confluence The direction in which the poles 13b extend is orthogonal to the plane direction of the single crystal germanium substrate 12. That is, the first direction and the second direction are orthogonal to each other in the plane direction of the single crystal germanium substrate 12. Further, the direction in which the gate electrode 13a extends and the direction in which the bus electrode 13b extends may intersect at an angle other than a right angle in the plane direction of the single crystal germanium substrate 12. In other words, the first direction and the second direction may intersect at an angle other than a right angle in the plane direction of the single crystal germanium substrate 12. Similarly to the light-receiving surface side electrode 13, the back side electrode includes a gate electrode having an elongated shape (not shown) and two bus electrodes having a width wider than the gate electrode. The longitudinal direction of the bus electrode of the back side electrode is the same as the longitudinal direction of the bus electrode 13b of the light receiving surface side electrode 13.

Next, the light-receiving surface side electrode 13 in the solar battery cell 11 will be described. Fig. 2 is a plan view showing a principal part of the shape of the gate electrode 13a of the solar battery cell 11 of the first embodiment. Fig. 3 is a plan view showing a principal part of the shape of the bus electrode 13b of the solar battery cell 11 of the first embodiment. Fig. 4 is a plan view showing a principal part of the light-receiving surface side electrode 13 in the solar battery cell 11 of the first embodiment of the present invention. Fig. 5 is a cross-sectional view showing a principal part of a light-receiving surface side electrode in the solar battery cell 11 according to the first embodiment of the present invention, and a cross-sectional view of a principal part of a line V-V in Fig. 4. Fig. 6 is a cross-sectional view showing the principal part of the light-receiving surface side electrode 13 in the solar battery cell 11 of the first embodiment of the present invention, and a cross-sectional view of a principal part of the line VI-VI in Fig. 4.

As shown in FIG. 2, the gate electrode 13a is divided and arranged in the longitudinal direction. That is, the gate electrodes 13a adjacent in the longitudinal direction are arranged on a straight line with each other. Moreover, the gate electrode 13a adjacent to each other in the longitudinal direction At this time, the gate electrode ends 21 of the respective ends thereof are opposed to each other. In addition, the gate electrode 13a is arranged in a direction intersecting with the longitudinal direction of the gate electrode 13a in the surface direction of the single crystal germanium substrate 12, and is arranged in parallel at a predetermined interval in the direction orthogonal to the longitudinal direction of the gate electrode 13a. In a slender shape. The predetermined interval is the length between the center positions of the adjacent gate electrodes 13a in the width direction of the gate electrode 13a.

As shown in FIG. 3, the bus electrode 13b is provided with a notch portion 22 on the side surface 23 in the longitudinal direction. The notch portion 22 is formed in an elongated shape from the side surface 23 of the bus electrode 13b in the short-side direction of the bus electrode 13b, that is, in the width direction, and penetrates in the thickness direction of the bus electrode 13b. The direction in which the notch portion 22 is elongated is the same direction as the direction in which the gate electrode 13a extends in the surface direction of the single crystal germanium substrate 12. The notch portion 22 has a U-shape which is recessed and formed in a surface direction of the single crystal germanium substrate 12 corresponding to the shape of the gate electrode end portion 21 and having a size larger than the outer shape of the gate electrode end portion 21.

The notch portion 22 is arranged side by side at a predetermined interval in the longitudinal direction of the bus electrode 13b in order to accommodate the gate electrode end portion 21 of the gate electrode 13 on the n-type impurity diffusion layer 12a. The predetermined interval is the length between the center positions of the adjacent notch portions 22 in the longitudinal direction of the bus electrode 13b. The predetermined interval in which the bus electrodes 13b are juxtaposed is the same as the predetermined interval in which the gate electrodes 13a are juxtaposed. In the state in which the gate electrode end portion 21 is housed in the notch portion 22 of the gate electrode 13, the gate electrode 13a and the bus electrode 13b are disposed on the n-type impurity diffusion layer 12a to form the light-receiving surface side electrode 13.

In the plane of the single crystal germanium substrate 12, the inside of the notch portion 22 is gated. A clearance 24 is provided between the side surface of the electrode end portion 21 and the side surface of the bus electrode 13b as shown in Figs. 4 to 6. That is, in the surface of the single crystal germanium substrate 12, the gate electrode end portion 21 of the gate electrode 13a is disposed apart from the bus electrode 13b in the notch portion 22. By providing the gap 24, the gate electrode 13a and the bus electrode 13b are not in direct contact. Therefore, the gate electrode 13a and the bus electrode 13b do not overlap each other, and the occurrence of the uneven portion due to the overlap of the gate electrode 13a and the bus electrode 13b can be prevented on the surface of the bus electrode 13b. Thereby, when the connection lead and the bus electrode 13b are soldered, it is possible to ensure a wide bonding area between the bus electrode 13b and the connection lead, and the solderability of the bus electrode 13b and the connection lead is stabilized.

The gate electrode 13a is not continuous in the longitudinal direction and has a shape that is divided at the position of the bus electrode 13b, whereby the amount of use of the electrode material of the gate electrode 13a of the divided region portion can be suppressed.

Although the detailed description is omitted, the back side electrode also has the same structure as the light receiving surface side electrode 13. In addition, the back side electrode may have a structure in which the collector electrode which is elongated in the longitudinal direction of the bus electrode 13b is provided at a position corresponding to the bus electrode 13b on the back surface of the single crystal germanium substrate 12, and may not have a light receiving surface side electrode. 13 The same comb shape configuration.

Next, the steps for manufacturing the solar cell unit 11 will be described. Here, the steps described are the same as the manufacturing steps of a general solar battery cell using a ruthenium substrate, and therefore are not particularly illustrated.

First, the p-type single crystal germanium substrate 12b is cut out from silicon ingot by slice processing. A wire saw is attached to the surface of the p-type single crystal germanium substrate 12b cut out from the crucible by slicing. The powder generated by the cutting during processing, the organic impurities of the pollutants composed of the abrasive, and the like, and the metal impurities. Therefore, the p-type single crystal germanium substrate 12b cut out from the crucible is subjected to a washing treatment such as a water washing treatment.

Further, in the surface layer of the cut substrate, a processing deformation due to the slice called a damage layer having a depth of about 5 μm is generated. The damaged layer remains in the solar cell unit, and the damaged layer promotes recombination of electrons, resulting in deterioration of solar cell characteristics. Therefore, the damaged layer is removed.

Further, the surface of the p-type single crystal germanium substrate 12b is subjected to an anisotropic etching using a high-temperature wet etching liquid obtained by adding an organic substance such as IPA as an additive to an alkaline aqueous solution. The surface of the p-type single crystal germanium substrate 12b is formed into a texture structure composed of irregularities of a convex portion having a quadrangular pyramid shape surrounded by a (111) plane of a crucible.

Next, the p-type single crystal germanium substrate 12b having a textured structure on its surface is sent to a thermal diffusion furnace, and heated in the presence of phosphorous oxychloride (POCl ₃ ) vapor to be applied to the p-type single crystal germanium substrate 12b. Phosphorus glass is formed on the surface to diffuse phosphorus into the p-type single crystal germanium substrate 12b. Thereby, the n-type impurity diffusion layer 12a is formed on the surface layer of the p-type single crystal germanium substrate 12b, and the single crystal germanium substrate 12 having the pn junction is formed.

Next, the phosphor glass on the surface of the single crystal germanium substrate 12 is removed in a hydrofluoric acid solution, and then an electrode is formed. First, the light-receiving surface side electrode 13 is printed on the light-receiving surface of the single crystal germanium substrate 12. That is, the aluminum paste of aluminum is mixed on the light receiving surface of the single crystal germanium substrate 12. The (aluminum paste) screen printing is in the shape of the gate electrode 13a. Moreover, the silver paste in which silver is mixed on the light-receiving surface of the single crystal germanium substrate 12 is screen-printed into the shape of the bus electrode 13b. Here, although the silver paste is generally used for the material of the bus electrode, the electrode material of the bus electrode 13b of the first embodiment is not limited to the silver paste. The electrode material of the bus electrode 13b is selected from other metal pastes such as a gold paste, a copper paste, and a silver aluminum paste in terms of electrical conductivity and price.

Next, a back side electrode is formed by printing on the back surface of the single crystal germanium substrate 12. That is, the aluminum paste containing aluminum and glass frit is screen-printed into the same gate electrode shape as the gate electrode 13a on the back surface of the single crystal germanium substrate 12. Further, a silver paste containing silver and glass frit is printed on the back surface of the single crystal germanium substrate 12 in the same shape as the bus electrode of the bus electrode 13b. Then, the paste after printing is subjected to a baking treatment to form the light-receiving surface side electrode 13 and the back surface side electrode. In the above manner, the solar cell unit 11 is fabricated.

Next, a method of manufacturing the light-receiving surface side electrode 13 of the solar battery cell 11 will be described. First, an aluminum paste for forming an electrode containing aluminum and glass frit is printed on the light-receiving surface of the single crystal germanium substrate 12 as a gate electrode 13a by screen printing, and dried. The aluminum paste is printed on the light receiving surface of the single crystal germanium substrate 12 by the screen printing as shown in Fig. 2 in an elongated shape.

Then, on the light-receiving surface of the single crystal germanium substrate 12, a silver paste for forming an electrode including silver and glass frit is printed as a bus electrode 13b by screen printing, and dried. Silver paste is shown in Figure 3 The side surface 23 of the bus electrode 13b in the longitudinal direction is provided with a notch portion 22, and the gate electrode end portion 21 of the gate electrode 13a is housed in the notch portion 22, and is printed on the single crystal germanium substrate 12 by screen printing. The predetermined position on the light receiving surface. The printing order of the paste for forming the electrodes of the gate electrode 13a and the bus electrode 13b may be reversed from the above-described order.

At this time, in the surface of the single crystal germanium substrate 12, a gap 24 is provided between the gate electrode 13a and the bus electrode 13b to print the silver paste, whereby the gate electrode 13a and the bus electrode 13b are printed without being in direct contact with each other. Therefore, the gate electrode 13a and the bus electrode 13b do not overlap each other, and the occurrence of the uneven portion due to the overlap of the gate electrode 13a and the bus electrode 13b on the surface of the bus electrode 13b can be prevented. Therefore, as will be described later, when the connection lead and the bus electrode 13b are soldered, it is possible to ensure a wide bonding area between the bus electrode 13b and the connection lead, and the solderability of the bus electrode 13b and the connection lead is stabilized. In the third and fourth figures, the corners of the inside of the notch portion 22 are formed at right angles. However, as long as the gap 24 can be secured, the corners of the inside of the notch portion 22 may have a slight rounded corner.

The gate electrode 13a and the bus electrode 13b are paste electrodes formed by printing a paste material for electrode formation by screen printing. In the formation of the gate electrode 13a and the bus electrode 13b, there is a printing position accuracy when printing a paste material on the light receiving surface of the single crystal germanium substrate 12, and a printing width accuracy which is affected by other printing conditions. Therefore, the size of the gap 24, that is, the distance between the gate electrode end portion 21 and the bus electrode 13b in the plane of the single crystal germanium substrate 12 is preferably set to be the gate electrode in the longitudinal direction of the bus electrode 13b. 13a and the bus electrode 13b are each derived from a predetermined printing The total value of the allowable value of the deviation of the printing position of the position and the tolerance of the printing width derived from the predetermined printing width is the same value. The allowable value of the deviation of the printing position is the length allowed by the deviation of the original printing position in the longitudinal direction of the bus electrode 13b. The allowable value of the deviation of the printing width is the length allowed by the deviation of the original printing width.

Here, the size of the gap 24 is set to the same value as the total value of the allowable value of the deviation between the printing position and the printing width, whereby the gate electrode 13a and the confluence are in the longitudinal direction of the bus electrode 13b. The respective printing positions of the electrodes 13b are the largest deviations within the allowable value of the deviation of the printing position, and the respective printing widths of the gate electrode 13a and the bus electrode 13b are the largest deviations within the allowable value of the variation of the printing width. As shown in Fig. 7, the gate electrode 13a and the bus electrode 13b do not overlap each other even if they are in contact with each other in the longitudinal direction of the bus electrode 13b. Fig. 7 is a plan view showing a principal part of the light-receiving surface side electrode 13 in the solar battery cell 11 of the first embodiment of the present invention.

Therefore, irregularities due to the overlap of the gate electrode 13a and the bus electrode 13b do not occur on the bus electrode 13b. Therefore, when the connection lead 31 is soldered to the bus electrode 13b as will be described later, the bus electrode 13b and the connection lead 31 can obtain a good bonding area. Also, the size of the gap 24 may be slightly longer than the aforementioned sum value. At this time, as in the above, the gate electrode 13a and the bus electrode 13b do not overlap each other.

Similarly, the size of the gap 24 in the width direction of the bus electrode 13b, that is, the notch portion 22 in the width direction of the bus electrode 13b The distance between the gate electrode end portion 21 and the bus electrode 13b is also preferably a tolerance value and a printing length of the respective printing positions of the gate electrode 13a and the bus electrode 13b in the width direction of the bus electrode 13b. The sum of the allowable values of the deviations is the same value. The allowable value of the deviation of the printing length is the length allowed by the deviation of the original printing length in the width direction of the bus electrode 13b.

At this time, the size of the gap 24 is set to the same value as the sum of the allowable values of the deviation from the printing position and the tolerance of the printing length, whereby the gate electrode 13a and the width direction of the bus electrode 13b are provided. The respective printing positions of the bus electrodes 13b are the largest deviations within the allowable value of the deviation of the printing position, and the respective printing lengths of the gate electrode 13a and the bus electrode 13b are maximized within the allowable value of the deviation of the printing length. In the case of the deviation, the gate electrode 13a and the bus electrode 13b do not overlap each other even if the side faces in the width direction of the bus electrode 13b are in contact with each other.

When the thickness of the gate electrode 13a and the bus electrode 13b is set to the same thickness, and a connection lead to be described later is soldered to the bus electrode 13b, a good bonding area can be secured between the bus electrode 13b and the connection lead. Further, even if the difference between the thicknesses of the gate electrode 13a and the bus electrode 13b is the largest, the thickness of the plated solder connected to the connection lead of the light-receiving surface side electrode 13 is the same. As will be described later, in general, the connecting leads are copper wires having a surface plated with solder. Therefore, the solder to be plated is melted by heating the connection leads, and the gate electrode 13a and the bus electrode 13b can be soldered to the copper wire. The difference between the thicknesses of the gate electrode 13a and the bus electrode 13b is the thickness of the plated solder connected to the connection lead of the light-receiving surface side electrode 13. Hereinafter, when a connection lead to be described later is soldered to the bus electrode 13b, a good bonding area can be secured between the bus electrode 13b and the connection lead. In other words, by suppressing the difference between the thicknesses of the gate electrode 13a and the bus electrode 13b, the unevenness of the gate electrode 13a in the cutout portion 22 can be reduced, and the gate electrode 13a and the bus electrode 13b can be reliably connected to the connection lead. Thereby, the solder joint area of the appropriate connection lead can be ensured when the connection lead is joined, and power loss at the time of current collection can be suppressed.

Next, a solar battery module in which a plurality of solar battery cells 11 are welded by a connecting lead for inter-unit connection will be described. A plurality of solar battery cells 11 are formed, and the adjacent solar battery cells 11 are electrically connected in series to each other, whereby a solar battery module having excellent power extraction efficiency can be realized. At this time, first, one end side of the connection lead 31 to which the solder is coated is placed on the notch portion 22 of the first solar battery cell 11 including the gate electrode end portion 21 in which the gate electrode 13a is housed. On the bus electrode 13b. Next, the other end side of the connection lead 31 is placed on the bus electrode 13b of the back surface side electrode of the second solar cell including the notch portion 22 of the gate electrode end portion 21 in which the gate electrode 13a is housed. Then, by heating the connection lead 31, the gate electrode end portion 21 and the bus electrode 13b of the gate electrode 13a accommodated in the notch portion 22 are soldered to the first solar cell unit and the second solar cell unit, and the connection lead is formed. In the bonding step, the first solar battery unit and the second solar battery unit are electrically connected. For the sake of easy understanding, the constituent portions of the back side electrode are also described with the same reference numerals as those of the light receiving surface side electrode 13 . In addition, the solar cell module in this specification contains only The electrode of the solar cell unit 11 is joined to the surface of the connecting lead by soldering.

Fig. 8 is a perspective view showing a state in which the connection leads 31 for connecting the welding cells between the solar cells 11 of the first embodiment of the present invention are viewed from the light-receiving surface side. Fig. 9 is a plan view showing a principal part of a state in which the connection lead 31 for soldering unit connection between the light-receiving surface side electrodes 13 in the solar battery cell 11 of the first embodiment of the present invention is enlarged. Fig. 10 is a cross-sectional view showing a principal part of a state in which the connection leads 31 for connecting the cells are connected to each other in the solar cell unit 11 according to the first embodiment of the present invention, and a cross-sectional view of a main portion taken along line X-X in Fig. 9. Fig. 11 is a cross-sectional view showing a main part of a state in which the connection lead 31 for connecting the light-receiving surface side electrodes 13 in the solar cell unit 11 of the first embodiment of the present invention is connected, and the line XI in Fig. 9 is shown. - The main part of the XI section. Fig. 12 is a schematic perspective view showing a state in which the solar battery cells 11a, 11b, and 11c according to the first embodiment of the present invention are electrically connected in series by the connection leads 31 for connecting the cells.

As shown in FIG. 10, the connection lead 31 is coated with solder 32 on the surface of the connection lead 31 by plating. The metal wire used for the connection lead 31 is preferably copper in terms of conductivity and cost. The connection lead 31 is placed on the bus electrode 13b, and the connection lead 31 is heated, whereby the plated solder 32 is melted, and the gate electrode 13a of the gate electrode 13a disposed in the notch portion 22 is soldered by the solder 32. 21 and the bus electrode 13b are soldered to the connection lead 31.

Here, the connection lead 31 is attached to the width of the bus electrode 13b. The bus electrode 13b is placed on the bus electrode 13b within the allowable range of the arrangement accuracy of the connection lead 31. Thus, as shown in FIG. 10, the gate electrode 13a and the bus electrode are passed through the solder 32 plated on the surface of the connection lead 31. 13b electrical connection. The allowable range of the arrangement accuracy is the length allowed by the deviation of the original printing position within the width of the bus electrode 13b.

The gate electrode 13a and the bus electrode 13b are not overlapped by providing the gap 24, and thus are not electrically connected. However, the notch portion 22 is provided in the bus electrode 13b, and the gate electrode 13a is formed in a state in which the gate electrode end portion 21 of the gate electrode 13a enters the notch portion 22. Further, since the connection lead 31 is also disposed on the notch portion 22 of the bus electrode 13b, the bus electrode 13b is solder-bonded to the connection lead 31 by heating the connection lead 31, and the gate electrode end portion in the notch portion 22 is also formed. 21 is solder-bonded to the connection lead 31, and the bus electrode 13b and the gate electrode 13a are electrically connected through the connection lead 31. Thereby, the electric power generated by the solar battery cell 11 can be collected from the bus electrode 13b and the gate electrode end portion 21 to the connection lead 31.

Here, as shown in FIG. 4, the overlap width 26 of the gate electrode end portion 21 of the gate electrode 13a of the cutout portion 22 and the bus electrode 13b in the width direction of the bus electrode 13b is set to be larger than that at the bus electrode. In the width direction of 13b, the total value of the allowable value of the deviation between the printing positions of the gate electrode 13a and the bus electrode 13b when the paste material is printed on the light-receiving surface of the single crystal germanium substrate 12, and the tolerance of the printing length Further, a value obtained by the allowable value of the deviation of the position where the connection lead 31 is disposed on the bus electrode 13b is larger. Thereby, the gate electrode end portion 21 is always disposed in the notch portion 22 of the bus electrode 13b in the width direction of the bus electrode 13b. In addition, solder bonding of the gate electrode end portion 21 and the connection lead 31 can be obtained. The allowable value of the deviation of the arrangement position is the length allowed by the deviation of the arrangement position of the original connection lead 31 in the width direction of the bus electrode 13b on the bus electrode 13b.

In other words, even if the maximum deviation occurs within the allowable value of the deviation between the respective printing positions of the gate electrode 13a and the bus electrode 13b, and the maximum deviation occurs, the gate electrode end portion 21 is accommodated in the bus electrode 13b. In the inside of the notch portion 22, the gate electrode 13a and the connection lead 31 can be soldered to each other, and power loss at the time of current collection can be suppressed. Further, different materials may be selected as the electrode material of the gate electrode 13a and the electrode material of the bus electrode 13b. Therefore, when an inexpensive electrode material is selected, the solar cell unit 11 can be produced at low cost. Further, even when the same electrode material is selected as the electrode material of the gate electrode 13a and the electrode material of the bus electrode 13b, the amount of use of the electrode material can be reduced, and the price of the solar cell unit 11 can be made inexpensive.

When the connection lead 31 is soldered to the light-receiving surface side electrode 13, when the connection lead 31 is heated and the connection is made to the light-receiving surface side electrode 13, the solder 32 of the connection lead 31 is melted and flows into the gap 24. Therefore, the connection lead 31 is not only bonded to the upper surfaces of the gate electrode 13a and the bus electrode 13b, as shown in Figs. 10 and 11, the side surface of the gate electrode end portion 21 of the gate electrode 13a in the gap 24 and the side surface of the bus electrode 13b Since it is electrically connected by the solder 32, the joint area of the wide connection lead 31 and the light-receiving surface side electrode 13 can be ensured. Thereby, the electric resistance between the light-receiving surface side electrode 13 and the connection lead 31 can be reduced, and the solar cell unit 11 can be improved. Power extraction efficiency. Therefore, in the solar battery module of the first embodiment, the electric power generated by the solar battery unit 11 can be prevented from being wasted, and electric power can be efficiently collected.

Further, when the amount of the solder 32 plated on the connection lead 31 is small, and the molten solder 32 does not flow into the gap 24, the gate electrode 13a and the connection lead 31, and the bus electrode 13b and the connection lead 31 are solder-bonded, and can be collected. The electric power generated by the solar battery unit 11. Further, a conductive material such as a soldering paste may be applied to the bus electrode 13b in advance, or the gap 24 may be filled with solder or solder paste.

Fig. 13 is a plan view showing a principal part of a modification of the shape of the light-receiving surface side electrode 13 according to the first embodiment of the present invention. As shown in Fig. 13, the shape of the notch portion 22 of the bus electrode 13b may be a shape that penetrates the bus electrode 13b in the width direction of the bus electrode 13b. That is, the bus electrode 13b may be divided in the longitudinal direction of the bus electrode 13b. At this time, a gap 24 is provided between the gate electrode 13a and the bus electrode 13b, and the gate electrode end portion 21 is placed in the notch portion 22. When such a light-receiving surface side electrode 13 is formed, the same effect as in the case of the light-receiving surface side electrode 13 shown in Fig. 4 can be obtained. Further, both the gate electrode 13a and the bus electrode 13b are formed into a divided shape, and the amount of use of the electrode material of the gate electrode 13a and the bus electrode 13b can be suppressed.

Fig. 14 is a plan view showing a principal part of another modification of the shape of the light-receiving surface side electrode 13 according to the first embodiment of the present invention. The shape of the light-receiving surface side electrode 13 shown in Fig. 14 as the bus electrode 13b is the same as that of Fig. 13. On the other hand, the gate electrode 13a is tied to the gate electrode The direction of elongation of 13a is continuously formed without interruption. Therefore, in the extending direction of the gate electrode 13a in the notch portion 22, the storage length of the gate electrode end portion 21 is not required to be considered as an allowable value of the offset of the printing position and an allowable value of the offset of the printing length and the connection. The size after the allowable value of the deviation of the arrangement position of the lead wires 31.

In the above description, the light-receiving surface side electrode 13 will be described as an example. However, the same effect as described above can be obtained by the back side electrode in which the gate electrode and the bus electrode are arranged to have a comb shape.

On the other hand, when the light-receiving surface side electrode having the shape of the light-receiving surface side electrode 13 of the first embodiment is not provided, that is, when the light-receiving surface side electrode having no gap between the gate electrode and the bus electrode is separated, the gate electrode and the confluence are separated. When the electrodes are printed and formed by separate printing, the gate electrodes are formed on the light-receiving surface side of the ruthenium substrate, and then the bus electrodes are formed by printing. At this time, since the gate electrode and the bus electrode overlap each other, uneven portions are formed in a portion where the gate electrode and the bus electrode overlap. Therefore, when the connection lead is soldered to the bus electrode, only the convex portion of the uneven portion is solder-bonded to the connection lead, and the solder joint of the bus electrode and the connection lead becomes smaller, and the resistance between the bus electrode and the connection lead increases. Large, causing power loss.

Further, the gate electrode and the bus electrode are separately printed, and in order to reduce the overlapping area of the gate electrode and the bus electrode, even when the end surface of the gate electrode in the longitudinal direction is connected to the side surface of the bus electrode, the electrode is connected to the sides of the bus electrode. Concavities and convexities are generated by overlapping the periphery of the end portion of the gate electrode. Therefore, similarly to the above, only the convex portions of the uneven portions are welded and joined to the connection leads, and the welding of the bus electrodes and the connection leads is reduced, whereby the confluence is small. The electrical resistance between the electrode and the connecting lead increases, resulting in power loss.

As described above, in the first embodiment of the present invention, the gap 24 is provided between the gate electrode 13a and the bus electrode 13b, and even if the gate electrode 13a and the bus electrode 13b are separately printed, the gate electrode 13a and the bus electrode 13b do not overlap. Therefore, even when screen printing of the gate electrode 13a and the bus electrode 13b is performed, the surface of the bus electrode 13b can be flattened, and uneven portions where the electrodes overlap each other can be formed on the bus electrode 13b, and the bus electrode 13b can be secured. And the connection lead 31 has a stable and wide solder joint area, and the gate electrode 13a and the connection lead 31 are also soldered. Thereby, the electric power generated by the solar battery unit 11 can be collected with low loss.

Further, in the first embodiment of the present invention, since the gap 24 is provided between the gate electrode 13a and the bus electrode 13b by providing the notch portion 22 in the bus electrode 13b, the amount of use of the electrode material can be reduced, and the manufacturing cost can be reduced to realize the sun. The battery unit 11 is inexpensive. Further, even when a conductive material such as solder paste is additionally used for bonding the light-receiving surface side electrode 13 and the connection lead 31, the electrode material of the bus electrode 13b is a high-priced material such as silver, and the solder material is very inexpensive, so that it is comparable. The electrodes of a typical solar cell unit form electrodes at a lower cost.

Therefore, according to the first embodiment of the present invention, the solar battery unit and the solar battery module that collect the generated electric power with low loss can be realized at low cost.

Embodiment 2.

In the second embodiment, the light-receiving surface side electrode 13 in the first embodiment is used. The modification will be described. In the drawings shown below, the same members as those in the first embodiment are denoted by the same reference numerals. Fig. 15 is a plan view showing the principal part of the shape of the gate electrode 13a of the solar battery cell according to the second embodiment of the present invention. Fig. 16 is a plan view showing the principal part of the shape of the bus electrode 13b of the solar battery cell according to the second embodiment of the present invention. Fig. 17 is a plan view showing a principal part of the light-receiving surface side electrode 13 in the solar battery cell according to the second embodiment of the present invention. Fig. 18 is a cross-sectional view showing a principal part of a light-receiving surface side electrode 13 in a solar battery cell according to a second embodiment of the present invention, and a cross-sectional view of a main portion taken along line XVIII-XVIII in Fig. 17.

In order to collect the electric power collected by the gate electrode 13a with low loss, it is necessary to collect electric power to the bus electrode 13b having a larger cross-sectional area than the gate electrode 13a, and collect the connection lead 31 having a larger cross-sectional area than the bus electrode 13b. Therefore, as shown in Fig. 15, the gate electrode 13a in the second embodiment is formed by being divided in the longitudinal direction, and the gate electrode end portions 41 of the divided end portions are opposed to each other. Further, the gate electrode end portion 41 is formed in a direction orthogonal to the longitudinal direction of the gate electrode 13a, that is, a rectangular shape in which the longitudinal direction of the bus electrode 13b is a longitudinal direction thereof, and the gate electrode 13a is formed on the single crystal germanium substrate 12. The plane direction has a T shape. That is, the gate electrode end width 43 of the width of the gate electrode end portion 41 in the longitudinal direction of the bus electrode 13b is formed to be wider than the gate electrode width 42 of the other portion of the gate electrode 13a.

Further, as shown in Fig. 16, the bus electrode 13b in the second embodiment is provided with a notch portion 44 on the side surface 23. The notch portion 44 is from the side surface 23 of the bus electrode 13b in the short side direction of the bus electrode 13b, that is, the width The width direction is recessed into the elongated shape on the inner side, and penetrates in the thickness direction of the bus electrode 13b. The direction in which the notch portion 44 is elongated is the same as the direction in which the gate electrode 13a extends in the surface direction of the single crystal germanium substrate 12.

Further, the notch portion 44 has a T-shape which corresponds to the shape of the gate electrode end portion 41 in the surface direction of the single crystal germanium substrate 12, and has a larger size than the outer shape of the gate electrode end portion 41. . In other words, the notch portion 44 has a rectangular wide notch portion 45 that is elongated in the longitudinal direction of the bus electrode 13b in a portion on the inner side in the width direction. The wide notch portion 45 has a wide notch width 46 which is wider in the longitudinal direction of the bus electrode 13b than the notch width 47 of the width of the other portion of the notch portion 44, and is wider than the gate electrode end portion 43. In a state in which the gate electrode end portion 41 is housed in the wide notch portion 45, the gate electrode 13a is disposed in the notch portion 44 to form the light-receiving surface side electrode 13.

Further, in the plane of the single crystal germanium substrate 12, a gap 24 is provided between the gate electrode 13a and the bus electrode 13b as shown in Fig. 17. By providing the gap 24, the gate electrode 13a and the bus electrode 13b are not in direct contact. Therefore, the gate electrode 13a and the bus electrode 13b do not overlap each other, and the occurrence of irregularities due to the overlap of the gate electrode 13a and the bus electrode 13b can be prevented on the surface of the bus electrode 13b.

Further, since the bus electrode 13b has the notch portion 44, the notch portion 44 has the wide notch portion 45, and the amount of material used for the bus electrode 13b can be suppressed.

The gate electrode end width 43 is set to a value larger than the gate electrode width 42, and the allowable value and print width of the deviation of the printing position are as described above. The relationship between the allowable value of the deviation of the degree and the size of the gap 24 makes it easy for the side faces of the gate electrode 13a and the bus electrode 13b to face each other.

Fig. 19 is a plan view showing, in an enlarged manner, a main portion of the light-receiving surface side electrode 13 when the gate electrode 13a and the bus electrode 13b are in contact with each other in the width direction of the bus electrode 13b. For example, as shown in FIG. 19, when the gate electrode 13a and the bus electrode 13b are printed in a width direction of the bus electrode 13b in the width direction, the tolerance of the printing position, and the tolerance of the printing width, the gate electrode end portion is printed. The side surface on the right side of the 41 is in contact with the side surface on the right side of the wide notch portion 45.

Next, the same phenomenon can be caused in both the width direction of the gate electrode 13b and the longitudinal direction of the bus electrode 13b. Therefore, the possibility of contact with the wide notch portion 45 of the bus electrode 13b at all the gate electrode end portions 41 is improved. Further, even when the gate electrode 13a and the bus electrode 13b are not in contact, the gate electrode 13a and the bus electrode 13b are soldered to the connection lead 31, so that power loss does not occur.

Fig. 20 is a plan view showing the main part of the other light-receiving surface side electrode 13 in the solar battery cell according to the second embodiment of the present invention. As shown in Fig. 20, even if the shape of the gate electrode end portion 41 and the wide notch portion 45 is circular, the above-described effects can be obtained similarly to the case where the gate electrode end portion 41 is rectangular.

According to the second embodiment of the present invention, in addition to the effects of the first embodiment described above, the shape of the gate electrode end portion 41 is made rectangular or circular, and the wide notch portion 45 of the bus electrode 13b corresponds to the end portion of the gate electrode. 41 shape and having a larger size than the outer dimension of the gate electrode end 41 The shape is increased to increase the possibility of contact between the gate electrode 13a and the bus electrode 13b. Thereby, the contact area between the gate electrode 13a and the bus electrode 13b is increased, and the solar cell unit and the solar cell module excellent in power extraction efficiency between the gate electrode 13a and the bus electrode 13b can be realized.

The configuration disclosed in the above embodiments is an example of the present invention, and may be combined with other known techniques, and a part of the configuration may be omitted or changed without departing from the gist of the present invention. .

12a‧‧‧n type impurity diffusion layer

13‧‧‧Photon side electrode

13a‧‧‧ gate electrode

13b‧‧‧Concurrent electrode

21‧‧‧ gate electrode end

22‧‧‧ nicks

23‧‧‧ side

24‧‧‧ gap

26‧‧‧Overlap width

Claims (13)

A solar battery unit comprising: an electrode having an elongated shape in a first direction extending in a first direction of a surface direction of the semiconductor substrate, and a surface of the semiconductor substrate having a pn junction, and the solar cell a bus electrode that is elongated in the second direction and has a width wider than the gate electrode; and the bus electrode has a notch portion that is recessed inward from the side surface in the second direction toward the first direction, and the gate electrode is the aforementioned The end on the bus electrode side is housed in the notch portion in a state of not overlapping the bus electrode, and the width of the end portion on the bus electrode side of the gate electrode is wider than the notch portion of the gate electrode. The solar cell unit according to claim 1, wherein the gate electrode is in the notch portion, a part of a side surface thereof is in contact with a side surface of the bus electrode, and between the other side surface of the bus bar electrode The gap is provided, and an end portion of the gate electrode on the side of the bus electrode is housed in the notch portion without being overlapped with the bus electrode. The solar battery unit according to claim 1, wherein the gate electrode is in the notch portion, and has a gap between all side faces of the bus electrode, and an end portion of the gate electrode on the side of the bus electrode is The state in which the bus electrode is not overlapped is accommodated in the notch portion. A solar cell module is a connecting wire with a surface covered with solder The connection electrode of the solar cell according to any one of the first to third aspect, wherein the connection lead is disposed along the second direction and includes an end including the gate electrode. The state on the bus electrode on the notch portion of the portion is connected to the bus electrode and the end portion of the gate electrode housed in the notch portion by the solder. The solar cell module according to claim 4, wherein the gate electrode and the bus electrode have the same thickness, or a difference in thickness is a thickness equal to or less than a thickness of the solder covering a surface of the connection lead. The solar battery module according to claim 4, wherein a side surface of the bus electrode of the notch portion and a side surface of an end portion of the gate electrode housed in the cutout portion are joined by soldering. A method of manufacturing a solar cell includes: a first step of forming a pn junction on a semiconductor substrate; and a second step of forming an electrode on a surface of the semiconductor substrate having the pn junction, the electrode being included in the semiconductor substrate a gate electrode having an elongated shape in which the surface direction is elongated in the first direction, and a bus electrode extending in a second direction intersecting the first direction and having a width wider than the gate electrode; wherein the second step includes: Formed by screen printing having a side from the second direction a third step of the bus electrode in the notch portion recessed inward in the first direction; and a fourth step of forming the gate electrode by screen printing in a step different from the third step, wherein the gate electrode is The inside of the notch portion is housed in the notch portion so as not to overlap with the bus electrode, and the end portion of the gate electrode on the side of the bus electrode is wider than the notch portion of the gate electrode. The method of manufacturing a solar cell according to claim 7, wherein in the fourth step, the gate electrode is formed in the cutout portion, and a portion of a side surface of the gate electrode is in contact with a side surface of the bus electrode. A gap is formed between the other side surface of the bus electrode, and an end portion of the gate electrode on the side of the bus electrode is housed in the notch portion without being overlapped with the bus electrode. The method of manufacturing a solar cell according to claim 7, wherein in the fourth step, the gate electrode is formed in the cutout portion, and between the side surfaces of the bus electrode of the gate electrode In the gap, the end portion of the gate electrode on the side of the bus electrode is housed in the notch portion in a state of not overlapping the bus electrode. The method for manufacturing a solar cell according to the eighth or ninth aspect, wherein the width of the gap is a tolerance value and a printing width of a printing position different from each of the gate electrode and the bus electrode. Partial The sum of the difference tolerances is greater. A method of manufacturing a solar cell module, comprising the steps of: forming a solar cell unit by the method for manufacturing a solar cell according to any one of claims 7 to 10; and connecting the surface to a solder-covered connecting lead a fifth step of disposing the bump electrode on the notch portion including the end portion of the gate electrode along the second direction; and heating the connection lead to be received by the notch portion by solder bonding The sixth step of the end portion of the gate electrode and the bus electrode and the connection lead. The method for manufacturing a solar cell module according to claim 11, wherein the gate electrode and the bus electrode are made to have the same thickness, or the difference in thickness is to cover the connection lead. The thickness of the surface of the solder below the thickness of the solder. The method for manufacturing a solar cell module according to claim 11 or claim 12, wherein in the sixth step, the side surface of the bus electrode on the notch portion and the notch portion are accommodated by the solder The side surfaces of the ends of the aforementioned gate electrodes are joined.