TWI603486B - Solar cell and solar cell manufacturing method - Google Patents

Description

Solar cell and solar cell manufacturing method

The present invention relates to a solar cell system in which a region where a high electron concentration is generated when an irradiation light or the like is formed on a substrate, and an insulating film that transmits light or the like is formed on the substrate. And having a bus electrode for taking out electrons from an electron take-out port formed in the insulating film.

In the past, solar cells using one of the renewable energy sources were developed based on the semiconductor technology of the protagonist of the 20th century. It is an important development at the global level that affects human survival. The development of the project is not only the efficiency of converting sunlight into electrical energy, but also continuing to progress while facing the problem of reducing manufacturing costs and pollution. In order to achieve such problems, it is particularly important to reduce the amount of silver (Ag) and lead (Pb) used in the electrode, and not to use silver (Ag) and lead (pb).

In general, the structure of the solar cell is as shown in the plan view of Fig. 10(a) and the cross-sectional view of (b), and is composed of the following elements: an N-type/P-type ruthenium substrate 43, which is a solar energy source. Converting into electric energy; the tantalum nitride film 45 is for preventing reflection of the surface of the tantalum substrate 43, and is an insulator film; A finger electrode 42 takes out electrons generated in the ruthenium substrate 43; a bus bar electrode 41 collects electrons taken out by the finger electrode 42; and a lead wire 47 that is collected to the bus bar The electrons of the electrode 41 are taken out to the outside.

Among them, silver and lead (lead glass) are used for the bus bar electrode (bus bar electrode) 41 and the finger electrode 42, and it is preferable to reduce or reduce the amount of silver used, and further reduce or remove lead (lead glass). The amount of use is low cost and pollution-free.

In the components of the solar cell of the above-described tenth embodiment, silver and lead (lead glass as a binder) are used for the finger electrodes 42 and the like, and the amount of silver used is reduced or reduced, and lead is reduced or removed. The use amount of (lead glass) reduces the manufacturing cost of the solar cell and becomes a problem of no pollution.

The inventors of the present invention have found that it is possible to produce a bus electrode or the like when the paste is used 100% of the NTA glass to be described later, and it is possible to produce a bus electrode or the like which is superior or superior to the conventional silver paste. The characteristics of the solar cell (described later).

The present invention is based on the findings that in order to reduce or eliminate the amount of silver used, and to reduce or eliminate the amount of lead (lead glass) used, vanadium is formed when forming a bus electrode (bus bar electrode) of a constituent element of a solar cell. Acid crystal glass (hereinafter referred to as conductive NTA glass, "NTA" is the day This registered trademark 5009023) is prepared by firing a paste to remove or reduce the amount of silver and lead (lead glass) used.

Therefore, the present invention is such that an area where a high electron concentration is generated when irradiated light or the like is formed on a substrate, and an insulating film that transmits light or the like is formed on the area, and has an electron extraction port formed from the insulating film. A solar cell in which an electron sink electrode is taken out, wherein, in order to form a bus electrode, a conductive glass is fired as a glass frit in a conductive paste to form a bus electrode, and conductive glass is used as a conductive electrode. Sexual cream.

In this case, the conductive glass is set to have a weight ratio of 100% to 71%, and the remainder is made of silver instead of 100% by weight of the conductive glass.

Further, the conductive glass is a vanadate glass containing at least vanadium or vanadium and niobium.

Moreover, the time of the step of baking the conductive glass and baking is set to the maximum of 1 minute or less, and it is 1 second or more.

Moreover, the conductive glass system was made to have no Pb.

Further, when the finger electrode is fired, the finger electrode is formed to have a portion having a high electron concentration region at one end and a portion having the same height as the upper surface of the bus electrode at the other end, or to protrude and protrude on the upper surface. part.

Further, it is assumed that a wire electrode is provided on the bus electrode formed by firing.

Further, it is assumed that the wire electrode is formed by ultrasonic welding on the bus electrode formed by firing, and is bonded to the wire electrode. The bus electrode, the finger electrode and other parts increase the bonding strength of the wire electrode.

The present invention is capable of removing or reducing the conventional silver paste by using 100% conductive NTA glass, or even 71% (or less) content instead of the conventional silver paste. The amount of silver used, and can reduce or eliminate the use of lead (lead glass). Thereby, it has the following characteristics.

First, when forming a bus bar electrode (bus bar electrode) of a solar cell, NTA glass which is 100% or even 71% of conductive vanadate glass is used (Japanese registered trademark No. 5009023, Japanese Patent No. 5333976) No.) replaces the silver paste, which can reduce or reduce the amount of Ag used, and can reduce or eliminate the use of lead (lead glass).

Secondly, since the bus bar electrodes (bus bar electrodes) use NTA glass by 100% to 71% (and can also reduce the content), the initial experimental results obtained at this stage can form the conversion of solar energy into electron energy. The efficiency is an electrode which is almost equal to or slightly higher and exhibits an effect as a bus bar electrode (see Fig. 9). It is noted that the NTA glass is as follows: (1) having conductivity; (2) by using NTA glass, the finger electrode is formed at a portion having the same height as the upper surface of the bus bar electrode (sink electrode), Or a portion that protrudes from the upper surface, and the portions are joined by ultrasonic welding of the wires. As a result, the high electron concentration region and the wire are directly connected by the finger electrodes; other elements (for example, refer to Caused by the "3rd" mentioned.

Third, unlike the past, the formation of the finger electrodes and the formation of the bus bar electrodes use a paste containing a different glass frit. Conventionally, in the formation of a finger electrode, a phenomenon called firing is required. This is formed by using a component molecule in a frit used as a sintering aid for silver, for example, a lead molecule in lead glass, to break through an insulating layer of a tantalum nitride film formed on the surface layer of the tantalum substrate to form a finger. The electrodes are used to efficiently collect the electrons generated on the germanium substrate. However, with regard to the formation of the bus bar electrodes, the calcination phenomenon is not essential. Conventionally, the bus bar electrode also sinters the lead glass containing the lead component as a sintering aid. Therefore, the structure is different, but electrical conduction between the bus bar electrode and the ruthenium substrate is formed to reduce the conversion efficiency. By using NTA glass which does not cause calcination as a sintering aid when forming the bus bar electrode, the reduction in conversion efficiency can be eliminated.

Fourth, there is a problem that the cost of the solar cell caused by the use of the silver powder material is high (the raw material cost is high). Moreover, material scheduling problems due to excessive demand for silver materials have emerged. Even if the content ratio of the NTA glass of the conductive glass is greatly increased to 100% to 71%, and the amount of silver should be increased by increasing the amount, the solar cell can be produced without lowering the conversion efficiency, and it will be produced by the industry. A major impact.

Fifthly, the lead glass which has been used in the formation of the conventional bus bar electrode is not used, that is, it can be lead-free. Thereby, the environmental problem of lead pollution can be completely avoided.

11‧‧‧矽 substrate

12‧‧‧High electron concentration region (diffusion doping)

13‧‧‧Insulating film (tantalum nitride film)

14‧‧‧Electronic take-out (finger electrode)

15‧‧‧ bus bar electrode

16‧‧‧Back electrode

17‧‧‧Wire

Fig. 1 is a structural view of an embodiment of the present invention (completed step of the step: section Face view).

Fig. 2 is a flow chart showing the operation of the present invention.

Figure 3 is a detailed step-by-step diagram of the present invention (part 1).

Figure 4 is a detailed step-by-step diagram of the present invention (part 2).

Fig. 5 is a detailed explanatory view of the present invention (baking of the bus bar electrode).

Fig. 6 is an explanatory view (bus bar electrode) of the present invention.

Fig. 7 is an explanatory view (bus bar electrode) of the present invention.

Figure 8 is an explanatory view of the present invention (ultrasonic welding).

Fig. 9 is a measurement example (efficiency) of the present invention.

Fig. 10 is an explanatory view of the prior art.

(Example)

Fig. 1 is a view showing the construction of an embodiment of the present invention (completed view of the steps: sectional view).

In the first drawing, the ruthenium substrate 11 is a known semiconductor ruthenium substrate.

The high electron concentration region (diffusion doped layer) 12 is a diffusion-doped region equal to a known region (layer) on which a desired p-type/n-type layer is formed on the germanium substrate 11, and is incident from the upper direction in the drawing. In the case of sunlight, an area where electrons (power generation) are generated on the substrate 11 and the electrons are accumulated. Here, the accumulated electrons are taken out in the upward direction by the electronic take-out port (finger electrode (silver)) 14 (refer to the effect of the invention).

The insulating film (tantalum nitride film) 13 is known to pass (penetrate) sunlight and electrically insulate the bus bar electrode 15 from the high electron concentration region 14. Membrane.

The electron extraction port (finger electrode (silver)) 14 is a port (finger electrode) through which electrons accumulated in the high electron concentration region 12 are taken out through holes formed in the insulating film 13. In the present invention, as shown in the figure, when the bus bar electrode 15 is fired by 100% (to about 71%) of the NTA glass, the finger electrode 14 is formed (fired) and the bus bar electrode 15 is formed. The upper surface is a portion of the same height or a portion that protrudes and protrudes from the upper surface, and electrons in the high electron concentration region 12 can be directly flowed into the wire 17 (directly extracting electrons) via the finger electrode 14. That is, the high electron concentration region 12, the finger electrode 14, the bus bar electrode 15, the path 1 of the wire 17 (traditional path 1), and the high electron concentration region 12, the finger electrode 14, and the path 2 of the wire 17 can be used ( The path 2) added by the present invention takes the electrons (current) in the high electron concentration region 12 to the outside via the wire 17, and as a result, the high electron concentration region 12 and the wire 17 can be made. The resistance value is very small, reducing the loss, and as a result, improving the efficiency of the solar cell.

The bus bar electrode (electrode 1 (NTA glass 100%)) 15 is an electrode that electrically connects a plurality of electron extraction ports (finger electrodes) 14 and is an electrode that does not use Ag or reduces the amount of Ag used (refer to the invention) Effect).

The back electrode (electrode 2 (aluminum)) 16 is a well-known electrode formed on the lower surface of the ruthenium substrate 11.

A wire (welding formation) 17 electrically connecting a plurality of bus bar electrodes 15 for taking out electrons (current I) to the outside; or further ultrasonically bonding the wires to the finger electrodes 14 of the present invention A portion having the same height as the upper surface of the bus bar electrode 15 or a portion passing through the upper surface of the bus bar electrode 15 takes out electrons (current) to the external wires.

According to the structure of Fig. 1 described above, when sunlight is irradiated from the top to the bottom, the sunlight passes through the portion of the non-conductive wire 17 and the electron-free take-out port 14 and the insulating film 13, and enters the ruthenium substrate 11 to generate electrons. Then, the electrons accumulated in the high electron concentration region 12 pass through the electronic take-out port (finger electrode) 14, the bus bar electrode 15, the path 1 of the wire 17, and the path of the electron take-out port (finger electrode) 14 and the wire 17. 2 These two paths are taken out to the outside. At this time, as shown in FIG. 2 to FIG. 9 to be described later, 100% to 71% (or less, see FIG. 9) of NTA glass (conductive glass) is mixed into the solder paste as a glass frit and fired. Forming the bus bar electrode 15 can eliminate the use of Ag or reduce the amount of Ag used. The details will be described in detail below.

Fig. 2 is a flow chart showing the operation of the present invention, and Figs. 3 and 4 show the detailed construction of each step.

In Fig. 2, S1 is a substrate for preparation.

The S2 system is cleaned. As shown in Fig. 3(a), these S1 and S2 are well cleaned on the surface of the tantalum substrate 11 prepared in S1 (the surface on which the high electron concentration region 12 is formed).

The S3 system performs diffusion doping. As shown in FIG. 3(b), a known diffusion doping is performed on the germanium substrate 11 cleaned in FIG. 3(a) to form a high electron concentration region 12.

S4 forms an antireflection film (tantalum nitride film). This is shown in Fig. 3(c), after forming the high electron concentration region 12 of Fig. 3(b), For example, a tantalum nitride film is formed as an antireflection film (a film that allows sunlight to pass through and minimizes surface reflection) by a known method.

S5 is a screen printed finger electrode. This is a pattern of the finger electrodes 14 formed by screen printing after forming the tantalum nitride film 13 of FIG. 3(c) as shown in FIG. 3(d). The printing material is used, for example, in which silver is mixed with lead glass as a frit.

The S6 system fires the finger electrodes and fire-throughs them. This is to burn the pattern of the finger electrodes 14 (the glass frit mixed with silver and lead glass) after screen printing in FIG. 3(d), as shown in FIG. 3(e), The tantalum nitride film 13 is burned through to form a finger electrode 14 in which silver (conductivity) is formed.

The S7 is a screen printing bus bar electrode (electrode 1). As shown in FIG. 4(f), after the finger electrodes 14 of FIG. 3(e) are formed, the pattern of the bus bar electrodes 15 is formed by screen printing. The printing material is, for example, a glass frit using NTA gas (100%).

The S8 system fires the bus bar electrodes. This is to burn the pattern of the bus bar electrode 15 (NTA glass (100%) frit) after screen printing in FIG. 3(f) (the firing time is within 1 minute even if it is long, The firing is performed for 1 to 3 seconds or longer. As shown in FIG. 4(g), the bus bar electrode 15 is formed on the uppermost layer, and is a feature of the present invention, and the finger electrode 14 is formed and formed on the uppermost layer of the confluence. The upper surface of the discharge electrode 15 is a portion of the same height or a portion that passes through the upper surface of the bus bar electrode 15.

In addition, printing of S5 and S7 may be performed, or both may be fired at the same time.

S9 forms a back electrode (electrode 2). As shown in FIG. 4(h), for example, an aluminum electrode is formed on the lower side (back surface) of the ruthenium substrate 11.

S10 is a wire formed of solder. This is shown in FIG. 4(i), and is formed by soldering, for example, by ultrasonic welding to form a wire electrically connected to the bus bar electrode of FIG. 4(g) and electrically connected, so that the electron concentration region 12 can be high. The finger 1 (the conventional path 1) of the finger electrode 14, the bus bar electrode 16, and the wire 17, and the path 2 of the high electron concentration region 12, the finger electrode 14, and the wire 17 (the path 2 added by the present invention) In both paths, the electrons (current) in the high electron concentration region 12 are taken out to the outside via the wire 17, so that the resistance value between the high electron concentration region 12 and the wire 17 can be made very small to reduce the loss, thereby improving the solar cell. effectiveness. That is, the path 2 added by the present invention is such that one end of the finger electrode 14 is located in the high electron concentration region 12 and has the same height or the same end as the upper surface of the bus bar electrode 15 of the NTA glass 100%. A portion of the upper surface of the bus bar electrode 15 is taken out, and the wire is directly joined (directly bonded by ultrasonic welding) to the portion, thereby forming a path 2 of the high electron concentration region 12, the finger electrode 14, and the wire 17. Also, path 1 is a traditional path.

By the above steps, the solar cell can be fabricated on the germanium substrate.

Fig. 5 is a detailed explanatory view of the present invention (firing of the bus bar electrode).

Fig. 5(a) is a view schematically showing an example of firing a bus bar electrode with silver of 100% and NTA0% by weight, and Fig. 5(b) is a schematic representation of 50% of silver and 50% by weight of NTA. Example of firing a bus bar electrode, Figure 5 (c) An example of firing a bus bar electrode with NTA 100% by weight is schematically shown. The firing time is within 1 minute even if it is long, and it is set to 1 to 3 seconds or longer.

As shown in Fig. 5 (a), Fig. 5 (b), and Fig. 5 (c), the experimental results of the solar cell formed by the substantially identical structure were obtained.

As a result of the test, the conversion efficiency of the solar cell when the solar cell was fabricated in Fig. 5(a) and Fig. 5(b) was about 17.0% in terms of the material of the pattern of the printed bus bar electrode, and the results were substantially the same. Furthermore, in Fig. 5 (c), the conversion efficiency was about 17.2% on average. From the initial experimental results, it is known that the fifth graphs (a) to (c) are all within the range of substantially the same conversion efficiency, or the NTA 100% of the fifth graph (c) is slightly higher conversion efficiency. In addition, the NTA glass is composed of vanadium, niobium, and iron. In particular, the iron system is strongly bonded internally and remains inside, and has a property of being extremely small even when mixed with other materials (refer to Japanese Patent No. 5333976). Further, it is presumed that the high electron concentration region of the present invention and the path between the wires (the path 1 and the path 2 are juxtaposed) are improved.

Fig. 6 and Fig. 7 are explanatory views (bus bar electrodes) of the present invention.

Figure 6 (a) and Figure 6 (b) are NTA 50%, Ag50% Here, Fig. 6(a) shows a general plan view, and Fig. 6(b) shows an enlarged view. Fig. 7(c) shows NTA 100% and Ag 0%, and Fig. 7(c) shows an enlarged view.

In FIGS. 6(a) and 6(b), the bus bar electrode 15 is an elongated electrode as shown in the entire plan view of Fig. 6(a), and when enlarged by an optical microscope, The configuration as shown in Fig. 6(b) was observed.

In Fig. 6(b), when the bus bar electrode 15 is fired using a conventional glass frit of Ag and lead glass, the Ag system is uniformly dispersed, but is fired using the glass frit of the Ag and NTA glass of the present invention. In the case of firing (1 to 3 seconds or longer, even if it is longer than 1 minute), as shown in Fig. 6(b), it is clear that Ag is formed in the central portion of the bus bar electrode 15. Therefore, as described in the effect of the invention, when Ag is mixed into the NTA glass and fired for a short period of time (even if it is longer than 1 minute and 1 to 3 seconds or more), Ag gathers in the central portion. The conductivity is improved (the conductivity is improved compared to the case where the conventional Ag is uniformly dispersed), and the NTA glass itself has a general effect of conductivity, and the NTA glass is increased even if the ratio of Ag is decreased, and the solar cell is manufactured. The conversion efficiency at that time was about 16.9% as described above, and substantially the same results were obtained in the experiment.

Further, the firing temperature is from 500 ° C to 900 ° C, but it is necessary to determine the optimum temperature for use as a solar cell depending on the experiment. If the structure is too low or too high, the structure as shown in Fig. 6(b) cannot be obtained, and it is determined by experiment.

In Fig. 7(c), the bus bar electrode 15 is a strip-shaped electrode having a wide lateral width in the central portion of the figure, and shows an example of a magnified photograph of 100% of the NTA of the present invention.

It can be clearly understood that the bus bar electrode 15 of FIG. 7(c) has a portion in which the finger electrode 14 having a narrow width in the longitudinal direction passes through the bus bar electrode 15 and slightly protrudes on the upper side, and the protruding portion is The circumference is thicker than the original finger electrode 14. Then, supersonic welding is performed on the bus bar electrode 15 as shown in the figure, which is the same as the width of the bus bar electrode 15, and has a slightly smaller width or a slightly larger width, as described in detail in FIG. 8 which will be described later. Thereby, the path 1 (the photoelectron concentration region 12, the finger electrode 14, the bus bar electrode 15, and the path 1 of the wire 17) and the path 2 (the photoelectron concentration region 12, the finger electrode 14, and the path 2 of the wire 17) can be used. The two paths electrically connect the high-concentration electron region and the wire to reduce the loss of electrons (current) and efficiently take it out to the outside, and obtain substantially the same conversion efficiency as that of FIGS. 6(a) and (b), or slightly higher. Conversion efficiency (about 17.2%).

Further, the firing temperature is approximately 500 ° C to 900 ° C which is substantially the same as in Figs. 6 (a) and (b), but it is necessary to determine the optimum temperature for use as a solar cell by experiment. If the structure is too low or too high, the structure as shown in Fig. 7(c) cannot be obtained, and it is determined by experiment.

Fig. 8 is an explanatory view (ultrasonic welding) of the present invention. This is the case where the NTA of the above-mentioned Fig. 7(c) is 100% (and the same applies to Fig. 6 (a), (b)).

Fig. 8(a) shows a state in which the finger electrodes 14 are fired.

Figure 8(b) shows a conventional example, which is on the bus bar electrode 15 of Fig. 8(a), and the wire is indicated by a broken line, which is slightly larger (may be the same or smaller). 17. In this conventional example, a As a general soldering, the portion (Ag) where the finger electrode 14 protrudes is soldered to the wire 17, but the unprojected portion of the finger electrode 14 (100% of the NTA) is not sufficiently soldered to the wire 17, mechanical The strength is not sufficient. On the other hand, in the ultrasonic welding of Fig. 8(c) to be described later, the welding is performed, and the mechanical strength is greatly improved.

Fig. 8(c) is a view showing an example of the present invention, which is supersonically welded on the bus bar electrode 15 of Fig. 8(a) (the bus bar electrode 15 of Fig. 7(c)). Large wire 17. In the example of the present invention, ultrasonic welding is performed, so that the portion (Ag) where the finger electrode 14 protrudes is soldered to the wire 17, and the portion of the fingerless electrode 14 (100% of the NTA) is also soldered to the wire 17. When joined, the mechanical strength is greatly improved, and the conductivity of the aforementioned path 2 (the high electron concentration region 12, the finger electrode 14, the bus bar electrode 15, and the path 2 of the wire 17) is improved.

Fig. 9 is a view showing the measurement example (efficiency) of the present invention. This ninth graph is a good measurement example in the case where the NTA is changed from 100% to 70% in the above-described bus bar electrode 15, and the horizontal axis of the ninth graph indicates the number of the sample, and the vertical axis indicates the efficiency (%). The sample is set to:

‧NTA 100% Ag 0%

‧NTA 90% Ag 10%

‧NTA 80% Ag 20%

‧NTA 70% Ag 30%, the solar cells were made in these, and the results (efficiency) of each measurement are shown in the figure. In addition, since it is an initial experiment, as shown in the figure, the measurement results show considerable dispersion, but both fall within the range of 16.9 to 17.5, and even in When the NTA 100% is made of the bus bar electrode 15 (that is, it is made without Ag) to produce a solar cell, it can still be obtained to the same extent or slightly compared with NTA 70% (or further 80%, 90%). High efficiency, and it is clear that NTA can also be used 100% (the inventors found this fact).

11‧‧‧矽 substrate

12‧‧‧High electron concentration region (diffusion doping)

13‧‧‧Insulating film (tantalum nitride film)

14‧‧‧Electronic take-out (finger electrode)

15‧‧‧ bus bar electrode

16‧‧‧Back electrode

17‧‧‧Wire

Claims (18)

A solar cell is a region on a substrate on which a high electron concentration is generated when irradiated light is formed, and an insulating film that transmits light is formed on the region, and the electron is taken out from an electron take-out port formed in the insulating film. In the bus electrode, in order to form the bus electrode, a conductive glass having a weight ratio of 100% is used as a glass frit and fired to form a bus bar electrode, and conductive glass is used as a conductive paste. . The solar cell according to claim 1, wherein the conductive glass is set to have a weight ratio of less than 100% to 70% or more, and the remainder is made of silver, instead of the above-mentioned conductive material having a weight ratio of 100% without silver. Glass. The solar cell according to claim 1, wherein the conductive glass is a vanadate glass containing at least vanadium, vanadium and niobium. The solar cell according to claim 2, wherein the conductive glass is a vanadate glass containing at least vanadium, vanadium and niobium. The solar cell according to the first aspect of the invention, wherein the step of mixing the conductive glass and firing is performed for a maximum of 1 minute or longer and 1 second or longer. The solar cell according to the second aspect of the invention, wherein the step of baking the conductive glass and firing is performed for a maximum of 1 minute or longer and 1 second or longer. The solar cell according to the third aspect of the invention, wherein the step of baking the conductive glass and firing is performed for a maximum of 1 minute or longer and 1 second or longer. The solar cell according to any one of claims 1 to 4, wherein the conductive glass is lead-free (Pb-Free). The solar cell according to any one of claims 1 to 7, wherein when the finger electrode (electron take-out port) is fired, the finger electrode has one end located in the high electron concentration region, and The other end forms a portion having the same height as the upper surface of the bus electrode, or a portion that protrudes and protrudes from the upper surface. The solar cell according to any one of claims 1 to 7, wherein the wire electrode is provided on the bus electrode formed by the firing. The solar cell according to any one of claims 1 to 7, wherein the wire electrode is formed by ultrasonic welding on the bus electrode formed by the firing, and is bonded to the wire electrode. The bus electrodes, the finger electrodes, and other portions increase the adhesion strength of the wire electrodes. A method of manufacturing a solar cell, wherein a region where a high electron concentration is generated when irradiated light is formed on a substrate, and an insulating film that transmits light is formed on the region, and has an electron extraction port formed from the insulating film A method for producing a solar cell according to the method of manufacturing a solar cell, wherein the method for producing a solar cell has the following steps: in order to form the bus electrode, a conductive glass having a weight ratio of 100% is used as a glass frit in the conductive paste and is fired. A bus bar electrode was formed to form a conductive paste as a conductive paste. The method for manufacturing a solar cell according to claim 12, Here, the weight ratio of the conductive glass is set to be less than 100% to 70% or more, and silver is mixed as the remainder, instead of the above-mentioned conductive glass having a weight ratio of 100% and not containing silver. The method for producing a solar cell according to claim 12, wherein the conductive glass is a vanadate glass containing at least vanadium, vanadium and niobium. The method for producing a solar cell according to claim 13, wherein the conductive glass is a vanadate glass containing at least vanadium or vanadium and niobium. The method for producing a solar cell according to claim 12, wherein the step of mixing the conductive glass and firing is performed for a maximum of 1 minute or longer and 1 second or longer. The method for producing a solar cell according to claim 13, wherein the step of mixing the conductive glass and firing is performed for a maximum of 1 minute or longer and 1 second or longer. The method for producing a solar cell according to claim 14, wherein the step of mixing the conductive glass and firing is performed for a maximum of 1 minute or longer and 1 second or longer.