JP5014503B2 - Solar cell and solar cell module - Google Patents

Description

The present invention relates to a solar battery cell and a solar battery module .

  2. Description of the Related Art Conventionally, a solar cell module is known in which a plurality of solar cells arranged between a front surface protective material and a back surface protective material are electrically connected by an interconnector. When creating this solar cell module, it can be electrically connected by bonding an interconnector made of a metal material such as copper to the light incident side electrode and the back surface electrode of the adjacent solar cell by soldering. It is common.

  In such a solar cell module, it is important to improve resistance to stress accompanying temperature change. In order to solve the problem with respect to stress, conventionally, a structure has been proposed in which the warpage of the substrate is reduced by making the structure of the front and back surfaces of the solar battery cells into the front and back object structures including the electrodes (see Patent Document 1). In addition, there has been proposed one that relaxes stress concentration by preventing the center lines in the longitudinal direction of the front and back busbar electrodes from overlapping (refer to Patent Document 2).

JP 2003-197943 A JP 2004-119687 A

  However, in the conventional solar cell module, due to the difference in the coefficient of linear expansion between the substrate and the interconnector, stress is applied at the intersection of the finger electrode and the bus bar electrode, resulting in destruction of the intersection and a decrease in output. End up. Here, in the solar cell modules described in Patent Document 1 and Patent Document 2, although stress relaxation is performed, if the temperature rise and fall occur repeatedly as in an actual use environment, the possibility of destruction of the intersection portion is possible. Cannot be denied, and there is a risk of causing a decrease in output.

An object of this invention is to provide the photovoltaic cell and photovoltaic module which can suppress the fall of a module output in view of said problem.

The solar cell according to the present invention includes a photoelectric conversion unit and a pair of positive and negative electrodes for taking out photogenerated carriers generated by the photoelectric conversion unit, and at least one of the positive and negative pair of electrodes is A plurality of finger electrodes for collecting photogenerated carriers generated by the photoelectric conversion unit, and an auxiliary electrode for electrically connecting at least two finger electrodes of the plurality of finger electrodes to each other The auxiliary electrode has a distance range within half of the distance from the connection region where the interconnector of the auxiliary electrode connecting finger electrodes electrically connected to each other by the auxiliary electrode is connected to the tip of the auxiliary electrode connecting finger electrode It is provided only in the interior, away from the connection area with the interconnector.

Moreover, the solar cell module according to the present invention is a solar cell module in which a plurality of solar cells electrically connected by an interconnector are disposed between the front surface protective material and the back surface protective material, The solar battery cell is provided.

  According to the present invention, it is possible to suppress a decrease in module output.

It is sectional drawing of the solar cell module which concerns on this embodiment. It is sectional drawing of the photovoltaic cell of the solar cell module shown in FIG. FIG. 3 is a top view of the solar battery cell shown in FIG. 2. It is a top view which shows the 1st modification of a photovoltaic cell. It is sectional drawing which shows the 2nd modification of a photovoltaic cell. It is a top view of the photovoltaic cell shown in FIG. It is sectional drawing which shows the 3rd modification of a photovoltaic cell. It is sectional drawing which shows the 4th modification of a photovoltaic cell. It is a top view which shows the 5th modification of a photovoltaic cell. It is a top view which shows the 6th modification of a photovoltaic cell. It is a top view which shows the 7th modification of a photovoltaic cell. It is a top view which shows the 8th modification of a photovoltaic cell. It is a top view of the photovoltaic cell which concerns on the comparative example after a temperature cycle test.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  FIG. 1 is a cross-sectional view of the solar cell module according to the present embodiment. The solar cell module according to the present embodiment includes a plurality of solar cells, an interconnector 40, a surface protective material 50, a back surface protective material 60, and a sealing material 70. Each solar cell includes a photoelectric conversion unit 10 that generates a photogenerated carrier by light incidence, and a pair of positive and negative electrodes for taking out the photogenerated carrier generated by the photoelectric conversion unit 10.

  The photoelectric conversion unit 10 has a semiconductor junction such as a pn or pin junction, a crystalline semiconductor material such as single crystal Si or polycrystalline Si, an amorphous Si alloy or a thin film semiconductor material such as CuInSe, or GaAs. It is made of a semiconductor material such as a compound semiconductor material such as InP. Recently, those using an organic material such as a dye-sensitized type have been studied.

  In addition, an electrode provided on the light incident side of the photoelectric conversion unit 10 of the pair of electrodes includes a plurality of narrow finger electrodes 20 and a wide bus bar electrode 30 in order to minimize the area that blocks incident light. For example, it is formed in a comb shape. The finger electrode 20 is an electrode for collecting photogenerated carriers generated by the photoelectric conversion unit 10. A linear finger electrode 20 having a width of, for example, about 100 μm is provided over almost the entire light incident surface of the photoelectric conversion unit 10. It is arranged every 2 mm. The bus bar electrode 30 is a collecting electrode for photogenerated carriers collected by the plurality of finger electrodes 20, and is formed in a line shape so as to intersect with all the finger electrodes 20 with a width of 1 mm, for example. Further, the number of bus bar electrodes 30 is appropriately set in consideration of the size and resistance of the solar battery cell.

  Further, since the other electrode is usually provided on the back side of the photoelectric conversion unit 10, it is not necessary to consider incident light. Therefore, the other electrode may be formed so as to cover substantially the entire back surface of the photoelectric conversion unit 10, or may be formed in a comb shape like the light incident side electrode. In the present invention, the shape of the electrode provided on the back side of the photoelectric conversion unit 10 is not limited. However, in FIG. 1, a solar cell including a plurality of finger electrodes 20 and bus bar electrodes 30 on the back side is taken as an example. explain.

  The plurality of solar cells are made of a transparent film such as glass or translucent plastic and a transparent film 50 and a resin film such as PET (Poly Ethylene Terephthalate) or a laminated film having a structure in which a resin film is sandwiched between Al nights. A plurality of members are disposed between the rear surface protective material 60 and the like. Moreover, between the surface protection material 50 and the back surface protection material 60, the sealing material 70 which has translucency, such as EVA, is filled, and the several photovoltaic cell is fixed with the sealing material 70. It becomes. The plurality of solar cells are electrically connected by the interconnector 40. The interconnector 40 is a wiring material for electrically connecting the photovoltaic cells, and is made of a conductive material such as copper molded into a thin plate shape or a twisted wire shape. The interconnector 40 is configured to electrically connect the bus bar electrode 30 provided on the light incident side of one of the adjacent solar cells and the bus bar electrode 30 provided on the back side of the other cell. These electrodes 30 and 30 are connected using a conductive adhesive such as solder or conductive resin. Therefore, in this embodiment, the laminated region of the bus bar electrode 30, the conductive adhesive, and the interconnector 40 that are bonded to each other is a connection region between the photoelectric conversion unit 10 and the interconnector 40.

  2 is a cross-sectional view showing an example of the solar battery cell of the solar battery module shown in FIG. 1, and FIG. 3 is a top view of the solar battery cell shown in FIG. As shown in FIG. 2, in the photoelectric conversion unit 10 of the solar battery cell, a p-type amorphous silicon layer 10b is formed on the upper surface side of an n-type single crystal silicon substrate 10d via an i-type amorphous silicon layer 10c. Has been. Further, in the solar battery cell, an ITO film 10a is formed on the p-type amorphous silicon layer 10b. On the other hand, an n-type amorphous silicon layer 10f is formed on the lower surface side of the n-type single crystal silicon substrate 10d via an i-type amorphous silicon layer 10e. Further, in the solar battery cell, an ITO film 10g is formed on the n-type amorphous silicon layer 10f. The bus bar electrode 20 and the finger electrode 30 shown in FIG. 1 are formed on the ITO films 10a and 10g. The solar cell having the structure shown in FIG. 2 is called a HIT solar cell, and substantially contributes to power generation between a pn junction formed of an n-type crystalline semiconductor and a p-type amorphous semiconductor film. The conversion efficiency is drastically improved by interposing an intrinsic amorphous semiconductor film having a thickness that does not occur.

  Further, the solar battery cell has an auxiliary electrode 80 on the ITO film 10a. As shown in FIG. 3, the auxiliary electrode 80 has a structure in direct contact with all the finger electrodes 20 of the solar battery cell. The auxiliary electrode 80 is formed approximately 2 mm away from the bus bar electrode 30 and parallel to the bus bar electrode 30. Therefore, the auxiliary electrode 80 is not in direct contact with the bus bar electrode 30 and the interconnector 40, and is separated from the connection region between the bus bar electrode 30 and the interconnector 40.

  By the way, in the conventional solar cell module, in the temperature cycle test, a part of the finger electrodes out of the plurality of finger electrodes are disconnected, which causes a problem that output characteristics are deteriorated.

  The following factors can be considered as reasons why this phenomenon occurs. In the solar cell module, the linear expansion coefficient of the interconnector is about 1.7 × 10 −5 / ° C. (Cu), and the linear expansion coefficient of the photoelectric conversion portion is about 3.6 × 10 −6 / ° C. (Si These linear expansion coefficients differ by about 5 times. For this reason, when a temperature cycle is applied, stress resulting from the difference between the linear expansion coefficients of the two is repeatedly applied to the bus bar electrode located in the middle thereof. At this time, since the interconnector has a larger linear expansion coefficient, a force that causes the bus bar electrode itself to expand and contract more than the amount that the bus bar electrode itself originally expands or contracts due to the temperature cycle is applied to the bus bar electrode. On the other hand, the finger electrode electrically connected to the bus bar electrode has a very small width of about 100 μm, and the adhesive force between the bus bar electrode and the finger electrode is not so strong from the beginning. For this reason, it is inferred that the force electrode was repeatedly applied to the connection between the bus bar electrode and the finger electrode due to the temperature cycle, and the finger electrode was disconnected from the base. Is done. And it is thought that the output fall has arisen because the finger electrode disconnects in this way.

  However, the solar cell module 1 according to the present embodiment includes the auxiliary electrode 80 that is electrically connected to all the finger electrodes 20, and the auxiliary electrode 80 is connected to the bus bar electrode 30 and the interconnector 40. It is away from. For this reason, even if stress is applied to each part of the solar cell module 1 due to the difference in the linear expansion coefficient between the photoelectric conversion unit 10 and the interconnector 40, the auxiliary electrode 80 is less likely to be stressed. As a result, even if a break occurs in a portion of the finger electrode 20 at the intersection, the auxiliary electrode 80 is unlikely to break, and current collection in a portion such as a break is realized through the auxiliary electrode 80.

  Since current collection is realized in this way, the materials of the photoelectric conversion unit 10 and the interconnector 40 can be selected from many materials without being constrained by the linear expansion coefficient. For example, even if a material having a relatively small coefficient of linear expansion, such as a silicon substrate such as single crystal silicon or polycrystalline silicon, a stainless steel substrate, or a glass substrate, is used as the substrate of the photoelectric conversion unit 10, current collection is realized through the auxiliary electrode 80. . Further, even if a material having a relatively large linear expansion coefficient such as copper, silver, aluminum, nickel, tin, gold, or an alloy thereof is used as the material of the interconnector 40, current collection is realized through the auxiliary electrode 80.

  In the above configuration, the finger electrode 20 and the bus bar electrode 30 are formed of a conductive paste. In the above configuration, since the HIT solar cell is used as the solar cell, it is desirable to form the conductive paste that is cured in a temperature range in which thermal damage to each amorphous semiconductor layer is small. As such a conductive paste, for example, a resin-type conductive paste using a resin material such as an epoxy resin as a binder and conductive particles such as silver particles as a filler can be used. The filler is intended to obtain electrical conductivity, and at least one metal particle selected from aluminum, nickel, tin, gold, or the like, or an alloy or a mixture thereof can be applied. Further, it may be one in which at least one inorganic oxide selected from alumina, silica, titanium oxide, glass and the like is subjected to metal coding, epoxy resin, acrylic resin, polyimide resin, phenol resin, urethane resin, silicone At least one selected from resins and the like, or a copolymer or mixture of these resins may be provided with a metal coating. Furthermore, the shape of the conductive particles may be a mixture of flakes and spheres, a mixture of particles having different sizes, or an uneven shape on the surface.

  Furthermore, the main purpose of the binder is to adhere, and in order to maintain reliability, the binder is required to have excellent moisture resistance and heat resistance. Examples of the resin satisfying these include an epoxy resin, an acrylic resin, a polyimide resin, a phenol resin, a urethane resin, a silicone resin, and the like, and at least one selected from these, or a mixture or copolymerization of these resins. It can also be applied.

  The ratio of the resin and the conductive particles is preferably 70% by weight or more of the resin in consideration of electric conductivity. Further, these resins 60 may be in the form of a film and can be welded by heating.

  Furthermore, when the solar cell is made of a material having higher heat resistance than an amorphous semiconductor such as a crystalline semiconductor, the conductive paste is baked and cured at a higher temperature than the resin-type conductive paste as a conductive paste. Paste material can be used. For example, a fired conductive paste made of metal powder such as silver or aluminum, glass frit, organic vehicle, or the like can be used.

  Needless to say, even with the finger electrode 20 and the bus bar electrode 30 configured as described above, current collection in a portion such as disconnection is realized through the auxiliary electrode 80.

  Further, the shape of the auxiliary electrode 80 is not limited to a linear shape as in the above configuration, but may be another house shape such as a wavy line shape. Furthermore, the auxiliary electrode 80 does not need to be parallel to the bus bar electrode 30 or the interconnector 40, and may be provided to extend obliquely. Even if it is in any shape and arrangement, the effect of the present invention can be achieved as long as it is electrically connected to all the finger electrodes 20.

  In consideration of a current path from the disconnected portion of the finger electrode 20 to the bus bar electrode 30 via the auxiliary electrode 80, it is preferable to provide the auxiliary electrode 80 as close to the bus bar electrode 30 as possible. As described above, the disconnection of the finger electrode 20 mainly occurs at the intersection with the bus bar electrode 30. Therefore, the auxiliary electrode 80 is preferably provided at a distance within half of the distance from the bus bar electrode 30 to the tip of the finger electrode 20. By doing in this way, since the distance of the electric current path from the disconnection part of the finger electrode 20 to the bus-bar electrode 30 via the auxiliary electrode 80 can be shortened, the resistance loss at the time of carrier collection can be made as small as possible.

  Further, by providing the auxiliary electrode 80 apart from the bus bar electrode 30 as described above, it is possible to effectively collect photogenerated carriers from the finger electrode 20 that is disconnected at the intersection with the bus bar electrode 30.

  The solar battery cell may have the following configuration. FIG. 4 is a top view showing a first modification of the solar battery cell. As shown in FIG. 4, a plurality of auxiliary electrodes 80 are provided. Each auxiliary electrode 80 is electrically connected to some finger electrodes 20 among all the finger electrodes 20 of the solar battery cell. All the finger electrodes 20 are electrically connected to any one of the plurality of auxiliary electrodes 80. With such a configuration, the photogenerated carriers collected by the disconnected finger electrode 20 can be collected to the bus bar electrode 30 via any of the auxiliary electrodes 80. The effect of.

  Moreover, in the modification 1 shown in FIG. 4, the sum total of the length of each auxiliary electrode 80 is shorter than the length of the auxiliary electrode 80 shown in FIG. For this reason, since the amount of incident light blocked by the auxiliary electrode 80 can be reduced, the light receiving loss of the solar battery cell can be reduced, and the photoelectric conversion rate can be improved. In particular, in Modification 1 shown in FIG. 4, the auxiliary electrode 80 has a structure in which the auxiliary electrode 80 shown in FIG. 3 is divided between the finger electrodes 20. For this reason, the auxiliary electrode 80 according to the modified example 1 does not block the light at the divided portion A, thereby reducing the light receiving loss.

  FIG. 5 is a cross-sectional view showing a second modification of the solar battery cell, and FIG. 6 is a top view of the solar battery cell shown in FIG. As shown in FIGS. 5 and 6, the auxiliary electrode 80 is provided on each side of the bus bar electrode 30. For this reason, when disconnection occurs at the intersection, current collection is more easily realized, and the output reduction of the solar cell module 1 is further suppressed.

  FIG. 7 is a cross-sectional view showing a third modification of the solar battery cell. As shown in FIG. 7, the auxiliary electrode 80 is also provided in the vicinity of both sides of the bus bar electrode 30 on the back surface. Thereby, it becomes the structure which suppresses the output fall of the solar cell module 1 further.

  FIG. 8 is a cross-sectional view showing a fourth modification of the solar battery cell. In FIG. 8, the interconnector 40 is also shown for convenience. In the example shown in FIG. 8, the solar battery cell does not include the bus bar electrode 30. In this case, the interconnector 40 is electrically connected to all the finger electrodes 20 by a conductive adhesive (not shown) such as solder or conductive resin. With this configuration, the photogenerated carriers collected by each finger electrode 20 can be collected by the interconnector 40. Further, in the fourth modified example, the adhesion region by the conductive adhesive is a connection region with the interconnector 40. An auxiliary electrode 80 is provided away from this connection region.

  FIG. 9 is a top view showing a fifth modification of the solar battery cell, and FIG. 10 is a top view showing a sixth modification of the solar battery. In the solar battery cell, the auxiliary electrode 80 is provided closer to the interconnector 40 than a position that is half the distance from the interconnector 40 (bus bar electrode 30) to the tip of the finger electrode 20 closest to the interconnector 40. . On the other hand, in the fifth and sixth modifications shown in FIGS. 9 and 10, the installation position of the auxiliary electrode 80 is different from that of the solar battery cell. That is, as shown in FIG. 9, the auxiliary electrode 80 is provided at the tip of the finger electrode 20 closest to the interconnector 40. As shown in FIG. 10, the auxiliary electrode 80 is provided at a position half the distance from the interconnector 40 (bus bar electrode 30) to the tip of the nearest finger electrode 20. Even with these, current collection can be realized in the same manner as in the solar cell.

  FIG. 11 is a top view illustrating a seventh modification of the solar battery cell, and FIG. 12 is a top view illustrating an eighth modification of the solar battery cell. As shown in FIGS. 11 and 12, the auxiliary electrode 80 may not be connected to all of the finger electrodes 20. For example, the auxiliary electrode 80 may be connected to only about 50% of the finger electrode 20 as shown in FIG. 11, or may be connected to only about 20% of the finger electrode 20 shown in FIG. Good. Also in the seventh and eighth modifications, it is possible to suppress a decrease in output due to the disconnection of the finger electrode 20 as compared with the case where the auxiliary electrode 80 is not provided at all. Of course, it is preferable to provide one or a plurality of auxiliary electrodes 80 so as to be electrically connected to all the auxiliary electrodes 80, but some of the finger electrodes 20 are formed as narrow finger electrodes 20. If one or a plurality of auxiliary electrodes 80 are provided so as to be electrically connected to each other, and the other finger electrodes 20 are widened so that disconnection hardly occurs, substantially the same effect can be obtained.

  As described above, the solar cell module of the present invention has a wiring interconnector connected to a finger electrode for collecting photogenerated carriers generated in the photoelectric conversion unit, and at least two of the finger electrodes. An auxiliary electrode for electrically connecting the above finger electrodes to each other is provided apart from the connection region with the interconnector. For this reason, since the output fall accompanying the disconnection of the finger electrode considered to arise due to the thermal cycle exposed at the time of outdoor use for a long time can be suppressed, a solar cell module with little output fall can be provided.

  In addition, according to the solar battery cell of the present invention, it is possible to provide a solar battery cell that is easy to manufacture a solar battery module with little decrease in output.

  Note that the finger electrode only needs to be provided on at least one surface of the photoelectric conversion unit. For example, the finger electrode has a finger electrode on the light incident surface of the photoelectric conversion unit, and does not have the finger electrode on the back surface and has a full surface electrode. May be. Moreover, you may have a pair of positive / negative electrode which has a finger electrode in the back surface of a photoelectric conversion part.

  Moreover, the material which comprises a photoelectric conversion part is not specifically limited, A various material can be used.

  Moreover, the auxiliary electrode should just be electrically connected to the finger electrode, and may be formed in the same surface, and may be formed after finger electrode formation. Further, a finger electrode may be formed after the auxiliary electrode is formed.

  Further, the auxiliary electrode only needs to have conductivity, and may be formed of the same material as the finger electrode or may be formed of a different material.

  Next, an example of the manufacturing method of the solar cell module 1 according to the present embodiment will be described. First, an n-type single crystal silicon substrate (103.5 mm) having a resistivity of about 1 Ω · cm from which impurities have been removed by cleaning and a thickness of about 200 μm is prepared.

  Next, an RF plasma CVD method is used to form an i-type amorphous silicon layer having a thickness of about 5 nm on the upper surface of the n-type single crystal silicon substrate, and a p-type non-crystal having a thickness of about 5 nm on the upper surface. A crystalline silicon layer is formed. The specific formation conditions of the i-type amorphous silicon layer and the p-type amorphous silicon layer by the RF plasma CVD method are a frequency of about 13.56 MHz and a formation temperature of about 100 ° C. to about 250 ° C. Yes, the reaction pressure is about 26.6 Pa to about 80.0 Pa, and the RF power is about 10 W to about 100 W.

  Next, an i-type amorphous silicon layer having a thickness of about 5 nm is formed on the lower surface of the n-type single crystal silicon substrate, and an n-type amorphous silicon layer having a thickness of about 20 nm is formed on the lower surface. The i-type amorphous silicon layer and the n-type amorphous silicon layer are formed by the same process as the above-described i-type amorphous silicon layer and p-type amorphous silicon layer.

  Next, an ITO film having a thickness of about 100 nm is formed on each of the p-type amorphous silicon layer and the n-type single crystal silicon layer by using a magnetron sputtering method. The specific formation conditions of the ITO film by the magnetron sputtering method are a formation temperature of about 50 ° C. to about 250 ° C., an Ar gas flow rate of about 200 sccm, an O 2 gas flow rate of about 50 sccm, and a power of about 0.5 kW to about 3 kW, and the magnetic field strength is about 500 Gauss to about 3000 Gauss.

  Thereafter, an epoxy thermosetting silver paste is transferred onto a predetermined region of the ITO film 10a on the light receiving surface side by screen printing, and then heated at 150 ° C. for 5 minutes to temporarily cure the silver paste. Moreover, after transferring the epoxy thermosetting silver paste onto a predetermined region on the back side, the silver paste is temporarily cured by heating at 150 ° C. for 5 minutes. Thereafter, the silver paste is completely cured by heating at 200 ° C. for 1 hour. Thereby, a photovoltaic cell is manufactured. In this step, finger electrodes 20 (for example, width: about 100 μm, height: about 40 μm, 2 mm pitch), bus bar electrodes 30 (for example, width: about 1.0 m, height: about 50 μm) and auxiliary electrodes 80 (width: about 200 μm, height 45 μm) is formed. Thus, the step of forming the finger electrode 20 (first step) and the step of forming the auxiliary electrode 80 (second step) are performed simultaneously in the same step. The front and back bus bar electrodes 30 are arranged so that the center lines in the longitudinal direction overlap. This is because such an arrangement is effective in suppressing warping after electrode formation when the wafer is thin.

  Next, when the interconnector 40 (a copper foil coated with solder having a width of 1.5 mm and a thickness of 200 μm) is heated on the front and back bus bar electrodes 30, the solder melts and an alloy layer with the bus bar electrodes 30 is obtained. Form. Thereby, a plurality of photovoltaic cells are connected by the interconnector 40. That is, the interconnector 40 is connected so as to be directly or indirectly electrically connected to the finger electrode 20 in a region where the auxiliary electrode 80 is separated.

  Then, after mounting the sealing material 70 which consists of an EVA sheet | seat of the substantially same outer dimension as the said surface protection material 50 on the surface protection material 50 which consists of a glass substrate, the several photovoltaic cell connected by the interconnector 40 is carried out. Put on. Next, the sealing material 70 which consists of an EVA sheet | seat is mounted on it, and the back surface protection material 60 of the outer dimension substantially the same as the surface protection material 50 and a filler sheet | seat is mounted. This back surface protective material 60 has a three-layer structure of PET / aluminum / PET. And after making the circumference | surroundings of these laminated bodies into a vacuum, it heat-presses for 10 minutes at the temperature of 150 degreeC, and carries out temporary pressure bonding. Thereafter, it is completely cured by heating at a temperature of 150 ° C. for 1 hour. A terminal box and a frame are attached to this. Thus, the solar cell module 1 is manufactured.

  In the case of the solar battery cell shown in FIG. 8, the bus bar electrode 30 is not formed and is directly provided on all the finger electrodes 20. At this time, the interconnector 40 is provided on the finger electrode 20 in the region where the auxiliary electrode 80 is separated as described above.

  As described above, according to the solar cell module 1 according to this embodiment, the auxiliary electrode 80 is provided apart from the connection region with the interconnector 40. For this reason, even if stress is applied to each part of the solar cell module 1 due to the difference in the linear expansion coefficient between the photoelectric conversion unit 10 and the interconnector 40 in an actual usage environment where the temperature rise and fall are repeated, the auxiliary electrode 80 is stressed. Is difficult to add. As a result, even if disconnection or the like occurs in other parts, disconnection is unlikely to occur in the auxiliary electrode 80, and current collection in the part such as disconnection is realized through the auxiliary electrode 80. Therefore, the output fall of the solar cell module 1 can be suppressed.

  In particular, in this embodiment, the finger electrode 20 is made of a resin-type conductive paste. Here, the resin-type conductive paste is easily hydrolyzed and easily exposed to the atmosphere, so that it contains water and becomes brittle. However, the auxiliary electrode 80 is provided in this embodiment. For this reason, even if the finger electrode 20 contains water and becomes brittle, current collection is realized by the auxiliary electrode 80, and thus the effect of this embodiment is more remarkably exhibited.

  In addition, the auxiliary electrode 80 is preferably provided in the vicinity of the connection region between the finger electrode 20 and the interconnector 40. As a result, when disconnection or the like occurs and current collection is performed by the auxiliary electrode 80, the auxiliary electrode 80 and the interconnector 40 are located close to each other, so the auxiliary electrode 80 is removed from the disconnected portion of the finger electrode 20. Thus, the distance of the current path to the interconnector 40 can be shortened, and the resistance loss at the time of carrier collection can be minimized. Therefore, the output reduction of the solar cell module 1 can be further suppressed.

  In addition, it is preferable that one electrode includes a bus bar electrode 30 for collecting photogenerated carriers collected by the plurality of finger electrodes 20, and the interconnector 40 is connected to the bus bar electrode 30. As a result, the auxiliary electrode 80 is separated from the region where the interconnector 40 and the bus bar electrode 30 exist, and even if the bus bar electrode 30 itself is damaged due to a difference in linear expansion coefficient, the auxiliary electrode 80 collects current. Is realized. Therefore, the output reduction of the solar cell module 1 can be further suppressed.

  Moreover, it is preferable that the interconnector 40 is directly connected to the plurality of finger electrodes 20 using a conductive adhesive. Thereby, the current collection from the finger electrode 20 is performed through the interconnector 40, and the configuration of the bus bar electrode 30 is omitted. Therefore, the configuration can be simplified.

  The auxiliary electrode 80 is preferably electrically connected to all the finger electrodes 20. Since it is such a structure, it becomes possible to collect electric current from all the finger electrodes 20 by the auxiliary electrode 80, and the output fall of the solar cell module 1 can be suppressed further.

  In addition, a plurality of auxiliary electrodes 80 that electrically connect some of the plurality of finger electrodes 20 to each other are provided, and the plurality of finger electrodes 20 are connected to one of the finger electrodes by the plurality of auxiliary electrodes 80. 20 is preferably electrically connected. Thereby, since the photogenerated carrier collected by the disconnected finger electrode 20 can be collected by any of the auxiliary electrodes 80, the output drop 1 of the solar cell module can be suppressed. In particular, when the total length of the plurality of auxiliary electrodes 80 is shorter than the length of one auxiliary electrode 80 (auxiliary electrode 80 shown in FIG. 3) electrically connected to all of the finger electrodes 20, The light receiving loss can be reduced.

  Moreover, according to the manufacturing method of the solar cell module 1 which concerns on this embodiment, since the 1st process which forms the finger electrode 20, and the 2nd process which forms the auxiliary electrode 80 are simultaneously performed by the same process, a solar cell is simply performed. Modules can be manufactured.

  Further, according to the solar cell according to the present embodiment, the plurality of finger electrodes 20 for collecting the photogenerated carriers generated in the photoelectric conversion unit 10 and the photogenerated carriers collected by the plurality of finger electrodes 20 are collected. It has a bus bar electrode 30 for conducting electricity and an auxiliary electrode 80 for electrically connecting at least some of the finger electrodes 20 among the plurality of finger electrodes 20. Thereby, even if stress is added to each part of the solar cell module 1 due to the difference in linear expansion coefficient between the photoelectric conversion unit 10 and the interconnector 40 by connecting the interconnector 40 to the bus bar electrode 30 to form a module. It is possible to make it difficult for stress to be applied to the electrode 80. Therefore, for example, even if a partial disconnection occurs between the finger electrode 20 and the bus bar electrode 30, the auxiliary electrode 80 is less likely to be disconnected, and current collection in a portion such as the disconnection is realized through the auxiliary electrode 80. Therefore, the solar cell module 1 in which the output decrease is suppressed can be manufactured.

  Moreover, according to the solar cell according to the present embodiment, the photovoltaic cell has a plurality of finger electrodes 20 for collecting photogenerated carriers generated in the photoelectric conversion unit 10, and at least a part of the plurality of finger electrodes 20. An auxiliary electrode 80 for electrically connecting the finger electrodes 20 to each other is provided apart from a connection region to which the wiring interconnector 40 is connected. In this way, by connecting the interconnector 40 away from the installation area of the auxiliary electrode 80, it is assumed that stress is applied to each part of the solar cell module 1 due to the difference in the linear expansion coefficient between the photoelectric conversion unit 10 and the interconnector 40. However, it is possible to make it difficult for stress to be applied to the auxiliary electrode 80. Thus, for example, even if a partial disconnection occurs between the interconnector 40 and the finger electrode 20, the auxiliary electrode 80 is less likely to be disconnected, and current collection at a portion such as the disconnection is realized through the auxiliary electrode 80. Therefore, the solar cell module 1 in which the output decrease is suppressed can be manufactured.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and modifications may be made without departing from the spirit of the present invention. Example) may be combined.

  Hereinafter, the solar cell module 1 according to the present embodiment will be specifically described with reference to examples, but the present invention is not limited to those shown in the following examples, and the gist thereof is not changed. In the range, it can implement by changing suitably.

  As a solar cell module according to the example, a solar cell module using the solar cell shown in FIGS. 2 and 3 (Example 1), a solar cell module using the solar cell shown in FIG. 4 (Example 2) ), The solar cell module using the solar cell shown in FIGS. 5 and 6 (Example 3), and the solar cell module using the solar cell shown in FIG. 7 (Example 4) as described above. It was produced in the same manner as the method. Moreover, the solar cell module (Example 5) using the solar cell shown in FIG. 8, the solar cell module (Example 6) using the solar cell shown in FIG. 9, and the solar shown in FIG. A solar cell module (Example 7) using battery cells was produced in the same manner as in the production method described above. Furthermore, the solar cell module (Example 8) using the solar cell shown in FIG. 11 and the solar cell module (Example 9) using the solar cell shown in FIG. It was made.

  Moreover, the solar cell module using the photovoltaic cell without the auxiliary electrode 80 was produced as a solar cell module which concerns on a comparative example. This solar cell module was produced in the same manner as the above-described manufacturing method.

Next, a temperature cycle test (JIS C8917) was performed on each of the solar cell modules according to the example and the comparative example, and an output comparison of the solar cell module before and after the test and a light emission test by an electroluminescence method were performed (note that The luminescence test was conducted only for Examples 1 to 5 and Comparative Example). In the temperature cycle test, a test of 400 cycles was performed under the condition conforming to the JIS standard. According to the JIS standard, the output change rate after 200 cycles is specified, but in order to evaluate the durability over a longer period, a 400 cycle test was conducted. Moreover, the output of the solar cell module was measured under light irradiation of AM 1.5 and 100 mW / cm ² .

  The electroluminescence method is based on Charactarization of Polycrystalline Silicon Solar Cells by Electroluminescence (PVSEC-15, Shanghai, China: Oct. 2005.). External luminescence was observed. According to this method, light emission is weakened in a region where the electrode resistance is large and difficult to flow, or in a region where the minority carrier diffusion length is short, so that it is observed as a dark portion.

  About Examples 1-4 and a comparative example, Table 1 shows the normalized output reduction rate by a temperature cycle test.

  The output reduction rate was calculated from the equation (1−post-test output / pre-test output) × 100 (%), and the output reduction rate in the comparative example was normalized to 1.00. As shown in Table 1, it can be seen that the normalized output decrease rate in Examples 1 to 4 is smaller than that in the comparative example.

  In addition, as a result of observing light emission by the electroluminescence method, no abnormality was particularly observed in the sample before the temperature cycle test, but in the sample after the temperature cycle test, a dark portion as shown in FIG. It was. On the other hand, in Examples 1-4, such a dark part did not appear even after the temperature cycle test. In Table 1, a sample in which no dark part appeared was indicated by a circle, and a sample in which a dark part appeared was indicated by an x mark. Thus, it became clear that the output reduction of the solar cell module 1 can be suppressed by the auxiliary electrode 80.

  Next, with respect to Example 5 and the comparative example, Table 1 shows the normalized output decrease rate by the temperature cycle test.

  As shown in Table 2, it can be seen that the normalized output reduction rate in Example 5 is smaller than that in the comparative example. Furthermore, as a result of observing light emission by the electroluminescence method, in Example 5, no dark portion appeared even after the temperature cycle test. Thus, it has been clarified that the output reduction of the solar cell module 1 can be suppressed by the auxiliary electrode 80 even in the structure without the bus bar electrode 30.

  Next, with respect to Example 1, Example 6, Example 7, and Comparative Example, Table 3 shows the normalized output decrease rate by the temperature cycle test.

  As shown in Table 3, it can be seen that the normalized output reduction rate in Example 6 and Example 7 is smaller than that in the comparative example. Thus, it became clear that the output reduction of the solar cell module 1 can be suppressed by the presence of the auxiliary electrode 80 regardless of the position where the auxiliary electrode 80 is installed. As shown in Table 3, the normalized output decrease rate of Example 1 is the smallest, and then the normalized output decrease rate of Example 7 is the smallest. This is because, when a disconnection or a contact failure occurs at the intersection of the bus bar electrode 30 and the finger electrode 20, the resistance value is more compensated for the disconnection in a region farther away than in the region closer to the bus bar electrode 30. This is because the current collection loss is small.

  Next, with respect to Example 1, Example 8, Example 9, and Comparative Example, Table 4 shows the normalized output reduction rate by the temperature cycle test.

  As shown in Table 4, it can be seen that the normalized output reduction rate in Example 8 and Example 9 is smaller than that in the comparative example. Thus, it has been clarified that as long as the auxiliary electrode 80 is provided, the output decrease of the solar cell module 1 can be suppressed by the auxiliary electrode 80 without covering all of the finger electrodes 20. As shown in Table 4, the normalized output reduction rate of Example 1 is the smallest, and then the normalized output reduction rate of Example 8 is the smallest. This is because if the auxiliary electrode 80 is in contact with many finger electrodes 20, the disconnection can be compensated so much.

  As described above, in any of the examples, the normalized output decrease rate was smaller than that of the comparative example. That is, according to the solar cell module 1 which concerns on an Example, it became clear that the output fall was suppressed.

DESCRIPTION OF SYMBOLS 1 ... Solar cell module 10 ... Solar cell 20 ... Finger electrode 30 ... Bus-bar electrode 40 ... Interconnector 50 ... Surface protective material 60 ... Back surface protective material 70 ... Sealing material 80 ... Auxiliary electrode

Claims (8)

A photoelectric conversion unit;
A pair of positive and negative electrodes for taking out photogenerated carriers generated in the photoelectric conversion unit;
With
At least one of the pair of positive and negative electrodes is:
A plurality of finger electrodes for collecting photogenerated carriers generated by the photoelectric conversion unit;
A bus bar electrode for electrically connecting all of the plurality of finger electrodes;
An auxiliary electrode for electrically connecting at least two finger electrodes among the plurality of finger electrodes;
Consist only of
The auxiliary electrode has a distance from the bus bar electrode of the auxiliary electrode connecting finger electrode electrically connected to the auxiliary electrode to the tip of the auxiliary electrode connecting finger electrode in the direction of the tip of the auxiliary electrode connecting finger electrode. only within a distance of half and is disposed away from the bus bar electrode, the solar cell. The solar cell according to claim 1, wherein the auxiliary electrode is provided in parallel with the bus bar electrode. The solar cell according to claim 1, wherein the auxiliary electrode is formed of the same material as the finger electrode. The solar cell according to any one of claims 1 to 3, wherein the auxiliary electrode electrically connects all of the plurality of finger electrodes. The solar cell according to any one of claims 1 to 4, wherein the auxiliary electrode electrically connects at least some finger electrodes of the plurality of finger electrodes. The photovoltaic cell according to claim 5, wherein the auxiliary electrode electrically connects 50% or less of the finger electrodes of the plurality of finger electrodes. The solar cell according to claim 5, wherein the auxiliary electrode electrically connects finger electrodes of 20% or less of the plurality of finger electrodes. A solar cell module in which a plurality of solar cells electrically connected by an interconnector are disposed between the surface protective material and the back surface protective material,
  The solar cell module is a solar cell module according to any one of claims 1 to 7.

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