Solar cell unit, method for preparing the same, and solar cell module containing the same

Abstract

The present invention relates to a solar cell unit, a method for preparing the same, and a solar cell module containing the same, wherein the solar cell unit comprises a cell sheet and a first layer located on one side of the cell sheet, wherein the first layer comprises a first adhesive film layer and a substrate located on one side of the first adhesive film layer. The cell sheet in the solar cell unit according to the present invention can have fewer hidden cracks after being packaged into a solar cell module compared to conventional cell sheets.

Description

Technical Field

[0001] The present invention relates to a solar cell unit, which comprises a cell and a first layer located on one side of the cell, wherein the first layer comprises a first adhesive film layer and a substrate located on one side of the first adhesive film layer. The solar cell unit according to the present invention can prevent the cell from cracking, thereby reducing the probability of the cell inside the solar cell module from cracking, thereby slowing down the decline of the power generation efficiency of the solar cell module and extending its power generation life. Background Art

[0002] Solar cells convert sunlight into electrical energy through the photovoltaic effect, and mainly include PN junctions.

[0003] Common solar cell materials include but are not limited to crystalline silicon and amorphous silicon, CdTe, CdAs, CuInSe, CuInGaSe, dye sensitization and polymer thin films, among which solar cells based on crystalline silicon (including monocrystalline silicon and polycrystalline silicon) are the most mature.

[0004] The production process of cells in crystalline silicon solar cells mainly includes silicon material purification, crystal pulling or ingot casting, slicing, cleaning and roughening, diffusion to form PN junction, secondary cleaning, preparation of anti-reflection film, printing electrodes and sintering.

[0005] Due to cost considerations, there is a trend to slice the monocrystalline silicon rod or polycrystalline silicon ingot thinner and thinner in the above slicing step. In addition, in the process of making silicon chips into battery cells, the silicon chips need to be subjected to high temperature, etching, coating and other treatments, so thermal stress or mechanical stress is easily residual inside. The thinning of the battery cell and the residual internal stress make it easy to produce subtle cracks that are not easy to observe with the naked eye in the subsequent process, that is, hidden cracks. In addition to the above factors, the crystal defects of the silicon chip itself are also one of the main factors leading to hidden cracks.

[0006] In addition, a single solar cell cannot be used directly as a power source due to its low operating voltage; therefore, multiple solar cells need to be connected and packaged in series or parallel to obtain a solar cell module that can be used as an independent power source.

[0007] The process of preparing solar cell modules mainly includes laying a light-transmitting front cover, laying a first layer of light-transmitting packaging film, connecting several single solar cells in series, welding into series, positioning the series and welding the series, laying a second layer of packaging film, laying a back plate, laminating, trimming, sealing and framing, and installing a junction box. The stringing machine, laminating machine and framing machine used in the above steps directly apply force to the solar cells; therefore, if the processing parameters are improperly set (for example, but not limited to, the welding temperature is too high, the hardness of the welding strip is too high, and the mechanical force of the stringing machine probe pressing down is too large), the cell will be more difficult to resist the external stress due to the thinning of the thickness and the residual stress inside, resulting in hidden cracks.

[0008] Specifically, for example but not limited to, heating and welding a local position of the battery cell in the string welding step causes a temperature difference and expansion degree between the position and the surrounding area. The differences pull each other in the same plane to cause in-plane stress. The thinned battery cell has poor ability to withstand in-plane stress and is prone to hidden cracks due to the temperature difference caused by welding. The hidden cracks mainly occur near the busbar, especially the head and tail, because the position has a stress concentration effect. In addition, if the welding temperature is too high or the time is too long, it will cause over-welding, causing hidden cracks under the busbar and its surrounding area and disconnecting the fine fingers on the front of the battery cell.

[0009] The impact of hidden cracks can be large or small, and the key lies in the shape of the cracks. According to the shape of the hidden cracks in the cell, they can be divided into tree-like cracks, comprehensive cracks, oblique cracks, cracks parallel to the main grid lines, cracks perpendicular to the grid lines, and cracks that run through the entire cell. Among them, cracks parallel to the main grid lines are most likely to affect the fine grid lines. If the fine grid lines are broken, the collected current cannot be transmitted to the main grid lines, resulting in partial or even complete failure of the cell, greatly reducing the efficiency of the cell.

[0010] Therefore, the technical field is expected to have a solar cell unit that can prevent hidden cracks in the cell and a thin, lightweight and frameless solar module, thereby increasing the applicability of the solar module. The technical field is also expected to have a solar module that can reduce in-plane stress, such as but not limited to reducing the use of welding. Summary of the invention

[0011] The purpose of the present invention is to provide a solar cell unit that can prevent hidden cracks in the solar cell. The solar cell is additionally combined with an anti-hidden crack film layer to enhance the resistance of the cell to mechanical stress and thermal stress, thereby reducing the probability of hidden cracks in the cell inside the solar cell module, thereby slowing down the decline in the power generation efficiency of the solar cell module and extending its power generation life.

[0012] Another object of the present invention is to provide a method for manufacturing the above-mentioned solar cell unit.

[0013] Another object of the present invention is to provide a solar cell module including the above-mentioned solar cell unit, wherein the connection between the welding ribbon and the electrode wire is partially or completely replaced by a non-welding method, such as but not limited to heating bonding or adhesive bonding.

[0014] Additional aspects and advantages of the embodiments of the present invention will be described, shown, or explained in part in the following description or through implementation of the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following will briefly describe the drawings necessary for describing the embodiments of the present application or the prior art. The drawings are only some of the embodiments in the present application. For those with ordinary knowledge in the technical field to which the present invention belongs, other embodiments can still be obtained based on the structures illustrated in these drawings without excessive experiments.

[0016] Figure 1 : The solar cell unit according to the present invention comprises a first anti-hidden crack adhesive film layer and an anti-hidden crack substrate.

[0017] Figure 2 :like Figure 1 A solar cell unit, wherein the first adhesive film layer covers the welding ribbon.

[0018] Figure 3 :like Figure 1 The solar cell unit further comprises a second adhesive film layer.

[0019] Figure 4 :like Figure 3 A solar cell unit, wherein the adhesive film layer covers the soldering ribbon.

[0020] Figure 5 :like Figure 3 A solar cell unit, wherein the second adhesive film layer is covered with an optical film.

[0021] Figure 6 : In the prior art, the solder strip and the battery cell are directly joined by welding.

[0022] Figure 7 : According to a specific aspect of the method for preparing a battery cell of the present invention, the welding strip is first aligned with the electrode line on the battery cell, and then the anti-hidden crack film layer is joined to the battery cell, wherein the aligned welding strip and the electrode line are joined due to the joining of the anti-hidden crack film layer to the battery cell.

[0023] Figure 8: According to another specific aspect of the method for preparing a battery unit of the present invention, the welding strip is first aligned with the anti-hidden crack film layer according to the size and spacing of the electrode lines on the battery cell, and then the battery cell is joined to the anti-hidden crack film layer, wherein the welding strip and the electrode lines are joined due to the joining of the anti-hidden crack film layer to the battery cell.

[0024] Fig. 9 : According to another specific aspect of the method for preparing a battery cell of the present invention, the anti-hidden crack film layer is first joined to the battery cell, wherein the anti-hidden crack film layer has a plurality of openings, and the positions of the plurality of openings are configured to coincide with the positions of the electrode lines on the battery cell so as to join the welding strip to the electrode lines from the openings.

[0025] Fig.10 : A cell string comprising solar cells of the prior art.

[0026] Fig.11 :Include Fig.10 Solar cell module with strings of cells.

[0027] Fig.12 :Contains the present invention Figure 2 A string of solar cells.

[0028] Fig.13 :Contains the present invention Figure 4 A string of solar cells.

[0029] Fig.14 :Include Fig.12 Solar cell modules with strings of solar cells.

[0030] Fig.15 :Include Fig.13 Solar cell modules with strings of solar cells.

[0031] Fig.16 : EL images of a solar cell before and after an impact test according to the prior art, wherein the left image is the EL image before the impact test and the right image is the EL image after the impact test.

[0032] Fig.17 : EL images of the solar cell unit according to the present invention before and after the impact test, wherein the left image is the EL image before the impact test and the right image is the EL image after the impact test.

[0033] Fig.18 : EL images of another solar cell unit according to the present invention before and after the impact test, wherein the left image is the EL image before the impact test and the right image is the EL image after the impact test. DETAILED DESCRIPTION

[0034] To facilitate understanding of the disclosure set forth herein, several terms are defined below.

[0035] As used herein, the term "about" means an acceptable error for a particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined.

[0036] In the present invention, the term "cell" refers to a solar cell that converts sunlight into electrical energy through the photovoltaic effect, such as but not limited to a crystalline silicon solar cell.

[0037] In the present invention, the term "solar cell unit" is equivalent to the combination of a solar cell and an anti-crack film layer, and can be regarded as a solar cell in the packaging process of a solar cell module.

[0038] Solar cell

[0039] Compared with the prior art, the solar cell unit according to the present invention, such as Figure 1 As shown, in addition to the battery cell (1), it further includes a first anti-hidden crack film layer (hereinafter referred to as: the first layer (6)), wherein the first anti-hidden crack film layer includes a first anti-hidden crack adhesive film layer (hereinafter referred to as: the first adhesive film layer (7)) and an anti-hidden crack substrate (hereinafter referred to as: substrate (8)), wherein the first layer is preferably located on the back side of the battery cell.

[0040] The solar cell unit according to the present invention has stronger mechanical stress resistance than the cell of the prior art. Therefore, after being packaged into a module, the mechanical load capacity of the module will also be higher, which can reduce the probability of hidden cracks in the cell.

[0041] Battery Cell(1)

[0042] The cell material used in the solar cell unit according to the present invention is not particularly limited, and can be easily selected by those with ordinary knowledge in the art to which the present invention belongs, such as but not limited to crystalline silicon solar cells and amorphous silicon, CdTe, CdAs, CuInSe, CuInGaSe, dye-sensitized and polymer thin film cells, etc. The solar cell unit according to the present invention is particularly suitable for crystalline silicon solar cells, which can be single crystal silicon or polycrystalline silicon solar cells.

[0043] The thickness of the cell used in the solar cell unit according to the present invention is not particularly limited. The solar cell unit according to the present invention is particularly suitable for cells with a thickness not exceeding about 180 microns, more preferably not exceeding about 150 microns, and even more preferably not exceeding about 120 microns.

[0044] First adhesive film layer (7)

[0045] The material of the first adhesive film layer used in the solar cell unit according to the present invention is not particularly limited, and can be easily selected by those with ordinary knowledge in the art to which the present invention belongs, such as but not limited to EVA (ethylene vinyl acetate copolymer resin), POE (polyolefin elastomer resin), PVB (polyvinyl butyral resin), organic silicone resin, epoxy resin glue, acrylic glue, etc. The material of the first adhesive film layer used in the present invention can be the same as or different from the packaging material used in the subsequent solar cell module.

[0046] The first adhesive film layer according to the present invention may have or be free of openings; if it has openings, the positions of the openings are preferably arranged to coincide with the positions of the electrode lines on the battery cell.

[0047] According to a specific implementation of the present invention, the first adhesive film layer may have more than two openings per square centimeter (for example but not limited to a honeycomb structure).

[0048] The thickness of the first adhesive film layer used in the solar cell unit according to the present invention is not particularly limited, and is preferably about 50 to 1000 microns, more preferably about 150 to 500 microns, and particularly preferably about 250 to 400 microns.

[0049] Substrate(8)

[0050] The solar cell unit according to the present invention comprises a substrate, so that there is at least one layer of material different from the first film layer and the encapsulation film laid in the subsequent encapsulation process of the solar cell module.

[0051] The substrate material used in the solar cell unit according to the present invention is different from the material of the first adhesive film layer, but can be easily selected by those with ordinary knowledge in the art to which the present invention belongs, such as but not limited to metal (such as but not limited to gold, silver, copper, iron, tin, stainless steel or alloys of aluminum, magnesium or titanium, etc.), ceramic (such as but not limited to aluminum oxide, aluminum nitride, boron nitride or zirconium oxide, etc.), organic plastic (such as but not limited to PET, PC, PE, PVC or PP, etc.), glass fiber reinforced thermosetting plastic, carbon fiber reinforced thermosetting plastic, glass fiber cloth, glass or other composite materials, etc. The substrate material used in the solar cell unit according to the present invention is preferably a material with excellent thermal conductivity and / or airtightness, such as but not limited to metal or ceramic.

[0052] The thickness of the substrate used in the solar cell unit according to the present invention is not particularly limited, and is preferably about 10 to 1000 microns, more preferably about 20 to 100 microns, and even more preferably about 30 to 50 microns.

[0053] The substrate according to the present invention may have or be free of openings; if it has openings, the positions of the openings are preferably arranged to coincide with the positions of the electrode lines on the battery cell.

[0054] According to a specific embodiment of the present invention, the substrate may have more than two openings per square centimeter (for example but not limited to a honeycomb structure).

[0055] In a specific embodiment of the present invention, the substrate used in the solar cell unit according to the present invention has a rough design with uneven concave-convex microstructure on the surface in contact with the first adhesive film layer, and the rough design can improve the bonding between the substrate and the first adhesive film layer.

[0056] In a specific embodiment of the present invention, Figure 2 As shown, the first adhesive film layer covers the welding strip (for example but not limited to 9).

[0057] In a specific implementation of the present invention, the first adhesive film layer covers the soldering tape and the soldering tape is in contact with the aforementioned substrate.

[0058] The material of the solder strip coated by the first adhesive film layer in the solar cell unit according to the present invention is not particularly limited and can be easily selected by those with ordinary knowledge in the art to which the present invention belongs, such as but not limited to copper, tin, silver, lead, bismuth or a combination thereof.

[0059] The welding strip material covered by the first adhesive film layer in the solar cell unit according to the present invention can be used, for example but not limited to, to connect busbars and busbars or to connect solar cells and solar cells.

[0060] In a specific embodiment of the present invention, Figure 3 As shown, the solar cell unit further comprises a second adhesive film layer (10), and the second adhesive film layer is preferably located on the front side of the solar cell.

[0061] The second adhesive film material used in the solar cell unit according to the present invention is not particularly limited, and can be easily selected by those with ordinary knowledge in the art to which the present invention belongs, such as but not limited to EVA (ethylene vinyl acetate copolymer resin), POE (polyolefin elastomer resin), PVB (polyvinyl butyral resin), organic silicone resin, epoxy resin glue, acrylic glue, etc. The second adhesive film material used in the solar cell unit according to the present invention preferably has a high light transmittance property, which can increase the amount of sunlight incident on the battery cell, thereby helping to increase the power generation efficiency of the solar cell module. The second adhesive film material used in the present invention can be the same as or different from the packaging material used in the subsequent solar cell module, and can also be the same as or different from the first adhesive material.

[0062] The thickness of the second adhesive film layer used in the solar cell unit according to the present invention is not particularly limited, preferably about 50 to 1000 microns, more preferably about 150 to 750 microns, and particularly preferably about 250 to 650 microns. The thickness of the second adhesive film layer material used in the present invention can be the same as or different from the thickness of the first adhesive layer.

[0063] The second adhesive film layer according to the present invention may have or be free of openings; if it has openings, the positions of the openings are preferably arranged to coincide with the positions of the electrode lines on the battery cell.

[0064] According to a specific implementation of the present invention, the second adhesive film layer may have more than two openings per square centimeter (for example but not limited to a honeycomb structure).

[0065] In a specific embodiment of the present invention, Figure 4 As shown, the second adhesive film layer covers the welding strip (for example but not limited to 9).

[0066] The material of the solder strip coated by the second adhesive film layer in the solar cell unit according to the present invention is not particularly limited and can be easily selected by those with common knowledge in the art to which the present invention belongs, such as but not limited to copper, tin, silver, lead, bismuth or a combination thereof.

[0067] The welding strip material covered by the second adhesive film layer in the solar cell unit according to the present invention can be used, for example but not limited to, to connect busbars and busbars or to connect solar cells and solar cells.

[0068] In a specific embodiment of the present invention, Figure 5 As shown, the second adhesive film layer is covered with an optical film (11).

[0069] There is no special limitation on the optical film material used in the solar cell unit according to the present invention, such as but not limited to coating a multi-layer oxide film structure on a PET film to increase the sunlight incident on the solar cell unit, or making a concave-convex structure on the surface of the PET film to increase the sunlight incident on the solar cell unit. The optical film can preferably form a focusing structure with the front cover plate of the subsequent process, such as but not limited to a Fresnel lens structure.

[0070] Method for preparing solar cell unit

[0071] The preparation method of the solar cell unit according to the present invention requires additional steps because the solar cell unit according to the present invention further includes an anti-hidden crack film layer, and thus requires additional steps, mainly to join the anti-hidden crack film layer to the battery cell, wherein if a welding strip exists, the welding strip in the solar cell unit is precisely aligned with the electrode line on the battery cell, and the joining of the welding strip and the electrode line can be completed through the joining of the anti-hidden crack film layer and the battery cell, and a local secondary joining can also be performed depending on the situation to improve the joining between the welding strip and the electrode line.

[0072] The conventional method of directly welding the welding ribbon to the battery cell (see Figure 6 ) method, according to the method for preparing a solar cell unit of the present invention, the welding strip and the electrode wire can be joined without welding to reduce the stress remaining on the battery cell, thereby reducing the probability of hidden cracks in the battery cell during or after packaging.

[0073] The method for preparing a solar cell unit according to the present invention comprises the following steps:

[0074] Bonding the first adhesive film layer to the substrate to form a first anti-crack thin film layer (hereinafter referred to as the first layer); and

[0075] At least one selected from the group consisting of:

[0076] First, align the soldering tape with the electrode line on the battery cell, and then bond the first layer obtained in step (A) to the battery cell, wherein the aligned soldering tape and the electrode line are bonded due to the bonding of the first layer to the battery cell, and the bonding is locally strengthened as appropriate to improve the bonding between the soldering tape and the electrode line, and wherein the first adhesive film layer and the substrate may be respectively perforated or not perforated, preferably not perforated (see Figure 7 );

[0077] First, the welding strip is placed on the first layer obtained in step (A) according to the size and spacing of the electrode lines on the battery cell, and then the first layer is bonded to the battery cell, wherein the welding strip and the electrode lines are bonded due to the bonding of the first layer and the battery cell, and the bonding is locally strengthened as appropriate to improve the bonding between the welding strip and the electrode lines, wherein the first adhesive film layer and the substrate may be respectively perforated or not perforated, preferably not perforated (see Figure 8 );and

[0078] First, the first layer obtained in step (A) is bonded to the battery cell, wherein the first adhesive film layer and / or the substrate has a plurality of openings and the positions of the plurality of openings are arranged to coincide with the positions of the electrode lines on the battery cell so that the welding strips are bonded to the electrode lines from the openings (see Fig. 9 );

[0079] Wherein in step (A), the first adhesive film layer and the substrate are bonded to each other by, for example but not limited to, coating (for example but not limited to screen coating, spin coating, slot coating, dip coating, extrusion coating) or heating bonding (for example but not limited to roll-to-roll infrared heating, roll-to-roll hot air heating);

[0080] In step (B), the battery cell and the first layer may be bonded by, for example but not limited to, heat bonding, wherein the heat bonding temperature is preferably 60 to 250° C., more preferably 100 to 150° C., or bonding via an adhesive, and optionally, by, for example but not limited to, a heater for local secondary bonding to improve the bonding between the solder strip and the electrode wire; and

[0081] The soldering strip may be joined to the electrode wire on the battery cell by, for example but not limited to, heating bonding and / or adhesive bonding and / or welding. Preferably, the soldering strip is precisely joined to the electrode wire on the battery cell only by heating bonding and / or adhesive bonding. More preferably, the soldering strip is precisely joined to the electrode wire on the battery cell only by heating bonding. The heating temperature is preferably between 60 and 250°C, more preferably between 100 and 150°C.

[0082] According to a specific embodiment of the present invention, the battery cell and the first layer are joined by heating, wherein when the battery cell and the first layer are heated and pressed down, the metal particles in the first layer can be crushed, so that the electrode wire on the battery cell and the welding strip are tightly joined together, wherein the heating temperature is preferably 60 to 250° C., more preferably 100 to 150° C. The solar cell unit according to the present invention is prepared by the above method, which can reduce the stress generated when the welding strip and the electrode wire on the battery cell are joined, such as but not limited to thermal stress and in-plane stress.

[0083] According to a specific embodiment of the present invention, the method further comprises bonding the second adhesive film layer to the other side of the battery cell, for example but not limited to bonding by heating, wherein the bonding temperature is preferably 60 to 250°C, more preferably 100 to 150°C.

[0084] According to a specific implementation of the present invention, the second adhesive film layer covers the welding strip.

[0085] Solar cell modules

[0086] The solar cell module according to the present invention can be manufactured into a solar cell unit by processing a single cell sheet into a solar cell unit by the above-mentioned method for manufacturing a solar cell unit, and then manufactured into a solar cell module by a conventional solar cell module packaging process. In a conventional solar cell module, the cell sheets and the welding ribbons are connected in series to form a cell sheet string (e.g. Fig.10 The cells are then welded in series and packaged to form a conventional solar cell module (such as Fig.11 shown).

[0087] The solar cell module according to the present invention comprises a plurality of solar cell strings, wherein the plurality of solar cell strings are as follows: Fig.12 or Fig.13 As shown, it includes the solar cell unit according to the present invention.

[0088] According to a specific embodiment of the present invention, the solar cell module further comprises a front cover plate (12), a first packaging film (14), a second packaging film (14) and a back plate (13).

[0089] According to a specific embodiment of the present invention, the solar cell module comprises a front cover plate (12), a first packaging film (14), Fig.12 The solar cell string, the second packaging film (14) and the back panel (13) shown, and the front cover (12) and the first packaging film (14) preferably further include an optical film, and the optical film preferably forms a focusing structure with the front cover, such as but not limited to a Fresnel lens structure.

[0090] Front cover(12)

[0091] The front cover material used in the solar cell module according to the present invention is not particularly limited, and can be easily selected by those with ordinary knowledge in the art to which the present invention belongs, such as but not limited to high-light-transmittance polymer plastic or high-light-transmittance tempered glass, preferably high-light-transmittance polymer plastic. Since the solar cell unit of the present invention has a stronger ability to resist mechanical stress, the demand for the strength of the front cover can be reduced, thereby reducing the thickness of the front cover. Thin plastic film materials, such as but not limited to ETFE film materials, PVDF film materials, PTFE film materials, organic silicone film materials, PET film materials or composite film materials formed by bonding the above film materials together, can also be used as a protective film for the front cover, so as to achieve the purpose of thinning, lightening and frameless solar cell modules.

[0092] Back Panel(13)

[0093] The back sheet material used in the solar cell module according to the present invention is not particularly limited and can be easily selected by a person having ordinary knowledge in the art to which the present invention belongs, such as but not limited to polymer plastics.

[0094] First and second packaging films (14)

[0095] The packaging film material used for the solar cell module according to the present invention is not particularly limited and can be easily selected by those with general knowledge in the art to which the present invention belongs, such as but not limited to EVA (ethylene vinyl acetate copolymer resin), POE (polyolefin elastomer resin), PVB (polyvinyl butyral resin), organic silicone resin, epoxy resin glue, acrylic glue, etc.

[0096] Compared with conventional solar cell modules, the solder strip is only covered with a packaging film ( Fig.11 ), the solder strip of the solar cell module according to the present invention is as follows Fig.14 or Fig.15 As shown, an additional first adhesive film layer is used for covering and at least one layer different from the packaging adhesive film material exists between the back plate and the battery cell as a substrate.

[0097] Examples

[0098] Hidden cracks are not easy to observe with the naked eye. Therefore, electroluminescence (EL) is often used in the technical field to detect internal defects of solar cells or modules. EL uses the electroluminescence principle of crystalline silicon to obtain near-infrared images by photographing the components with a high-resolution infrared camera. Hidden cracks can be detected simply and effectively from the images. The black, non-luminous area in the EL image is called the "necrotic area." The necrotic area cannot generate electricity, so the current produced by the cell with the necrotic area will be relatively small, resulting in a reduction in the power generation of the entire module. When the necrotic area of ​​the cell is too large, not only will the power of the cell decrease, but the loss will be further magnified after the cells are connected in series. The necrotic area will not only reduce power generation, but if the area is too large, it will also cause overheating and burn the module.

[0099] Test experiment: Drop ball impact test

[0100] The steel ball used in the experiment has a weight of 227 grams and a diameter of 3.8 centimeters.

[0101] Drop ball impact test height: 50 cm.

[0102] Sample 1 (comparative example): transparent plastic front cover (300 microns) / POE film (500 microns) / crystalline silicon solar cell (150 microns) / POE film (500 microns) / plastic photovoltaic back panel (350 microns).

[0103] Sample 2 (invention example): transparent plastic front cover (300 microns) / POE film (500 microns) / battery unit A (480 microns) / POE film (500 microns) / plastic photovoltaic backplane (350 microns), wherein the structure of battery unit A is crystalline silicon solar cell (150 microns) / first adhesive film layer-POE (300 microns) / stainless steel film substrate (30 microns).

[0104] Sample three (invention example): transparent plastic front cover (300 microns) / POE film (500 microns) / battery unit B (500 microns) / POE film (500 microns) / plastic photovoltaic backplane (350 microns), wherein the structure of battery unit B is crystalline silicon solar cell (150 microns) / first adhesive film layer-POE (300 microns) / stainless steel film substrate (50 microns).

[0105] The test results are summarized in the table below:

[0106]

[0107] Sample 1 (comparative example) has a weak ability to withstand the impact of falling ball gravity, causing the crystalline silicon cell to form a relatively large area of ​​hidden cracks due to external stress, among which the black necrotic area accounts for a large area.

[0108] Sample 2 and Sample 3 (invention examples) are battery cells according to the present invention (i.e., combining the battery cell with the first adhesive film layer and the substrate (30 micron / 50 micron stainless steel sheet material)). Through the falling ball gravity impact test, it can be found that the crystalline silicon battery cell in the battery cell according to the present invention forms a relatively small area of ​​hidden crack area after being subjected to external stress, and the proportion of the black necrotic area is also small.

[0109] From the above results, it can be seen that the battery unit according to the present invention can withstand stronger external stress than a single crystalline silicon cell, and reduce the probability of hidden cracks in the crystalline silicon cell and reduce the area of ​​the black necrotic area. The solar cell module using the battery unit of the present invention can reduce the probability of hidden cracks due to external stress, thereby reducing power attenuation and increasing service life.

[0110] From the above results, it can be seen that the battery unit according to the present invention improves the stress resistance of a single battery cell through the first adhesive film layer and the substrate, and the thickness of the substrate also has the ability to resist stress. The thicker the thickness, the more obvious the improvement effect.

[0111] Instruction drawing components

[0112] 1: Battery Cell

[0113] 2: Front of the battery cell

[0114] 3: Back of the battery cell

[0115] 4: Upper electrode line

[0116] 5: Lower electrode line

[0117] 6: The first layer (the first anti-hidden crack film layer)

[0118] 7: The first adhesive film layer (the first anti-hidden crack adhesive film layer)

[0119] 8: Substrate (anti-hidden crack substrate)

[0120] 9: Soldering strip

[0121] 10: Second adhesive film layer (second anti-hidden crack adhesive film layer)

[0122] 11: Optical film

[0123] 12:Front cover

[0124] 13: Back panel

[0125] 14: Encapsulation film

[0126] 15: Opening position

Claims

1. A solar cell string, comprising a plurality of solar cell units, wherein at least one of the plurality of solar cell units comprises a cell and a first layer located on one side of the cell, wherein the first layer comprises a first adhesive film layer and a substrate located on one side of the first adhesive film layer, and wherein the first layer substantially covers no more than one cell.

2. The solar cell string according to claim 1, wherein the first adhesive film layer covers the welding strip.

3. The solar cell string according to claim 2, wherein the soldering ribbon contacts the substrate. 4 . The solar cell string according to claim 1 , wherein the material of the substrate is different from the material of the first adhesive film layer. 5 . The solar cell string according to claim 1 , wherein the surface of the substrate in contact with the first adhesive film layer has a concave-convex microstructure. 6 . The solar cell string according to claim 1 , further comprising a second adhesive film layer located on the other side of the solar cell.

7. The solar cell string according to claim 6, wherein the second adhesive film layer covers the welding strip.

8. The solar cell string according to claim 6, wherein one side of the second adhesive film layer is covered with an optical film.

9. The solar cell string according to claim 8, wherein the optical film is a light-concentrating film.

10. A method for preparing a solar cell string according to any one of claims 1 to 9, wherein at least one of the plurality of solar cell units is prepared by the following steps: bonding the first adhesive film layer and the substrate to form a first layer; and At least one selected from the group consisting of: Firstly align the welding strip with the electrode line on the battery cell, and then bond the first layer with the battery cell, wherein the aligned welding strip and the electrode line are bonded due to the bonding of the first layer with the battery cell, and the bonding is locally strengthened as appropriate to improve the bonding between the welding strip and the electrode line, and wherein the first adhesive film layer and the substrate may be respectively perforated or not perforated; Firstly, the welding strip is placed on the first layer according to the size and spacing of the electrode lines on the battery cell, and then the first layer is bonded to the battery cell, wherein the welding strip and the electrode lines are bonded due to the bonding of the first layer to the battery cell, and the bonding is locally strengthened as appropriate to improve the bonding between the welding strip and the electrode lines, wherein the first adhesive film layer and the substrate may be respectively perforated or not perforated; and First, the first layer is joined to the battery cell, wherein the first adhesive film layer and / or the substrate has a plurality of openings and the positions of the plurality of openings are configured to coincide with the positions of the electrode lines on the battery cell so as to join the welding strip to the electrode lines from the openings.

11. A solar cell module, comprising the solar cell string according to any one of claims 1 to 9. 12 . The solar cell module according to claim 11 , further comprising a front cover and an optical film, wherein the front cover and the optical film form a light-collecting structure.

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