Solar cell conductive paste and photovoltaic module

Abstract

The application provides a solar cell conductive paste and a photovoltaic module. The solar cell conductive paste comprises a main glass powder and a secondary glass powder. The main glass powder is Pb-Si-B system glass, and the secondary glass powder is Pb-Ti-Si-B system glass. The mass fraction of the main glass powder in the paste is 1.5-2.5%, and the mass fraction of the secondary glass powder is 0.2-1%. The paste further comprises silver powder and an organic carrier. The mass fraction of the silver powder is 82-90%, and the mass fraction of the organic carrier is 8-15%. The secondary glass adjusts the low solubility of the electrode grid line in acetic acid, resists acetic acid corrosion, makes the electrode grid line resistant to high temperature and high humidity, improves the reliability of the module, and solves the problem that the acetic acid produced by the decomposition of EVA in the double-sided EVA module packaging battery affects the battery efficiency. The application further provides a photovoltaic module using the above paste.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular to a solar cell conductive paste and a photovoltaic module. BACKGROUND

[0002] EVA is a kind of transparent glue with good flexibility and bonding performance, good light transmission performance and aging resistance. It encapsulates the crystal silicon group with "upper cover and lower pad", and is bonded into a crystal silicon module with the upper protective material glass and the lower protective material TPT by vacuum laminating technology. Single-glass photovoltaic module is a solar energy absorbed from one side of the module; and double-glass photovoltaic module is a solar energy absorbed from two sides, which is composed of two tempered glasses, POE or EVA adhesive film and cell pieces.

[0003] The formal name of EVA resin is ethylene-vinyl acetate copolymer, and the content of vinyl acetate in EVA used in photovoltaic module is usually 28-33%. As a common chemical bond, ester has a basic property of decomposing into acid and alcohol in the presence of water, and the slowly accumulated acetic acid in the photovoltaic module becomes an important inducement for most of the quality problems of the photovoltaic module. Because acetic acid can gradually corrode and narrow the silver grid line on the surface of the cell piece, and with the narrowing of the silver grid line, the power generation efficiency of the module gradually decreases. Therefore, the decomposed acetic acid during the encapsulation of the module leads to the decrease of the battery performance, the interaction with the electrode, the degradation of the metallization site and the cell piece interface, the increase of the contact resistance, and the EL imaging as a dark area, which seriously affects the battery efficiency.

[0004] In order to solve the problem that the acetic acid produced by the decomposition of EVA affects the battery efficiency of the double-sided EVA module encapsulated battery, the present application provides a solar cell conductive paste and a photovoltaic module. SUMMARY

[0005] In order to solve the problem that the acetic acid produced by the decomposition of EVA affects the battery efficiency of the double-sided EVA module encapsulated battery, the present application provides a solar cell conductive paste, which comprises a main glass powder and a secondary glass powder, the mass fraction of the main glass powder in the paste is 1.5%-2.5%, the mass fraction of the secondary glass powder is 0.2%-1%, the secondary glass powder is a Pb-Ti-Si-B system glass, and the total mole percentage content of the secondary glass powder is 100 mol%, the secondary glass powder comprises PbO 15 mol%-45 mol%, TiO2 5 mol%-20 mol%, SiO2 and GeO2 accounting for 15 mol%-50 mol%, B2O318 mol%-30 mol%, Al2O30 mol%-20 mol%, RO 0 mol%-12 mol%, and a modified additive 1 mol%-20 mol%, wherein R is one or more of alkali metals Li, Na or K.

[0006] Acetic acid is a decomposition product of ethylene-vinyl acetate (EVA), a common module encapsulation material, which interacts with metallization, often leading to interfacial degradation between front metal contacts and underlying silicon (Si) substrates. This results in loss of cell performance and contact adhesion, increased contact resistance, and dark areas seen in electroluminescence (EL) imaging, so it is urgent to develop new metallization pastes that are more resistant to acetic acid.

[0007] The introduction of Ti can improve the acetic acid performance of the glass, and the present application adjusts the low solubility of the electrode grid in acetic acid through a secondary glass (Pb-Ti-Si-B system glass), improves the good chemical stability of the electrode, and resists acetic acid erosion.

[0008] Optionally, the elements in the modification additive include one or more of W, Ca, Mg, Zn, Bi, and Ba.

[0009] Optionally, the main glass powder is a Pb-Si-B system glass, and the main glass powder includes 15-40 mol% SiO2, 18-40 mol% B2O3, 0-20 mol% Al2O3, 15-45 mol% PbO and BaO, 0-12 mol% RO, 1-20 mol% modification additive, and R is one or more of alkali metals Li, Na, or K, based on the total mole percentage of the main glass powder being 100 mol%.

[0010] Optionally, the elements in the modification additive include one or more of Ca, Mg, Se, Ag, Zn, P, Ga, and Fe.

[0011] Optionally, the paste further includes silver powder and an organic carrier, and in the paste, the mass fraction of the silver powder is 82-90%, and the mass fraction of the organic carrier is 8-15%.

[0012] Optionally, the organic carrier includes an organic solvent, an organic resin, and an additive, and in the organic carrier, the mass fraction of the organic solvent is 60-93%, the mass fraction of the organic resin is 5-20%, and the mass fraction of the additive is 2-20%.

[0013] Optionally, the glass powder includes a main glass powder and a secondary glass powder, and the preparation method of the glass powder includes:

[0014] The raw materials are uniformly mixed, heated to melt, and then cooled to obtain a glass frit;

[0015] The glass frit is ground and sieved to obtain a glass powder.

[0016] Optionally, the preparation method specifically comprises:

[0017] The raw materials are uniformly mixed, loaded into a platinum crucible, and then melted at 900-1300°C for 30-90 min, and after cooling, a glass frit is obtained.

[0018] After the glass frit is ground and sieved, a glass powder is obtained, and the D100 of the glass powder is less than or equal to 6 um.

[0019] Optionally, the paste is applied to an N-type solar cell treated by a laser enhanced contact optimization process.

[0020] The application also provides a photovoltaic module, which comprises a first cover plate, a first adhesive film, a cell string, a second adhesive film, and a second cover plate arranged in layers, the first adhesive film and the second adhesive film being EVA; the cell string comprises a plurality of solar cells electrically connected, and the electrodes of the solar cells are formed by using the solar cell conductive paste according to any one of the above.

[0021] The application provides a solar cell conductive paste, which comprises a main glass powder and a secondary glass powder. The main glass powder is a Pb-Si-B glass, and the secondary glass powder is a Pb-Ti-Si-B glass. In the paste, the mass fraction of the main glass powder is 1.5%-2.5%, and the mass fraction of the secondary glass powder is 0.2%-1%. The paste further comprises silver powder and an organic carrier, the mass fraction of the silver powder is 82%-90%, and the mass fraction of the organic carrier is 8%-15%. The application adjusts the low solubility of the electrode grid line in acetic acid by the secondary glass, improves the good chemical stability of the electrode, resists acetic acid corrosion, makes the electrode grid line resistant to high temperature and high humidity, improves the reliability of the module, and solves the problem that the acetic acid generated by the decomposition of EVA in the packaging of a double-sided EVA module affects the efficiency of the battery. The application also provides a photovoltaic module using the above paste. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings needed in the embodiments. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0023] Figure 1 It is a schematic diagram of the electrode cross section of the B1 battery piece before the acetic acid atmosphere;

[0024] Figure 2 It is a schematic diagram of the electrode cross section of the B1 battery piece after the acetic acid atmosphere;

[0025] Figure 3 It is a schematic diagram of the electrode cross section of the K2 battery piece before the acetic acid atmosphere;

[0026] Figure 4 Figure 6 is a schematic diagram of the electrode cross-section of a K2 cell after exposure to an acetic acid environment. DETAILED DESCRIPTION

[0027] The embodiments will be described in detail below with reference to examples thereof as illustrated in the accompanying drawings. In the following description, unless otherwise indicated, like numbers in the different figures represent the same or similar elements. The embodiments described in the following examples do not represent all of the implementations consistent with the present application. Rather, they are merely examples of systems and methods consistent with some aspects of the present application as detailed in the appended claims.

[0028] In order to solve the problem that the acetic acid produced by decomposition of EVA in a double-sided EVA encapsulated battery affects the efficiency of the battery, the present application provides a solar cell conductive paste, which comprises a main glass powder and a secondary glass powder, the mass fraction of the main glass powder in the paste is 1.5% to 2.5%, the mass fraction of the secondary glass powder is 0.2% to 1%, the secondary glass powder is a Pb-Ti-Si-B system glass, and the total mole percentage of the secondary glass powder is 100 mol%, the secondary glass powder comprises 15 mol% to 45 mol% of PbO, 5 mol% to 20 mol% of TiO2, 15 mol% to 50 mol% of SiO2 and GeO2 in total, 18 mol% to 30 mol% of B2O3, 0 mol% to 20 mol% of Al2O3, 0 mol% to 12 mol% of RO, and 1 mol% to 20 mol% of a modified additive, wherein R is one or more of alkali metals Li, Na or K.

[0029] EVA plays a role of air and electrical insulation in the module, protects it from mechanical damage and prevents corrosion from the external environment. However, under the action of photosynthetic heat, acetic acid is the decomposition product of the module packaging material ethylene-vinyl acetate (EVA). Acetic acid solution does not basically corrode pure aluminum at room temperature, but as the temperature rises, the corrosion rate accelerates, and the corrosion rate of 1% dilute acetic acid solution on aluminum at boiling temperature is 100 times that at room temperature; the corrosion rate of acetic acid on aluminum is also related to the purity of aluminum, and impurities such as iron, silicon and aluminum salt on the surface of low-purity aluminum form a loose and non-dense oxidation protective film, which has low corrosion resistance.

[0030] The minority carrier lifetime of solar cells is also increasing, that is, the diffusion length of minority carriers is increasing, and when the diffusion length of minority carriers is comparable to or exceeds the thickness of the silicon wafer, the back surface recombination rate has a significant impact on the characteristics of the solar cell. After sintering, the back surface forms a silicon-aluminum alloy, and aluminum acts as a P-type dopant in silicon, which can reduce the recombination of minority carriers at the metal-silicon interface, thereby improving the open-circuit voltage and short-circuit current and improving the response to infrared light. The quality of the aluminum back surface directly affects the output characteristics of the solar cell.

[0031] The solder ribbon is soaked in dilute acetic acid solution at 60℃ for one week, the front main grid lines of the battery sheet turn yellow, the back grid lines of the battery sheet turn black, and the aluminum back field of the battery sheet falls off. The acetic acid produced by EVA can cause electrochemical corrosion of the tin-coated copper solder ribbon, at the same time, corrode the silver grid lines on the surface of the battery sheet to make them black, and corrode the aluminum back field of the battery to reduce the adhesion of the aluminum back field and the silicon sheet, which seriously affects the electrical performance of the battery. Further reduce the electrical performance of the module. Therefore, in the future development of photovoltaic modules, new packaging materials, new EVA formula or other measures to reduce the generation of acetic acid by EVA aging need to be studied to protect the battery from the harm of acetic acid and have a longer service life.

[0032] More importantly, acetic acid interacts with metallization, often leading to interfacial degradation between the front metal contacts and the underlying silicon (Si) substrate. This results in loss of cell performance and contact adhesion, increased contact resistance, and dark areas seen in electroluminescence (EL) imaging, so it is urgent to develop new pastes that are more resistant to acetic acid.

[0033] The introduction of Ti can improve the acetic acid performance of the glass, and the application adjusts the low solubility of the electrode grid line in acetic acid through the secondary glass (Pb-Ti-Si-B system glass), improves the good chemical stability of the electrode, and resists acetic acid corrosion.

[0034] In some embodiments, the elements in the modification additive include one or more of W, Ca, Mg, Zn, Bi, and Ba.

[0035] In some embodiments, the main glass powder is a Pb-Si-B system glass, and the main glass powder includes 15mol%-40mol% of SiO2, 18mol%-40mol% of B2O3, 0mol%-20mol% of Al2O3, 15mol%-45mol% of PbO and BaO in total, 0mol%-12mol% of RO, 1mol%-20mol% of a modification additive, and R is one or more of alkali metals Li, Na, or K, based on the total mole percentage content of the main glass powder being 100mol%.

[0036] In some embodiments, the elements in the modification additive include one or more of Ca, Mg, Se, Ag, Zn, P, Ga, and Fe.

[0037] In some embodiments, the slurry further comprises silver powder and an organic carrier, wherein the mass fraction of the silver powder is 82% to 90%, and the mass fraction of the organic carrier is 8% to 15%. The silver powder is spherical silver powder, and the D50 of the silver powder is 1.4 to 2.0 um. D50 refers to the particle size corresponding to the cumulative percentage of 50% of a sample. Its physical meaning is that the particles with a particle size greater than it account for 50%, and the particles with a particle size less than it also account for 50%. D50 is also called median diameter or median particle size.

[0038] In some embodiments, the organic carrier comprises an organic solvent, an organic resin, and an additive, wherein the mass fraction of the organic solvent is 60% to 93%, the mass fraction of the organic resin is 5% to 20%, and the mass fraction of the additive is 2% to 20%.

[0039] In some embodiments, the glass powder comprises a main glass powder and a secondary glass powder, and the preparation method of the glass powder comprises:

[0040] The raw materials of the components are uniformly mixed, heated to melt, cooled, and a glass frit is obtained. The glass frit is sieved to obtain a glass powder.

[0041] In some embodiments, the preparation method specifically comprises:

[0042] The raw materials of the components are uniformly mixed, loaded into a platinum crucible, and heated to melt at 900 to 1300°C for 30 to 90 min. After cooling, a glass frit is obtained. The glass frit is sieved to obtain a glass powder, and the D100 of the glass powder is less than or equal to 6 um.

[0043] In some embodiments, the slurry is applied to an N-type solar cell treated by a laser enhanced contact optimization process.

[0044] The application also provides a photovoltaic module, which comprises a first cover plate, a first adhesive film, a cell string, a second adhesive film, and a second cover plate arranged in layers, wherein the first adhesive film and the second adhesive film are EVA; the cell string comprises a plurality of electrically connected solar cells, and the electrodes of the solar cells are formed by using the solar cell conductive paste according to any one of the above.

[0045] The solar cell includes, but is not limited to, one or any combination of a PERC (Passivated Emitter Rear Cell) cell, an IBC (Interdigitated Back Contact) cell, a TOPCon (Tunnel Oxide Passivated Contact) cell, an HIT / HJT (Heterojunction Technology) cell, a solar thin film cell, and a stacked cell. The solar thin film cell includes, but is not limited to, a perovskite solar thin film cell, a copper-indium-selenium solar thin film cell, a gallium arsenide solar thin film cell, and a cadmium sulfide solar thin film cell. The stacked cell includes, but is not limited to, a perovskite cell stacked with a crystalline silicon cell, a perovskite cell stacked with a perovskite cell, and a perovskite cell stacked with a thin film cell.

[0046] Embodiment:

[0047] The sub-glass GL001-GL008 is prepared according to the material ratio in Table 1, and the main glass powder BL001-BL005 is prepared according to the material ratio in Table 2. The material ratio of the glass powder in Table 1 and Table 2 is in terms of mole percentage. For example, in the sub-glass powder GL001, PbO is 25 mol%, B2O3 is 26 mol%, TiO2 is 8 mol%, SiO2 is 36 mol%, ZnO is 4 mol%, and CaO is 1 mol%.

[0048] The components are mixed in a mixer according to the mole percentage, and then the components are weighed and mixed uniformly. The materials are loaded into a platinum crucible, and then melted at 900-1300°C using an elevator furnace, and the holding time is 30-90 min. After the glass state is homogenized, the glass frit is prepared by a melt water quenching method or a cold rolling method. After the glass frit is ground and sieved, the sub-glass GL001-GL008 and the main glass powder BL001-BL005 are obtained, and the particle size of the glass powder is D100≤6um.

[0049] The GL001-GL004 and BL001-BL002 are melted at 1000°C, and the holding time is 60 min; the GL005 and BL003 are melted at 900°C, and the holding time is 30 min; the GL006, GL007, GL008, BL004 and BL005 are melted at 1300°C, and the holding time is 90 min.

[0050] Table 1 Material ratio of sub-glass powder

[0051] Raw materials GL001 GL002 GL003 GL004 GL005 GL006 GL007 GL008 PbO 25 20 27 30 15 45 15 15 B2O3 26 18 28 15 18 18 30 18 TiO2 8 13 10 15 5 5 20 7 Al2O3 0 12 2 8 7 15 20 0 SiO2 36 25 20 18 45 9.5 0 23 GeO2 0 0.5 2 5 5 5.5 0 5 Li2CO3 0 1.5 0 0 1 1 0 5 [K2CO3] 0 0 0.5 0 0.5 0 2 2 Na2CO3 0 0.5 0 0 0 0 1 5 Bi2O3 0 5 7 0 0 0 3 0 ZnO 4 0 3.5 2 1 0 0 0 TeO2 0 1 0 5 0 0 5.5 5.5 WO3 0 0.5 0 0 1 0.5 3.5 3.5 BaO 0 2 0 0 0 0 0 7.5 MgO 0 1 0 0 1.5 0 0 2.5 CaO 1 0 0 2 0 0.5 0 1

[0052] Table 2 Main glass powder material ratio

[0053]

[0054]

[0055] Example One:

[0056] The silver powder, organic carrier, glass powder BL001 and glass powder GL001 were weighed according to the weight ratio of 88.5wt%, 9wt%, 2.0wt% and 0.5wt% respectively. The organic carrier includes 75wt% organic solvent, 15wt% organic resin and 10wt% additives. The silver powder and organic carrier were premixed by a planetary mixer, and the slurry was ground for 6 times by a ceramic three-roll mill. The fineness of the slurry was tested by a doctor blade fineness gauge, and the fineness of the slurry was less than 10um. The slurry was filtered by a 250 mesh filter cloth to obtain the front electrode silver paste K1.

[0057] Example Two:

[0058] The silver powder, organic carrier, glass powder BL001 and glass powder GL002 were weighed according to the weight ratio of 85.7wt%, 12wt%, 1.5wt% and 0.8wt% respectively. The organic carrier includes 75wt% organic solvent, 15wt% organic resin and 10wt% additives. The silver powder and organic carrier were premixed by a planetary mixer, and the slurry was ground for 6 times by a ceramic three-roll mill. The fineness of the slurry was tested by a doctor blade fineness gauge, and the fineness of the slurry was less than 10um. The slurry was filtered by a 250 mesh filter cloth to obtain the front electrode silver paste K2.

[0059] Example Three:

[0060] The silver powder, organic carrier, glass powder BL002 and glass powder GL003 were weighed according to the weight ratio of 87.4wt%, 10wt%, 2.2wt% and 0.4wt% respectively. The organic carrier includes 75wt% organic solvent, 15wt% organic resin and 10wt% additives. The silver powder and organic carrier were premixed by a planetary mixer, and the slurry was ground for 6 times by a ceramic three-roll mill. The fineness of the slurry was tested by a doctor blade fineness gauge, and the fineness of the slurry was less than 10um. The slurry was filtered by a 250 mesh filter cloth to obtain the front electrode silver paste K3.

[0061] Example Four:

[0062] The silver powder, the organic vehicle, the glass powder BL002, and the glass powder GL004 are weighed in the proportions of 88.8wt%, 9wt%, 1.7wt%, and 0.5wt% respectively. The organic vehicle comprises 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. The silver powder and the organic vehicle are premixed in a planetary mixer, and the slurry is ground for 6 times using a ceramic three-roll mill. The fineness of the slurry is tested using a doctor blade fineness gauge, and the fineness of the slurry is less than 10um. The slurry is filtered using a 250-mesh filter cloth to obtain the front electrode silver paste K4.

[0063] Example Five

[0064] The silver powder, the organic vehicle, the glass powder BL002, and the glass powder GL004 are weighed in the proportions of 88.8wt%, 9wt%, 1.7wt%, and 0.5wt% respectively. The organic vehicle comprises 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. The silver powder and the organic vehicle are premixed in a planetary mixer, and the slurry is ground for 6 times using a ceramic three-roll mill. The fineness of the slurry is tested using a doctor blade fineness gauge, and the fineness of the slurry is less than 10um. The slurry is filtered using a 250-mesh filter cloth to obtain the front electrode silver paste K4.

[0065] Example Six

[0066] The silver powder, the organic vehicle, the glass powder BL002, and the glass powder GL004 are weighed in the proportions of 88.8wt%, 9wt%, 1.7wt%, and 0.5wt% respectively. The organic vehicle comprises 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. The silver powder and the organic vehicle are premixed in a planetary mixer, and the slurry is ground for 6 times using a ceramic three-roll mill. The fineness of the slurry is tested using a doctor blade fineness gauge, and the fineness of the slurry is less than 10um. The slurry is filtered using a 250-mesh filter cloth to obtain the front electrode silver paste K4.

[0067] Example Seven

[0068] The silver powder, the organic vehicle, the glass powder BL002, and the glass powder GL004 are weighed in the proportions of 88.8wt%, 9wt%, 1.7wt%, and 0.5wt% respectively. The organic vehicle comprises 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. The silver powder and the organic vehicle are premixed in a planetary mixer, and the slurry is ground for 6 times using a ceramic three-roll mill. The fineness of the slurry is tested using a doctor blade fineness gauge, and the fineness of the slurry is less than 10um. The slurry is filtered using a 250-mesh filter cloth to obtain the front electrode silver paste K4.

[0069] Example Eight

[0070] The 88wt% silver powder, 9wt% organic carrier, 2.0wt% glass powder BL005, and 1wt% glass powder GL008 were weighed. The organic carrier included 75wt% organic solvent, 15wt% organic resin, and 10wt% additives. The silver powder had a D50 of 1.9μ. The silver powder and the organic carrier were first premixed using a planetary mixer, and the slurry was ground 6 times using a ceramic three-roll grinder. The grinding fineness was tested using a doctor blade fineness gauge, and the slurry fineness was <10um. The slurry was filtered using 250-mesh filter cloth to obtain a front electrode silver paste K8.

[0071] Comparative Example 1

[0072] The 89wt% silver powder, 9wt% organic carrier, and 2.0wt% glass powder BL001 were weighed. The organic carrier included 75wt% organic solvent, 15wt% organic resin, and 10wt% additives. The silver powder and the organic carrier were first premixed using a planetary mixer, and the slurry was ground 6 times using a ceramic three-roll grinder. The grinding fineness was tested using a doctor blade fineness gauge, and the slurry fineness was <10um. The slurry was filtered using 250-mesh filter cloth to obtain a front electrode silver paste B1.

[0073] Comparative Example 2

[0074] The 89wt% silver powder, 9wt% organic carrier, and 2.0wt% glass powder BL002 were weighed. The organic carrier included 75wt% organic solvent, 15wt% organic resin, and 10wt% additives. The silver powder and the organic carrier were first premixed using a planetary mixer, and the slurry was ground 6 times using a ceramic three-roll grinder. The grinding fineness was tested using a doctor blade fineness gauge, and the slurry fineness was <10um. The slurry was filtered using 250-mesh filter cloth to obtain a front electrode silver paste B2.

[0075] The slurry obtained in Examples 1-8 and Comparative Examples 1-2 was printed on N-type 182 silicon wafers using a Mayway automatic printing machine, and 100 pieces of each slurry were printed. The wafers were sintered using a sintering furnace, and then treated by laser-enhanced contact optimization (LECO). The IV of the wafers was tested, and the data was recorded.

[0076] Vinegar acid test conditions:

[0077] 1) The to-be-eroded wafers were placed in corresponding size baskets in a staggered manner (one wafer was placed every other interval); the basket box was placed at the edge of the basket box, and 2 wafer companions were placed at the edge of the basket box;

[0078] 2) The vinegar acid solution was prepared according to the requirements, poured into a PP fresh-keeping box, and then the basket was placed in the center of the fresh-keeping box and covered with a box cover to buckle the buckle, and then sealed with a plastic sealing film;

[0079] 3) Put the prepared acetic acid box into an oven at 85°C, keep for 8h, then take out the battery piece for testing.

[0080] Formula: Eta attenuation value = (1-Eta after acetic acid / Eta before acetic acid) x 100%.

[0081] The experimental temperature, testing time and acetic acid solution preparation method are shown in Table 3, and the measurement data are shown in Table 4.

[0082] Table 3: Experimental conditions for acetic acid test

[0083]

[0084] In Table 3, "with fan" means that a fan is installed in the acetic acid box container to make the concentration of the atmosphere in the acetic acid box container uniform; "test time 8 hours" means that the battery piece is kept in the acetic acid box container for 8 hours.

[0085] Table 4: Experimental measurement data

[0086]

[0087]

[0088] As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The battery piece prepared by the slurry provided in the present application has not only smaller changes in the open circuit voltage and fill factor before and after the acetic acid atmosphere, but also smaller attenuation values of the photoelectric conversion efficiency of the battery piece, and the photoelectric conversion efficiency of the battery piece after the acetic acid atmosphere still remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid. Figure 1 As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The battery piece prepared by the slurry provided in the present application has not only smaller changes in the open circuit voltage and fill factor before and after the acetic acid atmosphere, but also smaller attenuation values of the photoelectric conversion efficiency of the battery piece, and the photoelectric conversion efficiency of the battery piece after the acetic acid atmosphere still remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid. Figure 2 As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The battery piece prepared by the slurry provided in the present application has not only smaller changes in the open circuit voltage and fill factor before and after the acetic acid atmosphere, but also smaller attenuation values of the photoelectric conversion efficiency of the battery piece, and the photoelectric conversion efficiency of the battery piece after the acetic acid atmosphere still remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid. Figure 3 As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The battery piece prepared by the slurry provided in the present application has not only smaller changes in the open circuit voltage and fill factor before and after the acetic acid atmosphere, but also smaller attenuation values of the photoelectric conversion efficiency of the battery piece, and the photoelectric conversion efficiency of the battery piece after the acetic acid atmosphere still remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid. Figure 4 As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The battery piece prepared by the slurry provided in the present application has not only smaller changes in the open circuit voltage and fill factor before and after the acetic acid atmosphere, but also smaller attenuation values of the photoelectric conversion efficiency of the battery piece, and the photoelectric conversion efficiency of the battery piece after the acetic acid atmosphere still remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid. Figures 1-4 As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The battery piece prepared by the slurry provided in the present application has not only smaller changes in the open circuit voltage and fill factor before and after the acetic acid atmosphere, but also smaller attenuation values of the photoelectric conversion efficiency of the battery piece, and the photoelectric conversion efficiency of the battery piece after the acetic acid atmosphere still remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid.

[0089] As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The battery piece prepared by the slurry provided in the present application has not only smaller changes in the open circuit voltage and fill factor before and after the acetic acid atmosphere, but also smaller attenuation values of the photoelectric conversion efficiency of the battery piece, and the photoelectric conversion efficiency of the battery piece after the acetic acid atmosphere still remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid.

[0090] The application provides a solar cell conductive paste, which comprises a main glass powder and a secondary glass powder; the main glass powder is Pb-Si-B glass, the secondary glass powder is Pb-Ti-Si-B glass, the mass fraction of the main glass powder in the paste is 1.5-2.5%, and the mass fraction of the secondary glass powder in the paste is 0.2-1%. The paste further comprises silver powder and an organic carrier, the mass fraction of the silver powder is 82-90%, and the mass fraction of the organic carrier is 8-15%.

[0091] The application adjusts the low solubility of the electrode grid line in acetic acid through the secondary glass, improves the good chemical stability of the electrode, resists the acetic acid corrosion, makes the electrode grid line resistant to high temperature and high humidity, improves the reliability of the module, and solves the problem that the acetic acid generated by the decomposition of the EVA in the double-sided EVA module packaging battery affects the battery efficiency. The application further provides a photovoltaic module using the above paste.

[0092] The similar parts among the embodiments provided by the application can be referred to each other, the specific embodiments provided above are only several examples under the general concept of the application, and do not constitute the limitation of the protection scope of the application. Any other embodiments extended according to the application scheme without creative labor belong to the protection scope of the application for the person skilled in the art.

Claims

1. A conductive paste for solar cells, characterized in that, The slurry comprises primary glass powder and secondary glass powder. The primary glass powder has a mass fraction of 1.5%–2.5%, and the secondary glass powder has a mass fraction of 0.2%–1%. The secondary glass powder is a Pb-Ti-Si-B glass system. Based on a total molar percentage content of 100 mol%, the secondary glass powder comprises: PbO 15 mol%–45 mol%, TiO2 5 mol%–20 mol%, SiO2 and GeO2 (total) 15 mol%–50 mol%, B2O3 18 mol%–30 mol%, Al2O3 0 mol%–20 mol%, and RO. The primary glass powder comprises 0 mol%–12 mol%, modified additives 1 mol%–20 mol%, wherein R is one or more of the alkali metals Li, Na, or K, and the modified additives in the secondary glass powder include one or more of W, Ca, Mg, Zn, Bi, and Ba; the primary glass powder is a Pb-Si-B system glass, and based on a total molar percentage content of 100 mol%, the primary glass powder comprises SiO2 15 mol%–40 mol%, B2O3 18 mol%–40 mol%, Al2O3 0 mol%–20 mol%, PbO and BaO totaling 15 mol%–45 mol%, and RO. The slurry contains 0 mol% to 12 mol% of modified additives and 1 mol% to 20 mol% of main glass powder, wherein R is one or more of alkali metals Li, Na, or K, and the modified additives of the main glass powder contain one or more of Ca, Mg, Se, Ag, Zn, P, Ga, and Fe. The slurry also contains silver powder and an organic carrier. In the slurry, the mass fraction of the silver powder is 82% to 90%, and the mass fraction of the organic carrier is 8% to 15%.

2. The conductive paste for solar cells according to claim 1, characterized in that, The organic carrier includes an organic solvent, an organic resin, and additives, wherein the organic solvent has a mass fraction of 60% to 93%, the organic resin has a mass fraction of 5% to 20%, and the additives have a mass fraction of 2% to 20%.

3. The conductive paste for solar cells according to claim 1, characterized in that, The glass powder includes primary glass powder and secondary glass powder, and the preparation method of the glass powder includes: The raw materials are mixed evenly, heated to melt, and then cooled to obtain glass frit; After grinding and sieving the glass material, glass powder is obtained.

4. The solar cell conductive paste according to claim 3, characterized in that, The preparation method specifically includes: The raw materials are mixed evenly and placed in a platinum crucible. The mixture is then melted at 900-1300℃ for 30-90 minutes. After cooling, the glass material is obtained. After grinding and sieving the glass material, glass powder is obtained, wherein the glass powder has a D100 of less than or equal to 6 μm.

5. The conductive paste for solar cells according to claim 1, characterized in that, The conductive paste for solar cells is used in N-type solar cells processed with laser-enhanced contact optimization technology.

6. A photovoltaic module, characterized in that, The photovoltaic module includes a first cover plate, a first encapsulant film, a battery string, a second encapsulant film, and a second cover plate stacked together, wherein the first and second encapsulant films are EVA; the battery string includes multiple electrically connected solar cells, and the electrodes of the solar cells are formed using the solar cell conductive paste according to any one of claims 1 to 5.

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