Back contact solar cell and packaging mode thereof

Abstract

The invention discloses a back contact solar cell and a packaging mode thereof, and belongs to the field of solar cells, and the back contact solar cell is connected with conductive glass by printing conductive adhesive and UV adhesive points on the back surface of a cell piece; after heating and curing, glass solder is printed on the peripheral edge of the glass, the periphery of the glass is heated through laser, and sealing is conducted after the solder is molten and rapidly cooled. The beneficial effects of the invention are that the edge of the glass is hermetically connected with the battery piece through the glass solder, so that corrosion caused by water vapor entering the inside of the assembly in subsequent outdoor use of the battery piece is avoided, the battery piece is connected with the glass through cooperation of the conductive adhesive and the UV adhesive, and then the conductive adhesive and the UV adhesive are cured at the same time, so that the service life of the battery piece is prolonged. And the battery piece is directly adhered to the glass, so that the problem of warping caused by welding the back contact battery by using a metal welding strip can be improved.

Description

Technical Field

[0001] The present invention relates to the field of solar cells, and more particularly, to a back-contact solar cell and its encapsulation method. Background Art

[0002] In the technical field of solar cells, a single crystalline silicon solar cell has a small power generation capacity and is very fragile. In practical applications, solar cells need to be encapsulated into modules. Among them, for a back-contact cell, positive and negative grid lines are usually printed in a cross arrangement on the back of the cell. The main grids are arranged longitudinally in a cross pattern, and the fine grids are arranged horizontally in a cross pattern. The positive electrode is disconnected at the intersection with the negative fine grid and an insulating adhesive is printed, and the negative electrode is disconnected at the intersection with the positive fine grid and an insulating adhesive is printed. Then, the back of the cell is turned upwards, and tin-lead solder tapes are laid directly above the positive and negative electrodes, and the solder tapes are pressed by spring pressure pins, and infrared lamps are used for heating to achieve welding.

[0003] However, during the welding process, the heating temperature of the infrared lamp is relatively high. Due to the large deviation in the thermal expansion coefficients of the tin-lead solder tape and the cell, single-sided welding easily causes the bowing of the cell, which increases the fragmentation rate during the lamination process when encapsulating the cell into a module. Moreover, a fully glass module cannot be repaired, which greatly affects the reliability of the product quality and increases the manufacturing cost. In addition, during the outdoor use of the module, moisture will penetrate from the backplane and the frame positions to the inside. Coupled with long-term ultraviolet radiation, temperature and other factors, the EVA film connecting the cell and the glass will age and decompose, generating acidic groups that corrode the cell grid lines, resulting in power attenuation of the cell.

[0004] In view of this, how to provide a new encapsulation method to improve the problems of warping, cracking and film aging of back-contact cell modules during the encapsulation process is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In order to improve the problems of serious warping of the cell during welding, cracking or fragmentation of the cell during lamination, and film aging of back-contact cell modules in the prior art, the present application provides a back-contact solar cell and its encapsulation method, and its technical solution is as follows:

[0006] An encapsulation method for a back-contact solar cell, comprising the following steps:

[0007] Step 1: Use screen printing technology to print metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grids of the cell, and perform high-temperature sintering on the glass printed with the paste to obtain conductive glass;

[0008] Step 2: Print conductive adhesive on the silver paste contact points of the positive and negative electrodes of the main grids on the back of the cell, and print UV glue dots in the non-main grid areas;

[0009] Step 3: Connect the positive contact point of the battery cell to the positive contact point on the conductive glass, and connect the negative contact point of the battery cell to the negative contact point on the conductive glass. Make the UV glue dots contact the non-conductive area of the conductive glass.

[0010] Step 4: Press the conductive glass on the surface of the battery cell, heat the conductive glass on the back of the battery cell to cure the conductive adhesive, and at the same time irradiate the conductive glass with a UV lamp.

[0011] Step 5: Print the glass solder on the four peripheral edges of the conductive glass, heat the four sides of the glass with a laser, melt the solder, and perform sealing after rapid cooling.

[0012] By printing the glass solder on the four peripheral edges of the glass, melting it and then rapidly cooling it to connect with the battery cell, a tight connection can be formed between the four sides of the glass and the battery cell, thereby preventing moisture from entering the component interior and causing corrosion during the subsequent outdoor use of the battery cell.

[0013] Preferably, in Step 5, the glass solder is lead silicate glass, with a printing width of 5 - 10 mm and a thickness of 30 - 100 μm. The main components of the lead silicate glass are SiO2 and PbO, which have unique high refractive index and high volume resistance, good wettability with metals, and can block X-rays and γ-rays. In this application, the lead silicate glass solder is heated and melted to connect the front and back glasses of the component and perform sealing. It is a vacuum glass sealing material, with a low melting point to avoid glass cracking after heating, high reliability, resistance to moisture, acids, and alkalis, strong sealing performance, and can isolate air to achieve a vacuum effect.

[0014] Preferably, the lead silicate glass includes 40 - 70% by mass of PbO and 20% - 30% by mass of SiO2.

[0015] Preferably, in Step 5, the laser is an infrared laser with a wavelength of 10.6 μm and a heating temperature of 400 - 600 °C.

[0016] Preferably, in Step 1, the metal paste is copper or aluminum, with a high-temperature sintering temperature of 800 - 1000 °C and a sintering time of 10 - 30 min.

[0017] Preferably, in Step 2, the UV glue dots are evenly distributed in the non-main grid area, with a diameter of 5 - 10 mm and a thickness of 100 - 300 μm. After traditional metal solder tapes are heated, they expand more than the battery cells. After cooling, due to the solder joints hindering the free contraction of the solder tapes, there is shrinkage stress, which causes the battery cells to bend. In the present invention, by using UV glue to replace the traditional metal solder tapes and directly adhering the battery cells to the glass, the problem of battery cell shrinkage and bending can be improved.

[0018] Preferably, in the fourth step, the curing temperature of the conductive adhesive is 100~200°C, and the heating time is 10~20 s. The conductive adhesive is an adhesive that can effectively bond various materials and has electrical conductivity. It usually consists of a matrix resin and conductive fillers, namely conductive particles. Through the bonding action of the matrix resin, the conductive particles are combined together to form a conductive path to achieve the conductive connection of the adhered materials.

[0019] Preferably, in the fourth step, the power of the UV lamp is 1~2 KW, and the time is 2~4 s.

[0020] Preferably, before the first step, the following steps are further included: successively performing cleaning and texturing, front boron diffusion, and etching and alkaline polishing on the battery wafers; successively depositing a tunneling oxide layer and a phosphorus-doped polysilicon layer on the back of the battery wafers; RCA cleaning; depositing a front antireflection layer and a back antireflection layer on the front and back of the battery wafers respectively.

[0021] The present invention also provides a back-contact battery, which is obtained by encapsulating using the above encapsulation method.

[0022] The beneficial effects produced by adopting the technical solution of the present invention are as follows:

[0023] The present invention seals and connects the glass edge and the battery wafer through a glass solder, thereby avoiding water vapor from entering the inside of the component and causing corrosion during the subsequent outdoor use of the battery wafer. In addition, the present invention uses a conductive adhesive and a UV adhesive in combination to connect with the glass on the battery wafer, and then cures the conductive adhesive and the UV adhesive simultaneously, directly adhering the battery wafer to the glass, which can improve the problem of shrinkage and bending of the battery wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0025] Figure 1 is a schematic diagram of the back structure of the battery wafer of a back-contact solar cell provided by the present invention;

[0026] Figure 2 is a schematic diagram of the conductive glass structure of a back-contact solar cell provided by the present invention.

[0027] Among them, 1. Battery wafer; 2. Silver paste contact point; 3. Conductive adhesive; 4. UV adhesive point; 5. Conductive glass; 6. Conductive circuit; 7. Metal paste. SPECIFIC EMBODIMENTS

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will, in conjunction with the accompanying drawings in the embodiments of the present invention, clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are some, rather than all, of the embodiments of the present invention. Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0029] In this embodiment, glass solder is used on the solar cell to hermetically connect the glass edge to the solar cell, thereby preventing moisture from entering the component interior and causing corrosion during subsequent outdoor use of the solar cell. In addition, the present invention uses a combination of conductive adhesive and UV adhesive to connect the solar cell to the glass, and then cures the conductive adhesive and UV adhesive simultaneously to directly bond the solar cell to the glass, which can improve the problem of solar cell shrinkage and bending. The specific implementation is as follows:

[0030] A packaging method for a back-contact solar cell, comprising the following steps:

[0031] Step 1: Use screen printing technology to print metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the solar cell, and perform high-temperature sintering on the glass with the printed paste to obtain conductive glass;

[0032] Step 2: Print conductive adhesive on the silver paste contact points of the positive and negative electrodes on the back of the solar cell, and print UV adhesive dots in the non-main grid area;

[0033] Step 3: Connect the positive contact point of the solar cell to the positive contact point on the conductive glass, connect the negative contact point of the solar cell to the negative contact point on the conductive glass, and bring the UV adhesive dots into contact with the non-conductive area of the conductive glass;

[0034] Step 4: Press the conductive glass on the surface of the solar cell, heat the conductive glass on the back of the solar cell to cure the conductive adhesive, and simultaneously irradiate the conductive glass with a UV lamp;

[0035] Step 5: Print glass solder on the four edges of the conductive glass, heat the four sides of the glass with a laser, melt the solder, and perform sealing after rapid cooling.

[0036] By printing glass solder on the four edges of the glass, melting it and then rapidly cooling it to connect with the solar cell, a tight connection can be formed between the four sides of the glass and the solar cell, thereby preventing moisture from entering the component interior and causing corrosion during subsequent outdoor use of the solar cell.

[0037] As a preferred embodiment, in step five, the glass solder is lead silicate glass, with a printing width of 5 - 10 mm and a thickness of 30 - 100 μm. The main components of the lead silicate glass are SiO2 and PbO, which have unique high refractive index and high volume resistance, good wettability with metals, and can block X-rays and γ-rays.

[0038] As a preferred embodiment, the lead silicate glass comprises 40 - 70% by mass of PbO and 20% - 30% by mass of SiO2.

[0039] As a preferred embodiment, in step five, the laser is an infrared laser, with a wavelength of 10.6 μm and a heating temperature of 400 - 600 °C.

[0040] As a preferred embodiment, in step one, the metal paste is copper or aluminum, with a high-temperature sintering temperature of 800 - 1000 °C and a sintering time of 10 - 30 min.

[0041] As a preferred embodiment, in step two, the UV glue dots are evenly distributed in the non-main grid area, with a diameter of the UV glue dots of 5 - 10 mm and a thickness of 100 - 300 μm. After traditional metal solder tapes are heated, they expand and elongate more than the solar cells. After cooling, due to the solder joints hindering the free contraction of the solder tapes, there is shrinkage stress, which causes the solar cells to bend. By using UV glue to replace the traditional metal solder tapes in the present invention and directly adhering the solar cells to the glass, the problem of shrinkage and bending of the solar cells can be improved.

[0042] As a preferred embodiment, in step four, the curing temperature of the conductive glue is 100 - 200 °C and the heating time is 10 - 20 s. The conductive glue is an adhesive that can effectively bond various materials and has electrical conductivity. It usually consists mainly of a matrix resin and a conductive filler, i.e., conductive particles. Through the bonding action of the matrix resin, the conductive particles are combined together to form a conductive path to achieve the electrical connection of the adhered materials.

[0043] As a preferred embodiment, in step four, the power of the UV lamp is 1 - 2 KW and the time is 2 - 4 s.

[0044] As a preferred embodiment, before step one, the following steps are further included: successively performing cleaning and texturing, front boron diffusion, and etching and alkaline polishing on the solar cells; successively depositing a tunneling oxide layer and a phosphorus-doped polysilicon layer on the back of the solar cells; RCA cleaning; and respectively depositing a front antireflection layer and a back antireflection layer on the front and back of the solar cells.

[0045] The present invention also provides a back-contact solar cell, which is obtained by encapsulating using the above encapsulation method.

[0046] The beneficial effects of a back-contact solar cell and its encapsulation method in the present invention are further reviewed through several sets of embodiments below.

[0047] Embodiment 1:

[0048] This Embodiment 1 provides a back-contact solar cell and its encapsulation method, which includes the following steps:

[0049] Step 1, use screen printing technology to print copper metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the cell, and perform high-temperature sintering on the glass with the printed paste at a temperature of 800 °C for 10 minutes to obtain conductive glass;

[0050] Step 2, print conductive glue on the silver paste contact points of the positive and negative electrodes on the back of the cell, and print UV glue dots in the non-main grid area. The diameter of the UV glue dots is 5 mm and the thickness is 100 μm;

[0051] Step 3, connect the positive contact point of the cell to the positive contact point on the conductive glass, connect the negative contact point of the cell to the negative contact point on the conductive glass, and make the UV glue dots contact the non-conductive area of the conductive glass;

[0052] Step 4, press the glass on the surface of the cell, and heat the conductive glass on the back of the cell to cure the conductive glue at a temperature of 100 °C for 10 seconds. At the same time, irradiate the conductive glass with a UV lamp. The power of the UV lamp is 1 KW and the time is 2 seconds;

[0053] Step 5, print glass solder lead silicate glass on the four edges of the glass. The printing width is 5 mm and the thickness is 30 μm. Use an infrared laser to heat the four sides of the glass. The wavelength is 10.6 μm and the temperature is 400 °C. The solder melts and is sealed after rapid cooling.

[0054] Embodiment 2:

[0055] This Embodiment 2 provides a back-contact solar cell and its encapsulation method, which includes the following steps:

[0056] Step 1, use screen printing technology to print aluminum metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the cell, and perform high-temperature sintering on the glass with the printed paste at a temperature of 850 °C for 15 minutes to obtain conductive glass;

[0057] Step 2, print conductive glue on the silver paste contact points of the positive and negative electrodes on the back of the cell, and print UV glue dots in the non-main grid area. The diameter of the UV glue dots is 7 mm and the thickness is 150 μm;

[0058] Step 3: Connect the positive contact point of the cell to the positive contact point on the conductive glass, and connect the negative contact point of the cell to the negative contact point on the conductive glass. Make the UV glue dots contact the non-conductive area of the conductive glass.

[0059] Step 4: Press the glass on the surface of the cell, and heat the conductive glass on the back of the cell to cure the conductive glue. The temperature is 120 °C, and the heating time is 12 s. At the same time, irradiate the conductive glass with a UV lamp. The power of the UV lamp is 1.5 KW, and the time is 3 s.

[0060] Step 5: Print lead silicate glass solder on the four edges of the glass. The printing width is 7 mm, and the thickness is 50 μm. Use an infrared laser to heat the four sides of the glass. The wavelength is 10.6 μm, and the temperature is 450 °C. The solder melts and is sealed after rapid cooling.

[0061] Example 3:

[0062] This Example 3 provides a back-contact solar cell and its encapsulation method includes the following steps:

[0063] Step 1: Use screen printing technology to print copper metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the cell, and perform high-temperature sintering on the glass with the printed paste. The temperature is 900 °C, and the time is 20 min to obtain conductive glass.

[0064] Step 2: Print conductive glue on the silver paste contact points of the positive and negative electrodes of the main grid on the back of the cell, and print UV glue dots in the non-main grid area. The diameter of the UV glue dots is 8 mm, and the thickness is 200 μm.

[0065] Step 3: Connect the positive contact point of the cell to the positive contact point on the conductive glass, and connect the negative contact point of the cell to the negative contact point on the conductive glass. Make the UV glue dots contact the non-conductive area of the conductive glass.

[0066] Step 4: Press the glass on the surface of the cell, and heat the conductive glass on the back of the cell to cure the conductive glue. The temperature is 140 °C, and the heating time is 14 s. At the same time, irradiate the conductive glass with a UV lamp. The power of the UV lamp is 2 KW, and the time is 4 s.

[0067] Step 5: Print lead silicate glass solder on the four edges of the glass. The printing width is 8 mm, and the thickness is 60 μm. Use an infrared laser to heat the four sides of the glass. The wavelength is 10.6 μm, and the temperature is 500 °C. The solder melts and is sealed after rapid cooling.

[0068] Example 4:

[0069] Embodiment 4 provides a back-contact solar cell and its encapsulation method, which includes the following steps:

[0070] Step 1: Use screen printing technology to print aluminum metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the cell, and perform high-temperature sintering on the glass with the printed paste at a temperature of 950 °C for 25 minutes to obtain conductive glass.

[0071] Step 2: Print conductive adhesive on the silver paste contact points of the positive and negative electrodes on the back of the cell, and print UV adhesive dots in the non-main grid area. The diameter of the UV adhesive dots is 9 mm and the thickness is 250 μm.

[0072] Step 3: Connect the positive contact point of the cell to the positive contact point on the conductive glass, connect the negative contact point of the cell to the negative contact point on the conductive glass, and make the UV adhesive dots contact the non-conductive area of the conductive glass.

[0073] Step 4: Press the glass on the surface of the cell, and heat the conductive glass on the back of the cell to cure the conductive adhesive at a temperature of 180 °C for 18 seconds. At the same time, irradiate the conductive glass with a UV lamp. The power of the UV lamp is 2 KW and the time is 3 seconds.

[0074] Step 5: Print lead silicate glass solder on the four edges of the glass. The printing width is 9 mm and the thickness is 80 μm. Use an infrared laser to heat the four sides of the glass. The wavelength is 10.6 μm and the temperature is 550 °C. The solder melts and is sealed after rapid cooling.

[0075] Embodiment 5:

[0076] Embodiment 5 provides a back-contact solar cell and its encapsulation method, which includes the following steps:

[0077] Step 1: Use screen printing technology to print copper metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the cell, and perform high-temperature sintering on the glass with the printed paste at a temperature of 1000 °C for 30 minutes to obtain conductive glass.

[0078] Step 2: Print conductive adhesive on the silver paste contact points of the positive and negative electrodes on the back of the cell, and print UV adhesive dots in the non-main grid area. The diameter of the UV adhesive dots is 10 mm and the thickness is 300 μm.

[0079] Step 3: Connect the positive contact point of the cell to the positive contact point on the conductive glass, connect the negative contact point of the cell to the negative contact point on the conductive glass, and make the UV adhesive dots contact the non-conductive area of the conductive glass.

[0080] Step 4: Press the glass on the surface of the cell, and heat the conductive glass on the back of the cell to cure the conductive adhesive. The temperature is 200°C, and the heating time is 20 s. At the same time, irradiate the conductive glass with a UV lamp. The power of the UV lamp is 2 KW, and the time is 2 s;

[0081] Step 5: Print the glass solder, lead silicate glass, on the four peripheral edges of the glass. The printing width is 10 mm, and the thickness is 100 μm. Heat the four sides of the glass with an infrared laser. The wavelength is 10.6 μm, and the temperature is 600°C. The solder melts and is sealed after rapid cooling.

[0082] Comparative Example 1:

[0083] This Comparative Example 1 provides a back-contact solar cell, and its encapsulation method includes the following steps:

[0084] Step 1: Prepare a back-contact cell, and the back of the cell is printed with a positive main grid line and a negative main grid line;

[0085] Step 2: Make insulating glue at the ends of the positive main grid line and the negative main grid line;

[0086] Step 3: Print solder paste on the positive and negative main grid lines on the back of the cell. First, bake it in a low-temperature oven at 100°C for pre-curing, and then melt it at 150°C for high-temperature connection to the silver paste on the cell;

[0087] Step 4: Lay a solder strip on the solder paste. After aligning and pressing the pad and the solder strip with a pressing tool, perform welding and fixing;

[0088] Step 5: Lay EVA, a cell string, EVA, and a backplane on the tempered glass in sequence, heat and form them integrally with a laminator, and apply glue around the component to install an aluminum frame to complete the encapsulation.

[0089] Comparative Example 2:

[0090] This Comparative Example 2 provides a back-contact solar cell, and its encapsulation method includes the following steps:

[0091] Step 1: Prepare a back-contact cell, and the back of the cell is printed with a positive main grid line and a negative main grid line;

[0092] Step 2: Make insulating glue at the ends of the positive main grid line and the negative main grid line;

[0093] Step 3: Print solder paste on the positive and negative main grid lines on the back of the cell. First, bake it in a low-temperature oven at 150°C for pre-curing, and then melt it at 185°C for high-temperature connection to the silver paste on the cell;

[0094] Step 4: Lay a solder strip on the solder paste. After aligning and pressing the pad and the solder strip with a pressing tool, perform welding and fixing;

[0095] Step 5: Lay EVA, cell strings, EVA, and backsheet on the tempered glass in sequence, heat and form them integrally using a laminator, and apply glue around the component to install an aluminum frame to complete the encapsulation.

[0096] Comparative Example 3:

[0097] This Comparative Example 3 provides a back-contact solar cell, and its encapsulation method includes the following steps:

[0098] Step 1: Prepare a back-contact cell, and print a positive main grid line and a negative main grid line on the back of the cell;

[0099] Step 2: Make insulating glue at the ends of the positive main grid line and the negative main grid line;

[0100] Step 3: Print solder paste on the positive and negative main grid lines on the back of the cell, first place it in a low-temperature oven at 150 °C for baking for pre-curing, and then place it at 185 °C for high-temperature melting to connect the silver paste on the cell;

[0101] Step 4: Lay a welding tape on the solder paste. After using a press tool to align and press the pads and the welding tape, perform welding and fixation;

[0102] Step 5: Print glass solder lead silicate glass on the four peripheral edges of the glass, with a printing width of 10 mm and a thickness of 100 μm. Use an infrared laser to heat the four peripheries of the glass, with a wavelength of 10.6 μm and a temperature of 600 °C. The solder melts and is quickly cooled for sealing.

[0103] Comparative Example 4:

[0104] This Comparative Example 4 provides a back-contact solar cell, and its encapsulation method includes the following steps:

[0105] Step 1: Use screen printing technology to print copper metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the cell, and perform high-temperature sintering on the printed paste glass at a temperature of 1000 °C for 30 min to obtain conductive glass;

[0106] Step 2: Print conductive glue on the silver paste contact points of the positive and negative electrodes of the main grid on the back of the cell, and print UV glue dots in the non-main grid area. The diameter of the UV glue dots is 10 mm and the thickness is 300 μm;

[0107] Step 3: Connect the positive contact point of the cell to the positive contact point on the conductive glass, connect the negative contact point of the cell to the negative contact point on the conductive glass, and make the UV glue dots contact the non-conductive area of the conductive glass;

[0108] Step 4: Press the glass on the surface of the cell, and heat the conductive glass on the back of the cell to cure the conductive adhesive. The temperature is 200 °C, the heating time is 20 s. At the same time, irradiate the conductive glass with a UV lamp. The power of the UV lamp is 2 KW, and the time is 2 s.

[0109] Step 5: Lay EVA, cell string, EVA, and backsheet on the tempered glass in sequence, and use a laminator to heat and form them integrally. Apply glue around the component to install the aluminum frame to complete the encapsulation.

[0110] Comparative Example 5:

[0111] This Comparative Example 5 provides a back-contact solar cell. Except for Step 5, lay POE, cell string, POE, and backsheet on the tempered glass in sequence, and use a laminator to heat and form them integrally. Apply glue around the component to install the aluminum frame to complete the encapsulation.

[0112] Others are the same as Comparative Example 4.

[0113] Next, the solar cells obtained in the above examples and comparative examples were subjected to performance tests, and the results are as follows:

[0114] Table 1 Warpage of the solar cells prepared in the examples and comparative examples

[0115] Solution Warpage of solar cell Example 1 0.5mm Example 2 0.3mm Example 3 0.4mm Example 4 0.25mm Example 5 0.35mm Comparative Example 1 5.6mm Comparative Example 2 5.7mm Comparative Example 3 5.4mm Comparative Example 4 0.4mm Comparative Example 5 0.5mm

[0116] Table 2 Water vapor transmission rate of the solar cells prepared in the examples and comparative examples

[0117] Solution Water vapor transmission rate Example 1 1.0g / ㎡.24h Example 2 0.8g / ㎡.24h Example 3 0.65g / ㎡.24h Example 4 0.75g / ㎡.24h Example 5 0.95g / ㎡.24h Comparative Example 1 25.3g / ㎡.24h Comparative Example 2 28.2g / ㎡.24h Comparative Example 3 0.75g / ㎡.24h Comparative Example 4 26.4g / ㎡.24h Comparative Example 5 7.3g / ㎡.24h

[0118] Examples 1 - 5 are solar cells prepared by adopting the technical solutions of the present invention, that is, connecting with the conductive glass using conductive adhesive and UV adhesive, and encapsulating through lead silicate glass solder. Comparative Examples 1 - 2 are solar cells obtained by conventional solder ribbon connection and laminator encapsulation, where EVA film is used for encapsulation; Comparative Example 3 is a solar cell obtained by conventional solder ribbon connection and encapsulation through lead silicate glass solder; Comparative Example 4 is a solar cell obtained by connecting with the conductive glass using conductive adhesive and UV adhesive, and laminator encapsulation, where EVA film is used for encapsulation; Comparative Example 5 is a solar cell obtained by connecting with the conductive glass using conductive adhesive and UV adhesive, and laminator encapsulation, where POE film is used for encapsulation.

[0119] As can be seen from Table 1, the warpage of the solar cell prepared by connecting the conductive adhesive and the UV adhesive with the conductive glass in the present invention is significantly lower than that of the hot welding with the solder tape, which can be obtained from Examples 1 to 5 and Comparative Examples 1 to 3. As can be seen from Table 2, for the solar cell prepared by encapsulation with the lead silicate glass solder in the present invention, its water vapor transmission rate is significantly better than that of the solar cell encapsulated with the EVA film or the POE film, which can be obtained from Examples 1 to 5 and Comparative Examples 1 to 2, Comparative Examples 3 to 4.

[0120] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A packaging method for a back-contact solar cell, characterized in that, It includes the following steps: Step 1: Use screen printing technology to print metal paste on the glass surface to form conductive lines corresponding to the positive and negative electrodes of the main grid of the battery cell, and perform high-temperature sintering on the glass printed with the paste to obtain conductive glass; Step 2: Print conductive adhesive on the silver paste contact points of the positive and negative electrodes of the main grid on the back of the battery cell, and print UV adhesive dots in the non-main grid area; Step 3: Connect the positive contact point of the battery cell to the positive contact point on the conductive glass, connect the negative contact point of the battery cell to the negative contact point on the conductive glass, and make the UV adhesive dots contact the non-conductive area of the conductive glass; Step 4: Press the conductive glass on the surface of the battery cell, heat the conductive glass on the back of the battery cell to cure the conductive adhesive, and irradiate the conductive glass with a UV lamp at the same time; Step 5: Print glass solder on the four peripheral edges of the conductive glass, use a laser to heat the four sides of the glass, the solder melts, and it is sealed after rapid cooling.

2. The encapsulation method of the back-contact solar cell according to claim 1, wherein In step 5, the glass solder is lead silicate glass, the printing width is 5 - 10 mm, and the thickness is 30 - 100 μm.

3. The encapsulation method of the back-contact solar cell according to claim 1, characterized in that The lead silicate glass includes 40 - 70% by mass of PbO and 20% - 30% by mass of SiO2.

4. The encapsulation method of the back-contact solar cell according to claim 1, characterized in that, In step 5, the laser is an infrared laser, the wavelength is 10.6 μm, and the heating temperature is 400 - 600 °C.

5. The encapsulation method of the back-contact solar cell according to claim 1, characterized in that, In step 1, the metal paste is copper or aluminum, the high-temperature sintering temperature is 800 - 1000 °C, and the sintering time is 10 - 30 min.

6. The encapsulation method of the back-contact solar cell according to claim 1, characterized in that, In step 2, the UV adhesive dots are evenly distributed in the non-main grid area, the diameter of the UV adhesive dots is 5 - 10 mm, and the thickness is 100 - 300 μm.

7. The encapsulation method of the back-contact solar cell according to claim 1, characterized in that, In step 4, the curing temperature of the conductive adhesive is 100 - 200 °C, and the heating time is 10 - 20 s.

8. The encapsulation method of the back-contact solar cell according to claim 1, characterized in that, In step 4, the power of the UV lamp is 1 - 2 KW, and the time is 2 - 4 s.

9. The encapsulation method of the back-contact solar cell according to claim 1, characterized in that, Before step 1, the following steps are also included: successively perform cleaning and texturing, front boron diffusion and etching and alkali polishing on the battery cell; successively deposit a tunneling oxide layer and a phosphorus-doped polysilicon layer on the back of the battery cell; perform RCA cleaning; deposit a front anti-reflection layer and a back anti-reflection layer on the front and back of the battery cell respectively.

10. A back-contact battery, characterized in that, It is obtained by encapsulation using the encapsulation method described in any one of claims 1 - 9.

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