Main-grid-free back contact battery assembly and photovoltaic system

Abstract

The invention discloses a main-grid-free back contact battery assembly and a photovoltaic system, and the main-grid-free back contact battery assembly comprises main-grid-free back contact battery pieces which are arranged along a first direction. The backlight surface of the main-grid-free back contact battery piece is provided with grid lines which are alternately arranged along a first direction and are opposite in polarity and pad points which are alternately arranged along a second direction and are opposite in polarity, and the pad points are electrically connected with the grid lines with the same polarity and are insulated from the grid lines with the opposite polarity; the pad point is provided with an end line, one end of the end line is connected with the pad point along a first direction, the end line is electrically connected with the grid line with the same polarity, and the grid line with the polarity opposite to that of the end line is provided with a discontinuous part, so that the end line is insulated from the grid line with the polarity opposite to that of the end line; the solder strips are alternately arranged along a second direction, and the solder strips are electrically connected with the grid lines with one polarity through the pad points and are insulated from the grid lines with the other polarity; and along a second direction, the projection of the welding strip on the main-grid-free back contact battery piece and the end line are mutually staggered, the welding strip is partially arranged on the discontinuous part, and a preset distance is formed between the welding strip and the grid line which is arranged in an insulating manner. According to the invention, the end part of the solder strip extending out of the pad point can be prevented from puncturing the insulating layer to be communicated with the grid line needing to be insulated, and the risk of short circuit of the main-grid-free back contact battery piece is reduced.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a gridless back-contact solar cell module and photovoltaic system. Background Technology

[0002] In gridless back-contact solar cell modules, solder ribbons are primarily used for connecting the cells. The ribbons are electrically connected to one type of grid line on the cell, while being insulated from the other type of grid line through an insulating layer. To prevent the ends of the solder ribbons from extending beyond the edge of the cell and causing a short circuit, the ends of the solder ribbons need to maintain a certain distance from the edge of the cell. To improve current collection efficiency, pad points are set at the edge of the cell to collect the current and converge it onto the solder ribbon connected to the pad points. If the ends of the solder ribbons extend beyond the pad points, they may puncture the insulating layer, causing the ends of the solder ribbons to come into contact with the grid lines that need to be insulated, resulting in a short circuit and reducing the photoelectric conversion efficiency and reliability of the gridless back-contact solar cell module. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a gridless back contact cell module and photovoltaic system, which avoids the solder strip end protruding from the pad point from piercing the insulation layer and connecting with the grid line that needs to be insulated, thereby reducing the risk of short circuit in gridless back contact cells.

[0004] To address the aforementioned technical problems, this invention provides a gridless back-contact battery assembly, comprising gridless back-contact battery cells arranged along a first direction. The back surface of the gridless back-contact battery cells has grid lines arranged alternately along the first direction with opposite polarities and pad points arranged alternately along a second direction with opposite polarities. The pad points are electrically connected to the grid lines of the same polarity and insulated from the grid lines of opposite polarities. Each pad point has an end line. Along the first direction, one end of the end line is connected to the pad point. The end line is electrically connected to the grid lines of the same polarity, and the grid lines with opposite polarities have a discontinuity to insulate the end lines from the grid lines of opposite polarities. The solder strips are arranged alternately along a second direction, and the solder strips are electrically connected to a grid line of one polarity through the pad point and insulated from a grid line of another polarity. Along the second direction, the projection of the solder strip on the back contact cell without main grid is offset from the end line, the solder strip is partially disposed on the discontinuity, and there is a preset distance between the solder strip and the grid line which is insulated.

[0005] As an improvement to the above scheme, along the second direction, the width of the discontinuity is L1, and the preset distance is L2, where L1 and L2 satisfy: L2:L1 = 0.2~0.7.

[0006] As an improvement to the above scheme, L1 and L2 satisfy: L2:L1 = 0.3~0.5.

[0007] As an improvement to the above solution, along the first direction, the gridless back contact solar cell is provided with a first region and a second region. The first region is located close to the edge of the gridless back contact solar cell, and the second region is located away from the edge of the gridless back contact solar cell relative to the first region. The pad point is located in the first area, and the solder strip extends along the first direction, with the projection of the solder strip on the back contact cell without main grid coinciding with the pad point.

[0008] As an improvement to the above solution, the end line extends along the first direction, and along the second direction, there is an offset distance L3 between the end line and the center line of the pad point.

[0009] As an improvement to the above scheme, L3 is 0.5mm~1.5mm.

[0010] As an improvement to the above scheme, along the second direction, the solder strip coincides with the center line of the pad point.

[0011] As an improvement to the above solution, along the second direction, the positive projection range of the solder strip on the non-main grid back contact cell partially covers the end line.

[0012] As an improvement to the above solution, along the second direction, the orthogonal projection range of the solder strip on the non-main grid back contact cell does not cover the end line, so that the end line is exposed outside the solder strip.

[0013] As an improvement to the above scheme, along the second direction, the distance between the welding strip and the end line is L4, where L4 is 0.3mm to 1.5mm.

[0014] As an improvement to the above solution, along the first direction, the distance between the solder strip and the edge of the gridless back contact cell is greater than the distance between the end of the end line away from the pad point and the edge of the gridless back contact cell.

[0015] As an improvement to the above scheme, along the second direction, the distance between the gate line with the opposite polarity to the pad point and the pad point is L5, and L2 and L5 satisfy: L5 < L2.

[0016] As an improvement to the above scheme, along the second direction, the width of the solder strip is smaller than the width of the pad point, and the width of the solder strip is larger than the width of the end line.

[0017] As an improvement to the above scheme, in the second region, the solder strip is electrically connected to a gate line of one polarity and insulated from a gate line of another polarity through an insulating layer.

[0018] As an improvement to the above scheme, along the first direction, the second region is located between two adjacent first regions.

[0019] Accordingly, the present invention also provides a photovoltaic system including the above-mentioned gridless back contact cell module.

[0020] Implementing this invention has the following beneficial effects: In this invention, the projection of the solder strip on the back contact cell without a main grid is staggered from the end line, which can avoid stress concentration and microcracks caused by the solder strip completely covering the end line. Furthermore, there is an interruption on the grid line with opposite polarity of the end line, and the solder strip is located on the interruption. There is a preset distance between the solder strip and the grid line that is insulated. When the solder strip extends beyond the pad point, the solder strip does not contact the grid line that needs to be insulated, and there is no grid line with opposite polarity to the end line between the solder strip and the end line. This ensures that the grid line current is smoothly discharged while avoiding short circuits caused by the solder strip end contacting the grid line that needs to be insulated. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a gridless back contact battery assembly provided in an embodiment of the present invention; Figure 2 yes Figure 1 Enlarged view of part A; Figure 3 This is a schematic diagram of the structure of a gridless back-contact battery assembly provided in another embodiment of the present invention; Figure 4 yes Figure 3 Enlarged view of part B. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] In this invention, references to "embodiment" or "implementation" mean that a particular feature, component, or characteristic described in connection with an embodiment or implementation may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "left," "right," "horizontal," "top," and "bottom," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a gridless back contact battery assembly, including gridless back contact battery cells 100 arranged along a first direction. The back surface of the gridless back contact battery cell 100 has grid lines 1 arranged alternately along the first direction and with opposite polarities, and pad points 2 arranged alternately along a second direction and with opposite polarities. The pad points 2 are electrically connected to the grid lines 1 with the same polarity and are insulated from the grid lines 1 with opposite polarities. The pad points 2 are provided with end lines 3. Along the first direction, one end of the end line 3 is connected to the pad point 2. The end line 3 is electrically connected to the grid lines 1 with the same polarity. The grid lines 1 with opposite polarities to the end line 3 are provided with discontinuities 11 to insulate the end line 3 from the grid lines 1 with opposite polarities. Solder strip 4, the solder strip 4 is arranged alternately along the second direction, the solder strip 4 is electrically connected to a grid line 1 of one polarity through the pad point 2, and is insulated from a grid line 1 of another polarity; Along the second direction, the projection of the solder strip 4 onto the non-main grid back contact cell 100 is offset from the end line 3. The solder strip 4 is partially disposed on the discontinuity 11, and there is a preset distance between the solder strip 4 and the insulated grid line 1.

[0027] The projection of the solder ribbon 4 on the back contact cell without a main grid in this invention is staggered from that of the end line 3, which can avoid stress concentration and microcracks caused by the solder ribbon 4 completely covering the end line 3. Furthermore, the grid line 1 with opposite polarity of the end line 3 is provided with a discontinuity 11, and the solder ribbon 4 is partially provided on the discontinuity 11. There is a preset distance between the solder ribbon 4 and the grid line 1 that is insulated. When the solder ribbon 4 extends out of the pad point 2, the solder ribbon 4 does not contact the grid line 1 that needs to be insulated, and there is no grid line 1 with opposite polarity to the end line 3 between the solder ribbon 4 and the end line 3. This ensures that the current of the grid line 1 is smoothly discharged while avoiding short circuit caused by the end of the solder ribbon 4 contacting the grid line 1 that needs to be insulated.

[0028] In embodiments of the present invention, the first direction and the second direction are arranged intersectingly, preferably, the first direction and the second direction are arranged perpendicularly. Specifically, the first direction can be the length direction of the gridless back contact cell 100, and the second direction can be the width direction of the gridless back contact cell 100.

[0029] The gridless back-contact solar cells 100 can be located on the same plane or overlapped to form a shingled structure, but are not limited thereto. The gridless back-contact solar cells 100 can be a single solar cell or segmented solar cells; specifically, they can be segments cut from a single solar cell into two, three, or four segments, but are not limited thereto. Preferably, in one embodiment, the gridless back-contact solar cell 100 is a segment cut from a single solar cell.

[0030] In one embodiment, along the second direction, the width of the interruption 11 is L1, and the preset distance is L2. L1 and L2 satisfy: L2:L1 = 0.2~0.7, exemplarily 0.25, 0.3, 0.4, 0.5, or 0.6, but not limited thereto. The interruption 11 ensures insulation between the end wire 3 and the gate wire 1 requiring insulation, while providing sufficient space for the placement of the solder ribbon 4, preventing the solder ribbon 4 from contacting the gate wire 1 after being placed behind the interruption 11, thus avoiding a short circuit. If L2:L1 < 0.2, the preset distance between the end of the solder ribbon 4 and the gate wire 1 requiring insulation is too small. If the placement of the solder ribbon 4 is offset, it may lead to communication between the solder ribbon 4 and the gate wire 1 requiring insulation. If L2:L1 > 0.7, in order to reserve sufficient placement space for the solder ribbon 4, the width of the interruption 11 needs to be increased accordingly. An excessively large interruption 11 increases the transmission path of charge carriers in the gate-free region, thereby increasing power loss. Preferably, L1 and L2 satisfy: L2:L1 = 0.3~0.5. It can be understood that the preset distance L2 is the distance between the edge of the solder strip 4 away from the end line 3 and the gate line 1 that needs to be insulated.

[0031] In one embodiment, along a first direction, the gridless back contact solar cell 100 is provided with a first region 110 and a second region 120. The first region 110 is located close to the edge of the gridless back contact solar cell 100, and the second region 120 is located away from the edge of the gridless back contact solar cell 100 relative to the first region 110. The pad point 2 is located within the first region 110. The solder ribbon 4 extends along the first direction, and its projection on the gridless back contact cell 100 coincides with the pad point 2. It is understood that the grid line 1 within the second region 120 may or may not have an interruption 11. In a preferred embodiment, the grid line 1 within the second region 120 does not have an interruption 11. An insulating layer is simply placed between the solder ribbon 4 and the grid line 1 to prevent contact between the solder ribbon 4 and the grid line 1, thus reducing the fabrication difficulty of the grid line 1. To prevent the end of the solder ribbon 4 from protruding from the pad point 2 and piercing the insulating layer, the solder ribbon portion is placed on the interruption 11 to ensure that the solder ribbon 4 and the grid line 1 are not connected.

[0032] In a preferred embodiment, along the first direction, the second region 120 is located between two adjacent first regions 110. That is, the gridless back-contact solar cell 100 has two first regions 110. Along the first direction, the first regions 110 are located at the beginning and end of the gridless back-contact solar cell 100, and the second region 120 is located between the two first regions 110. Each solder strip 4 extends along the first direction and is disposed on the first region 110 and the second region 120, with the two ends of the solder strip 4 respectively disposed on the two first regions 110. Optionally, the grid line 1 structures of the two first regions 110 can be the same or different; preferably, the grid line 1 structures of the two first regions 110 can be the same.

[0033] Along the second direction, the projection of the solder ribbon 4 onto the gridless back contact cell 100 is offset from the end line 3, avoiding the adverse effects caused by the solder ribbon 4 completely covering the end line 3. Specifically, in one embodiment, the end line 3 extends along the first direction, and along the second direction, there is an offset distance L3 between the end line 3 and the center line of the pad point 2. Specifically, the offset distance L3 is 0.5mm to 1.5mm, exemplarily 0.6mm, 0.8mm, 1mm, 1.2mm, or 1.4mm, but is not limited thereto.

[0034] In one embodiment, the solder strip coincides with the centerline of the pad point along the second direction to improve current collection efficiency. It is understood that, in this case, the orthogonal projection range of the solder strip 4 onto the gridless back contact cell 100 along the second direction may partially cover or not cover the end line 3.

[0035] Preferred, such as Figure 3 and Figure 4 As shown, the orthogonal projection range of the solder ribbon 4 on the gridless back contact cell 100 does not cover the end line 3, so that the end line 3 is exposed outside the solder ribbon 4. More preferably, along the second direction, the distance between the solder ribbon and the end line is L4, where L4 is 0.3mm to 1.5mm, exemplarily 0.5mm, 0.8mm, 1mm, 1.2mm, or 1.4mm, but not limited to these. If L4 < 0.3mm, to avoid the adhesive dots fixing the solder ribbon 4 from adversely affecting the end line 3, the width of the adhesive dots along the second direction needs to be reduced accordingly, resulting in a decrease in the connection stability between the solder ribbon 4 and the pad point 2; if L4 > 1.5mm, the gridless area between the solder ribbon 4 and the end line 3 is large, which is not conducive to the collection and output of current in this area. In addition, by exposing the end line 3 outside the solder ribbon 4, the offset end line 3 can also serve as a positioning reference for the solder ribbon 4 during the setting process, improving the positioning accuracy of the solder ribbon 4. At the same time, it can also ensure the accuracy of the electrical connection between the solder strip 4 and the pad point 2, reduce problems such as poor contact caused by the position deviation of the solder strip 4, and improve the electrical connection reliability of the gridless back contact battery module.

[0036] Understandably, the end wire 3 can be used for testing as well as for pad spot welding of the solder strip 4, reducing process and space waste and improving battery efficiency.

[0037] Specifically, along the first direction, the distance between the solder ribbon 4 and the edge of the gridless back contact cell 100 is greater than the distance between the end of the end line 3 away from the pad point 2 and the edge of the gridless back contact cell 100. Compared to the middle region, the area near the edge of the cell has a higher surface state density and defects, making recombination more likely. Therefore, setting the end line 3 closer to the edge of the cell in the first direction relative to the solder ribbon 4 can shorten the current transmission distance of the grid lines near the edge of the cell, reduce recombination, reduce output loss, and increase overall output power. Moreover, the end of the end line can also be connected to the outermost grid line 1 of the gridless back contact cell 100, realizing full-edge collection of current on the gridless back contact cell 100.

[0038] Furthermore, along the second direction, the distance between the gate line 1 (with polarity opposite to that of the pad point 2) and the pad point 2 is L5, where L5 < L2. The width of the solder strip 4 is less than the width of the pad point 2, and the width of the solder strip 4 is greater than the width of the end line 3. Since the solder strip 4 is disposed on the pad point 2, the distance between the pad point 2 and the gate line 1 (with polarity opposite) does not need to be set too large; it is only necessary to ensure that the two are insulated.

[0039] It is understood that the gridless back-contact battery assembly provided in this embodiment of the invention may include a battery string layer, a frame, a cover plate, and an adhesive film. The battery string layer includes, but is not limited to, the aforementioned gridless back-contact battery cell 100, solder ribbon 4, insulating layer, and busbar. The adhesive film may be filled between the battery string layer and the back plate and / or cover plate. As a filler, the adhesive film may be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0040] A cover plate can be placed over the front of the battery string layer. The cover plate can be made of ultra-clear glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the back contact batteries while minimizing impact on their efficiency. Simultaneously, an adhesive film bonds the cover plate and the battery string layer together, providing sealing, insulation, and waterproofing / moisture protection for the battery string layer.

[0041] The backplate can be attached to the back of the battery string layer. The backplate can protect and support the battery string layer, and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplate, which can usually be tempered glass, plexiglass, aluminum alloy TPT composite film, etc. The specific choice can be set according to the specific situation, and there are no restrictions here.

[0042] The backsheet, battery string layer, encapsulant film, and cover plate can be set on the frame. The frame serves as the main external support structure for the entire gridless back contact battery module and can provide stable support and installation for the gridless back contact battery module.

[0043] Accordingly, this invention also provides a photovoltaic system, including the aforementioned gridless back-contact battery module. In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants, and can also be applied to equipment or devices that utilize solar energy for power generation, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy for power generation. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0044] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A gridless back-contact battery assembly, characterized in that, The device includes gridless back-contact solar cells arranged along a first direction. The back surface of the gridless back-contact solar cell has grid lines arranged alternately along the first direction with opposite polarities and pads arranged alternately along a second direction with opposite polarities. The pads are electrically connected to the grid lines of the same polarity and insulated from the grid lines of opposite polarities. Each pad has an end line. Along the first direction, one end of the end line is connected to the pad. The end line is electrically connected to the grid lines of the same polarity. The grid lines with opposite polarities have a discontinuity to insulate the end lines from the grid lines of opposite polarities. The solder strips are arranged alternately along a second direction, and the solder strips are electrically connected to a grid line of one polarity through the pad point and insulated from a grid line of another polarity. Along the second direction, the projection of the solder strip on the back contact cell without main grid is offset from the end line, the solder strip is partially disposed on the discontinuity, and there is a preset distance between the solder strip and the grid line which is insulated.

2. The gridless back-contact battery assembly as described in claim 1, characterized in that, Along the second direction, the width of the discontinuity is L1, and the preset distance is L2, where L1 and L2 satisfy: L2:L1 = 0.2~0.

7.

3. The gridless back-contact battery assembly as described in claim 2, characterized in that, L1 and L2 satisfy the condition: L2:L1 = 0.3~0.

5.

4. The gridless back-contact battery assembly as described in claim 1, characterized in that, Along a first direction, the gridless back contact solar cell has a first region and a second region. The first region is located close to the edge of the gridless back contact solar cell, and the second region is located away from the edge of the gridless back contact solar cell relative to the first region. The pad point is located in the first area, and the solder strip extends along the first direction and the projection of the solder strip on the back contact cell without main grid coincides with the pad point.

5. The gridless back-contact battery assembly as described in claim 1, characterized in that, The end line extends along the first direction, and along the second direction, there is an offset distance L3 between the end line and the center line of the pad point.

6. The gridless back-contact battery assembly as described in claim 5, characterized in that, L3 is 0.5mm~1.5mm.

7. The gridless back-contact battery assembly as described in claim 4, characterized in that, Along the second direction, the solder strip coincides with the center line of the pad point.

8. The gridless back-contact battery assembly as described in claim 7, characterized in that, Along the second direction, the solder strip partially covers the end line within the orthogonal projection range on the gridless back contact cell.

9. The gridless back-contact battery assembly as described in claim 7, characterized in that, Along the second direction, the orthogonal projection of the solder strip onto the gridless back contact cell does not cover the end line, so that the end line is exposed outside the solder strip.

10. The gridless back-contact battery assembly as described in claim 9, characterized in that, Along the second direction, the distance between the solder strip and the end line is L4, where L4 is 0.3mm to 1.5mm.

11. The gridless back-contact battery assembly as described in claim 1, characterized in that, Along the first direction, the distance between the solder strip and the edge of the gridless back contact cell is greater than the distance between the end of the end line away from the pad point and the edge of the gridless back contact cell.

12. The gridless back-contact battery assembly as described in claim 1, characterized in that, Along the second direction, the distance between the gate line with the opposite polarity to the pad point and the pad point is L5, and L2 and L5 satisfy: L5 < L2.

13. The gridless back-contact battery assembly as described in claim 1, characterized in that, Along the second direction, the width of the solder strip is less than the width of the pad point, and the width of the solder strip is greater than the width of the end line.

14. The gridless back-contact battery assembly as described in claim 4, characterized in that, In the second region, the solder strip is electrically connected to a gate line of one polarity and insulated from a gate line of another polarity by an insulating layer.

15. The gridless back-contact battery assembly as described in claim 4, characterized in that, Along the first direction, the second region is located between two adjacent first regions.

16. A photovoltaic system, characterized in that, Includes the gridless back contact battery assembly as described in any one of claims 1 to 15.

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