WO2017117125A1

WO2017117125A1 - Systems and methods for production and testing of segmented pv cells

Info

Publication number: WO2017117125A1
Application number: PCT/US2016/068705
Authority: WO
Inventors: Sandeep Rammohan KOPPIKAR; Lee William FERRY; Aditya Janardan DESHPANDE; Eugene Rhee; Bhavananda Reddy NADIMPALLY; Gang Shi; Rituraj NANDAN
Original assignee: Sunedison, Inc.
Priority date: 2015-12-31
Filing date: 2016-12-27
Publication date: 2017-07-06

Abstract

A method of manufacturing a photovoltaic (PV) module includes disposing a first set of fingers for a first PV cell segment on a first section of a silicon substrate. A second set of fingers for a second PV cell segment is disposed on a second section of the silicon substrate. The first set of fingers and the second set of fingers are separated by an isolation gap. At least one busbar is disposed on the silicon substrate proximate the isolation gap. The at least one busbar is electrically coupled to at least one of the first set of fingers and the second set of fingers. The method further includes contacting the at least one busbar with a contact member of a cell tester to test the first PV cell segment and the second PV cell segment.

Description

SYSTEMS AND METHODS FOR PRODUCTION AND

TESTING OF SEGMENTED PV CELLS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Indian provisional patent application no. 4353/DEL/2015 , filed 31 December 2015, which is hereby incorporated by reference in its entirety.

FIELD

[0002] This disclosure generally relates to photovoltaic (PV) modules and, more specifically, to systems and methods for production and testing of segmented PV cells.

BACKGROUND

[0003] At least some known solar modules include several photovoltaic (PV) cells (connected in series and/or in parallel) that generate electricity in response to sunlight incident on the surface of the cells.

[0004] To extract energy from the PV cells, electrodes are manufactured on one or both faces of a crystalline silicon substrate. In some known PV modules, the electrodes include fingers. Two or more busbars are connected to at least one of a top surface and a bottom surface of the PV cells in contact with the fingers to extract current carried by the fingers. The busbars are typically spaced apart so that the distance that current must travel in the fingers to reach a busbar is similar in all directions. The PV cells are typically subjected to I- V curve testing before incorporation into a string of PV cells to measure the output of the PV cells for sorting by cell current and efficiency. To test the PV cells, a cell tester's test electrodes simultaneously contact each busbar of the cell. The test electrodes are spaced apart by a fixed amount to align properly with the busbars on the PV cell.

[0005] In some systems multiple, smaller, electrically isolated PV cell segments are fabricated on one silicon substrate. Each of the cell segments includes fingers and a busbar. These cell segments are mechanically separated or singulated from one another before being interconnected into strings. The individual cell segments may be subjected to I-V curve testing after being

singulated through use of specially constructed segment test equipment. However, such equipment needs to be specifically constructed for testing cell segments and requires more test operations per silicon substrate, thereby increasing the time and cost of production.

Testing the segments prior to singulation is typically not possible with existing equipment because the busbars are positioned in different locations on a single PV cell silicon substrate than busbars on a silicon substrate with multiple PV cell segments.

[0006] For example, Figure 1 shows prior art arrangements of busbars 10 on PV cells 12 and busbars 14 on PV cells 16. PV cells 12 have a standard configuration and PV cells 16 have a segmented configuration. As shown in Figure 1, busbars 14 do not align with busbars 10. In particular, the six busbars 14 connected to PV cells 16 do not align with the three busbars 10 connected to PV cells 12. Accordingly, it may not be possible to test PV cells 16 with a standard cell tester including three test electrodes configured for testing PV cells 12.

[0007] This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure.

Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art .

BRIEF SUMMARY

[0008] In one aspect, a method of

manufacturing a photovoltaic (PV) module includes disposing a first set of fingers for a first PV cell segment on a first section of a silicon substrate. A second set of fingers for a second PV cell segment is disposed on a second section of the silicon substrate. The first set of fingers and the second set of fingers are separated by an isolation gap. At least one busbar is disposed on the silicon substrate proximate the isolation gap. The at least one busbar is electrically coupled to at least one of the first set of fingers and the second set of fingers. The method further includes contacting the at least one busbar with a contact member of a cell tester to test the first PV cell segment and the second PV cell segment.

[0009] In another aspect, a photovoltaic (PV) cell for singulation into PV cell segments includes a first set of fingers for a first PV cell segment on a first section of a silicon substrate and a second set of fingers for a second PV cell segment on a second section of the silicon substrate. The first set of fingers and the second set of fingers are separated by a first isolation gap. A third set of fingers for a third PV cell segment is on a third section of the silicon substrate. The second set of fingers and the third set of fingers are separated by a second isolation gap. A fourth set of fingers for a fourth PV cell segment is on a fourth section of the silicon substrate. The third set of fingers and the fourth set of fingers are separated by a third isolation gap. A first busbar is on the silicon substrate proximate the first isolation gap. The first busbar is electrically coupled to at least one of the first set of fingers and the second set of fingers. A second busbar is on the silicon substrate proximate the third isolation gap. The second busbar is electrically coupled to at least one of the third set of fingers and the fourth set of fingers.

[0010] Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above- mentioned aspects as well. These refinements and

additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above -described aspects, alone or in any combination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a top plan view of prior art

PV cells; [0012] Fig. 2 is a perspective view of an example PV module;

[0013] Figs. 3-6 are top plan views of PV cells for use in the PV module shown in Fig. 2;

[0014] Fig. 7 is a bottom plan view of PV cells for use in the PV module shown in Fig. 2;

[0015] Fig. 8 is a schematic view comparing locations of busbars on the front and back sides of PV cells; and

[0016] Fig. 9 is a side view of contact members of PV cell testers.

[0017] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0018] Referring initially to Figure 2, a PV module of one embodiment is indicated generally by

reference number 100. A perspective view of PV module 100 is shown in Figure 2. PV module 100 includes a PV laminate 102 and a frame 104 circumscribing PV laminate 102. PV laminate 102 includes a top surface 106 and a bottom surface (not shown) . In this embodiment, PV laminate 102 is rectangular shaped. In other embodiments, PV laminate 102 may have any suitable shape.

[0019] PV laminate 102 has a laminate structure that includes several layers. The layers may include, for example, glass layers, non-reflective layers, electrical connection layers, n-type silicon layers, p-type silicon layers, ethylene vinyl acetate (EVA) layers, and/or backing layers. In normal operation of PV module 100, PV module 100 is oriented such that top surface 106 faces the sun and bottom surface faces away from the sun. In other

embodiments, PV laminate 102 may have more or fewer, including one, layers, may have different layers, and/or may have different types of layers.

[0020] As shown in Figure 2, frame 104 circumscribes PV laminate 102 and is coupled to PV laminate 102. Frame 104 assists in protecting PV laminate 102. In the example embodiment, frame 104 is made of aluminum.

More particularly, in some embodiments frame 104 is made of 6000 series anodized aluminum. In other embodiments, frame 104 may be made of any other suitable material providing sufficient rigidity including, for example, rolled or stamped stainless steel, plastic, or carbon fiber.

[0021] Referring now to Figure 3, at least one layer 118 of PV laminate 102 includes photovoltaic (PV) cells 201. In one suitable embodiment, cells 201 are constructed from crystalline silicon wafers. Each cell 201 has a front surface 202 and a rear surface. Each cell 201 is operable to convert the energy of light (e.g., solar energy) into electricity via the photovoltaic effect.

Cells 201 are arranged in two or more electrically isolated sections 203. Sections 203 are mechanically separated or singulated from one another before being interconnected into strings.

[0022] Fingers 204 are disposed on front surface 202 of each cell 201 according to any suitable process, such as screen printing. The number, size, configuration, and spacing of fingers 204 shown in the Figures is an example and may be modified. Moreover, only one such finger 204 is numbered in the Figures. These fingers 204 are electrically connected to front surface 202 of each cell 201 to conduct electricity generated by the cell. As shown in the Figures, fingers 204 are spaced apart from each other and thus separated by gaps.

Moreover, fingers 204 are arranged in sets of fingers 204 that are separated by isolation gaps. Isolation gaps electrically separate two PV segments or the fingers of two segments .

[0023] Busbars 210 are disposed on front surface 202 of cells 201 and are connected to fingers 204 to conduct electricity from fingers 204. In particular, busbars 210 are disposed adjacent the isolation gaps between sets of fingers 204. Six busbars 210 are depicted in the embodiment of Figure 3, although other embodiments may use different numbers of busbars 210. In embodiments, busbars 210 may have suitable widths measured in a

direction transverse to the longitudinal direction of busbars 210. For example, busbars 210 may have a width in a range between about 0.5 mm and about 1.5 mm. In some embodiments, busbars 210 may have a double, or greater, width such that busbars 210 may be connected to multiple sections and divided after testing.

[0024] In the illustrated embodiment, cells 201 are scribed and singulated into strips 212, which are overlapped, i.e., shingled, into a string 214. Suitably, cells 201 may be any size. For example, cells 201 may be at least one of the following sizes: 156mm, a Nl standard size, a N1+ standard size, and any other suitable sizes. Suitably, the widths of busbars 210 facilitate connecting cells 201. For example, in some embodiments, the width is large enough to allow electrically conductive adhesive to be applied to busbars 210 and to provide an overlap for connecting cells 201. In addition, the size of the width is limited to reduce waste and inefficiencies.

[0025] Figure 3 shows an arrangement of cells 201 where busbars 210 are spaced apart varying distances. In particular, at least one pair of adjacent busbars 210 i closely spaced to facilitate contacts on a standard tester simultaneously contacting both busbars 210. Accordingly, the locations of busbars 210 approximate the locations of standard number of busbars 210. For example, the

illustrated cell arrangement includes six busbars 210 that may be contacted by a standard tester including 3 busbar contacts. Figures 3-5 illustrate specific examples where busbars 210 connected to cells 201 are located to

approximate standard busbar locations. In particular, Figure 3 illustrates a l/6-cut cell pattern having 6 busbars that emulates a 3 busbar cell. Figure 4

illustrates a 1/4 -cut cell pattern having 4 busbars that emulates a 2 busbar cell. Figure 5 illustrates a 1/3 -cut cell pattern having 3 busbars that emulates a 2 busbar cell. In other embodiments, a 1/8 -cut cell pattern emulates a 4 busbar cell. In further embodiments, busbars 210 may be configured to approximate locations of any suitable numbers of busbars.

[0026] In addition, Figure 4 compares busbars 210 having standard positioning to busbars 210 configured to emulate a 2 busbar cell. Bus bars 210 having standard positioning may require a custom cell tester to test.

However, busbars 210 emulating the standard 2 busbar cell include adjacent pairs of busbars 210 that are closely spaced such that a single contact member of a cell tester can contact each pair of busbars 210.

[0027] In some embodiments, multiple sections 203 may share a single busbar 210. For example, busbar 210 may extend across a gap between two sections 203 such that cells 201 of different sections 203 may be tested by contacting the single busbar 210. After testing, sections 203 may be divided along a line through busbar 210 such that busbar 210 is divided into portions attached to each respective section 203. In further embodiments, PV module 100 may include some busbars 210 connecting multiple sections 203 and some pairs of busbars 210 on adjacent sections 203 separated by a gap.

[0028] Suitably, at least some of busbars 210 may be spaced apart any distance that enables busbars 210 to be contacted by a single contact member. In the illustrated embodiment, some busbars 210 are spaced apart less than approximately 1 mm to facilitate adjacent busbars 210 being contacted by a single contact member. In some embodiments, busbars 210 may be spaced apart a distance greater than the size of the contact sensors.

[0029] As shown in Figures 6-8, interconnects 218 can be disposed between busbars 210 to facilitate busbars 210 making electrical connection with the contact members of the standard tester. Suitably, interconnects 218 are located at an approximate position of a probe of a tester and form a bridge to connect adjacent busbars 210. The bridge between busbars 210 can be severed during further processing. Figures 6 and 7 show front and rear sides of PV module 100 including interconnects 218. As shown in Figure 8, interconnects 218 between corresponding pairs of busbars 210 on the front and rear sides of PV module 100 can be staggered to reduce the risk of shunting. Interconnects 218 on the front and rear sides are separated by an offset 220. Suitably, offset 220 is any distance that reduces the risk of shunting. For example, in some embodiments, offset 220 is at least about 1 mm.

[0030] As shown in Figure 9, in some embodiments, probe tips 900 of contact elements 902 on cell testers may facilitate contact elements 902 contacting multiple busbars 210 simultaneously. For example, probe tips 900 include standard probe tip 904, wide probe tip 906, and dual-tip probe tip 908. Probe tip 904 is a standard size and shape having a width greater than the gap between some busbars 210. Probe tip 906 has a greater width to facilitate probe tip 906 contacting multiple busbars. Probe tip 908 has a plurality of tips 910 to facilitate probe tip 908 contacting multiple busbars. In other suitable embodiments, probe tips 900 may be extended and/or replaced with larger probe-tips to facilitate probe tips 900 contacting multiple busbars. In further suitable embodiments, probe tips 900 are configured in any manner that enable the cell tester to operate as described.

[0031] In some embodiments, a PV module includes a plurality of PV cells arranged in a plurality of sections and connected to busbars. In particular, the PV cells include a nonstandard number of sections and/or busbars. The busbars are configured such that a standard cell tester can be used to test the PV cells of the PV module including a nonstandard number of sections and/or busbars. For example, in some embodiments the PV module includes PV cells arranged in 4, 6, or 8 sections with at least 1 busbar per section. The PV module is configured such that the PV cells can be tested with cell testers designed for testing standard PV cells arranged in 2 , 3, or 4 sections with 1 busbar per section. Accordingly, the PV module can include PV cells arranged in unique

configurations that increase the operating efficiency of the PV module without requiring customized equipment and increasing manufacturing costs.

[0032] The PV cells and methods described achieve superior results to some known PV cells and methods. The PV cells may be included in a PV module and separated into sections that facilitate the PV module having increased production of PV energy and operating more efficiently. Nonstandard numbers of busbars may be connected to the PV cells and configured such that standard cell testers may be used to test and sort the PV cells. Accordingly, the sorted PV cells increase the efficiency and reduce the cost for PV modules.

[0033] When introducing elements of the present invention or the embodiment ( s ) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0034] As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above

description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:

1. A method of manufacturing a photovoltaic (PV) module, the method comprising:

disposing a first set of fingers for a first PV cell segment on a first section of a silicon substrate;

disposing a second set of fingers for a second PV cell segment on a second section of the silicon substrate, the first set of fingers and the second set of fingers

separated by an isolation gap;

disposing at least one busbar on the silicon substrate proximate the isolation gap, the at least one busbar electrically coupled to at least one of the first set of fingers and the second set of fingers; and

contacting the at least one busbar with a contact member of a cell tester to test the first PV cell segment and the second PV cell segment.

2. The method of claim 1, wherein disposing at least one busbar comprises disposing a first busbar proximate the isolation gap and electrically coupled to the first set of fingers and disposing a second busbar proximate the isolation gap and electrically coupled to the second set of fingers, and contacting the at least one busbar comprises contacting the first busbar and the second busbar with a contact member of a cell tester to test the PV cells in the first section and the second section.

3. The method of claim 2, wherein the first busbar and the second busbar define a busbar gap therebetween and the contact member has a width greater than a width of the busbar gap .

4. The method of claim 3 , wherein the width of the busbar gap is less than approximately 1 mm.

5. The method of claim 2, wherein the first busbar and the second busbar define a busbar gap therebetween, and further comprising disposing at least one interconnect between the first busbar and the second busbar, the interconnect positioned to be contacted by the contact member of the cell tester.

6. The method of claim 5, wherein the contact member has a width less than a width of the busbar gap.

7. The method of claim 1, wherein the at least one busbar comprises a first busbar connected to both the first set of fingers and the second set of fingers.

8. The method of claim 7 further comprising

physically and electrically dividing the first busbar into a plurality of busbars.

■1-Θ- 9. The method of claim 1 further comprising physically separating the first PV cell segment from the second PV cell segment at the isolation gap after

contacting the at least one busbar with the contact member of the cell tester to test the first PV cell segment and the second PV cell segment. ϋ 10. A photovoltaic (PV) cell for singulation into PV cell segments, the PV cell comprising:

a first set of fingers for a first PV cell segment on a first section of a silicon substrate;

a second set of fingers for a second PV cell segment on a second section of the silicon substrate, the first set of fingers and the second set of fingers separated by a first isolation gap;

a third set of fingers for a third PV cell segment on a third section of the silicon substrate, the second set of fingers and the third set of fingers separated by a second isolation gap;

a fourth set of fingers for a fourth PV cell segment on a fourth section of the silicon substrate, the third set of fingers and the fourth set of fingers separated by a third isolation gap;

a first busbar on the silicon substrate proximate the first isolation gap, the first busbar electrically coupled to at least one of the first set of fingers and the second set of fingers; and

a second busbar on the silicon substrate proximate the third isolation gap, the second busbar electrically coupled to at least one of the third set of fingers and the fourth set of fingers.