Shingled solar cell module
A high efficiency configuration for a solar cell module comprises solar cells arranged in a shingled manner to form super cells, which may be arranged to efficiently use the area of the solar module, reduce series resistance, and increase module efficiency.
1. A method comprising:
obtaining or providing a silicon wafer comprising a front surface metallization pattern including a first bus bar or row of contact pads arranged parallel to and adjacent a first outside edge of the wafer and a second bus bar or row of contact pads arranged parallel to and adjacent a second outside edge of the wafer opposite from and parallel to the first edge of the wafer, the first bus bar or row of contact pads and second bus bar or row of contact pads disposed on portions of the silicon wafer having the same electrical polarity;
cleaving the silicon wafer along one or more scribe lines parallel to the first and second outside edges of the wafer to form a plurality of physically discrete separate rectangular solar cells each of which comprises two oppositely positioned parallel short outside edges and two oppositely positioned long outside edges, with the first bus bar or row of contact pads arranged parallel to and adjacent to a long outside edge of a first one of the rectangular solar cells and the second bus bar or row of contact pads arranged parallel to and adjacent to a long outside edge of a second one of the rectangular solar cells; and
arranging the rectangular solar cells in line with long sides of adjacent rectangular solar cells overlapping and conductively bonded to each other to electrically connect the solar cells in series to form a super cell;
wherein the first bus bar or row of contact pads on the first one of the rectangular solar cells is overlapped by and conductively bonded to a bottom surface of an adjacent rectangular solar cell in the super cell.
2. The method of claim 1 , wherein the second bus bar or row of contact pads on the second one of the rectangular solar cells is overlapped by and conductively bonded to a bottom surface of an adjacent rectangular solar cell in the super cell.
3. The method of claim 1 , wherein the silicon wafer is a square or pseudo square silicon wafer.
4. The method of claim 3 , wherein the silicon wafer comprises sides of about 125 mm in length or about 156 mm in length.
5. The method of claim 3 , wherein the ratio of length to width of each rectangular solar cell is between about 2:1 and about 20:1.
6. The method of claim 1 , wherein the silicon wafer is a crystalline silicon wafer.
7. The method of claim 1 , wherein the first bus bar or row of contact pads and the second bus bar or row of contact pads are located in edge regions of the silicon wafer that convert light to electricity less efficiently than central regions of the silicon wafer.
8. The method of claim 1 , wherein the front surface metallization pattern comprises a first plurality of parallel fingers electrically connected to the first bus bar or row of contact pads and extending inward from the first outside edge of the wafer and a second plurality of parallel fingers electrically connected to the second bus bar or row of contact pads and extending inward from the second outside edge of the wafer.
9. The method of claim 1 , wherein the front surface metallization pattern comprises at least a third bus bar or row of contact pads oriented parallel to and located between the first bus bar or row of contact pads and the second bus bar or row of contact pad and a third plurality of parallel fingers oriented perpendicular to and electrically connected to the third bus bar or row of contact pads, and the third bus bar or row of contact pads is arranged parallel to and adjacent a long outside edge of a third one of the rectangular solar cells after the silicon wafer is separated to form the plurality of rectangular solar cells.
10. The method of claim 1 , comprising applying a conductive adhesive to the first bus bar or row of contact pads by which to conductively bond the first rectangular solar cell to an adjacent solar cell.
11. The method of claim 10 , wherein the metallization pattern comprises a barrier configured to confine spreading of the conductive adhesive.
12. The method of claim 10 , comprising applying the conductive adhesive by screen printing.
13. The method of claim 10 , comprising applying the conductive adhesive by ink jet printing.
14. The method of claim 10 , wherein the conductive adhesive is applied before formation of the scribe lines in the silicon wafer.
15. The method of claim 1 , wherein separating the silicon wafer along the one or more scribe lines comprises applying a vacuum between a bottom surface of the silicon wafer and a curved supporting surface to flex the silicon wafer against the curved supporting surface and thereby cleave the silicon wafer along the one or more scribe lines.
16. The method of claim 1 wherein:
the silicon wafer is a pseudo square silicon wafer comprising chamfered corners and after separation of the silicon wafer to form the plurality of rectangular solar cells one or more of the rectangular solar cells comprises one or more of the chamfered corners; and
the spacing between scribe lines is selected to compensate for the chamfered corners by making the width perpendicular to the long axis of the rectangular solar cells that comprise chamfered corners greater than the width perpendicular to the long axis of the rectangular solar cells that lack chamfered corners, so that each of the plurality of rectangular solar cells in the super cell has a front surface of substantially the same area exposed to light in operation of the super cell.
17. The method of claim 1 , comprising arranging the super cell in a layered structure between a transparent front sheet and a back sheet and laminating the layered structure.
18. The method of claim 17 , wherein laminating the layered structure completes curing of a conductive adhesive disposed between the adjacent rectangular solar cells in the super cell to conductively bond the adjacent rectangular solar cells to each other.
19. The method of claim 17 , wherein the super cell is arranged in the layered structure in one of two or more parallel rows of super cells, and the back sheet is a white sheet comprising parallel darkened stripes having locations and widths corresponding to locations and widths of gaps between the two or more rows of super cells such that white portions of the back sheet are not visible through gaps between the rows of super cells in the assembled module.
20. The method of claim 17 , wherein the front sheet and the back sheet are glass sheets and the super cell is encapsulated in a thermoplastic olefin layer sandwiched between the glass sheets.
21. The method of claim 1 , comprising arranging the super cell in a first module comprising a junction box in mating arrangement with a second junction box of a second solar module.