System for manufacturing a shingled solar cell module
A high efficiency configuration for a solar cell module comprises solar cells conductively bonded to each other 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. The front surface metallization patterns on the solar cells may be configured to enable single step stencil printing, which is facilitated by the overlapping configuration of the solar cells in the super cells. A solar photovoltaic system may comprise two or more such high voltage solar cell modules electrically connected in parallel with each other and to an inverter. Solar cell cleaving tools and solar cell cleaving methods apply a vacuum between bottom surfaces of a solar cell wafer and a curved supporting surface to flex the solar cell wafer against the curved supporting surface and thereby cleave the solar cell wafer along one or more previously prepared scribe lines to provide a plurality of solar cells. An advantage of these cleaving tools and cleaving methods is that they need not require physical contact with the upper surfaces of the solar cell wafer. Solar cells are manufactured with reduced carrier recombination losses at edges of the solar cell, e.g., without cleaved edges that promote carrier recombination. The solar cells may have narrow rectangular geometries and may be advantageously employed in shingled (overlapping) arrangements to form super cells.
1. A system, comprising:
a scriber to form a plurality of scribe lines in a solar cell wafer;
a printer to apply an electrically conductive bonding material to the solar cell wafer; and
a belt to, after the electrically conductive bonding material is applied to the solar cell wafer, separate the solar cell wafer along the scribe lines to provide a plurality of physically separated solar cell strips.
2. The system according to claim 1 , wherein the belt is a perforated belt and a vacuum manifold applies a vacuum to a bottom surface of the solar cell wafer.
3. The system according to claim 1 , wherein the printer is a screen, ink jet, or mask printer.
4. The system according to claim 1 , wherein the scriber is a laser scriber.
5. A system, comprising:
means for scribing a solar cell wafer to form a plurality of scribe lines in the solar cell wafer;
means for applying an electrically conductive bonding material to the solar cell wafer; and
means for separating, after the applying the electrically conductive bonding material to the solar cell wafer, the solar cell wafer along the scribe lines to provide a plurality of physically separated solar cell strips.
6. The system of claim 1 , comprising a vacuum manifold, wherein:
the belt advances the solar cell wafer along a surface of the vacuum manifold;
the vacuum manifold applies a vacuum to a bottom surface of the solar cell wafer through perforations in the belt to pull the solar cell wafer against the surface of the vacuum manifold; and
as the belt advances the solar cell wafer along the surface of the vacuum manifold the solar cell wafer is flexed by the vacuum against a curved portion of the surface of the vacuum manifold to thereby cleave the solar cell wafer along one or more of the scribe lines.
7. The system of claim 6 , wherein the vacuum applied to the bottom surface of the solar cell wafer by the vacuum manifold varies along the direction in which the solar cell wafer is advanced and is strongest in a region of the surface of the vacuum manifold in which the solar cell wafer is cleaved.
8. The system of claim 6 , wherein the perforations in the belt are arranged so that leading and trailing edges of the solar cell wafer along the direction in which the solar cell wafer is advanced must overlie at least one perforation in the belt.
9. The system of claim 6 , wherein:
the surface of the vacuum manifold comprises a flat region, a transitional curved region adjoining the flat region and having a first curvature, and a cleave region adjoining the transitional curved region and having a second curvature tighter than the first curvature; and
the belt advances the solar cell wafer along the flat region, then into and through the transitional region, then into the cleave region where the solar cell wafer is cleaved along one or more of the scribe lines.
10. The system of claim 9 , wherein the vacuum manifold applies a stronger vacuum in the cleave region than in the flat region.
11. The system of claim 9 , wherein:
the surface of the vacuum manifold comprises a post-cleave region adjoining the cleave region and having a third curvature tighter than the second curvature;
the belt advances solar cell strips cleaved from the solar cell wafer from the cleave region into the post-cleave region; and
the third curvature is sufficiently tight to prevent cleaved edges of sequentially cleaved solar cell strips from touching as the cleaved solar cell strips are advanced by the belt.
12. The system of claim 11 , wherein the vacuum manifold applies a stronger vacuum in the cleave region than in the flat region and the post-cleave region.
13. The system of claim 6 , wherein the vacuum applied by the vacuum manifold causes an asymmetric stress distribution along a scribe line that promotes nucleation and propagation of a single cleaving crack along the scribe line.
14. A system comprising:
a vacuum manifold having a surface; and
a belt that advances a solar cell wafer along the surface of the vacuum manifold;
wherein the vacuum manifold applies a vacuum to a bottom surface of the solar cell wafer to flex the solar cell wafer against a curved portion of the surface of the vacuum manifold and thereby sequentially cleave the solar cell along a plurality of scribe lines in the solar cell wafer.
15. The system of claim 14 , wherein:
the surface of the vacuum manifold comprises a flat region, a transitional curved region adjoining the flat region and having a first curvature, and a cleave region adjoining the transitional curved region and having a second curvature tighter than the first curvature; and
the belt advances the solar cell wafer along the flat region, then into and through the transitional region, then into the cleave region where the solar cell wafer is cleaved along one or more of the scribe lines.
16. The system of claim 15 , wherein the vacuum manifold applies a stronger vacuum in the cleave region than in the flat region.
17. The system of claim 15 , wherein:
the surface of the vacuum manifold comprises a post-cleave region adjoining the cleave region and having a third curvature tighter than the second curvature;
the belt advances solar cell strips cleaved from the solar cell wafer from the cleave region into the post-cleave region; and
the third curvature is sufficiently tight to prevent cleaved edges of sequentially cleaved solar cell strips from touching as the cleaved solar cell strips are advanced by the belt.
18. The system of claim 14 , wherein the vacuum applied by the vacuum manifold causes an asymmetric stress distribution along a scribe line that promotes nucleation and propagation of a single cleaving crack along the scribe line.
19. The system of claim 14 , comprising a laser scriber that forms the plurality of scribe lines in the solar cell wafer.
20. The system of claim 14 , comprising a printer that applies an electrically conductive bonding material to the solar cell wafer before the solar cell wafer is cleaved.