Solar cell and solar cell panel including the same
Disclosed is a solar cell including a semiconductor substrate, a first conductive area formed on one surface of the semiconductor substrate, a second conductive area formed on a remaining surface of the semiconductor substrate, a first electrode connected to the first conductive area, and a second electrode connected to the second conductive area. The second electrode includes a pad portion and an electrode portion that include different conductive materials as main components. The pad portion includes at least one pad extending in a given direction, the wire being attached to the pad. The electrode portion and the pad are spaced apart from each other in the given direction so as to form a spacer therebetween.
1. A solar cell comprising: a semiconductor substrate; a first doped area formed on a first surface of the semiconductor substrate, the first surface being incident to radiation; a second doped area formed on a second surface of the semiconductor substrate opposite the first surface; a first electrode connected to the first doped area; and a second electrode connected to the second doped area, wherein the second electrode includes a pad portion and an electrode portion the pad portion and the electrode portion being formed of different conductive materials, wherein the pad portion includes at least one pad extending in a first direction, wherein the electrode portion includes a through hole disposed within an interior of the electrode portion so as to be surrounded by the electrode portion, the through hole being disposed over the at least one pad; wherein the width of the through hole in a second direction orthogonal to the first direction is smaller than the width of the at least one pad in the second direction so that the electrode portion and the at least one pad overlap each other in the second direction forming an overlap portion, and wherein the length of the through hole in the first direction is larger than the length of the at least one pad in the first direction forming a spacer between the electrode portion and the at least one pad in the first direction.
2. The solar cell according to claim 1 , wherein the overlap portion is located on either side of the at least one pad in the second direction, and the spacer is located on either side of the at least one pad in the first direction.
3. The solar cell according to claim 1 , wherein the overlap portion has a width in the second direction, and the width of the overlap portion in the second direction is smaller than a length of the spacer in the first direction.
4. The solar cell according to claim 1 , wherein the at least one pad includes a plurality of pads spaced apart from one another in the first direction so as to form a single row, and wherein the distance between two adjacent pads of the plurality of pads, is greater than the distance between an edge of the semiconductor substrate and a pad of the plurality of pads located closest to the edge.
5. The solar cell according to claim 1 , wherein the at least one pad has a thickness less than a thickness of the electrode portion.
6. The solar cell according to claim 1 , wherein the electrode portion and the at least one pad have a thickness difference less than a length of the spacer in the first direction.
7. The solar cell according to claim 6 , wherein the thickness difference between the electrode portion and the at least one pad ranges from 5 .mu.m to 30 .mu.m, and wherein the length of the spacer in the first direction ranges from 0.5 mm to 3 mm.
8. The solar cell according to claim 7 , wherein a ratio of the thickness difference between the electrode portion and the at least one pad to the length of the spacer ranges from 1:60 to 1:100.
9. The solar cell according to claim 1 , further comprising a passivation film disposed on the second surface of the semiconductor substrate, wherein the passivation film is formed so as to correspond to the pad portion and the spacer, and wherein the second doped area is formed on a portion of the second surface not including the pad portion and the spacer.
10. The solar cell according to claim 1 , wherein the first electrode includes a plurality of finger electrodes arranged in parallel in second direction and a plurality of bus-bar lines extending in the first direction, and wherein six to thirty-three bus-bar lines are provided on one surface of the solar cell.
11. A solar cell panel comprising: a plurality of solar cells; and a wire for interconnecting two neighboring solar cells among the solar cells, wherein each of the solar cells includes: a semiconductor substrate; a first doped area formed on a first surface of the semiconductor substrate, the first surface being incident to radiation; a second doped area formed on a second surface of the semiconductor substrate opposite the first surface; a first electrode connected to the first doped area; and a second electrode connected to the second doped area, wherein the second electrode includes a pad portion and an electrode portion the pad portion and the electrode portion being formed of different conductive materials, wherein the pad portion includes at least one pad extending in a first direction, the wire being attached to the pad, wherein the electrode portion includes a through hole disposed within an interior of the electrode portion so as to be surrounded by the electrode portion, the through hole being disposed over the at least one pad; wherein the width of the through hole in a second direction orthogonal to the first direction is smaller than the width of the at least one pad in the second direction so that the electrode portion and the at least one pad overlap each other in the second direction forming an overlap portion, and wherein the length of the through hole in the first direction is larger than the length of the at least one pad in the first direction forming a spacer between the electrode portion and the at least one pad in the first direction.
12. The solar cell panel according to claim 11 , wherein the wire has a circular or oval cross section, or takes the form of a ribbon having a rectangular cross section.
13. The solar cell panel according to claim 11 , wherein the wire connects the at least one pad, the spacer, and the electrode portion to one another.
14. The solar cell panel according to claim 11 , wherein the wire has a width less than a length of the spacer in the first direction.
15. The solar cell panel according to claim 14 , wherein a ratio of the width of the wire to the length of the spacer in the first direction ranges from 1:10 to 1:15.
16. The solar cell panel according to claim 11 , wherein, within each solar cell, the wire includes a first portion disposed on the at least one pad and a second portion disposed on the spacer, and a width of the first portion is greater than a width of the second portion, and wherein at least 95% of the at least one pad is attached to the wire.
17. The solar cell according to claim 1 , wherein six to thirty-three wires are provided on the first surface of each solar cell, and wherein each wire has a width ranging from 250 .mu.m to 500 .mu.m.