Flexible solar array and method for fabricating the same
A flexible solar cell assembly and methods for its manufacture are described. The flexible solar cell assembly comprises: solar cells comprising opposing top and back surfaces of different polarities, a contact at the top surface and a contact at the back surface; a flexible substrate; and conductive traces having end portions bonded to the top and bottom contacts of different solar cells so as to interconnect them in electrical series.
1. A method of producing a solar cell assembly, comprising:
providing a flexible substrate;
providing a plurality of conductive traces on the flexible substrate, the plurality of conductive traces including a first conductive trace portion and a second conductive trace portion, each of the conductive traces being at least partly adhered to the flexible substrate and each of the conductive traces comprising a first end portion and a second end portion;
providing a plurality of solar cells including a first solar cell and a second solar cell, each solar cell comprising a top surface with a top contact of a first polarity and a back surface with a back contact of a second polarity; and
bonding the back contact of the first solar cell to the first end portion of the first conductive trace portion, bonding the back contact of the second solar cell to the first end portion of the second conductive trace portion, and bonding the second end portion of the first conductive trace portion to the top contact of the second solar cell for connecting the first solar cell and the second solar cell in electrical series,
wherein the conductive traces further comprise a third portion connecting the first end portion and second end portion, wherein the plurality of solar cells are arranged with their back contacts in a first plane and their top contacts in a second plane, and wherein the third portion of the first conductive trace portion is bent so as to pass through the first plane and the second plane,
wherein the step of bonding the second end portion of the first conductive trace portion to the top contact of the second solar cell comprises displacing the second end portion of the first conductive trace portion upwards from an original position.
2. The method according to claim 1 , wherein the step of providing a plurality of conductive traces on the flexible substrate comprises:
providing a conductive layer on the flexible substrate; and
removing part of the conductive layer so as to produce the plurality of conductive traces, each one of the plurality of conductive traces being electrically separate from the other conductive traces of the plurality of conductive traces.
3. The method according to claim 1 , further comprising the step of providing through holes in the flexible substrate in correspondence with the second end portion of said conductive traces.
4. The method according to claim 1 , wherein the step of displacing the second end portion of the first conductive trace portion upwards comprises bending a third portion of the first conductive trace portion, wherein the third portion of the first conductive trace portion electrically interconnects the first end portion and the second end portion of the first conductive trace portion.
5. The method according to claim 1 , wherein the step of displacing the second end portion of the first conductive trace portion upwards is carried out prior to bonding the back contact of the second solar cell to the first end portion of the second conductive trace portion.
6. The method according to claim 1 , wherein the step of displacing the second end portion of the first conductive trace portion upwards comprises locally deforming the flexible substrate.
7. The method according to claim 1 , comprising the step of providing an insulating top layer after providing the plurality of conductive traces on the flexible substrate, the insulating top layer covering the plurality of conductive traces.
8. The method according to claim 7 , comprising the step of removing part of the top layer providing recesses, one recess providing access to the second end portion of the first conductive trace portion and to the first end portion of the second conductive trace portion.
9. The method according to claim 8 , comprising the step of placing solar cells in the recesses.
10. A solar cell assembly, comprising:
a plurality of solar cells including a first solar cell and a second solar cell, each solar cell comprising a top surface with a top contact of a first polarity and a back surface with a back contact of a second polarity;
a flexible substrate;
a plurality of conductive traces including a first conductive trace portion and a second conductive trace portion, each of the conductive traces being at least partly adhered to the flexible substrate;
wherein the first solar cell is arranged on the flexible substrate with its back contact bonded to a first end portion of the first conductive trace portion, and wherein the second solar cell is arranged on the flexible substrate with its back contact bonded to a first end portion of the second conductive trace portion;
wherein the first conductive trace portion comprises a second end portion bonded to the top contact of the second solar cell for connecting the first solar cell and the second solar cell in electrical series; and
wherein the conductive traces further comprise a third portion connecting the first end portion and second end portion, wherein the plurality of solar cells are arranged with their back contacts in a first plane and their top contacts in a second plane, and wherein the third portion of the first conductive trace portion is bent so as to pass through the first plane and the second plane,
wherein the first end portion of the conductive traces is adhered to the flexible substrate and wherein the second end portion of the conductive traces is not adhered to the flexible substrate.
11. The solar cell assembly according to claim 10 , wherein the third portion is at least partly adhered to the flexible substrate, so that the flexible substrate is bent in accordance with the third portion.
12. The solar cell assembly according to claim 10 , wherein the flexible substrate comprises a through hole in correspondence with the second end portion.
13. The solar cell assembly according to claim 10 , further comprising a flexible top layer on top of the flexible substrate, the solar cells being arranged in recesses in the flexible top layer.
14. The solar cell assembly according to claim 10 , wherein the third portion comprises at least one curved section.
15. The solar cell assembly according to claim 10 , wherein the conductive trace portions are metal traces having a thickness in the range of from 1 μm and up to 50 μm.
16. The solar cell assembly according to claim 10 , wherein the flexible substrate comprises a polyimide film layer.
17. The solar cell assembly according to claim 10 , wherein the solar cells are III-V compound semiconductor solar cells.